Highly Efficient Visible-Light-Driven [2+2] Cycloaddition of Maleimides to Alkenes and Alkynes for the Synthesis of 3-Aza­bicyclo[3.2.0]heptane-Fused Scaffolds

Abstract

A highly efficient [2+2] cycloaddition between maleimides and unsaturated moieties, utilizing a visible-light triplet sensitization mode, has been developed for the direct synthesis of multifunctional 3-azabicyclo[3.2.0]heptane derivatives. This reaction relies on selective activation of the maleimide functionality upon energy transfer from a new photosensitizer that outperforms diverse well-established photosensitizers. The strategy developed herein overcomes previous obstacles such as limited substrate scope and undesired reaction pathways under harsh UV irradiation.

Recently, bicyclic pyrrolidines are gradually being introduced as conformationally restricted analogues of common pyrrolidines and piperidines, resulting in numerous bioactive compounds currently under clinical investigation.[1] Typically, both the antischizophrenia agent Belaperidone and the antibacterial drug Ecenofloxacin are derived from isomeric 3-azabicyclo[3.2.0]heptane scaffolds (Scheme [1a]). Additionally, 3-azabicyclo[3.2.0]heptanes also serve as high-value intermediates of multifunctional cyclobutanes, which have been a focus in recent studies on molecular diversity,[2] and have been proposed as mechanophores,[3] modulators of glycopeptide conformation,[4] or selective ligands for therapeutically relevant biological receptors.[5]

However, presumably due to a lack of practical synthetic methods from easily available starting materials, 3-azabicyclo[3.2.0]heptanes remain somewhat in the shadow compared to other popular cores such as 3-azabicyclo­[3.1.0]hexanes and 3-azabicyclo[3.3.0]octanes. The main approaches to the construction of 3-azabicyclo­[3.2.0]heptanes rely on cyclization reactions, such as intramolecular [2+2] cycloadditions of N-substituted bis-allylamines via metal catalysis[6] or photocatalysis[7] (Scheme [1b]), intermolecular photocycloadditions with ultraviolet-mediated dihydropyrrole analogues (Scheme [1c]),[1b] [8] and three-component cascade reactions of α,β-unsaturated aldehydes, N-benzylaminocrotonate, and secondary amines (Scheme [1d]).[9]

Despite the substantial developments in established cyclization reactions, these approaches might have to some extent inhibited the scope of substrates by the use of prefunctional starting materials or high-energy UV light. Considering the scarcity of visible-light-driven intermolecular [2+2] cycloadditions to synthesize 3-azabicyclo[3.2.0]heptanes via an energy-transfer (EnT) pathway, a systematic study of it relying on a visible-light triplet-sensitization mode would be highly desirable. Despite the continuing efforts in exploring visible-light-driven EnT protocols with maleimide compounds,[10] little attention has been paid to highly efficient synthesis of multifunctional 3‑azabicyclo­[3.2.0]heptane-fused scaffolds. Therefore, on the basis of our previous explorations,[11] we focused on the synthesis of 3‑azabicyclo[3.2.0]heptane cores from the reaction between sensitized maleimides and multifunctional unsaturated moieties (Scheme [1e]).

Table 1 Optimization of the [2+2] Photocycloaddition Conditions^a

Entry	Photosensitizer	Yield (%)b	d.r.c
1d	Ru(ppy)3Cl2	0	–
2d	Ir(ppy)3	0	–
3	Ir[dF(CF3)ppy]2(dtbbpy)PF6	66	1.8:1
4	thioxanthone	8	2.4:1
5	Ir(dFppy)2(phpzpy)PF6	94	2.1:1
6	Ir[dF(CF3)ppy]2(phpzpy)PF6	96	1.9:1
7	none	0	–
8e	Ir[dF(CF3)ppy]2(phpzpy)PF6	0	–
9e,f	Ir[dF(CF3)ppy]2(phpzpy)PF6	0	–

^a Reaction conditions: 1a (0.2 mmol), 2a (0.24 mmol), photosensitizer (0.5 mol%), MeCN (4 mL), irradiation with 405 nm LEDs, r.t., under argon, 8 h.

^b Yield of isolated product after column chromatography.

^c The d.r. values (major/minor) were determined by ¹H NMR spectra of the crude reaction mixtures.

^d Irradiated with 458 nm LEDs or 405 nm LEDs.

^e In the dark.

^f Reaction performed at 80 °C.

Our experiments started by using phenylmaleimide 1a and acrylamide 2a as model substrates (Table [1]). To begin with, Ru(bpy)₃Cl₂ or Ir(ppy)₃ were examined as photosensitizers, but failed to catalyze the required cycloaddition (entries 1 and 2). Established photosensitizers such as the transition-metal-based [Ir(dF(CF₃)ppy)₂(dtbbpy)]PF₆ resulted in moderate yields of the desired products 3a and 3a′ (entry 3), while the reaction was less efficient with the organic sensitizer thioxanthone (entry 4). Compared with our previous activation protocol of the maleimide compound,[11] the iridium complexes Ir[dFppy]₂(phpzpy)PF₆ and Ir[dF(CF₃)ppy]₂(phpzpy)PF₆ were also found to be highly efficient in this [2+2] photocycloaddition reaction (entries 5 and 6). Control experiments confirmed that both photosensitizer and visible light are indispensable in this system (entries 7–9), and ruled out alternative mechanisms involving either direct excitation of substrates or a purely thermal process in which the Ir(Ⅲ) complexes served as Lewis acids.

Under the optimized reaction conditions, the substrate scope of the [2+2]-cycloaddition protocol revealed broad tolerability (Scheme [2]). Maleimides with various substitution patterns were tolerated, producing the desired products 3a–j, including sterically hindered skeletons 3h–j. Electron-poor alkenes were good coupling partners in this transformation, with the desired products forming from acrylamides (3k,l), pyrimidone (3m), acrylates (3n,o), and an enone (3p). At the same time, a variety of electron-rich olefins also performed well, leading to the desired products, such as from styrene (3q,r), vinylnaphthalene (3s), dihydronaphthalene (3t), indene (3u), and heteroaryl-substituted vinylthiophene (3v). In addition, we obtained dearomative [2+2]-cycloadducts with benzothiophene and benzofuran, thereby providing a concise access to benzofuro- or benzothienocyclobutapyrrole skeletons 3w,x. Further functional groups were screened for tolerance, giving the corresponding 3-azabicyclo[3.2.0]heptanes in excellent yields, including directly attached N (3y), S (3z), O (3aa–ac), and Si atoms (3ad).

Furthermore, halides (3ag), enols (3ah), aliphatic alkenes (3ai–al), oleic acid (3am), and alkynes (3an–ap) were also suitable for this cyclization, resulting in the desired products. It should be noted that maleimide could continue reacting with the cyclobutene products 3ao and 3ap to form the tetracyclic skeletons 3aq and 3ar, respectively. The superiority of the method was further demonstrated by highly efficient synthesis of functional 3-azabicyclo[3.2.0]heptane cores 3as–au, which had been previously prepared less efficiently by benzophenone-sensitized [2+2] cycloaddition using UV irradiation.[8i] Besides, we observed almost quantitative yields of dimers 3av–ax by solely using maleimides, and also accomplished intramolecular [2+2] cycloaddition (3ay). Surprisingly, when using 1,3-diketones as the coupling partners, we did not detect the desired products, but, instead, the De Mayo photocycloadducts 3az and 3aaa. To the best of our knowledge, so far only the König group has reported a sensitized version of the De Mayo photocycloaddition that allowed the use of visible light.[12] In general, our methodology could be applied to numerous unsaturated moieties, and features high yields, broad substrate scope (53 examples), and excellent functional group tolerance. According to the two X-ray analyses (major isomer 3ai, minor isomer 3w′) and the two ¹H NMR NOE data sets (major isomers 3b and 3ag), the major isomers have been demonstrated to have the exo-type configuration, also for the other products.

Although we propose that the reaction mechanism proceeds via a visible-light-mediated EnT pathway, we considered the possibility of a photoredox mechanism for this cycloaddition. Firstly, electrochemical studies indicated that the redox potentials of phenylmaleimide 1a lie well outside the potentials of photoexcited Ir[dF(CF₃)ppy]₂(phpzpy)PF₆*. (All potentials in V vs SCE; see SI, Table S4 for details). The electron-poor acrylamide 2a, a good coupling partner in our previous report,[13] has a reduction potential of −2.36 V, much lower than that of the excited-state Ir[dF(CF₃)ppy]₂(phpzpy)PF₆*. Obviously, photoinduced electron transfer between these substrates and photosensitizer is not thermodynamically feasible. Besides, the excited state Ir(ppy)₃* (–1.73 V)[14] has stronger reducibility than Ir[dF(CF₃)ppy]₂(phpzpy)PF₆* (–0.95 V). For electron-deficient maleimides and xanthates, Ir(ppy)₃ should be a more powerful photocatalyst if the [2+2] cycloaddition could proceed well through electron transfer. But no reaction took place when Ir(ppy)₃ was employed in this system (Table [1], entry 2). Therefore, energy transfer from the excited state Ir[dF(CF₃)ppy]₂(phpzpy)PF₆* to the substrates appears to be responsible for the cycloaddition.

Stern−Volmer quenching studies were conducted to measure the rate of EnT from excited-state photosensitizer to the substrates. These studies indicated that acrylamide 2a is a modest quencher of Ir[dF(CF₃)ppy]₂(phpzpy)PF₆*, because the calculated Stern−Volmer constant K _SV is substantially lower than that of 1a (360 M^–1 vs 2880 M^–1) (Figure [1]A). It is known that aromatic compounds can serve as the quenchers for the excited photosensitizer in the related photoinduced [2+2] cycloaddition reactions.[15] However, aromatic partners thianaphthene 2n and benzofuran 2o are modest quenchers of Ir[dF(CF₃)ppy]₂(phpzpy)PF₆* compared with 1a (Figure S3 for details). To further test the feasibility of the EnT process, we recorded the low-temperature phosphorescence spectra of the photosensitizers and 1a, which are in good agreement (Figure [1]B). A Dexter-type mechanism is completely feasible by triplet–triplet EnT from Ir[dF(CF₃)ppy]₂(phpzpy)PF₆* to 1a.

Therefore, a proposed reaction mechanism for the [2+2]-cycloaddition reaction is outlined in Scheme [3]. Firstly, we postulate that a triplet–triplet EnT process takes place from excited-state photosensitizer to maleimide 1. Next, the triplet-state maleimide 1 reacts with alkene/alkyne 2 to form a triplet-state 1,4-biradical intermediate, which subsequently undergoes intersystem crossing (ISC) and recombination to yield the desired product 3.

In summary, we reported visible-light-mediated intermolecular [2+2] cycloadditions that result in the direct formation of multifunctional 3-azabicyclo[3.2.0]heptane skeletons by selective activation of the maleimides with various alkene/alkyne moieties. Mechanistic investigations based on electrochemical analyses and spectroscopic studies suggested an efficient EnT mode of photocatalysis. Additionally, this strategy further demonstrated that our photosensitizer outperforms diverse well-established photosensitizers; this may provide a new platform for the synthesis of 3-azabicyclo[3.2.0]heptanes.

All reagents were purchased from commercial suppliers and used without additional purification. Except in the case of aqueous reactions, all reaction glassware was flame- or oven-dried prior to use. Reactions were monitored by TLC under 254 nm UV light, and the products were obtained by column chromatography on silica gel (200–300 mesh) with the indicated eluent. Common solvents for chromatography (pentane, EtOAc) were distilled prior to use. ¹H NMR spectra were internally referenced to TMS (δ = 0.00) or the residual protio-solvent peak in CDCl₃ (δ = 7.26), acetone-d ₆ (δ = 2.05), CD₃CN (δ = 1.94), or DMSO-d ₆ (δ = 2.50). ¹³C{¹H} NMR spectra were internally referenced to CDCl₃ (δ = 77.16), acetone-d ₆ (δ = 206.26), CD₃CN (δ = 118.26) or DMSO-d ₆ (δ = 39.52). ¹⁹F{¹H} NMR spectra were absolute-referenced to the corresponding ¹H NMR spectra using the method described by Harris. ¹H, ¹³C, and ¹⁹F NMR spectra were recorded at 303 K on a Bruker AM-400 or AM-600 spectrometer. ¹H NMR NOE data were obtained on a Bruker AM-600 spectrometer. Mass spectra were obtained with esquire6000, TRACE DSQ, and ORBITRAP ELITE spectrometers. High-resolution mass spectra were recorded on a Bruker Daltonics APEXII 47e Specifications spectrometer. Infrared spectra were recorded on a Bruker TENSOR27 instrument. Melting points were measured on a WRX^® X-4B apparatus.

3-Azabicyclo[3.2.0]heptanes 3; General Procedure

Maleimide 1 (0.2 mmol, 1.0 equiv), alkene 2 (0.24 mmol, 1.2 equiv), and photocatalyst [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%) were added to an oven-dried 10 mL Schlenk tube equipped with a magnetic stir bar. The combined materials were dissolved in deoxygenated MeCN (4 mL) under an argon atmosphere. The reaction mixture was irradiated by 405 nm LEDs for 8 h at r.t. (temperature maintained with cooling water). After full conversion, as indicated by TLC, the solution was concentrated under reduced pressure. The residue was purified by flash column chromatography (silica gel, pentane/EtOAc) to give the target product.

