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DOI: 10.1055/a-1526-7839
Facile Synthesis of Polysubstituted 2-Pyrones via TfOH-Mediated Ring Expansion of 2-Acylcyclopropane-1-carboxylates
This work was sponsored by the Shanghai Pujiang Program (Grant No. 19PJ1402700), the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, the National Natural Science Foundation of China (No. 22071059), and the East China Normal University (ECNU).
Abstract
A facile route to polysubstituted 2-pyrones from readily available 2-acylcyclopropane-1-aryl-1-carboxylates mediated by TfOH is reported. The strongly donating 1-aryl group is important for directing the C–C bond cleavage of the donor-acceptor cyclopropane ring, which then leads to the formation of the 2-pyrone ring through lactonization.
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Key words
carbocycles - heterocycles - ring expansion - Brønsted acid - synthetic methods - cyclopropanes - 2-pyronesBiographical Sketches
Jiru Shao received her B.S. in chemistry from the University of Shanghai for Science and Technology in 2019. She began her M.S. studies at East China Normal University (ECNU) in 2019, working in the laboratory of Prof. Sunewang R. Wang. Her research focuses on the stereoselective transformation of donor–acceptor cyclopropanes with two vicinal acceptors.
Caiyun An received her B.S. in chemistry from Shanxi Normal University in 2019. She began her M.S. studies at ECNU in 2020, working in the laboratory of Prof. Sunewang R. Wang. Her research focuses on the synthesis of aromatic compounds from cyclopropanes.
Sunewang R. Wang received his B.S. in applied chemistry from Shanghai Jiao Tong University in 2006 and his M.S. in organic chemistry at Shanghai Institute of Organic Chemistry, CAS, under the direction of Prof. Yong Tang in 2009. He then joined the group of Prof. Zuowei Xie in the Chinese University of Hong Kong, where he received his Ph.D. in 2012. After postdoctoral works with Prof. Alexander T. Radosevich at Pennsylvania State University and with Prof. Carlos A. Guerrero at the University of California, San Diego, he joined Shenzhen University in 2014 as an associate Professor. During 2015–2017, he worked with Prof. Holger Braunschweig at Julius-Maximilians-Universität of Würzburg as an Alexander von Humboldt fellow. In 2018, he joined Chang-Kung Chuang Institute at ECNU as a full professor. His research focuses on ring-strained molecules and boron- and phosphorus-containing functional compounds.
The 2-pyrone unit is an important unsaturated heterocyclic core that has been widely found in many bioactive natural products and pharmaceuticals (Figure [1]).[1] 2-Pyrones have been also extensively utilized as valuable synthetic intermediate in organic synthesis.[2] Thus, many protocols have been developed for 2-pyrones either through traditional cyclization of unsaturated δ-keto esters and the equivalent compounds[1f] [3] or by transition-metal-catalyzed reactions.[4] However, these methods suffer from disadvantages, such as strong basic conditions or limited structural diversity of 2-pyrones. Consequently, the development of more synthetic methods for 2-pyrones remains highly demanding.
Vicinal donor–acceptor-substituted cyclopropanes (DACs) are versatile 1,3-dipolar synthons for the synthesis of various acyclic and (poly)cyclic compounds.[5] Although DACs with two geminal acceptors are more popularly investigated and used in organic synthesis, we recently found that the synergistic activation of the two vicinal acceptors in DACs can also facilitate the ring-opening transformation of the cyclopropane ring.[6] Importantly, a δ-keto ester unit embedded in the DACs with two vicinal acceptors, that is, the ketone and ester groups, may be converted to the 2-pyrone skeleton if the cyclopropyl C–C bond between them is selectively cleaved (Scheme [1, a]). Although selective scission of such cyclopropyl C–C bond substituted by two vicinal acceptors is electronically unfavored, several elegant pioneering works on conversions of DACs with two vicinal acceptors to the 2-pyrones derivatives have been documented.[7]
In 2009, You’s group reported the ring expansion of 2-acyl-1-formylcyclopropanes 1 to 3,4-dihydro-2-pyrones 2 via umpolung of the formyl group with the N-heterocyclic carbene catalyst (Scheme [1, b]).[7a] Recently, an AlCl3-mediated ring expansion transformation of trans-2-aroyl-3-arylcyclopropane-1,1-dicarboxylates 3 to 3,5,6-trisubstituted 2-pyrones 4 has been reported by Srinivasan’s group (Scheme [1, c]).[7b] An unusual 1,2-shift of the aroyl group in the zwitterionic intermediate via a conventional ring-opening of DACs is critical for the success of this transformation. Later, a domino reaction between 2-acyl-1-chlorocyclopropane-1-carboxylates and amines to give 2-pyrones 6 was presented by Zhu and Gong (Scheme [1, d]).[7c] In this reaction, the in situ substitution of the chloro group by amines gives 2-acyl-1-aminocyclopropane-1-carboxylates 5, in which the strongly donating amino group initiates and controls the ring-opening reaction. Unfortunately, only 3,6-disubstituted 2-pyrone derivatives are accessible by this method. In our studies on the selective transformations of DACs synthesized by Kukhtin–Ramirez cyclopropanation of activated alkenes,[6] [8] we envisaged that a strongly donating aryl group may replace the amino group in the work of Zhu and Gong to direct the selective cleavage of the desired cyclopropyl C–C bond for the formation of 2-pyrones (Scheme [1, e]). Notably, the convenient availability of these tetrasubstituted DACs is more attractive for this transformation. Herein, we report an efficient and mild TfOH-promoted synthesis of polysubstituted 2-pyrones 8 from readily available DACs 7.