(1S,5R,6S)-N-Methyl-2,4-dioxo-N,3-diphenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3a)

According to the general procedure, 3a was prepared from 1a (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 42.8 mg (64%); white solid; R_f = 0.35 (pentane/EtOAc, 3:1); mp 135–137 °C.

IR (thin film): 3468, 3013, 1711, 1652, 1496, 1376, 1172, 1124, 757, 698, 563 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.46–7.41 (m, 4 H), 7.38–7.35 (m, 2 H), 7.21 (d, J = 7.5 Hz, 2 H), 7.15 (d, J = 7.4 Hz, 2 H), 3.88 (dd, J = 6.8, 4.4 Hz, 1 H), 3.48–3.42 (m, 1 H), 3.33 (s, 3 H), 3.24–3.19 (m, 1 H), 2.86 (ddd, J = 12.4, 10.9, 6.6 Hz, 1 H), 2.19 (ddd, J = 13.1, 9.3, 4.1 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.97, 176.84, 171.51, 142.60, 131.78, 129.90, 128.98, 128.46, 128.16, 127.05, 126.15, 41.15, 38.32, 37.67, 35.84, 27.58.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₉N₂O₃: 335.1390; found: 335.1389.

(1S,5R,6R)-N-Methyl-2,4-dioxo-N,3-diphenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3a′)

According to the general procedure, 3a′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 21.4 mg (32%); white solid; R_f = 0.3 (pentane/EtOAc, 3:1); mp 119–121 °C.

IR (thin film): 3468, 3014, 1711, 1652, 1497, 1376, 1172, 1124, 757, 698, 639, 563 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.37 (m, 10 H), 3.55–3.48 (m, 1 H), 3.29–3.22 (m, 5 H), 2.91–2.85 (m, 1 H), 2.63–2.55 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.96, 176.42, 170.05, 143.50, 132.36, 129.84, 129.19, 128.68, 128.19, 127.10, 126.95, 41.46, 37.54, 36.86, 35.27, 25.53.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₉N₂O₃: 335.1390; found: 335.1390.

(1S,5R,6S)-3-Benzyl-N-methyl-2,4-dioxo-N-phenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3b)

According to the general procedure, 3b was prepared from 1b (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 45.9 mg (66%); white solid; R_f = 0.36 (pentane/EtOAc, 3:1); mp 166–168 °C.

IR (thin film): 3397, 1702, 1652, 1389, 1165, 1124, 757, 701, 618, 561 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.43–7.34 (m, 3 H), 7.25–7.24 (m, 6 H), 7.13–7.11 (m, 2 H), 4.58 (dd, J = 17.6, 14 Hz, 2 H), 3.70 (dd, J = 6.8, 4.6 Hz, 1 H), 3.34–3.24 (m, 4 H), 3.06–3.00 (m, 1 H), 2.77 (ddd, J = 12.5, 10.8, 6.8 Hz, 1 H), 2.03–1.99 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.72, 177.55, 171.61, 142.58, 135.63, 129.90, 128.60, 128.46, 128.18, 127.86, 127.11, 42.41, 41.08, 38.11, 37.71, 35.75, 27.28.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₁H₂₁N₂O₃: 349.1547; found: 349.1545.

(1S,5R,6R)-3-Benzyl-N-methyl-2,4-dioxo-N-phenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3b′)

According to the general procedure, 3b′ was prepared from 1b (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 18.1 mg (26%); white solid; R_f = 0.25 (pentane/EtOAc, 3:1); mp 171–173 °C.

IR (thin film): 3398, 1702, 1652, 1390, 1165, 1124, 757, 701, 618, 561 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.25 (m, 10 H), 4.76 (dd, J = 44.0, 14.2 Hz, 2 H), 3.43–3.34 (m, 1 H), 3.26 (s, 3 H), 3.11–3.05 (m, 2 H), 2.79–2.73 (m, 1 H), 2.52–2.44 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.36, 176.79, 169.82, 143.46, 135.92, 129.82, 128.75, 128.55, 128.21, 127.76, 127.16, 42.84, 41.81, 37.49, 36.48, 25.20.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₁H₂₁N₂O₃: 349.1547; found: 349.1546.

(1S,5R,6S)-3-Cyclohexyl-N-methyl-2,4-dioxo-N-phenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3c)

According to the general procedure, 3c was prepared from 1c (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 46.2 mg (68%); white solid; R_f = 0.55 (pentane/EtOAc, 3:1); mp 43–44 °C.

IR (thin film): 2930, 1698, 1655, 1594, 1496, 1369, 1184, 1124, 773, 701, 561 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.43–7.39 (m, 2 H), 7.35 (t, J = 7.3 Hz, 1 H), 7.12 (d, J = 7.3 Hz, 2 H), 3.87 (tt, J = 12.4, 3.8 Hz, 1 H), 3.59 (dd, J = 6.8, 4.3 Hz, 1 H), 3.31 (s, 3 H), 3.18 (ddd, J = 10.7, 6.7, 4.4 Hz, 1 H), 3.01–2.98 (m, 1 H), 2.78–2.73 (m, 1 H), 2.10–1.96 (m, 3 H), 1.87–1.77 (m, 2 H), 1.64–1.61 (m, 1 H), 1.50–1.48 (m, 2 H), 1.31–1.19 (m, 3 H).

¹³C NMR (101 MHz, CDCl₃): δ = 179.30 (s), 178.12 (s), 171.82 (s), 142.73 (s), 129.87 (s), 128.12 (s), 127.12 (s), 60.33 (s), 51.63 (s), 40.84 (s), 38.34 (s), 37.70 (s), 35.44 (s), 28.50 (d, J = 9.9 Hz), 27.56 (s), 25.74 (s), 24.92 (s), 14.16 (s).

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₂₅N₂O₃: 341.1860; found: 341.1857.

(1S,5R,6R)-3-Cyclohexyl-N-methyl-2,4-dioxo-N-phenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3c′)

According to the general procedure, 3c′ was prepared from 1c (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 11.6 mg (17%); white solid; R_f = 0.55 (pentane/EtOAc, 3:1); mp 39–41 °C.

IR (thin film): 2931, 1698, 1655, 1595, 1496, 1370, 1184, 1124, 773, 701, 623, 561 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.46–7.38 (m, 5 H), 4.02 (ddd, J = 12.3, 8.6, 3.8 Hz, 1 H), 3.42–3.34 (m, 1 H), 3.25 (s, 3 H), 3.03–2.99 (m, 2 H), 2.71–2.67 (m, 1 H), 2.50–2.41 (m, 1 H), 2.24–2.15 (m, 2 H), 1.87–1.72 (m, 4 H), 1.36–1.23 (m, 4 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.29, 177.51, 169.86, 143.65, 129.89, 128.26, 127.25, 52.07, 41.27, 41.20, 37.62, 36.66, 34.65, 28.63, 26.02, 25.82, 25.33, 25.26.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₂₅N₂O₃: 341.1860; found: 341.1858.

(1S,5R,6S)-N,3-Dimethyl-2,4-dioxo-N-phenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3d)

According to the general procedure, 3d was prepared from 1d (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 36.7 mg (68%); white solid; R_f = 0.45 (pentane/EtOAc, 3:1); mp 95–98 °C.

IR (thin film): 2930, 1701, 1657, 1499, 1396, 1199, 1120, 781, 710 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.43–7.40 (m, 2 H), 7.37–7.33 m, 1 H), 7.12 (d, J = 7.4 Hz, 2 H), 3.73 (dd, J = 6.8, 4.4 Hz, 1 H), 3.31–3.25 (m, 4 H), 3.08–3.02 (m, 1 H), 2.94 (s, 3 H), 2.79–2.71 (m, 1 H), 2.06–2.00 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.17, 178.08, 171.79, 142.75, 129.95, 128.19, 127.14, 41.02, 38.14, 37.74, 35.79, 27.45, 25.06.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₇N₂O₃: 273.1234; found: 273.1232.

(1S,5R,6S)-3-Butyl-N-methyl-2,4-dioxo-N-phenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3e)

According to the general procedure, 3e was prepared from 1e (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 35 mg (56%); white solid; R_f = 0.55 (pentane/EtOAc, 3:1); mp 52–55 °C.

IR (thin film): 2929, 1700, 1655, 1595, 1496, 1393, 1125, 775, 702, 562 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.44–7.40 (m, 2 H), 7.37–7.34 (m, 1 H), 7.14–7.12 (m, 2 H), 3.69 (dd, J = 6.8, 4.5 Hz, 1 H), 3.44–3.41 (m, 2 H), 3.34–3.18 (m, 4 H), 3.06–3.01 (m, 1 H), 2.81–2.74 (m, 1 H), 2.01 (ddd, J = 12.8, 9.1, 4.0 Hz, 1 H), 1.50–1.43 (m, 2 H), 1.27–1.17 (m, 2 H), 0.87 (t, J = 7.3 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.10, 177.93, 171.72, 142.71, 129.87, 128.12, 127.12, 41.08, 38.60, 38.27, 37.66, 35.68, 29.55, 27.37, 19.89, 13.51.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₂₃N₂O₃: 315.1703; found: 315.1702.

(1S,5S,6S)-N-Methyl-2,4-dioxo-N-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxamide (3f)

According to the general procedure, 3f was prepared from 1f (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 28.3 mg (55%); white solid; R_f = 0.35 (pentane/EtOAc, 1:1); mp 173–176 °C.

IR (thin film): 3207, 2988, 1717, 1649, 1593, 1496, 1393, 1292, 1178, 1126, 914, 774, 702, 624 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 8.35 (br, 1 H), 7.45–7.34 (m, 3 H), 7.14–7.12 (m, 2 H), 3.74 (dd, J = 6.6, 4.6 Hz, 1 H), 3.34–3.25 (m, 4 H), 3.20–3.15 (m 1 H), 2.77 (ddd, J = 12.5, 10.9, 6.7 Hz, 1 H), 2.16–2.09 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.36, 178.24, 171.58, 142.51, 129.96, 128.29, 127.08, 42.32, 38.15, 37.76, 37.12, 27.34.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₄H₁₅N₂O₃: 259.1077; found: 259.1076.

(1S,5R,6S)-3-(Cyclopropylmethyl)-N-methyl-2,4-dioxo-N-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxamide (3g)

According to the general procedure, 3g was prepared from 1g (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 41.9 mg (67%); white solid; R_f = 0.42 (pentane/EtOAc, 2:1); mp 93–95 °C.

IR (thin film): 2939, 1701, 1655, 1595, 1496, 1428, 1381, 1326, 1215, 1147, 775, 733, 702, 562 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.42–7.40 (m, 2 H), 7.38–7.33 (m, 1 H), 7.13–7.11 (m, 2 H), 3.68 (dd, J = 6.8, 4.5 Hz, 1 H), 3.30–3.23 (m, 6 H), 3.05–3.01 (m, 1 H), 2.77 (ddd, J = 12.5, 10.8, 6.8 Hz, 1 H), 2.00 (ddd, J = 13.2, 9.4, 4.2 Hz, 1 H), 1.06–1.02 (m, 1 H), 0.38–0.34 (m, 2 H), 0.24–0.21 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.23, 178.04, 171.79, 142.78, 129.92, 128.16, 127.19, 43.36, 41.26, 38.31, 37.73, 35.81, 27.40, 9.69, 3.54, 3.49.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₂₁N₂O₃: 313.1547; found: 313.1546.

5-Ethyl-N,1-dimethyl-2,4-dioxo-N-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxamide (3h, 3h′)

According to the general procedure, 3h and 3h′ were prepared from 1h (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 51.8 mg (63%); mixture of exo and endo diastereomers (2:1); white solid; R_f = 0.33 (pentane/EtOAc, 1:1); mp 115–128 °C.

IR (thin film): 3209, 2933, 1706, 1651, 1498, 1365, 1188, 1124, 775, 703, 565 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 11.50 (br s, 1 H), 11.11 (br, 2 H, 1 × 2 H), 7.41–7.37 (m, 6 H, 2 × 2 H, 2 × 1 H), 7.33–7.30 (m, 2 H, 1 × 2 H), 7.26–7.21 (m, 7 H, 2 × 2 H, 3 × 1 H), 3.82 (t, J = 8.2 Hz, 1 H), 3.25 (s, 3 H, 3 × 1 H), 3.19–3.12 (m, 8 H, 4 × 2 H), 2.72 (dd, J = 12.0, 8.2 Hz, 1 H), 2.59 (dd, J = 11.9, 8.5 Hz, 2 H, 1 × 2 H), 2.10–2.03 (m, 2 H, 2 × 1 H), 1.93–1.88 (m, 4 H, 2 × 2 H), 1.74–1.65 (m, 5 H, 1 × 2 H, 3 × 1 H), 1.60–1.52 (m, 2 × 2 H, 1 × 1 H), 1.42–1.29 (m, 8 H, 3 × 2 H, 2 × 1 H), 0.99–0.98 (m, 1 H), 0.87–0.83 (m, 2 H).

¹³C NMR (100 MHz, DMSO-d ₆): δ = 182.92, 182.72, 181.34, 179.93, 169.12, 168.76, 143.97, 142.41, 129.53, 128.75, 127.55, 127.40, 126.13, 126.02, 49.16, 43.35, 41.14, 40.85, 37.69, 37.46, 27.19, 26.93, 26.33, 21.81, 21.32, 19.94, 19.71, 19.52.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₂₁N₂O₃: 313.1547; found: 313.1546.

(1S,5R,6S)-N,1,5-Trimethyl-2,4-dioxo-N,3-diphenyl-3-azabicyclo­[3.2.0]heptane-6-carboxamide (3i)

According to the general procedure, 3i was prepared from 1i (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 63.1 mg (87%); white solid; R_f = 0.68 (pentane/EtOAc, 3:1); mp 132–134 °C.

IR (thin film): 2934, 1711, 1651, 1595, 1496, 1385, 1148, 753, 700, 556 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.46–7.32 (m, 6 H), 7.21 (d, J = 7.3 Hz, 2 H), 7.08–7.05 (m, 2 H), 3.35 (s, 3 H), 3.27 (t, J = 8.0 Hz, 1 H), 2.76 (dd, J = 12.5, 7.5 Hz, 1 H), 2.22 (dd, J = 12.5, 8.6 Hz, 1 H), 1.42–1.41 (m, 6 H).

¹³C NMR (100 MHz, CDCl₃): δ = 180.77, 178.99, 169.69, 142.78, 131.92, 129.88, 128.92, 128.30, 127.98, 127.52, 126.06, 49.25, 44.89, 39.38, 37.68, 30.80, 15.76, 11.34.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₂H₂₃N₂O₃: 363.1703; found: 363.1703.

(1S,5R,6S)-1,5-Dichloro-N-methyl-2,4-dioxo-N,3-diphenyl-3-aza­bicyclo[3.2.0]heptane-6-carboxamide (3j)

According to the general procedure, 3j was prepared from 1j (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 52.3 mg (65%); white solid; R_f = 0.65 (pentane/EtOAc, 3:1); mp 160–162 °C.

IR (thin film): 3350, 2847, 1733, 1659, 1495, 1371, 1145, 975, 760, 617, 540 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.56–7.37 (m, 10 H), 3.73 (dd, J = 11.0, 6.1 Hz, 1 H), 3.35–3.29 (m, 4 H), 2.81 (dd, J = 13.7, 11.0 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 170.91, 169.85, 167.84, 142.18, 131.30, 130.00, 129.41, 129.33, 128.74, 126.77, 66.27, 62.62, 45.79, 37.85, 34.75.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₇Cl₂N₂O₃: 403.0611; found: 403.0608.

(1S,5R,6R)-1,5-Dichloro-N-methyl-2,4-dioxo-N,3-diphenyl-3-aza­bicyclo[3.2.0]heptane-6-carboxamide (3j′)

According to the general procedure, 3j′ was prepared from 1j (0.2 mmol, 1.0 equiv), 2a (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 26 mg (32%); white solid; R_f = 0.58 (pentane/EtOAc, 3:1); mp 149–151 °C.

IR (thin film): 3350, 2848, 1733, 1659, 1495, 1371, 1145, 975, 760, 617, 542 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.50–7.37 (m, 6 H), 7.32–7.30 m, 2 H), 7.08–7.05 (m, 2 H), 3.67–3.59 (m, 2 H), 3.41 (s, 3 H), 2.77–2.68 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 171.06, 169.39, 165.24, 141.92, 130.68, 130.24, 129.35, 129.31, 128.53, 127.90, 125.95, 66.97, 62.92, 42.14, 38.29, 33.83.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₇Cl₂N₂O₃: 403.0611; found: 403.0607.

2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxamide (3k, 3k′)

According to the general procedure, 3k and 3k′ were prepared from 1a (0.2 mmol, 1.0 equiv), 2b (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 40 mg (82%); mixture of exo and endo diastereomers (2:1); white solid; R_f = 0.25 (pentane/EtOAc, 1:2); mp 165–169 °C.

IR (thin film): 3466, 3025, 1710, 1655, 1505, 1379, 1178, 1125, 751, 698 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.54–7.40 (m, 12 H, 4 × 2 H, 4 × 1 H), 7.36–7.31 (m, 6 H, 2 × 2 H, 2 × 1 H), 7.12 (br, 2 H, 1 × 2 H), 7.03 (br s, 1 H), 3.60–3.50 (m, 4 H, 2 × 2 H), 3.38–3.33 (m, 3 H, 1 × 2 H, 1 × 1 H), 3.26–3.23 (m, 2 H, 2 × 1 H), 2.70–2.62 (m, 3 H, 1 × 2 H, 1 × 1 H), 2.48–2.40 (m, 2 H, 1 × 2 H), 2.32–2.27 (m, 1 H).

¹³C NMR (150 MHz, DMSO-d ₆): δ = 178.47, 178.44, 177.50, 176.32, 173.68, 172.66, 133.08, 132.65, 128.85, 128.72, 128.35, 128.18, 127.21, 127.15, 41.23, 40.22, 39.32, 37.94, 36.13, 35.60, 25.97, 24.41.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₃H₁₃N₂O₃: 245.0921; found: 245.0920.

(1S,5R,6R)-6-(Morpholine-4-carbonyl)-3-phenyl-3-azabicyclo­[3.2.0]heptane-2,4-dione (3l)

According to the general procedure, 3l was prepared from 1a (0.2 mmol, 1.0 equiv), 2c (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 33.9 mg (54%); white solid; R_f = 0.48 (pentane/EtOAc, 2:1); mp 191–193 °C.

IR (thin film): 3417, 2825, 1708, 1641, 1498, 1379, 1182, 1114, 761, 617, 533 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.49 (m, 2 H), 7.45–7.41 (m, 1 H), 7.35–7.32 (m, 2 H), 3.82–3.70 (m, 6 H), 3.66–3.41 (m, 5 H), 3.22 (ddd, J = 12.5, 10.9, 6.6 Hz, 1 H), 2.57–2.50 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.84, 177.20, 169.33, 131.76, 129.22, 128.80, 126.24, 66.74, 66.55, 45.60, 42.61, 41.84, 37.86, 35.88, 25.59.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₇H₁₉N₂O₄: 315.1340; found: 315.1338.

(1S,5R,6S)-6-(Morpholine-4-carbonyl)-3-phenyl-3-azabicyclo­[3.2.0]heptane-2,4-dione (3l′)

According to the general procedure, 3l′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2c (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 21.4 mg (34%); white solid; R_f = 0.36 (pentane/EtOAc, 2:1); mp 185–188 °C.

IR (thin film): 3417, 2820, 1708, 1641, 1497, 1379, 1182, 1115, 760, 617, 534 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.50–7.46 (m, 2 H), 7.42–7.38 (m, 1 H), 7.31–7.27 (m, 2 H), 3.89–3.82 (m, 2 H), 3.76–3.58 (m, 5 H), 3.54–3.36 (m, 4 H), 3.04–2.98 (m, 1 H), 2.76 (dt, J = 12.9, 9.9 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.73, 175.41, 168.28, 132.11, 129.22, 128.79, 126.81, 66.56, 66.23, 45.79, 42.39, 41.08, 35.74, 35.39, 24.85.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₇H₁₉N₂O₄: 315.1340; found: 315.1338.

(4aS,4bR,7aS,7bR)-1,3-Dimethyl-6-phenyltetrahydro-1H-pyrrolo­[3′,4′:3,4]cyclobuta[1,2-d]pyrimidine-2,4,5,7(3H,6H)-tetraone (3m)

According to the general procedure, 3m was prepared from 1a (0.2 mmol, 1.0 equiv), 2d (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 46.3 mg (74%); white solid; R_f = 0.52 (pentane/EtOAc, 2:1); mp 140–142 °C.

IR (thin film): 3461, 2815, 1711, 1645, 1417, 1385, 1182, 1112, 760, 627 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.53–7.49 (m, 2 H), 7.45–7.41 (m, 1 H), 7.08–6.99 (m, 2 H), 4.48 (dd, J = 9.8, 7.9 Hz, 1 H), 4.16 (t, J = 9.8 Hz, 1 H), 3.85 (ddd, J = 7.9, 6.6, 1.2 Hz, 1 H), 3.76 (dd, J = 9.9, 6.3 Hz, 1 H), 2.98 (s, 3 H), 2.90 (s, 3 H).

¹³C NMR (100 MHz, DMSO-d ₆): δ = 174.20, 174.16, 166.35, 151.47, 132.13, 129.12, 128.56, 126.44, 49.39, 45.50, 39.96, 38.66, 34.06, 27.35.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₆N₃O₄: 314.1136; found: 314.1135.

(4aR,4bR,7aS,7bS)-1,3-Dimethyl-6-phenyltetrahydro-1H-pyrrolo­[3′,4′:3,4]cyclobuta[1,2-d]pyrimidine-2,4,5,7(3H,6H)-tetraone (3m′)

According to the general procedure, 3m′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2d (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 10 mg (16%); white solid; R_f = 0.46 (pentane/EtOAc, 2:1); mp 121–122 °C.

IR (thin film): 3460, 2815, 1711, 1648, 1415, 1385, 1184, 1112, 761, 627 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.54–7.50 (m, 2 H), 7.46–7.42 (m, 1 H), 7.38–7.36 (m, 2 H), 4.34–4.30 (m, 1 H), 3.79 (dd, J = 9.3, 3.3 Hz, 1 H), 3.70 (ddd, J = 7.5, 4.1, 1.2 Hz, 1 H), 3.51–3.48 (m, 1 H), 3.10 (s, 3 H), 2.92 (s, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 174.27, 173.99, 167.05, 151.22, 131.42, 129.33, 129.08, 126.16, 54.24, 47.40, 40.32, 39.10, 33.82, 28.29.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₆N₃O₄: 314.1136; found: 314.1134.

Ethyl (1S,5S,6S)-2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxylate (3n)

According to the general procedure, 3n was prepared from 1a (0.2 mmol, 1.0 equiv), 2e (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 28.4 mg (52%); white solid; R_f = 0.45 (pentane/EtOAc, 3:1); mp 74–76 °C.

IR (thin film): 2919, 1709, 1488, 1366, 1182, 739, 690, 619, 539 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.50 (m, 2 H), 7.45–7.41 (m, 1 H), 7.34–7.31 (m, 2 H), 4.25 (q, J = 7.1 Hz, 2 H), 3.74 (dd, J = 6.9, 4.5 Hz, 1 H), 3.51–3.48 (m, 1 H), 3.37–3.34 (m, 1 H), 2.91 (ddd, J = 12.7, 10.7, 6.6 Hz, 1 H), 2.62 (ddd, J = 13.4, 9.7, 4.5 Hz, 1 H), 1.32 (t, J = 7.1 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.82, 176.47, 172.49, 131.68, 129.23, 128.80, 126.29, 61.70, 41.24, 39.23, 36.29, 26.76, 14.13.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₆NO₄: 274.1074; found: 274.1072.

Ethyl (1S,5S,6R)-2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxylate (3n′)

According to the general procedure, 3n′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2e (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 18.6 mg (34%); white solid; R_f = 0.38 (pentane/EtOAc, 3:1); mp 79–81 °C.

IR (thin film): 2920, 1709, 1488, 1366, 1182, 741, 688, 619, 539 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.49 (m, 2 H), 7.44–7.40 (m, 1 H), 7.37–7.35 (m, 2 H), 4.17 (qq, J = 10.8, 7.2 Hz, 2 H), 3.73–3.70 (m, 2 H), 3.47–3.43 (m, 1 H), 2.91–2.85 (m, 1 H), 2.72–2.67 (m, 1 H), 1.26 (t, J = 7.2 Hz, 4 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.79, 175.60, 171.66, 132.02, 129.25, 128.82, 126.66, 61.57, 40.54, 37.65, 35.64, 25.69, 14.12.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₆NO₄: 274.1074; found: 274.1073.

Benzyl (1S,5S,6S)-2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxylate (3o)

According to the general procedure, 3o was prepared from 1a (0.2 mmol, 1.0 equiv), 2f (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 37.5 mg (56%); white solid; R_f = 0.44 (pentane/EtOAc, 2:1); mp 145–147 °C.

IR (thin film): 2923, 1712, 1498, 1378, 1182, 750, 696, 616 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.49 (m, 2 H), 7.45–7.36 (m, 6 H), 7.34–7.31 (m, 2 H), 5.23 (s, 2 H), 3.75 (dd, J = 6.9, 4.5 Hz, 1 H), 3.52–3.40 (m, 2 H), 2.92 (ddd, J = 12.9, 10.7, 6.6 Hz, 1 H), 2.66–2.59 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.66, 176.29, 172.27, 135.23, 131.80, 129.24, 128.80, 128.69, 128.57, 128.34, 126.32, 67.40, 41.33, 39.34, 36.38, 26.84.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₈NO₄: 336.1231; found: 336.1230.

Benzyl (1S,5S,6R)-2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptane-6-carboxylate (3o′)

According to the general procedure, 3o′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2f (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 16 mg (24%); white solid; R_f = 0.39 (pentane/EtOAc, 2:1); mp 131–134 °C.