At the outset of our studies, p-methoxyphenyl DAC 7a with the benzoyl group residing cis to the ester group was first subjected to the optimal conditions with the use of 3.5 equivalents of TfOH in our previous study;[6] and pleasingly, 2-pyrone 8a was isolated in 95% yield (Scheme [2]). Consistent to the facile ring-opening reaction of the cyclopropyl ketones activated by electron-rich aromatic rings via the ring-opened 1,3-zwitterionic intermediates,[9] trans-7a with both carbonyls disposed trans to each other underwent the same ring expansion transformation to 8a as well, albeit in a slightly lower yield. Notably, another pair of diastereomers 7b and trans-7b gave 2-pyrone 8b in a close yield (Scheme [2]). These results demonstrate that the strongly donating p-methoxyphenyl group predominantly direct the cyclopropane ring opening over that through synergistic activation of the two vicinal carbonyl groups, which led to the formation of 3- or 5-ylidenebutenolides.[6]
As shown in Scheme [3, a] series of the pure cis-diastereomers of Kukhtin–Ramirez cyclopropanes 7 were then studied to elucidate the substrate scope. While the reaction of 4-chlorophenyl DAC 7c afforded 2-pyrone 8c in a comparable yield to that of 7b, a low yield (53%) was obtained from that of the 4-bromophenyl one 7d. Fortunately, after optimization of reaction conditions with 7d as the model substrate, we found that, heating the DCM solution of 7d at 45 °C in a sealed flask with 2.0 equivalents of TfOH (condition B in Scheme [3]) could improve the product yield to 87%. Under such conditions, DACs with electron-deficient aryls such as 4-trifluoromethylphenyl 7e and 4-nitrophenyl 7f reacted smoothly to give the corresponding 2-pyrones in excellent yields. 2-Bromophenyl DAC 7g is suitable for the reaction as well, which afforded 8g in 89% yield. The aroyl group with the aromatic ring substituted by electron-withdrawing groups is beneficial for the reaction, whereas electron-rich aroyl groups retard the reaction (8h vs 8i). 2-Pyrone 8j with the 3-(o-iodophenyl) substituent was readily obtained in 86% yield from DAC 7j. The reaction of DACs with heteroaryl substituents, such as 7k, is not as effective as the phenyl ones, which only gave a moderate yield of the product.
Notably, the 4- or 6-alkylated 2-pyrones are also accessible by this ring expansion (Scheme [3]). For example, 4-butyl-2-pyrone 8l was obtained in 61% yield from 7l under condition B. With respect to the 6-alkyl substituents, 2-pyrones with the primary 8m, secondary 8n, and tertiary 8o acyclic alkyl groups, and the cyclic alkyl group 8p were obtained in moderate to good yields from the corresponding DACs, respectively. Interestingly, 3,6-diaryl-2-pyrone 8q was isolated in 63% yield from 7q as well.
In contrast to the wide range for the 3-substituents (R1 in 7) and the 2-acyl groups (R2 in 7), the aryl donors (Ar in 7) are fairly limited to the p-methoxyphenyl group and those more donating, such as 2,3-dihydrobenzofuranyl 7r and 2,4-dimethoxyphenyl 7s. 2-Methoxyphenyl or 3-bromo-4-methoxyphenyl groups are not electron-rich enough for this transformation, which gave the 3-ylidenebutenolides as reported previously.[6]
In addition to the structural confirmation of 8a referring to the literature,[1f] the structure of 8n was further confirmed by single-crystal X-ray crystallography. Moreover, a 1 mmol scale reaction of 7j to 8j was examined and no evident loss of yield was observed (Scheme [3]).
Since both diastereomers are reactive for this ring expansion, a one-pot procedure of the current ring expansion coupled with the Kukhtin–Ramirez cyclopropanation of chalcone 9a was tried, which gave 8a in 81% isolated yield (Scheme [4]).
Moreover, the haloaryl substituents in the obtained 2-pyrones allow for further annulation to give the π-extended 2-pyrones.[10] For example, dibenzo[f,h]isocoumarin 11 was readily prepared in 87% yield from 8g via the Pd-catalyzed intramolecular C–Br/C–H cross-coupling reaction (Scheme [5]).[11] On the other hand, benzo[h]coumarin 13 was easily synthesized via TfOH-promoted intramolecular hydroarylation reaction of 12,[12] which was obtained by Pd/Cu catalyzed Sonogashira coupling reaction of 8j with phenylacetylene. Notably, 2-pyrone replaced fluorene-type product 14 was formed in 13% yield as a minor product in the latter TfOH-promoted cyclization (Scheme [5]).
In summary, by the use of the strongly electron-donating 1-aryl donors, facile TfOH-promoted ring expansion of easily accessible 2-acylcyclopropane-1-aryl-1-carboxylates to 3,4,6-trisubstituted 2-pyrones has been realized for the first time. While both aryl and alkyl substituents on the 4- and 6-sites of 2-pyrones are viable, the 3-substituents are only limited to the p-methoxyphenyl and the more electron-donating aryl groups. Efforts to overcome this limitation are in progress in our laboratory.
All reactions were carried out under dry argon atmosphere. All solvents and reagents were obtained from commercial sources and were purified according to standard procedures. All glassware were oven-dried at 80 °C over 4 h before use. NMR spectra were recorded on a Bruker 500 MHz (1H: 500 MHz, 13C: 125 MHz and 19F: 470 MHz) or Bruker 600 MHz (1H: 600 MHz, 13C: 150 MHz) in CDCl3 at 298 K. 1H and 13C NMR spectra in CDCl3 were internally referenced to the residual proton (1H) of the solvent signal at 7.26 ppm and the carbon nuclei (13C) of the solvent signal at 77.16 ppm, respectively. 19F NMR spectra were referenced to external standard CFCl3 at 0.00 ppm. The data are reported in ppm with standard abbreviations for multiplicity, coupling constant(s) in hertz (Hz), and integration. High-resolution mass spectra were determined on a Bruker MAXIS impact mass spectrometer (ESI-TOF). Melting points were obtained by SGW X4 Micro Melting Point Apparatus. The single-crystal X-ray diffraction data were collected on a Rigaku XtaLAB P2000 CCD diffractometer. Except α,β-unsaturated ketone 9l, which was prepared by the Wittig reaction,[13] other α,β-unsaturated ketones used in this study were prepared by the aldol condensation.[14] Methyl α-keto esters 10 were prepared according to the procedures reported in the literature.[15]
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Vicinal Donor–Acceptor-Substituted Cyclopropanes; 7a, Typical Procedure A (TP A)[8b]
To a stirred solution of α,β-unsaturated ketone 9a (417.3 mg, 2.004 mmol, 1.0 equiv) and methyl p-methoxybenzoylformate (10a; 505.0 mg, 2.6 mmol, 1.2 equiv) in DCM (6.0 mL) cooled at –78 °C, was added dropwise P(NMe2)3 (0.47 mL, 2.6 mmol, 1.3 equiv) via a microsyringe. After complete addition of P(NMe2)3, the solution was slowly warmed to rt and vigorously stirred at rt. Upon completion of the reaction as monitored by TLC, the mixture was concentrated under vacuum and separated by flash chromatography on silica gel eluting with PE/DCM/Et2O (20:2:1 to 14:2:1, v/v/v) to afford the products 7a; yield: 241.4 mg (31%) and trans-7a; yield: 260.3 mg (34%).