IR (thin film): 2924, 1713, 1498, 1378, 1182, 750, 696, 616, 543 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.49–7.45 (m, 2 H), 7.42–7.34 (m, 2 H), 7.32–7.29 (m, 6 H), 5.15–5.08 (m, 2 H), 3.79–3.65 (m, 2 H), 3.44–3.30 (m, 1 H), 2.90–2.82 (dt, J = 20.0, 5.4 Hz, 1 H), 2.72–2.65 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.61, 175.42, 171.42, 135.08, 132.07, 129.20, 128.74, 128.65, 128.56, 128.48, 126.68, 67.47, 40.67, 37.69, 35.68, 25.81.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₈NO₄: 336.1231; found: 336.1228.

(3aR,3bS,7aR,7bS)-2-Phenylhexahydro-1H-benzo[3,4]cyclobuta­[1,2-c]pyrrole-1,3,4(2H,3bH)-trione (3p)

According to the general procedure, 3p was prepared from 1a (0.2 mmol, 1.0 equiv), 2g (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 26 mg (48%); white solid; R_f = 0.56 (pentane/EtOAc, 3:1); mp 137–138 °C.

IR (thin film): 2870, 1712, 1496, 1375, 1186, 1154, 756, 694, 616 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.49 (m, 2 H), 7.44–7.40 (m, 1 H), 7.33–7.31 (m, 2 H), 3.61 (dd, J = 6.5, 3.4 Hz, 1 H), 3.34–3.29 (m, 1 H), 3.23–3.19 (m, 2 H), 2.60 (dt, J = 16.5, 5.5 Hz, 1 H), 2.47–2.39 (m, 1 H), 2.10–1.96 (m, 3 H), 1.85–1.78 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 209.31, 177.13, 176.46, 131.84, 129.24, 128.77, 126.34, 45.65, 42.95, 40.50, 40.33, 39.74, 27.27, 21.14.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₆NO₃: 270.1125; found: 270.1123.

(3aR,3bR,7aS,7bS)-2-Phenylhexahydro-1H-benzo[3,4]cyclobuta­[1,2-c]pyrrole-1,3,4(2H,3bH)-trione (3p′)

According to the general procedure, 3p was prepared from 1a (0.2 mmol, 1.0 equiv), 2g (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 20 mg (37%); white solid; R_f = 0.48 (pentane/EtOAc, 3:1); mp 121–123 °C.

IR (thin film): 2871, 1713, 1496, 1376, 1188, 1154, 756, 694, 617 cm^–1

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.47 (m, 2 H), 7.42–7.38 (m, 1 H), 7.29–7.27 (m, 2 H), 3.76–3.72 (m, 1 H), 3.67–3.52 (m, 3 H), 2.38–2.35 (m, 2 H), 1.98–1.76 (m, 4 H).

¹³C NMR (100 MHz, CDCl₃): δ = 208.97, 175.75, 175.12, 131.83, 129.23, 128.70, 126.09, 44.94, 41.98, 40.75, 40.50, 36.14, 23.66, 21.82.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₆NO₃: 270.1125; found: 270.1124.

(1S,5R,6S)-3,6-Diphenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3q)

According to the general procedure, 3q was prepared from 1a (0.2 mmol, 1.0 equiv), 2h (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 35 mg (63%); white solid; R_f = 0.62 (pentane/EtOAc, 3:1); mp 59–61 °C.

IR (thin film): 3020, 2881, 1710, 1497, 1375, 1166, 754, 694, 640, 516 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.43–7.36 (m, 5 H), 7.33–7.26 (m, 3 H), 3.85 (dd, J = 13.9, 8.5 Hz, 1 H), 3.55–3.52 (m, 1 H), 3.48–3.43 (m, 1 H), 2.91–2.76 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.56, 177.44, 142.09, 132.18, 129.18, 128.82, 128.62, 127.10, 126.46, 126.34, 46.56, 42.14, 35.87, 29.99.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₆NO₂: 278.1176; found: 278.1174.

(1S,5R,6R)-3,6-Diphenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3q′)

According to the general procedure, 3q′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2h (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 14.5 mg (26%); white solid; R_f = 0.54 (pentane/EtOAc, 3:1); mp 63–65 °C.

IR (thin film): 3021, 2883, 1710, 1497, 1453, 1376, 1166, 755, 695, 640, 517 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.33 (m, 5 H), 7.31–7.25 (m, 3 H), 7.01 (d, J = 7.6 Hz, 2 H), 4.30 (td, J = 10.2, 7.3 Hz, 1 H), 3.83 (dd, J = 10.4, 6.6 Hz, 1 H), 3.47 (ddd, J = 10.6, 6.4, 4.5 Hz, 1 H), 3.11 (dt, J = 13.4, 10.2 Hz, 1 H), 2.77–2.71 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.83, 175.41, 137.79, 131.82, 129.04, 128.62, 128.49, 127.53, 127.39, 126.19, 44.42, 39.76, 35.73, 27.39.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₆NO₂: 278.1176; found: 278.1175.

3,6,6-Triphenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3r)

According to the general procedure, 3r was prepared from 1a (0.2 mmol, 1.0 equiv), 2i (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 60.2 mg (85%); white solid; R_f = 0.47 (pentane/EtOAc, 3:1); mp 148–150 °C.

IR (thin film): 2946, 1711, 1495, 1376, 1175, 911, 699, 640, 534 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.40–7.20 (m, 13 H), 6.61–6.58 (m, 2 H), 4.33 (d, J = 7.0 Hz, 1 H), 3.57 (dd, J = 13.2, 3.0 Hz, 1 H), 3.42 (ddd, J = 10.2, 7.0, 3.0 Hz, 1 H), 3.14 (dd, J = 13.1, 10.6 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.41, 175.37, 148.18, 141.05, 131.74, 128.90, 128.71, 128.46, 128.43, 127.46, 127.05, 126.57, 126.18, 126.15, 54.13, 50.04, 34.70, 34.51.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₄H₂₀NO₂: 354.1489; found: 354.1488.

(1R,5S,6R)-6-(Naphthalen-2-yl)-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3s)

According to the general procedure, 3s was prepared from 1a (0.2 mmol, 1.0 equiv), 2j (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 38.7 mg (59%); white solid; R_f = 0.64 (pentane/EtOAc, 3:1); mp 209–211 °C.

IR (thin film): 2835, 1708, 1497, 1187, 754, 693, 616, 534, 433 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.91–7.85 (m, 3 H), 7.76 (s, 1 H), 7.57–7.41 (m, 8 H), 4.05 (dd, J = 14.0, 8.4 Hz, 1 H), 3.68–3.65 (m, 1 H), 3.54 (ddd, J = 10.6, 6.9, 3.7 Hz, 1 H), 3.03 (ddd, J = 12.8, 10.6, 8.0 Hz, 1 H), 2.89 (ddd, J = 12.9, 9.2, 3.7 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.62, 177.51, 139.23, 133.33, 132.49, 132.17, 129.29, 128.92, 128.75, 127.79, 127.75, 126.58, 126.51, 126.08, 124.76, 124.61, 46.55, 42.43, 35.98, 29.85.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₂H₁₈NO₂: 328.1332; found: 328.1330.

(1R,5S,6S)-6-(Naphthalen-2-yl)-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3s′)

According to the general procedure, 3s′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2j (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 15.7 mg (24%); white solid; R_f = 0.55 (pentane/EtOAc, 3:1); mp 192–194 °C.

IR (thin film): 2832, 1708, 1497, 1188, 755, 693, 616, 534, 433 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.83–7.76 (m, 3 H), 7.68 (s, 1 H), 7.48–7.45 (m, 2 H), 7.38 (dd, J = 8.5, 1.8 Hz, 1 H), 7.32–7.27 (m, 3 H), 6.94–6.96 (m, 2 H), 4.45 (td, J = 10.3, 7.3 Hz, 1 H), 3.90 (dd, J = 10.5, 6.6 Hz, 1 H), 3.53 (ddd, J = 10.8, 6.5, 4.6 Hz, 1 H), 3.19 (dt, J = 13.0, 10.1 Hz, 1 H), 2.92–2.85 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.85, 175.37, 135.57, 133.25, 132.70, 131.87, 129.04, 128.47, 128.43, 127.79, 127.75, 126.39, 126.22, 126.13, 126.08, 125.50, 44.57, 39.94, 35.77, 27.61.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₂H₁₈NO₂: 328.1332; found: 328.1331.

(6aS,6bR,9aS,9bR)-8-Phenyl-5,6,6a,6b,9a,9b-hexahydro-7H-naphtho[1′,2′:3,4]cyclobuta[1,2-c]pyrrole-7,9(8H)-dione (3t)

According to the general procedure, 3t was prepared from 1a (0.2 mmol, 1.0 equiv), 2k (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 35.9 mg (59%); white solid; R_f = 0.51 (pentane/EtOAc, 3:1); mp 140–142 °C.

IR (thin film): 2930, 1708, 1496, 1374, 1185, 1142, 750, 692, 612 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.49 (m, 2 H), 7.44–7.36 (m, 3 H), 7.25–7.19 (m, 4 H), 3.82–3.79 (m, 1 H), 3.20–3.12 (m, 3 H), 2.86–2.82 (m, 2 H), 2.08–2.02 (m, 1 H), 1.94–1.90 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.52, 177.71, 137.70, 136.46, 132.18, 129.34, 128.82, 128.78, 127.24, 127.12, 126.57, 46.35, 41.47, 39.73, 36.64, 26.89, 26.80.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₈NO₂: 304.1332; found: 304.1331.

(6aR,6bR,9aS,9bS)-8-Phenyl-5,6,6a,6b,9a,9b-hexahydro-7H-naphtho[1′,2′:3,4]cyclobuta[1,2-c]pyrrole-7,9(8H)-dione (3t′)

According to the general procedure, 3t′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2k (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 22.5 mg (37%); white solid; R_f = 0.45 (pentane/EtOAc, 3:1); mp 129–132 °C.

IR (thin film): 2930, 1708, 1496, 1375, 1185, 1142, 750, 693, 613 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.36–7.29 (m, 3 H), 7.24–7.17 (m, 3 H), 7.11 (d, J = 7.2 Hz, 1 H), 6.83–6.73 (m, 2 H), 4.19 (t, J = 10.0 Hz, 1 H), 3.85 (dd, J = 10.4, 6.7 Hz, 1 H), 3.61–3.52 (m, 2 H), 2.70–2.65 (m, 2 H), 2.05–2.00 (m, 1 H), 1.87–1.79 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.54, 175.69, 137.15, 132.60, 131.89, 130.13, 128.99, 128.93, 128.36, 126.93, 126.56, 125.97, 42.72, 40.07, 36.56, 33.74, 26.77, 22.11.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₀H₁₈NO₂: 304.1332; found: 304.1330.

(3aS,3bR,8aS,8bR)-2-Phenyl-3b,8,8a,8b-tetrahydroindeno­[1′,2′:3,4]cyclobuta[1,2-c]pyrrole-1,3(2H,3aH)-dione (3u)

According to the general procedure, 3u was prepared from 1a (0.2 mmol, 1.0 equiv), 2l (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 34.2 mg (59%); white solid; R_f = 0.53 (pentane/EtOAc, 3:1); mp 161–163 °C.

IR (thin film): 2920, 1709, 1499, 1382, 1187, 911, 730, 692, 646, 617, 523 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.54–7.50 (m, 2 H), 7.45–7.41 (m, 2 H), 7.39–7.30 (m, 5 H), 4.12 (d, J = 5.0 Hz, 1 H), 3.48–3.38 (m, 2 H), 3.28–3.21 (m, 2 H), 3.15 (dd, J = 6.3, 3.3 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.88, 177.15, 143.00, 142.24, 132.00, 129.14, 128.61, 128.03, 127.64, 126.39, 125.42, 125.08, 48.09, 47.61, 45.11, 41.30, 39.36.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₉H₁₆NO₂: 290.1176; found: 290.1175.

(3aS,3bS,8aR,8bR)-2-Phenyl-3b,8,8a,8b-tetrahydroindeno­[1′,2′:3,4]cyclobuta[1,2-c]pyrrole-1,3(2H,3aH)-dione (3u′)

According to the general procedure, 3u′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2l (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 19.7 mg (34%); white solid; R_f = 0.42 (pentane/EtOAc, 3:1); mp 152–154 °C.

IR (thin film): 2920, 1710, 1499, 1383, 1187, 911, 730, 692, 646, 617, 524 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.28–7.20 (m, 7 H), 6.38–6.33 (m, 2 H), 4.42 (t, J = 8.3 Hz, 1 H), 3.87 (dd, J = 9.1, 6.9 Hz, 1 H), 3.69 (dtd, J = 9.8, 8.7, 1.2 Hz, 1 H), 3.54 (ddd, J = 10.1, 6.9, 1.5 Hz, 1 H), 3.33 (d, J = 17.4 Hz, 1 H), 3.11 (dd, J = 17.3, 8.6 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 176.39, 176.14, 144.54, 140.02, 131.65, 128.94, 128.56, 128.26, 127.26, 126.50, 126.38, 125.38, 46.34, 43.63, 40.53, 36.89, 34.17.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₉H₁₆NO₂: 290.1176; found: 290.1176.