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Vicinal Donor–Acceptor-Substituted Cyclopropanes; 7e, Typical Procedure B (TP B)[8a]
To a solution of 10a (776.8 mg, 4.000 mmol, 2.0 equiv) and dimethyl phosphite (0.37 mL, 4.0 mmol, 2.0 equiv) in THF (6.0 mL) cooled at –15 °C, was added dropwise 1.0 M LiHMDS in THF (4.0 mL, 4.0 mmol, 2.0 equiv) at –15 °C. After an additional 10 min, a solution of 9e (552.7 mg, 2.001 mmol, 1.0 equiv) in THF (3.0 mL) was added dropwise. The reaction mixture was stirred at the same temperature and monitored by TLC. Once 9e was completely consumed (ca. 2 h), the mixture was quenched with sat. aq NH4Cl. After warming to rt, the mixture was extracted with EtOAc. The combined organics were then washed with brine, dried (anhyd Na2SO4), filtered, and concentrated under vacuum. The residue was purified by flash chromatography on silica gel eluting with PE/EtOAc (15:1 to 4:1, v/v) to give the product 7e; yield: 400.8 mg (44%).
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Methyl 2-Benzoyl-1-(4-methoxyphenyl)-3-phenylcyclopropane-1-carboxylate (7a)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 241.4 mg (31% based on 9a: 417.3 mg, 2.004 mmol); colorless oil.
1H NMR (600 MHz, CDCl3): δ = 8.08 (d, J = 7.2 Hz, 2 H), 7.61 (t, J = 7.2 Hz, 1 H), 7.51 (t, J = 7.2 Hz, 2 H), 7.17–7.12 (m, 5 H), 6.94–6.92 (m, 2 H), 6.74 (d, J = 8.4 Hz, 2 H), 3.77 (d, J = 6.6 Hz, 1 H), 3.75 (s, 3 H), 3.68 (d, J = 6.6 Hz, 1 H), 3.65 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 196.0, 170.9, 159.3, 137.7, 135.2, 133.4, 131.8, 128.9, 128.4, 128.2, 128.1, 126.9, 126.3, 114.0, 55.3, 52.9, 47.5, 37.4, 37.2.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H22O4Na: 409.1410; found: 409.1413.
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trans-Methyl 2-Benzoyl-1-(4-methoxyphenyl)-3-phenylcyclopropane-1-carboxylate (trans-7a)
Prepared by TP A: purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 260.3 mg (34% based on 9a: 417.3 mg, 2.004 mmol); white solid; mp 160.7–161.2 °C.
1H NMR (500 MHz, CDCl3): δ = 8.13 (d, J = 7.5 Hz, 2 H), 7.62 (t, J = 7.5 Hz, 1 H), 7.53 (t, J = 7.0 Hz, 2 H), 7.37–7.32 (m, 4 H), 7.28–7.27 (m, 1 H), 7.17 (d, J = 8.0 Hz, 2 H), 6.76 (d, J = 8.0 Hz, 2 H), 4.41 (d, J = 7.0 Hz, 1 H), 3.96 (d, J = 7.0 Hz, 1 H), 3.75 (s, 3 H), 3.42 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 194.3, 170.3, 159.2, 138.0, 135.3, 133.5, 131.2, 128.9, 128.8, 128.6, 128.5, 127.4, 126.8, 114.0, 55.2, 52.9, 48.4, 35.7, 35.5.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H22O4Na: 409.1410; found: 409.1413.
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Methyl 2-Benzoyl-1-(4-methoxyphenyl)-3-(p-tolyl)cyclopropane-1-carboxylate (7b)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 189.4 mg (47% based on 9b: 222.4 mg, 1.000 mmol); colorless oil.
1H NMR (500 MHz, CDCl3): δ = 8.07 (d, J = 7.5 Hz, 2 H), 7.60 (t, J = 7.5 Hz, 1 H), 7.50 (t, J = 7.5 Hz, 2 H), 7.13 (d, J = 8.5 Hz, 2 H), 6.95 (d, J = 7.5 Hz, 2 H), 6.80 (d, J = 8.0 Hz, 2 H), 6.75 (d, J = 8.5 Hz, 2 H), 3.76 (s, 3 H), 3.73 (d, J = 7.0 Hz, 1 H), 3.64 (s, 3 H), 3.63 (d, J = 7.0 Hz, 1 H), 2.25 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 196.2, 171.0, 159.2, 137.7, 136.5, 133.4, 132.1, 131.9, 128.9, 128.8, 128.4, 128.1, 126.5, 114.0, 55.3, 52.9, 47.4, 37.4, 37.3, 21.2.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C26H24O4Na: 423.1567; found: 423.1562.
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trans-Methyl 2-Benzoyl-1-(4-methoxyphenyl)-3-(p-tolyl)cyclopropane-1-carboxylate (trans-7b)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 119.2 mg (30% based on 9b: 222.4 mg, 1.000 mmol); white solid; mp 159.3–159.8 °C.
1H NMR (500 MHz, CDCl3): δ = 8.12 (d, J = 7.5 Hz, 2 H), 7.61 (t, J = 7.5 Hz, 1 H), 7.52 (t, J = 7.5 Hz, 2 H), 7.24 (d, J = 8.0 Hz, 2 H), 7.17–7.12 (m, 4 H), 6.76 (d, J = 8.5 Hz, 2 H), 4.37 (d, J = 7.0 Hz, 1 H), 3.91 (d, J = 7.0 Hz, 1 H), 3,74 (s, 3 H), 3.44 (s, 3 H), 2.33 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 194.4, 170.4, 159.2, 138.1, 137.0, 133.4, 132.2, 131.3, 129.2, 128.9, 128.7, 128.6, 126.9, 113.9, 55.2, 52.9, 48.4, 35.8, 35.4, 21.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C26H24O4Na: 423.1567; found: 423.1562.
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Methyl 2-Benzoyl-3-(4-chlorophenyl)-1-(4-methoxyphenyl)cyclopropane-1-carboxylate (7c)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 239.5 mg (57% based on 9c: 241.8 mg, 0.996 mmol); white solid; mp 117.8–118.4 °C.
1H NMR (500 MHz, CDCl3): δ = 8.07 (d, J = 8.0 Hz, 2 H), 7.62 (t, J = 7.5 Hz, 1 H), 7.52 (t, J = 7.5 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 4 H), 6.84 (d, J = 8.5 Hz, 1 H), 6.76 (d, J = 8.5 Hz, 1 H), 3.76 (s, 3 H), 3.73 (d, J = 6.5 Hz, 1 H), 3.63 (br s, 4 H).
13C NMR (125 MHz, CDCl3): δ = 195.6, 170.6, 159.4, 137.5, 133.9, 133.6, 132.8, 131.7, 129.5, 128.9, 128.4, 128.3, 125.9, 114.1, 55.3, 52.9, 47.5, 37.3, 36.5.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H21ClO4Na: 443.1021; found: 443.1013.
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Methyl 2-Benzoyl-3-(4-bromophenyl)-1-(4-methoxyphenyl)cyclopropane-1-carboxylate (7d)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 266.1 mg (57% based on 9d: 287.7 mg, 1.002 mmol); white solid; mp 130.3–130.9 °C.
1H NMR (500 MHz, CDCl3): δ = 8.06 (d, J = 7.5 Hz, 2 H), 7.62 (t, J = 7.5 Hz, 1 H), 7.52 (t, J = 7.5 Hz, 2 H), 7.27 (d, J = 8.0 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 6.79–6.76 (m, 4 H), 3.77 (s, 3 H), 3.72 (d, J = 6.0 Hz, 1 H), 3.63 (br s, 4 H).
13C NMR (125 MHz, CDCl3): δ = 195.6, 170.6, 159.4, 137.5, 134.4, 133.6, 131.7, 131.3, 129.9, 128.9, 128.4, 125.9, 120.9, 114.2, 55.3, 52.9, 47.5, 37.3, 36.6.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H21BrO4Na: 487.0515; found: 487.0516.
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Methyl 2-Benzoyl-1-(4-methoxyphenyl)-3-[4-(trifluoromethyl)phenyl]cyclopropane-1-carboxylate (7e)
Prepared by TP B; purified by silica gel column chromatography using PE/EtOAc (15:1 to 4:1) as eluent; yield: 400.8 mg (44% based on 9e: 552.7 mg, 2.001 mmol); white solid; mp 99.5–100.5 °C.
1H NMR (500 MHz, CDCl3): δ = 8.07 (d, J = 7.5 Hz, 2 H), 7.63 (t, J = 7.5 Hz, 1 H), 7.53 (t, J = 7.5 Hz, 2 H), 7.40 (d, J = 7.5 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 7.01 (d, J = 8.0 Hz, 2 H), 6.77 (d, J = 8.5 Hz, 2 H), 3.80 (d, J = 6.5 Hz, 1 H), 3.76 (s, 3 H), 3.71 (d, J = 6.5 Hz, 1 H), 3.64 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.5, 170.5, 159.4, 139.5, 137.3, 133.7, 131.7, 128.99 (CF, 2 J C,F = 33.1 Hz), 128.97, 128.44, 128.41, 125.5, 125.0 (CF, 3 J C,F = 3.1 Hz), 124.2 (CF, 1 J C,F = 269.8 Hz), 114.2, 55.3, 53.1, 47.9, 37.4, 36.7.
19F NMR (470 MHz, CDCl3): δ = –62.4.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C26H21F3O4Na: 477.1284; found: 477.1282.
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Methyl 2-Benzoyl-1-(4-methoxyphenyl)-3-(4-nitrophenyl)cyclopropane-1-carboxylate (7f)
Prepared by TP B; purified by silica gel column chromatography using PE/EtOAc (20:1 to 6:1) as eluent; yield: 367.5 mg (42% based on 9f: 506.7 mg, 2.001 mmol); white solid; mp 82.5–83.4 °C.
1H NMR (500 MHz, CDCl3): δ = 8.08 (d, J = 7.0 Hz, 2 H), 8.01 (d, J = 8.5 Hz, 2 H), 7.64 (t, J = 7.5 Hz, 1 H), 7.54 (t, J = 7.0 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 7.07 (d, J = 8.5 Hz, 2 H), 6.77 (d, J = 8.5 Hz, 2 H), 3.86 (d, J = 6.5 Hz, 1 H), 3.77 (d, J = 6.5 Hz, 1 H), 3.76 (s, 3 H), 3.64 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.0, 170.1, 159.6, 146.9, 143.4, 137.3, 133.8, 131.5, 129.0, 128.9, 128.4, 125.2, 123.3, 114.4, 55.4, 53.1, 48.4, 37.4, 36.4.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H21NO6Na: 454.1261; found: 454.1254.
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Methyl 2-Benzoyl-3-(2-bromophenyl)-1-(4-methoxyphenyl)cyclopropane-1-carboxylate (7g)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (10:1:1 to 7:1:1) as eluent; yield: 453.5 mg (24% based on 9g: 1.150 g, 4.005 mmol); light yellow solid; mp 110.3–110.9 °C.
1H NMR (500 MHz, CDCl3): δ = 8.11 (d, J = 7.5 Hz, 2 H), 7.62 (t, J = 7.5 Hz, 1 H), 7.56–7.51 (m, 3 H), 7.19 (d, J = 8.5 Hz, 2 H), 7.02–7.00 (m, 2 H), 6.71–6.67 (m, 3 H), 4.07 (d, J = 7.0 Hz, 1 H), 3.77 (d, J = 7.0 Hz, 1 H), 3.72 (s, 3 H), 3.63 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 195.3, 170.6, 159.1, 137.5, 134.7, 133.5, 133.0, 131.2, 128.93, 128.89, 128.6, 128.5, 128.1, 127.0, 126.7, 126.3, 113.8, 55.2, 52.8, 46.1, 37.7, 35.9.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H21BrO4Na: 487.0515; found: 487.0516.
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Methyl 1-(4-Methoxyphenyl)-2-(4-nitrobenzoyl)-3-phenylcyclopropane-1-carboxylate (7h)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (10:1:1 to 7:1:1) as eluent; yield: 189.4 mg (44% based on 9h: 253.0 mg, 0.999 mmol); white solid; mp 165.2–165.7 °C.