(3aR,3bS,8bR,8cS)-2-Phenyl-3a,3b,8b,8c-tetrahydro-1H-benzo­[4′,5′]thieno[2′,3′:3,4]cyclobuta[1,2-c]pyrrole-1,3(2H)-dione (3v)

According to the general procedure, 3v was prepared from 1a (0.2 mmol, 1.0 equiv), 2m (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 37 mg (60%); white solid; R_f = 0.63 (pentane/EtOAc, 3:1); mp 199–202 °C.

IR (thin film): 3011, 1713, 1588, 1460, 1277, 1155, 1113, 1040, 751, 694, 624 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.55–7.51 (m, 2 H), 7.44 (t, J = 7.4 Hz, 1 H), 7.37–7.33 (dd, J = 11.8, 4.6 Hz, 3 H), 7.28–7.23 (m, 2 H), 7.17–7.13 (m, 1 H), 4.64–4.53 (m, 1 H), 4.54 (dd, J = 8.1, 3.0 Hz, 1 H), 3.69 (ddd, J = 6.8, 3.5, 1.0 Hz, 1 H), 3.53 (dd, J = 6.8, 2.6 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 176.03, 175.59, 141.45, 138.58, 131.70, 129.31, 129.15, 128.93, 126.34, 125.43, 125.19, 122.08, 52.84, 49.98, 48.14, 47.80.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₄NO₂S: 308.0740; found: 308.0741.

(3aR,3bR,8bS,8cS)-2-Phenyl-3a,3b,8b,8c-tetrahydro-1H-benzo­[4′,5′]thieno[2′,3′:3,4]cyclobuta[1,2-c]pyrrole-1,3(2H)-dione (3v′)

According to the general procedure, 3v′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2m (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 23.4 mg (38%); white solid; R_f = 0.5 (pentane/EtOAc, 3:1); mp 183–185 °C.

IR (thin film): 3012, 1713, 1588, 1460, 1277, 1155, 1113, 1045, 751, 694, 624 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.34–7.28 (m, 3 H), 7.23–7.17 (m, 3 H), 7.06 (ddd, J = 7.9, 6.4, 1.8 Hz, 1 H), 6.64–6.59 (m, 2 H), 4.96 (t, J = 9.0 Hz, 1 H), 4.89 (t, J = 8.9 Hz, 1 H), 3.97 (dd, J = 8.7, 6.9 Hz, 1 H), 3.84–3.80 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 175.03, 174.35, 143.25, 135.83, 131.59, 129.11, 129.04, 128.69, 126.66, 126.43, 124.96, 121.90, 50.98, 45.74, 45.26, 44.61.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₄NO₂S: 308.0740; found: 308.0739.

(3aS,3bS,8bR,8cS)-2-Phenyl-3a,3b,8b,8c-tetrahydro-1H-benzo­furo[2′,3′:3,4]cyclobuta[1,2-c]pyrrole-1,3(2H)-dione (3w)

According to the general procedure, 3w was prepared from 1a (0.2 mmol, 1.0 equiv), 2n (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 40.9 mg (70%); white solid; R_f = 0.38 (pentane/EtOAc, 3:1); mp 189–191 °C.

IR (thin film): 3017, 1711, 1594, 1475, 1379, 1179, 1155, 1043, 755, 693, 624 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.30–7.24 (m, 5 H), 6.96–6.09 (m, 2 H), 6.51–6.49 (m, 2 H), 5.58 (td, J = 7.4, 0.8 Hz, 1 H), 4.68–4.64 (m, 1 H), 3.89–3.81 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 175.28, 172.73, 161.78, 131.60, 130.07, 129.02, 128.73, 126.75, 126.45, 124.41, 121.99, 110.67, 77.38, 46.01, 45.42, 42.33.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₄NO₃: 292.0968; found: 292.0966.

(1R,5R,6R)-3-Phenyl-6-(thiophen-2-yl)-3-azabicyclo[3.2.0]heptane-2,4-dione (3x)

According to the general procedure, 3x was prepared from 1a (0.2 mmol, 1.0 equiv), 2o (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 34 mg (60%); white solid; R_f = 0.68 (pentane/EtOAc, 3:1); mp 111–113 °C.

IR (thin film): 2841, 1709, 1497, 1374, 1130, 755, 693, 617, 533 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.49 (m, 2 H), 7.42 (t, J = 7.4 Hz, 1 H), 7.36 (d, J = 7.6 Hz, 2 H), 7.25 (dd, J = 4.3, 1.7 Hz, 1 H), 7.02–6.93 (m, 2 H), 4.04 (td, J = 8.3, 4.6 Hz, 1 H), 3.57–3.48 (m, 2 H), 2.93–2.82 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.33, 176.74, 146.03, 132.11, 129.37, 128.87, 127.35, 126.55, 124.69, 124.42, 48.18, 38.05, 35.90, 32.40.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₄NO₂S: 284.0740; found: 284.0739.

(1R,5R,6S)-3-Phenyl-6-(thiophen-2-yl)-3-azabicyclo[3.2.0]heptane-2,4-dione (3x′)

According to the general procedure, 3x′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2o (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 16.5 mg (29%); white solid; R_f = 0.59 (pentane/EtOAc, 3:1); mp 99–102 °C.

IR (thin film): 2840, 1709, 1497, 1375, 1131, 756, 694, 617, 533 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.44–7.40 (m, 2 H), 7.37–7.35 (m, 1 H), 7.26–7.24 (m, 1 H), 7.11–7.09 (m, 2 H), 6.99 (dd, J = 5.1, 3.6 Hz, 1 H), 6.94–6.93 (m, 1 H), 4.47 (td, J = 10.2, 6.9 Hz, 1 H), 3.81 (dd, J = 10.2, 6.6 Hz, 1 H), 3.45 (ddd, J = 10.7, 6.5, 4.5 Hz, 1 H), 3.27 (dt, J = 13.0, 10.2 Hz, 1 H), 2.67 (ddd, J = 11.4, 6.3, 4.4 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.55, 174.95, 141.92, 131.92, 129.06, 128.54, 127.25, 126.33, 125.38, 125.02, 44.87, 35.60, 35.02, 30.77.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₄NO₂S: 284.0740; found: 284.0737.

(1S,5S,6S)-6-(2-Oxopyrrolidin-1-yl)-3-phenyl-3-azabicyclo­[3.2.0]heptane-2,4-dione (3y)

According to the general procedure, 3y was prepared from 1a (0.2 mmol, 1.0 equiv), 2p (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 35.9 mg (63%); white solid; R_f = 0.58 (pentane/EtOAc, 3:1); mp 151–153 °C.

IR (thin film): 3465, 2892, 1710, 1496, 1422, 1378, 1298, 1186, 914, 730, 644 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.48 (m, 2 H), 7.43–7.39 (m, 1 H), 7.33–7.31 (m, 2 H), 4.65 (td, J = 8.2, 5.3 Hz, 1 H), 3.86–3.83 (m, 1 H), 3.58–3.50 (m, 2 H), 3.43 (ddd, J = 10.6, 7.4, 3.3 Hz, 1 H), 3.04 (ddd, J = 13.0, 11.2, 7.8 Hz, 1 H), 2.65–2.59 (m, 1 H), 2.45–2.41 (m, 2 H), 2.14–2.06 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.69, 176.21, 175.01, 131.82, 129.15, 128.68, 126.37, 50.11, 45.45, 45.00, 34.30, 31.35, 28.40, 18.00.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₇N₂O₃: 285.1234; found: 285.1232.

(1S,5S,6R)-6-(2-Oxopyrrolidin-1-yl)-3-phenyl-3-azabicyclo­[3.2.0]heptane-2,4-dione (3y′)

According to the general procedure, 3y′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2p (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 17.7 mg (31%); white solid; R_f = 0.49 (pentane/EtOAc, 3:1); mp 139–140 °C.

IR (thin film): 3466, 2890, 1711, 1497, 1422, 1378, 1298, 1186, 914, 730, 644 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–74.9 (m, 2 H), 7.44–7.40 (m, 1 H), 7.36–7.34 (m, 2 H), 4.82 (dd, J = 18.6, 9.6 Hz, 1 H), 3.75 (dd, J = 9.0, 6.3 Hz, 1 H), 3.55–3.49 (m, 1 H), 3.43–3.37 (m, 1 H), 3.32–3.17 (m, 2 H), 3.05–2.99 (m, 1 H), 2.42–2.37 (m, 2 H), 2.05–1.97 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.84, 176.09, 175.14, 132.12, 129.24, 128.69, 126.41, 46.80, 46.09, 45.48, 33.58, 31.46, 28.76, 18.38.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₇N₂O₃: 285.1234; found: 285.1233.

(1S,5R,6S)-3-Phenyl-6-(phenylthio)-3-azabicyclo[3.2.0]heptane-2,4-dione (3z)

According to the general procedure, 3z′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2q (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 40 mg (58%); white solid; R_f = 0.71 (pentane/EtOAc, 3:1); mp 69–71 °C.

IR (thin film): 2955, 1710, 1499, 1379, 1168, 759, 695, 618, 520 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.54–7.50 (m, 2 H), 7.46–7.42 (m, 1 H), 7.34–7.29 (m, 6 H), 7.23–7.19 (m, 1 H), 4.52 (td, J = 9.4, 7.0 Hz, 1 H), 3.95 (dd, J = 9.2, 6.7 Hz, 1 H), 3.44 (ddd, J = 10.1, 6.5, 4.9 Hz, 1 H), 3.29–3.23 (m, 1 H), 2.12–2.07 (m, 1 H).

¹³C NMR (101 MHz, DMSO-d ₆): δ = 178.30, 174.80, 135.50, 132.57, 128.94, 128.92, 128.36, 128.09, 127.03, 125.99, 44.58, 37.95, 35.87, 30.44.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₆NO₂S: 310.0896; found: 310.0898.

(1S,5R,6R)-3-Phenyl-6-(phenylthio)-3-azabicyclo[3.2.0]heptane-2,4-dione (3z′)

According to the general procedure, 3z′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2q (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 19.8 mg (32%); white solid; R_f = 0.62 (pentane/EtOAc, 3:1); mp 58–60 °C.

IR (thin film): 2958, 1710, 1500, 1379, 1168, 759, 694, 618, 520 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.54–7.50 (m, 2 H), 7.44 (t, J = 7.4 Hz, 1 H), 7.39–7.34 (m, 6 H), 7.27–7.22 (m, 1 H), 4.35 (td, J = 8.5, 6.5 Hz, 1 H), 3.56–3.50 (m, 1 H), 3.39 (dd, J = 7.1, 4.2 Hz, 1 H), 2.82 (ddd, J = 13.0, 8.6, 4.3 Hz, 1 H), 2.58–2.51 (m, 1 H).

¹³C NMR (100 MHz, DMSO-d ₆): δ = 177.88, 176.00, 134.95, 132.56, 129.24, 128.79, 128.40, 128.06, 127.25, 126.25, 47.08, 39.39, 35.77, 29.87.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₆NO₂S: 310.0896; found: 310.0895.

(4aS,4bS,7aS,7bS)-6-Phenylhexahydropyrano[2′,3′:3,4]cyclo­buta[1,2-c]pyrrole-5,7(2H,6H)-dione (3aa)

According to the general procedure, 3aa was prepared from 1a (0.2 mmol, 1.0 equiv), 2r (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 34.6 mg (67%); white solid; R_f = 0.59 (pentane/EtOAc, 3:1); mp 64–66 °C.

IR (thin film): 2937, 1713, 1501, 1388, 1166, 746, 722, 693, 617, 528 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.47 (m, 2 H), 7.40 (t, J = 7.4 Hz, 1 H), 7.32–7.31 (m, 2 H), 4.62 (t, J = 6.2 Hz, 1 H), 3.92–3.89 (m, 1 H), 3.63 (t, J = 6.4 Hz, 1 H), 3.44–3.40 (m, 1 H), 3.29 (td, J = 11.2, 2.2 Hz, 1 H), 3.00–2.97 (m, 1 H), 2.05–2.02 (m, 1 H), 1.79–1.69 (m, 1 H), 1.67–1.58 (m, 1 H), 1.51–1.47 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.55, 175.43, 132.46, 129.15, 128.55, 126.52, 71.10, 64.14, 43.09, 40.68, 33.15, 21.84, 19.78.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₆NO₃: 258.1125; found: 258.1123.

(4aR,4bS,7aS,7bR)-6-Phenylhexahydropyrano[2′,3′:3,4]cyclo­buta[1,2-c]pyrrole-5,7(2H,6H)-dione (3aa′)

According to the general procedure, 3aa′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2r (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 14 mg (27%); white solid; R_f = 0.44 (pentane/EtOAc, 3:1); mp 53–55 °C.

IR (thin film): 2936, 1713, 1500, 1388, 1166, 746, 721, 693, 617, 528 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.47 (m, 2 H), 7.42–7.39 (m, 1 H), 7.30–7.27 (m, 2 H), 4.43 (dd, J = 5.7, 1.7 Hz, 1 H), 3.90–3.88 (m, 1 H), 3.53–3.45 (m, 2 H), 3.38–3.35 (m, 1 H), 2.78–2.75 (m, 1 H), 2.03–1.94 (m, 1 H), 1.90–1.77 (m, 2 H), 1.64–1.55 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.62, 175.24, 131.90, 129.15, 128.62, 126.32, 72.36, 63.84, 45.77, 42.00, 38.06, 23.60, 21.30.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₆NO₃: 258.1125; found: 258.1123.