1H NMR (500 MHz, CDCl3): δ = 8.36 (d, J = 8.5 Hz, 2 H), 8.21 (d, J = 8.5 Hz, 1 H), 7.20–7.15 (m, 3 H), 7.11 (d, J = 8.5 Hz, 2 H), 6.92–6.91 (m, 2 H), 6.75 (d, J = 8.5 Hz, 2 H), 3.78 (d, J = 6.5 Hz, 1 H), 3.75 (s, 3 H), 3.65 (s, 3 H), 3.62 (d, J = 7.0 Hz, 1 H).
13C NMR (150 MHz, CDCl3): δ = 194.9, 170.6, 159.4, 150.5, 142.1, 134.5, 131.8, 129.4, 128.3, 128.2, 127.3, 125.6, 124.2, 114.1, 55.3, 53.1, 48.1, 37.9, 37.7.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H21NO6Na: 454.1261; found: 454.1261.
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Methyl 1-(4-Methoxyphenyl)-2-(4-methylbenzoyl)-3-phenylcyclopropane-1-carboxylate (7i)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 14:2:1) as eluent; yield: 196.3 mg (49% based on 9i: 224.5 mg, 1.010 mmol); white solid; mp 130.9–131.0 °C.
1H NMR (500 MHz, CDCl3): δ = 7.98 (d, J = 8.0 Hz, 2 H), 7.30 (d, J = 8.0 Hz, 2 H), 7.13–7.11 (m, 5 H), 6.93–6.92 (m, 2 H), 6.74 (d, J = 8.5 Hz, 2 H), 3.76 (d, J = 6.5 Hz, 1 H), 3.74 (s, 3 H), 3.66 (d, J = 6.5 Hz, 1 H), 3.64 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.5, 170.9, 159.2, 144.3, 135.3, 135.2, 131.8, 129.6, 128.6, 128.2, 128.1, 126.9, 126.4, 113.9, 55.3, 52.9, 47.4, 37.3, 37.2, 21.8.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C26H24O4Na: 423.1567; found: 423.1560.
#
Methyl 2-(2-Iodobenzoyl)-1-(4-methoxyphenyl)-3-phenylcyclopropane-1-carboxylate (7j)
Prepared by TP B; purified by silica gel column chromatography using PE/DCM/Et2O (10:1:1 to 7:1:1) as eluent; yield: 223.9 mg (22% based on 9j: 674.4 mg, 2.018 mmol); colorless oil.
1H NMR (600 MHz, CDCl3): δ = 7.96 (dd, J = 7.8, 1.2 Hz, 1 H), 7.61 (dd, J = 7.8, 1.2 Hz, 1 H), 7.48 (dd, J = 7.8, 1.2 Hz, 1 H), 7.18 (dd, J = 7.8, 1.8 Hz, 1 H), 7.14–7.12 (m, 3 H), 7.09 (d, J = 9.0 Hz, 2 H), 6.92–6.90 (m, 2 H), 6.70 (d, J = 9.0 Hz, 2 H), 3.81 (d, J = 6.6 Hz, 1 H), 3.73 (s, 3 H), 3.71 (s, 3 H), 3.55 (d, J = 6.6 Hz, 1 H).
13C NMR (125 MHz, CDCl3): δ = 200.6, 170.4, 159.2, 144.9, 140.6, 134.7, 132.1, 131.7, 128.8, 128.4, 128.3, 128.1, 126.9, 125.7, 113.9, 91.4, 55.3, 53.1, 49.6, 39.6, 38.7.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H21IO4Na: 535.0377; found: 535.0367.
#
Methyl 1-(4-Methoxyphenyl)-2-phenyl-3-(thiophene-2-carbonyl)cyclopropane-1-carboxylate (7k)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (10:1:1 to 6:1:1) as eluent; yield: 206.7 mg (53% based on 9k: 214.3 mg, 1.000 mmol); light yellow solid; mp 134.5–135.4 °C.
1H NMR (500 MHz, CDCl3): δ = 7.92 (d, J = 3.5 Hz, 1 H), 7.70 (d, J = 5.0 Hz, 1 H), 7.19 (t, J = 4.5 Hz, 1 H), 7.14–7.12 (m, 5 H), 6.93–6.91 (m, 2 H), 6.74 (d, J = 8.5 Hz, 2 H), 3.78 (d, J = 6.0 Hz, 1 H), 3.75 (s, 3 H), 3.65 (s, 3 H), 3.57 (d, J = 6.5 Hz, 1 H).
13C NMR (125 MHz, CDCl3): δ = 188.1, 170.6, 159.3, 144.6, 135.1, 134.2, 132.4, 131.8, 128.5, 128.2, 128.1, 126.9, 126.2, 114.0, 55.3, 52.9, 47.4, 37.9, 37.1.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C23H20SO4Na: 415.0975; found: 415.0970.
#
Methyl 2-Benzoyl-3-butyl-1-(4-methoxyphenyl)cyclopropane-1-carboxylate (7l)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (10:1:1 to 6:1:1) as eluent; yield: 265.1 mg (48% based on 9l: 285.0 mg, 1.514 mmol); colorless oil.
1H NMR (500 MHz, CDCl3): δ = 8.06 (d, J = 7.5 Hz, 2 H), 7.60 (t, J = 7.5 Hz, 1 H), 7.51 (t, J = 7.0 Hz, 2 H), 7.35 (d, J = 8.5 Hz, 2 H), 6.90 (d, J = 8.5 Hz, 2 H), 3.82 (s, 3 H), 3.57 (s, 3 H), 3.03 (d, J = 6.0 Hz, 1 H), 2.55–2.51 (m, 1 H), 1.55–1.50 (m, 1 H), 1.44–1.34 (m, 2 H), 1.29–1.22 (m, 2 H), 0.92–0.85 (m, 1 H), 0.81 (t, J = 7.5 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 196.9, 171.2, 159.4, 137.9, 133.2, 131.0, 128.8, 128.3, 127.6, 114.2, 55.4, 52.6, 46.3, 36.8, 34.0, 31.2, 28.9, 22.5, 14.1.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C23H26O4Na: 389.1723; found: 389.1719.