(1S,5S,6S)-2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptan-6-yl Acetate (3ab)

According to the general procedure, 3ab was prepared from 1a (0.2 mmol, 1.0 equiv), 2s (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 40.6 mg (78%); white solid; R_f = 0.54 (pentane/EtOAc, 5:1); mp 89–91 °C.

IR (thin film): 1745, 1711, 1497, 1377, 1226, 1176, 1076, 761, 694, 613 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.49 (m, 2 H), 7.44–7.40 (m, 1 H), 7.33–7.30 (m, 2 H), 5.51–5.45 (m, 1 H), 3.86–3.82 (m, 1 H), 3.26–3.15 (m, 2 H), 2.46–2.40 (m, 1 H), 2.06 (s, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.72, 173.11, 169.55, 131.94, 129.18, 128.71, 126.33, 64.46, 44.82, 33.31, 32.30, 20.57.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₄H₁₄NO₄: 260.0918; found: 260.0917.

(1S,5S,6R)-2,4-Dioxo-3-phenyl-3-azabicyclo[3.2.0]heptan-6-yl Acetate (3ab′)

According to the general procedure, 3ab′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2s (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 9.9 mg (19%); white solid; R_f = 0.48 (pentane/EtOAc, 5:1); mp 79–81 °C.

IR (thin film): 1745, 1712, 1497, 1377, 1227, 1176, 1076, 762, 694, 614 cm^–1.

¹H NMR (600 MHz, , CDCl₃): δ = 7.52–7.49 (m, 2 H), 7.44–7.41 (m, 1 H), 7.32–7.31 (m, 2 H), 5.26–5.23 (m, 1 H), 3.63–3.62 (m, 1 H), 3.53–3.49 (m, 1 H), 2.85 (dddd, J = 14.0, 7.2, 4.0, 1.2 Hz, 1 H), 2.73 (dddd, J = 14.1, 11.1, 5.5, 1.1 Hz, 1 H), 2.14 (s, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.35, 174.47, 169.62, 131.75, 129.22, 128.81, 126.34, 69.78, 47.04, 34.41, 32.25, 20.73.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₄H₁₄NO₄: 260.0918; found: 260.0916.

(1S,5S,6S)-6-Ethoxy-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3ac)

According to the general procedure, 3ac was prepared from 1a (0.2 mmol, 1.0 equiv), 2t (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 37.9 mg (77%); white solid; R_f = 0.56 (pentane/EtOAc, 5:1); mp 43–45 °C.

IR (thin film): 3411, 1711, 1497, 1376, 1173, 1122, 759, 694, 617, 537 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.43–7.39 (m, 1 H), 7.34–7.32 (m, 2 H), 4.42 (dd, J = 13.3, 7.8 Hz, 1 H), 3.79–3.71 (m, 2 H), 3.51–3.44 (m, 1 H), 3.23–3.17 (m, 1 H), 3.09–3.01 (m, 1 H), 2.34 (dt, J = 13.6, 5.0 Hz, 1 H), 1.20 (t, J = 7.0 Hz, 3 H).

¹³C NMR (101 MHz, CDCl₃): δ = 178.67, 174.45, 132.25, 129.16, 128.61, 126.57, 71.00, 65.31, 45.93, 33.14, 33.08, 15.05.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₄H₁₆NO₃: 246.1125; found: 246.1123.

(1S,5S,6R)-6-Ethoxy-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3ac′)

According to the general procedure, 3ac′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2t (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 9.3 mg (19%); white solid; R_f = 0.51 (pentane/EtOAc, 5:1); mp 33–35 °C.

IR (thin film): 3411, 1711, 1497, 1377, 1174, 1123, 759, 694, 616, 537 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.42 (ddd, J = 7.4, 3.8, 1.2 Hz, 1 H), 7.32–7.30 (m, 2 H), 4.20 (td, J = 6.6, 2.7 Hz, 1 H), 3.73–3.64 (m, 1 H), 3.53–3.39 (m, 3 H), 2.69 (t, J = 6.8 Hz, 2 H), 1.27 (t, J = 7.0 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.26, 175.74, 131.92, 129.19, 128.69, 126.36, 75.95, 64.53, 48.46, 34.02, 31.95, 14.97.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₄H₁₆NO₃: 246.1125; found: 246.1124.

(1S,5R,6S)-3-Phenyl-6-(trimethylsilyl)-3-azabicyclo[3.2.0]­heptane-2,4-dione (3ad)

According to the general procedure, 3ad was prepared from 1a (0.2 mmol, 1.0 equiv), 2u (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 47.7 mg (87%); white solid; R_f = 0.47 (pentane/EtOAc, 5:1); mp 103–106 °C.

IR (thin film): 2954, 1703, 1495, 1381, 1294, 1247, 1185, 1095, 836, 748, 692, 628 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.47 (m, 2 H), 7.42–7.38 (m, 1 H), 7.35–7.33 (m, 2 H), 3.35–3.30 (m, 1 H), 3.14 (t, J = 6.2 Hz, 1 H), 2.52 (ddd, J = 12.6, 10.1, 8.3 Hz, 1 H), 2.39 (ddd, J = 12.6, 10.4, 4.3 Hz, 1 H), 2.06–1.99 (m, 1 H), 0.13 (s, 9 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.99, 178.93, 132.29, 129.07, 128.43, 126.37, 39.36, 38.09, 24.74, 24.16, –4.09.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₂₀NO₂Si: 274.1258; found: 274.1256.

(1S,5S,6S)-3-Phenyl-6-[(trimethylsilyl)methyl]-3-azabicyclo­[3.2.0]heptane-2,4-dione (3ae)

According to the general procedure, 3ae was prepared from 1a (0.2 mmol, 1.0 equiv), 2v (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 36.8 mg (64%); white solid; R_f = 0.43 (pentane/EtOAc, 5:1); mp 74–76 °C.

IR (thin film): 2952, 1711, 1498, 1373, 1290, 1248, 1171, 841, 759, 693 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.42–7.39 (m, 1 H), 7.35–7.33 (m, 2 H), 3.36 (ddd, J = 10.5, 6.7, 3.7 Hz, 1 H), 3.08 (dd, J = 6.5, 4.8 Hz, 1 H), 2.71 (dq, J = 15.9, 7.9 Hz, 1 H), 2.53 (ddd, J = 12.4, 8.5, 3.7 Hz, 1 H), 2.29 (ddd, J = 12.6, 10.7, 7.2 Hz, 1 H), 1.16 (dd, J = 14.4, 6.8 Hz, 1 H), 1.02 (dd, J = 14.4, 9.2 Hz, 1 H), 0.06 (s, 9 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.05, 177.92, 132.11, 129.08, 128.47, 126.36, 47.59, 35.67, 35.42, 32.41, 25.88, –1.24.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₂₂NO₂Si: 288.1415; found: 288.1414.

6-Benzyl-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3af, 3af′)

According to the general procedure, 3af and 3af′ were prepared from 1a (0.2 mmol, 1.0 equiv), 2w (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 53 mg (91%); mixture of exo and endo diastereomers (4:1); white solid; R_f = 0.51 (pentane/EtOAc, 4:1); mp 90–99 °C.

IR (thin film): 2970, 1712, 1595, 1501, 1377, 1171, 1121, 754, 692, 640, 615 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.55–7.11 (m, 40 H, 10 × 3 H, 10 × 1 H), 3.62–3.51 (m, 1 H), 3.40–3.25 (m, 4 H, 1 × 3 H, 1 × 1 H), 3.18–3.08 (m, 8 H, 2 × 3 H, 2 × 1 H), 2.94–2.89 (m, 6 H, 2 × 3 H), 2.75 (dd, J = 22.3, 9.8 Hz, 1 H), 2.54 (dd, J = 14.5, 12.0 Hz, 1 H), 2.46–2.25 (m, 6 H, 2 × 3 H), 2.05 (dt, J = 12.8, 6.4 Hz, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.94, 178.65, 177.60, 176.45, 138.50, 138.08, 132.06, 129.14, 129.03, 128.54, 128.45, 128.38, 126.55, 126.38, 126.32, 44.07, 42.38, 41.70, 38.61, 38.39, 35.58, 35.37, 35.31, 29.69, 28.81.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₉H₁₈NO₂: 292.1332; found: 292.1330.

(1S,5S,6S)-6-(Bromomethyl)-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3ag)

According to the general procedure, 3ag was prepared from 1a (0.2 mmol, 1.0 equiv), 2x (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 47.6 mg (81%); white solid; R_f = 0.57 (pentane/EtOAc, 5:1); mp 86–87 °C.

IR (thin film): 3368, 2860, 1709, 1497, 1378, 1178, 762, 616, 535 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.49 (m, 2 H), 7.45–7.41 (m, 1 H), 7.34–7.31 (m, 2 H), 3.67 (d, J = 6.5 Hz, 2 H), 3.43–3.38 (m, 1 H), 3.32 (dd, J = 6.9, 4.4 Hz, 1 H), 3.04–2.99 (m, 1 H), 2.60–2.51 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.09, 176.80, 131.81, 129.23, 128.76, 126.34, 43.58, 38.69, 36.61, 35.16, 28.34.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₃H₁₃BrNO₂: 294.0124; found: 294.0123.

(1S,5R,6S)-6-(Hydroxymethyl)-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3ah)

According to the general procedure, 3ah was prepared from 1a (0.2 mmol, 1.0 equiv), 2y (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 37 mg (80%); white solid; R_f = 0.41 (pentane/EtOAc, 3:1); mp 128–130 °C.

IR (thin film): 3454, 2944, 1705, 1497, 1382, 1174, 1088, 741, 694, 618 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.42 (t, J = 7.4 Hz, 1 H), 7.31 (d, J = 7.6 Hz, 2 H), 3.82–3.72 (m, 2 H), 3.38–3.31 (m, 2 H), 2.76 (br, 2 H), 2.56–2.49 (m, 1 H), 2.38–2.32 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.07, 178.71, 132.06, 129.34, 128.84, 126.55, 64.63, 41.48, 39.30, 36.15, 25.50.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₃H₁₄NO₃: 232.0968; found: 232.0967.

(3aR,3bS,4R,7S,7aR,7bS)-2-Phenyloctahydro-1H-4,7-methano­benzo[3,4]cyclobuta[1,2-c]pyrrole-1,3(2H)-dione (3ai)

According to the general procedure, 3ai was prepared from 1a (0.2 mmol, 1.0 equiv), 2z (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 49.8 mg (93%); white solid; R_f = 0.58 (pentane/EtOAc, 3:1); mp 170–172 °C.

IR (thin film): 3457, 2938, 1703, 1491, 1377, 1171, 1131, 766, 724, 691, 616 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.41 (t, J = 7.4 Hz, 1 H), 7.32 (d, J = 7.4 Hz, 2 H), 2.89 (d, J = 1.7 Hz, 2 H), 2.50 (s, 2 H), 2.41 (s, 2 H), 1.82 (d, J = 10.8 Hz, 1 H), 1.57 (d, J = 7.7 Hz, 2 H), 1.45 (d, J = 11.0 Hz, 1 H), 1.11 (dd, J = 7.6, 2.0 Hz, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.43, 132.12, 129.14, 128.57, 126.42, 45.61, 41.84, 39.11, 32.41, 26.87.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₇H₁₈NO₂: 268.1332; found: 268.1333.

(3aR,3bS,7aR,7bS)-2-Phenyloctahydro-1H-benzo[3,4]cyclo­buta[1,2-c]pyrrole-1,3(2H)-dione (3aj)

According to the general procedure, 3aj was prepared from 1a (0.2 mmol, 1.0 equiv), 2aa (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 49.8 mg (51%); white solid; R_f = 0.55 (pentane/EtOAc, 3:1); mp 125–127 °C.

IR (thin film): 2917, 2805, 1704, 1378, 1187, 1167, 742, 652, 529 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.53–7.49 (m, 2 H), 7.41 (ddd, J = 6.5, 3.9, 1.2 Hz, 1 H), 7.35–7.32 (m, 2 H), 3.52 (dd, J = 6.8, 4.0 Hz, 2 H), 3.07–2.97 (m, 2 H), 1.76–1.72 (m, 2 H), 1.64–1.51 (m, 4 H), 1.37–1.26 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.65, 132.16, 129.18, 128.55, 126.38, 41.66, 32.87, 22.22, 20.33.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₈NO₂: 256.1332; found: 256.1330.

(3aR,3bR,7aS,7bS)-2-Phenyloctahydro-1H-benzo[3,4]cyclo­buta[1,2-c]pyrrole-1,3(2H)-dione (3aj′)

According to the general procedure, 3aj′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2aa (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 49.8 mg (34%); white solid; R_f = 0.52 (pentane/EtOAc, 3:1); mp 116–118 °C.

IR (thin film): 2918, 2805, 1705, 1496, 1378, 1187, 1168, 742, 529 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.48 (m, 2 H), 7.43–7.38 (m, 1 H), 7.33–7.30 (m, 2 H), 3.19–3.18 (m, 2 H), 2.77–2.70 (m, 2 H), 1.97–1.90 (m, 2 H), 1.69–1.60 (m, 4 H), 1.51–1.42 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.30, 132.24, 129.15, 128.52, 126.45, 43.42, 36.18, 26.60, 20.47.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₈NO₂: 256.1332; found: 256.1331.

(3aR,3bS,8aR,8bS)-2-Phenyloctahydrocyclohepta[3,4]cyclobuta[1,2-c]pyrole-1,3(2H,3aH)-dione (3ak, 3ak′)

According to the general procedure, 3ak and 3ak′ were prepared from 1a (0.2 mmol, 1.0 equiv), 2ab (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 53 mg (98%); mixture of exo and endo diastereomers (1.2:1); white solid; R_f = 0.53 (pentane/EtOAc, 4:1); mp 105–117 °C.

IR (thin film): 3352, 2919, 1705, 1384, 1186, 1127, 736, 618, 537 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.49–7.45 (m, 4.4 H, 2 × 1.2 H, 2 × 1 H), 7.39–7.36 (m, 2.2 H, 1 × 1.2 H, 1 × 1 H), 7.31–7.29 (m, 4.4 H, 2 × 1.2 H, 2 × 1 H), 3.36–3.32 (m, 1 H), 3.06–2.92 (m, 3.6 H, 3 × 1.2 H), 2.72–2.60 (m, 3.2 H, 1 × 1.2 H, 2 × 1 H), 2.36–2.31 (m, 1 H), 2.05–1.97 (m, 3.2 H, 1 × 1.2 H, 2 × 1 H), 1.92–1.87 (m, 3.2 H, 1 × 1.2 H, 2 × 1 H), 1.81–1.66 (m, 4.8 H, 4 × 1.2 H), 1.59–1.42 (m, 6.4 H, 2 × 1.2 H, 4 × 1 H), 1.34–1.24 (m, 2 H, 2 × 1 H), 1.15–1.01 (m, 2.4 H, 2 × 1.2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.35, 178.02, 176.46, 132.12, 129.00, 128.94, 128.92, 128.30, 128.27, 126.36, 126.33, 46.72, 42.59, 41.71, 41.62, 41.20, 40.54, 39.47, 38.69, 32.24, 32.16, 31.19, 29.12, 28.80, 28.71, 28.11, 27.98, 24.68.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₇H₂₀NO₂: 270.1489; found: 270.1486.

(1S,5R,6S)-6-Decyl-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3al)

According to the general procedure, 3al′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2af (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 46 mg (73%); white solid; R_f = 0.44 (pentane/EtOAc, 3:1); mp 54–56 °C.

IR (thin film): 2922, 2850, 1699, 1498, 1383, 1169, 763, 695, 616 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.48 (m, 2 H), 7.42–7.38 (m, 1 H), 7.34–7.31 (m, 2 H), 3.35 (ddd, J = 10.6, 6.7, 4.1 Hz, 1 H), 3.07 (dd, J = 6.6, 4.6 Hz, 1 H), 2.61–2.53 (m, 1 H), 2.48–2.42 (m, 1 H), 2.34–2.26 (m, 1 H), 1.75–1.60 (m, 2 H), 1.31–1.28 (m, 16 H), 0.89 (t, J = 6.8 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.15, 178.09, 132.22, 129.15, 128.54, 126.45, 44.69, 38.49, 36.45, 35.96, 31.91, 29.61, 29.59, 29.53, 29.43, 29.33, 26.47, 22.69, 14.12.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₂H₃₂NO₂: 315.2428; found: 315.2426.

(1S,5R,6R)-6-Decyl-3-phenyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3al′)

According to the general procedure, 3al′ was prepared from 1a (0.2 mmol, 1.0 equiv), 2af (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 11.3 mg (18%); white solid; R_f = 0.39 (pentane/EtOAc, 3:1); mp 38–40 °C.

IR (thin film): 2923, 2851, 1699, 1498, 1383, 1170, 764, 696, 616 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.51–7.48 (m, 2 H), 7.42–7.39 (m, 1 H), 7.32–7.30 (m, 2 H), 3.53–3.49 (m, 1 H), 3.37–3.32 (m, 1 H), 2.92–2.82 (m, 2 H), 1.97–1.90 (m, 1 H), 1.73–1.69 (m, 1 H), 1.33–1.25 (m, 17 H), 0.88 (t, J = 6.8 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 179.37, 176.81, 132.21, 129.20, 128.60, 126.49, 42.29, 35.55, 34.72, 33.06, 31.90, 29.85, 29.59, 29.57, 29.52, 29.38, 29.32, 26.66, 22.68, 14.11.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₂H₃₂NO₂: 315.2428; found: 315.2424.

8-[(1S,5R,6S,7R)-7-Octyl-2,4-dioxo-3-phenyl-3-azabicyclo­[3.2.0]heptan-6-yl]octanoic Acid (3am)

According to the general procedure, 3am was prepared from 1a (0.2 mmol, 1.0 equiv), 2ag (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 71 mg (78%); white solid; R_f = 0.31 (pentane/EtOAc, 1:1); mp 52–54 °C.

IR (thin film): 3337, 2924, 2853, 1710, 1498, 1375, 1179, 758, 617, 536 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.52–7.49 (m, 2 H), 7.43–7.39 (m, 1 H), 7.33–7.30 (m, 2 H), 3.46 (dd, J = 10.1, 6.9 Hz, 1 H), 2.96 (dd, J = 6.7, 4.9 Hz, 1 H), 2.47–2.32 (m, 3 H), 2.19–2.13 (m, 1 H), 1.68–1.67 (m, 4 H), 1.43–1.28 (m, 22 H), 0.92–0.88 (m, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 178.63, 178.57, 176.94, 132.27, 129.13, 128.49, 126.48, 45.33, 41.97, 41.68, 39.64, 36.19, 33.81, 32.79, 31.86, 29.70, 29.51, 29.46, 29.24, 29.12, 29.03, 28.90, 26.99, 26.60, 24.61, 22.65, 14.07.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₈H₄₂NO₄: 456.3109; found: 456.3106.

6-Cyclohexyl-3-phenyl-3-azabicyclo[3.2.0]hept-6-ene-2,4-dione (3an)

According to the general procedure, 3an was prepared from 1a (0.2 mmol, 1.0 equiv), 2ai (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 34.4 mg (61%); white solid; R_f = 0.49 (pentane/EtOAc, 3:1); mp 86–88 °C.

IR (thin film): 2935, 1710, 1495, 1375, 1170, 839, 748, 690, 618 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.48–7.44 (m, 2 H), 7.40–7.36 (m, 1 H), 7.25–7.23 (m, 2 H), 6.12 (s, 1 H), 3.86 (d, J = 3.2 Hz, 1 H), 3.73 (d, J = 1.0 Hz, 1 H), 2.20 (t, J = 10.2 Hz, 1 H), 1.92–1.89 (m, 2 H), 1.76–1.63 (m, 2 H), 1.70–1.52 (m, 1 H), 1.33–1.24 (m, 5 H).

¹³C NMR (100 MHz, CDCl₃): δ = 174.72, 174.05, 158.55, 132.03, 129.05, 128.50, 127.56, 126.54, 47.44, 43.48, 38.68, 30.13, 29.63, 25.84, 25.53, 25.38.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₈H₂₀NO₂: 282.1489; found: 282.1487.

3-Phenyl-6-(trimethylsilyl)-3-azabicyclo[3.2.0]hept-6-ene-2,4-dione (3ao)

According to the general procedure, 3ao was prepared from 1a (0.2 mmol, 1.0 equiv), 2ah (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 40.8 mg (75%); white solid; R_f = 0.57 (pentane/EtOAc, 3:1); mp 104–106 °C.

IR (thin film): 2960, 1705, 1495, 1378, 1248, 1186, 1127, 965, 836, 743, 694 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.47–7.43 (m, 2 H), 7.39–7.34 (m, 1 H), 7.24–7.21 (m, 2 H), 6.86 (d, J = 0.9 Hz, 1 H), 3.97 (dd, J = 3.1, 0.9 Hz, 1 H), 3.86 (d, J = 3.1 Hz, 1 H), 0.17 (s, 9 H).

¹³C NMR (100 MHz, CDCl₃): δ = 174.13, 173.89, 160.31, 147.93, 132.12, 128.99, 128.42, 126.40, 48.29, 48.22, –2.42.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₈NO₂Si: 272.1102; found: 272.1101.

6-Butyl-3-phenyl-3-azabicyclo[3.2.0]hept-6-ene-2,4-dione (3ap)

According to the general procedure, 3ap was prepared from 1a (0.2 mmol, 1.0 equiv), 2aj (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 41 mg (80%); white solid; R_f = 0.52 (pentane/EtOAc, 3:1); mp 76–79 °C.

IR (thin film): 2930, 1771, 1711, 1498, 1371, 1171, 833, 746, 692, 611 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.48–7.44 (m, 2 H), 7.39–7.36 (m, 1 H), 7.26–7.23 (m, 2 H), 6.17 (d, J = 1.0 Hz, 1 H), 3.81 (d, J = 3.1 Hz, 1 H), 3.74 (d, J = 2.0 Hz, 1 H), 2.23 (t, J = 7.5 Hz, 2 H), 1.56–1.48 (m, 2 H), 1.40–1.31 (m, 2 H), 0.91 (t, J = 7.3 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 174.67, 173.75, 154.36, 132.00, 129.34, 129.02, 128.47, 126.53, 48.50, 43.78, 29.62, 28.04, 22.20, 13.66.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₈NO₂: 256.1332; found: 256.1332.

5-Phenyl-3b-(trimethylsilyl)hexahydro-1-phenylpyrro­[3′′,4′′:3′,4′]cyclobuta[1′,2′:3,4]cyclobuta[1,2-c]­pyrrole-1,3,4,6(5H)-tetraone (3aq)

According to the general procedure, 3aq was prepared from 1a (0.2 mmol, 1.0 equiv), 3ao (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 39.2 mg (44%); white solid; R_f = 0.28 (pentane/EtOAc, 3:1); mp 275–277 °C.

IR (thin film): 3367, 2887, 1715, 1499, 1378, 1171, 733, 615 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.59–7.43 (m, 6 H), 7.40–7.38 (m, 2 H), 7.31–7.29 (m, 2 H), 3.97 (t, J = 8.4 Hz, 1 H), 3.74 (d, J = 8.3 Hz, 1 H), 3.41–3.34 (m, 3 H), 0.08 (s, 9 H).

¹³C NMR (100 MHz, DMSO-d ₆): δ = 177.30, 177.09, 177.03, 176.89, 132.90, 132.72, 129.63, 129.49, 129.38, 128.95, 128.02, 127.08, 45.10, 43.07, 42.86, 39.90, 37.85, –3.63.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₅H₂₅N₂O₄Si: 445.1578; found: 445.1572.

3b-Butyl-5-phenylhexahydro-1-phenylpyrro[3′′,4′′:3′,4′]cyclo­buta[1′,2′:3,4]cyclobuta[1,2-c]pyrrole-1,3,4,6(5H)tetraone (3ar)

According to the general procedure, 3ar was prepared from 1a (0.2 mmol, 1.0 equiv), 3ap (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 55.8 mg (65%); white solid; R_f = 0.25 (pentane/EtOAc, 3:1); mp 267–269 °C.

IR (thin film): 3373, 2870, 1713, 1497, 1377, 1175, 730, 616 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.54–7.50 (m, 4 H), 7.46–7.43 (m, 2 H), 7.32–7.29 (m, 4 H), 3.70 (d, J = 5.7 Hz, 2 H), 3.55 (d, J = 5.7 Hz, 2 H), 3.15 (s, 1 H), 1.63–1.51 (m, 4 H), 1.27–1.20 (m, 2 H), 0.86 (t, J = 7.3 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 175.78, 174.44, 131.61, 129.36, 129.00, 126.18, 53.09, 49.35, 44.27, 43.03, 32.94, 25.49, 23.18, 13.63.

ESI-HRMS: m/z [M + H]⁺ calcd for C₂₆H₂₅N₂O₄: 429.1809; found: 429.1804.

(1S,5R,6S)-3-Benzyl-6-propionyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3as)

According to the general procedure, 3as was prepared from 1b (0.2 mmol, 1.0 equiv), 2ac (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 23.9 mg (44%); white solid; R_f = 0.49 (pentane/EtOAc, 3:1); mp 72–74 °C.

IR (thin film): 2938, 1703, 1392, 1344, 1166, 1098, 702, 618, 536 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.39 (m, 2 H), 7.35–7.29 (m, 3 H), 4.71 (s, 2 H), 3.52 (dd, J = 6.7, 4.7 Hz, 1 H), 3.29–3.17 (m, 2 H), 2.74 (ddd, J = 12.9, 10.7, 6.9 Hz, 1 H), 2.54–2.42 (m, 2 H), 2.34–2.27 (m, 1 H), 1.10 (t, J = 7.3 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 207.77, 178.51, 177.64, 135.73, 128.77, 128.72, 128.08, 45.13, 42.68, 40.41, 35.76, 33.70, 25.29, 7.68.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₈NO₃: 272.1281; found: 272.1279.