#
Methyl 2-Butyryl-1-(4-methoxyphenyl)-3-phenylcyclopropane-1-carboxylate (7m)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 10:2:1) as eluent; yield: 160.7 mg (20% based on 9m: 405.1 mg, 2.325 mmol); colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.11 (br s, 3 H), 7.05 (d, J = 8.0 Hz, 2 H), 6.83 (br s, 2 H), 6.71 (d, J = 8.0 Hz, 2 H), 3.73 (s, 3 H), 3.64 (s, 3 H), 3.55 (d, J = 6.0 Hz, 1 H), 3.02 (d, J = 6.0 Hz, 1 H), 2.80–2.68 (m, 2 H), 1.76–1.72 (m, 2 H), 0.99 (t, J = 8.0 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 206.4, 170.6, 159.2, 135.2, 131.8, 128.1, 128.0, 126.8, 126.1, 113.9, 55.3, 52.8, 47.8, 46.5, 39.5, 36.6, 17.5, 13.9.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C22H24O4Na: 375.1567; found: 375.1570.
#
Methyl 2-Isobutyryl-1-(4-methoxyphenyl)-3-phenylcyclopropane-1-carboxylate (7n)
Prepared by TP B; purified by silica gel column chromatography using PE/EtOAc (20:1 to 10:1) as eluent; yield: 270.0 mg (76% based on 9n: 176.3 mg, 1.012 mmol); colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.12–7.11 (m, 3 H), 7.06 (d, J = 8.5 Hz, 2 H), 6.85–6.84 (m, 2 H), 6.71 (d, J = 8.5 Hz, 2 H), 3.73 (s, 3 H), 3.64 (s, 3 H), 3.53 (d, J = 6.5 Hz, 1 H), 3.08 (d, J = 6.0 Hz, 1 H), 2.95 (hept, J = 7.0 Hz, 1 H), 1.30 (d, J = 7.0 Hz, 3 H), 1.21 (d, J = 7.0 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 209.9, 170.6, 159.2, 135.3, 131.7, 128.1, 128.0, 126.8, 126.1, 113.9, 55.3, 52.8, 47.9, 42.3, 38.0, 36.8, 18.3, 18.0.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C22H24O4Na: 375.1567; found: 375.1574.
#
Methyl 1-(4-Methoxyphenyl)-2-phenyl-3-pivaloylcyclopropane-1-carboxylate (7o)
Prepared by TP B; purified by silica gel column chromatography using PE/DCM/Et2O (20:2:1 to 12:2:1) as eluent; yield: 450.4 mg (68% based on 9o: 339.1 mg, 1.801 mmol); white solid; mp 89.7–90.5 °C.
1H NMR (500 MHz, CDCl3): δ = 7.12–7.11 (m, 3 H), 7.06 (d, J = 8.5 Hz, 2 H), 6.87–6.86 (m, 2 H), 6.70 (d, J = 8.5 Hz, 2 H), 3.73 (s, 3 H), 3.65 (s, 3 H), 3.52 (d, J = 6.5 Hz, 1 H), 3.26 (d, J = 6.5 Hz, 1 H), 1.32 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 211.0, 170.6, 159.2, 135.4, 131.6, 128.1, 128.1, 126.7, 126.4, 114.0, 55.3, 52.7, 48.1, 44.7, 37.0, 35.1, 26.4.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C23H26NO4Na: 389.1723; found: 389.1723.
#
Methyl 2-(Cyclohexanecarbonyl)-1-(4-methoxyphenyl)-3-phenylcyclopropane-1-carboxylate (7p)
Prepared by TP B; purified by silica gel column chromatography using PE/EtOAc (20:1 to 10:1) as eluent; yield: 338.4 mg (72% based on 9p: 257.1 mg, 1.200 mmol); white solid; mp 92.0–92.9 °C.
1H NMR (500 MHz, CDCl3): δ = 7.12–7.11 (m, 3 H), 7.06 (d, J = 8.5 Hz, 2 H), 6.85–6.84 (m, 2 H), 6.71 (d, J = 8.0 Hz, 2 H), 3.73 (s, 3 H), 3.64 (s, 3 H), 3.52 (d, J = 6.5 Hz, 1 H), 3.09 (d, J = 6.5 Hz, 1 H), 2.71–2.66 (m, 1 H), 2.13–2.11 (m, 1 H), 1.96–1.94 (m, 1 H), 1.88–1.81 (m, 2 H), 1.72–1.70 (m, 1 H), 1.49–1.24 (m, 5 H).
13C NMR (125 MHz, CDCl3): δ = 209.2, 170.6, 159.2, 135.3, 131.7, 128.1, 128.0, 126.7, 126.2, 113.9, 55.3, 52.8, 52.1, 48.0, 38.2, 36.8, 28.6, 28.2, 26.0, 25.9, 25.7.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H28O4Na: 415.1880; found: 415.1878.
#
Methyl 2-Benzoyl-1-(4-methoxyphenyl)cyclopropane-1-carboxylate (7q)
Prepared by TP A; purified by silica gel column chromatography using PE/DCM/Et2O (10:1:1 to 7:1:1) as eluent; yield: 117.5 mg (19% based on 9q: 264.7 mg, 2.003 mmol); colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.97 (d, J = 7.5 Hz, 2 H), 7.59 (t, J = 7.5 Hz, 1 H), 7.48 (t, J = 7.5 Hz, 2 H), 7.03 (d, J = 8.5 Hz, 2 H), 6.71 (d, J = 8.0 Hz, 2 H), 3.75–3.72 (m, 7 H), 2.36–2.33 (m, 1 H), 1.93–1.90 (m, 1 H).
13C NMR (125 MHz, CDCl3): δ = 194.2, 173.6, 159.0, 138.1, 133.3, 131.9, 128.8, 128.4, 125.8, 113.6, 55.1, 53.2, 39.6, 32.9, 19.9.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C19H18O4Na: 333.1097; found: 333.1084.
#
Methyl 1-(2,3-Dihydrobenzofuran-5-yl)-2-(4-methylbenzoyl)-3-phenylcyclopropane-1-carboxylate (7r)
Prepared by TP B; purified by silica gel column chromatography using PE/EtOAc (20:1 to 10:1) as eluent; yield: 377.3 mg (82% based on 9r: 249.4 mg, 1.122 mmol); white solid; mp 146.0–146.7 °C.