(1S,5R,6R)-3-Benzyl-6-propionyl-3-azabicyclo[3.2.0]heptane-2,4-dione (3as′)

According to the general procedure, 3as′ was prepared from 1b (0.2 mmol, 1.0 equiv), 2ac (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 14 mg (26%); white solid; R_f = 0.42 (pentane/EtOAc, 3:1); mp 73–75 °C.

IR (thin film): 2938, 1703, 1392, 1345, 1167, 1099, 702, 618, 536 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.39 (dd, J = 7.8, 1.4 Hz, 2 H), 7.35–7.29 (m, 3 H), 4.71 (s, 2 H), 3.52 (dd, J = 6.5, 4.7 Hz, 1 H), 3.29–3.17 (m, 2 H), 2.74 (ddd, J = 12.8, 10.7, 6.8 Hz, 1 H), 2.54–2.42 (m, 2 H), 2.34–2.27 (m, 1 H), 1.10 (t, J = 7.3 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 207.71, 178.45, 177.58, 135.67, 128.70, 128.64, 128.00, 45.06, 42.60, 40.34, 35.69, 33.62, 25.23, 7.63.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₈NO₃: 272.1281; found: 272.1279.

(1S,5R,6S)-3-Benzyl-6-(methylsulfonyl)-3-azabicyclo[3.2.0]heptane-2,4-dione (3at)

According to the general procedure, 3at was prepared from 1b (0.2 mmol, 1.0 equiv), 2ad (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 33 mg (56%); white solid; R_f = 0.35 (pentane/EtOAc, 3:1); mp 100–102 °C.

IR (thin film): 2935, 1701, 1398, 1342, 1162, 982, 708, 628, 541 cm^–1.

¹H NMR (400 MHz, DMSO-d ₆): δ = 7.36–7.32 (m, 2 H), 7.30–7.26 (m, 3 H), 4.62 (s, 2 H), 4.16–4.11 (m, 1 H), 3.64 (dd, J = 7.1, 4.5 Hz, 1 H), 3.40–3.34 (m, 1 H), 3.03 (s, 3 H), 2.86 (ddd, J = 13.1, 11.0, 6.2 Hz, 1 H), 2.40 (ddd, J = 13.6, 9.3, 4.6 Hz, 1 H).

¹³C NMR (100 MHz, DMSO-d ₆): δ = 178.36, 176.19, 136.38, 129.02, 127.94, 127.90, 55.19, 42.38, 39.76, 38.00, 35.76, 23.62.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₄H₁₆NO₄S: 294.0795; found: 294.0797.

(3aS,3bS,6aS,6bS)-5-Benzylhexahydro-4H-furo[2′,3′:3,4]cyclo­buta[1,2-c]pyrrole-4,6(5H)-dione (3au)

According to the general procedure, 3au was prepared from 1b (0.2 mmol, 1.0 equiv), 2ae (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 31 mg (60%); white solid; R_f = 0.42 (pentane/EtOAc, 3:1); mp 73–75 °C.

IR (thin film): 2941, 2820, 1711, 1495, 1380, 1166, 749, 721, 696, 617, 532 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.40–7.37 (m, 2 H), 7.34–7.26 (m, 3 H), 4.69 (s, 2 H), 4.62 (dd, J = 5.3, 1.2 Hz, 1 H), 4.30–4.26 (m, 1 H), 3.93–3.87 (m, 1 H), 3.14–3.10 (m, 2 H), 2.80 (dd, J = 6.5, 3.1 Hz, 1 H), 2.02–1.88 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 177.94, 176.03, 135.74, 128.68, 128.58, 127.97, 76.69, 67.23, 46.90, 43.98, 42.63, 40.95, 31.28.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₆NO₃: 258.1125; found: 258.1123.

(3aR,3bR,6aS,6bS)-2,5-Dimethyltetrahydrocyclobuta[1,2-c:3,4-c′]-dipyrrole-1,3,4,6(2H,5H)-tetraone (3av)

According to the general procedure, 3av was prepared from 1d (0.2 mmol, 1.0 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 44 mg (99%); white solid; R_f = 0.22 (pentane/EtOAc, 3:1); mp >270 °C.

IR (thin film): 2980, 1692, 1435, 1379, 1283, 1131, 977, 789, 739, 654 cm^–1.

¹H NMR (400 MHz, CD₃CN): δ = 3.28 (s, 4 H), 2.94 (s, 6 H).

¹³C NMR (100 MHz, CD₃CN): δ = 176.93, 42.10, 25.57.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₀H₁₁N₂O₄: 223.0714; found: 223.0712.

(3aR,3bR,6aS,6bS)-2,5-Dibutyltetrahydrocyclobuta[1,2-c:3,-4-c′]-dipyrrole-1,3,4,6(2H,5H)-tetraone (3aw)

According to the general procedure, 3aw was prepared from 1e (0.2 mmol, 1.0 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 60.8 mg (99%); white solid; R_f = 0.2 (pentane/EtOAc, 3:1); mp >270 °C.

IR (thin film): 2970, 1770, 1700, 1405, 1352, 1136, 988, 760 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 3.60 (t, J = 7.4 Hz, 4 H), 3.38 (s, 4 H), 1.63–1.56 (m, 4 H), 1.32 (dt, J = 14.7, 7.4 Hz, 4 H), 0.94 (t, J = 7.3 Hz, 6 H).

¹³C NMR (100 MHz, CDCl₃): δ = 174.97, 41.50, 39.48, 29.71, 20.14, 13.74.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₂₃N₂O₄: 307.1653; found: 307.1652

(3aR,3bR,6aS,6bS)-Tetrahydrocyclobuta[1,2-c:3,4-c′]dipyrrole-1,3,4,6(2H,5H)-tetraone (3ax)

According to the general procedure, 3ax was prepared from 1f (0.2 mmol, 1.0 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 37 mg (95%); off-white solid; R_f = 0.3 (pentane/EtOAc, 1:1); mp >270 °C.

IR (thin film): 3150, 3096, 1766, 1710, 1320, 1216, 835, 746, 636 cm^–1.

¹H NMR (400, MHz, DMSO-d ₆): δ = 11.65 (s, 2 H), 3.29 (s, 4 H).

¹³C NMR (100, MHz, DMSO-d ₆): δ = 177.77, 42.53.

ESI-HRMS: m/z [M + H]⁺ calcd for C₈H₇N₂O₄: 195.0401; found: 195.0400.

(1S,9R)-7-Azatricyclo[5.2.1.03,9]decane-8,10-dione (3ay)

According to the general procedure, 3ay was prepared from 1k (0.2 mmol, 1.0 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 24 mg (72%); off-white solid; R_f = 0.7 (pentane/EtOAc, 3:1); mp 63–65 °C.

IR (thin film): 2932, 1771, 1700, 1445, 1350, 1055, 1015 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 3.87 (dd, J = 13.3, 5.9 Hz, 1 H), 3.68–3.58 (m, 2 H), 3.18–3.14 (m, 1 H), 3.02–2.93 (m, 2 H), 2.12–1.99 (m, 1 H), 1.95–1.89 (m, 1 H), 1.83–1.76 (m, 1 H), 1.67–1.59 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 187.02, 181.45, 45.55, 38.17, 32.89, 29.65, 27.70, 27.29, 23.79.

ESI-HRMS: m/z [M + H]⁺ calcd for C₉H₁₂NO₂: 166.0863; found: 166.0862

3-Acetyl-4-(2-oxopropyl)-1-phenylpyrrolidine-2,5-dione (3az)

According to the general procedure, 3az was prepared from 1a (0.2 mmol, 1.0 equiv), 2ak (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 23 mg (42%); white solid; R_f = 0.62 (pentane/EtOAc, 3:1); mp 122–125 °C.

IR (thin film): 2945, 2915, 1708, 1390, 1341, 1159, 981, 815, 702, 541 cm^–1.

¹H NMR (400 MHz, CDCl₃): δ = 7.50–7.46 (dd, J = 10.4, 4.8 Hz, 2 H), 7.43–7.39 (m, 1 H), 7.31–7.29 (m, 2 H), 3.92 (d, J = 5.7 Hz, 1 H), 3.68 (td, J = 5.8, 3.6 Hz, 1 H), 3.26 (dd, J = 19.1, 5.9 Hz, 1 H), 2.97 (dd, J = 19.1, 3.5 Hz, 1 H), 2.56 (s, 3 H), 2.20 (s, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 206.38, 200.05, 176.70, 171.07, 131.78, 129.20, 128.85, 126.64, 59.14, 42.17, 36.98, 30.60, 29.62.

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₅H₁₆NO₄: 274.1074; found: 274.1073.

(Z)-9-Hydroxy-2-phenyl-3a,6,7,8-tetrahydro-1H-cycloocta[c]pyrrole-1,3,5(2H,4H)-trione (3aaa)

According to the general procedure, 3aaa was prepared from 1a (0.2 mmol, 1.0 equiv), 2al (0.2 mmol, 1.2 equiv), and [Ir(dF(CF₃)ppy]₂(phpzpy)]PF₆ (0.001 mmol, 0.5 mol%).

Yield: 23.5 mg (41%); white solid; R_f = 0.48 (pentane/EtOAc, 3:1); mp 150–152 °C.

IR (thin film): 3321, 2825, 1710, 1499, 1370, 1146, 746, 682, 620, 518 cm^–1.

¹H NMR (600 MHz, CDCl₃): δ = 11.43 (s, 1 H), 7.50–7.48 (m, 2 H), 7.41 (t, J = 7.5 Hz, 1 H), 7.36 (d, J = 7.6 Hz, 2 H), 3.55 (dd, J = 12.8, 4.6 Hz, 1 H), 3.08 (dd, J = 11.0, 4.5 Hz, 1 H), 2.79–2.71 (m, 2 H), 2.48–2.45 (m, 2 H), 2.20 (td, J = 13.3, 5.3 Hz, 1 H), 2.08–2.02 (ddd, J = 11.6, 10.9, 4.7 Hz, 1 H), 1.89–1.82 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 210.01, 174.12, 172.72, 171.04, 131.11, 129.15, 128.66, 126.14, 99.56, 49.38, 39.52, 39.16, 31.39, 20.06.

DEPT (135°, CDCl₃): δ = 129.15 (CH), 128.66 (CH), 126.14 (CH), 49.38 (CH₂), 39.48 (CH₂), 39.13 (CH), 31.36 (CH₂), 20.03 (CH₂).

ESI-HRMS: m/z [M + H]⁺ calcd for C₁₆H₁₆NO₄: 286.1074; found: 286.1071.

X-ray Crystallographic Data of 3ai and 3w′

CCDC 2022116 (3ai) and 2022112 (3w′) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures.

Conflict of Interest

The authors declare no conflict of interest.

• References

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Corresponding Author

Publication History

Received: 18 March 2021

Accepted after revision: 12 April 2021

Accepted Manuscript online:
12 April 2021

Article published online:
12 May 2021

© 2021. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany

• References

• 1a Bach T, Krüger C, Harms K. Synthesis 2000; 305
  Thieme Connect
• 1b Petz S, Wanner KT. Eur. J. Org. Chem. 2013; 4017
  Crossref
• 1c Homon AA, Hryshchuk OV, Trofymchuk S, Michurin O, Kuchkovska Y, Radchenko DS, Grygorenko OO. Eur. J. Org. Chem. 2018; 5596
  Crossref
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For intramolecular metal-catalyzed cyclizations into 3-azabicyclo[3.2.0]heptanes, see:
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  Crossref
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For intramolecular [2+2]-photochemical cycloaddition leading to 3-azabicyclo[3.2.0] heptanes, see:
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  CrossrefSearch in Google Scholar
• 7b See ref. 1a
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• 7g Ischay MA, Lu Z, Yoon TP. J. Am. Chem. Soc. 2010; 132: 8572
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• 8b Andre V, Gras M, Awada H, Guillot R, Robin S, Aitken DJ. Tetrahedron 2013; 69: 3571
  CrossrefSearch in Google Scholar
• 8c Andre V, Vidal A, Ollivier J, Robin S, Aitken DJ. Tetrahedron Lett. 2011; 52: 1253
  CrossrefSearch in Google Scholar
• 8d Booker-Milburn KI, Gulten S, Sharpe A. Chem. Commun. 1997; 1385
  Crossref
• 8e Booker-Milburn KI, Cowell JK, Jiménez FD, Sharpe A, White AJ. Tetrahedron 1999; 55: 5875
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• 8f Booker-Milburn KI, Wood PM, Dainty RF, Urquhart MW, White AJ, Lyon HJ, Charmant JP. H. Org. Lett. 2002; 4: 1487
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• 8g Elliott LD, Knowles JP, Koovits PJ, Maskill KG, Ralph MJ, Lejeune G, Edwards LJ, Robinson RI, Clemens IR, Cox B, Pascoe DD, Koch G, Eberle M, Berry MB, Booker-Milburn KI. Chem. Eur. J. 2014; 20: 15226
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  Crossref
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  CrossrefPubMedSearch in Google Scholar
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  CrossrefPubMedSearch in Google Scholar
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  CrossrefPubMedSearch in Google Scholar
• 15e Strieth-Kalthoff F, Henkel C, Teders M, Kahnt A, Knolle W, Gómez-Suárez A, Dirian K, Alex W, Bergander K, Daniliuc CG, Abel B, Guldi DM, Glorius F. Chem 2019; 5: 2183
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• Supplementary Material