1H NMR (600 MHz, CDCl3): δ = 7.98 (d, J = 8.4 Hz, 2 H), 7.30 (d, J = 7.8 Hz, 2 H), 7.17–7.12 (m, 3 H), 7.02 (br s, 1 H), 6.94–6.93 (m, 3 H), 6.61 (d, J = 8.4 Hz, 1 H), 4.52 (t, J = 8.4 Hz, 2 H), 3.73 (d, J = 6.6 Hz, 1 H), 3.65 (s, 3 H), 3.64 (d, J = 6.6 Hz, 1 H), 3.14–3.03 (m, 2 H), 2.43 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.6, 171.0, 159.8, 144.3, 135.4, 135.1, 130.6, 129.5, 128.5, 128.2, 128.1, 127.33, 127.29, 126.8, 126.2, 109.1, 71.4, 52.8, 47.7, 37.4, 37.3, 29.6, 21.8.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C27H24O4Na: 435.1567; found: 435.1564.
#
Methyl 2-Benzoyl-1-(2,4-dimethoxyphenyl)-3-phenylcyclopropane-1-carboxylate (7s)
Prepared by TP B; purified by silica gel column chromatography using PE/EtOAc (20:1 to 9:1) as eluent; yield: 139.6 mg (17% based on 9s: 416.7 mg, 2.001 mmol); colorless oil; mp 146.0–146.7 °C.
1H NMR (500 MHz, CDCl3): δ = 8.07 (d, J = 8.0 Hz, 2 H), 7.57 (t, J = 7.0 Hz, 1 H), 7.47 (t, J = 7.5 Hz, 2 H), 7.25 (s, 1 H), 7.11–7.10 (m, 3 H), 6.94–6.93 (m, 2 H), 6.42 (dd, J = 8.0, 1.5 Hz, 1 H), 6.18 (d, J = 1.5 Hz, 1 H), 3.86 (d, J = 7.5 Hz, 1 H), 3.75 (s, 3 H), 3.61 (s, 3 H), 3.60 (d, J = 7.0 Hz, 1 H), 3.40 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.4, 171.1, 160.8, 159.6, 137.3, 135.6, 133.3, 131.9, 128.8, 128.6, 127.8, 127.7, 126.6, 116.0, 104.2, 98.7, 55.4, 55.3, 52.7, 42.5, 37.9, 36.6.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C26H24O5Na: 439.1516; found: 439.1504.
#
2-Pyrones 8; 8a, Typical Procedure C
Conditions A: To a dry Schlenk tube equipped with a high vacuum valve and a stir bar was added 7a (57.9 mg, 0.150 mmol, 1.0 equiv) and dissolved in DCM (2.0 mL). TfOH (47.0 μL, 0.525 mmol, 3.5 equiv) was added dropwise via a microsyringe to the solution at 0 °C. The reaction mixture was stirred overnight at rt, which was then neutralized with saturated NaHCO3. The mixture was extracted with DCM (3 × 20 mL). The combined organics were washed with brine, dried (anhyd Na2SO4), filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel eluting with PE/EtOAc (15:1 to 10:1, v/v) to afford 2-pyrone 8a as yellow-green crystals; yield: 50.4 mg (95%).
#
2-Pyrones 8; 8d, Typical Procedure D
Conditions B: To a dry Schlenk tube equipped with a high vacuum valve and a stir bar was added 7d (93.6 mg, 0.201 mmol, 1.0 equiv) and dissolved in DCM (2.0 mL). TfOH (36.0 μL, 0.400 mmol, 2.0 equiv) was added dropwise via a microsyringe to the solution at 0 °C. The reaction mixture was warmed to rt and then heated at 45 °C until the reaction was completed as monitored by TLC, which was then cooled to rt and neutralized with sat. aq NaHCO3. The mixture was extracted with DCM (3 × 20 mL). The combined organics were washed with brine, dried (anhyd Na2SO4), filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel eluting with PE/DCM/Et2O (12:1:1 to 6:1:1, v/v/v) to afford 2-pyrone 8d as yellow crystals; yield: 75.8 mg (87%).
#
3-(4-Methoxyphenyl)-4,6-diphenyl-2H-pyran-2-one (8a)
Known compound.[1f] Prepared by TP C; purified by silica gel column chromatography using PE/EtOAc (15:1 to 10:1) as eluent; yield: 50.4 mg (95% based on 7a: 57.9 mg, 0.150 mmol); yellow-green crystals; mp 194.5–195.3 °C.
1H NMR (500 MHz, CDCl3): δ = 7.91–7.90 (m, 2 H), 7.47–7.46 (m, 3 H), 7.28–7.27 (m, 3 H), 7.19–7.18 (m, 2 H), 7.13 (d, J = 9.0 Hz, 2 H), 6.83 (s, 1 H), 6.77 (d, J = 8.5 Hz, 2 H), 3.77 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 163.1, 159.2, 158.0, 152.2, 138.2, 132.3, 131.6, 130.8, 129.1, 128.8, 128.7, 128.6, 126.1, 125.7, 123.0, 113.6, 105.2, 55.3.
#
3-(4-Methoxyphenyl)-6-phenyl-4-(p-tolyl)-2H-pyran-2-one (8b)
Prepared by TP C. Purified by silica gel column chromatography using PE/EtOAc (30/1 to 15/1) as eluent; yield: 43.8 mg (80% based on 7b: 60.1 mg, 0.150 mmol); yellow-green crystals; mp 187.5–188.0 °C.
1H NMR (500 MHz, CDCl3): δ = 7.90–7.89 (m, 2 H), 7.47–7.46 (m, 3 H), 7.14 (d, J = 9.0 Hz, 2 H), 7.08 (s, 4 H), 6.82 (s, 1 H), 6.78 (d, J = 8.5 Hz, 2 H), 3.78 (s, 3 H), 2.33 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 163.2, 159.1, 157.9, 152.2, 138.9, 135.2, 132.3, 131.7, 130.7, 129.3, 129.0, 128.8, 126.3, 125.6, 122.6, 113.7, 105.3, 55.3, 21.4.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H20O3Na: 391.1305; found: 391.1299.
#
4-(4-Chlorophenyl)-3-(4-methoxyphenyl)-6-phenyl-2H-pyran-2-one (8c)
Prepared by TP C; purified by silica gel column chromatography using PE/EtOAc (40:1 to 20:1) as eluent; yield: 47.6 mg (82% based on 7c: 63.9 mg, 0.152 mmol); yellow-green crystals; mp 216.9–217.5 °C.
1H NMR (500 MHz, CDCl3): δ = 7.90–7.89 (m, 2 H), 7.48–7.47 (m, 3 H), 7.25 (d, J = 8.5 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 7.11 (d, J = 8.5 Hz, 2 H), 6.79 (d, J = 8.5 Hz, 2 H), 6.77 (s, 1 H), 3.79 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 162.9, 159.3, 158.3, 150.9, 136.6, 134.9, 132.2, 131.4, 130.9, 130.2, 129.1, 128.9, 125.7, 123.1, 113.8, 104.7, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H17ClO3Na: 411.0758; found: 411.0754.
#
4-(4-Bromophenyl)-3-(4-methoxyphenyl)-6-phenyl-2H-pyran-2-one (8d)
Prepared by TP D; purified by silica gel column chromatography using PE/DCM/Et2O (12:1:1 to 6:1:1) as eluent; yield: 75.8 mg (87% based on 7d: 93.6 mg, 0.201 mmol); yellow crystals; mp 232.2–232.5 °C.
1H NMR (500 MHz, CDCl3): δ = 7.90–7.89 (m, 2 H), 7.48–7.47 (m, 3 H), 7.41 (d, J = 8.0 Hz, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 7.06 (d, J = 8.0 Hz, 2 H), 6.79 (d, J = 8.5 Hz, 2 H), 6.76 (s, 1 H), 3.79 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 162.9, 159.3, 158.3, 150.9, 137.1, 132.2, 131.9, 131.4, 130.9, 130.5, 129.1, 125.69, 125.67, 123.14, 123.10, 113.8, 104.6, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H17BrO3Na: 455.0253; found: 455.0251.
#
3-(4-Methoxyphenyl)-6-phenyl-4-[4-(trifluoromethyl)phenyl]-2H-pyran-2-one (8e)
Prepared by TP D. Purified by silica gel column chromatography using PE/EtOAc (15:1 to 7:1) as eluent; yield: 74.7 mg (88% based on 7e: 91.2 mg, 0.201 mmol); yellow-green crystals; mp 179.0–179.9 °C.
1H NMR (500 MHz, CDCl3): δ = 7.90–7.89 (m, 2 H), 7.55 (d, J = 8.5 Hz, 2 H), 7.49–7.48 (m, 3 H), 7.31 (d, J = 8.0 Hz, 2 H), 7.11 (d, J = 8.5 Hz, 2 H), 6.79–6.78 (m, 3 H), 3.78 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 162.7, 159.4, 158.4, 150.5, 141.9, 132.2, 131.3, 130.9, 130.6 (CF, 2 J C,F = 32.0 Hz), 129.2, 129.1, 125.7, 125.6 (CF, 3 J C,F = 3.8 Hz), 125.3, 123.9 (CF, 1 J C,F = 271.2 Hz), 123.6, 113.8, 104.5, 55.3.
19F NMR (470 MHz, CDCl3): δ = –62.7.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H17F3O3Na: 445.1022; found: 445.1018.
#
3-(4-Methoxyphenyl)-4-(4-nitrophenyl)-6-phenyl-2H-pyran-2-one (8f)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (15:1 to 8:1) as eluent; yield: 67.8 mg (85% based on 7f: 86.2 mg, 0.200 mmol); yellow crystals; mp 183.7–184.5 °C.
1H NMR (600 MHz, CDCl3): δ = 8.14 (d, J = 8.4 Hz, 2 H), 7.91–7.89 (m, 2 H), 7.49–7.48 (m, 3 H), 7.37 (d, J = 9.0 Hz, 2 H), 7.09(d, J = 9.0 Hz, 2 H), 6.78 (d, J = 9.0 Hz, 2 H), 6.77 (s, 1 H), 3.78 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 162.4, 159.6, 158.8, 149.7, 147.6, 144.8, 132.2, 131.2, 131.1, 129.9, 129.2, 125.7, 125.0, 123.9, 123.8, 113.9, 103.9, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H17NO5Na: 422.0999; found: 422.0998.
#
4-(2-Bromophenyl)-3-(4-methoxyphenyl)-6-phenyl-2H-pyran-2-one (8g)
Prepared by TP D; purified by silica gel column chromatography using PE/DCM/Et2O (12:1:1 to 6:1:1) as eluent; yield: 77.1 mg (89% based on 7g: 93.3 mg, 0.200 mmol); light yellow crystals; mp 159.7–161.2 °C.
1H NMR (500 MHz, CDCl3): δ = 7.90–7.88 (m, 2 H), 7.59 (d, J = 8.0 Hz, 1 H), 7.47–7.46 (m, 3 H), 7.20–7.13 (m, 4 H), 6.99 (d, J = 7.0 Hz, 1 H), 6.73 (d, J = 9.0 Hz, 2 H), 6.71 (s, 1 H), 3.74 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 162.9, 159.3, 157.6, 151.9, 139.3, 133.2, 131.7, 131.5, 130.8, 130.5, 129.9, 129.1, 127.6, 125.7, 125.6, 124.5, 121.9, 113.5, 105.3, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H17BrO3Na: 455.0253; found: 455.0250.
#
3-(4-Methoxyphenyl)-6-(4-nitrophenyl)-4-phenyl-2H-pyran-2-one (8h)
Prepared by TP C; purified by silica gel column chromatography using PE/EtOAc (15:1 to 8:1) as eluent; yield: 56.0 mg (93% based on 7h: 65.0 mg, 0.151 mmol); orange crystals; mp 193.4–194.0 °C.
1H NMR (500 MHz, CDCl3): δ = 8.32 (d, J = 8.5 Hz, 2 H), 8.06 (d, J = 9.0 Hz, 2 H), 7.31–7.30 (m, 3 H), 7.20–7.18 (m, 2 H), 7.14 (d, J = 9.0 Hz, 2 H), 6.97 (s, 1 H), 6.78 (d, J = 8.5 Hz, 2 H), 3.78 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 162.3, 159.5, 155.0, 151.4, 148.8, 137.6, 137.1, 132.2, 129.1, 128.8, 126.3, 125.4, 125.0, 124.4, 113.7, 107.8, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H17NO5Na: 422.0999; found: 422.0989.
#
3-(4-Methoxyphenyl)-4-phenyl-6-(p-tolyl)-2H-pyran-2-one (8i)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (20:1 to 15:1) as eluent; yield: 47.0 mg (63% based on 7i: 80.7 mg, 0.202 mmol); yellow-green crystals; mp 206.6–207.4 °C.
1H NMR (500 MHz, CDCl3): δ = 7.79 (d, J = 7.5 Hz, 2 H), 7.28–7.26 (m, 5 H), 7.19–7.18 (m, 2 H), 7.12 (d, J = 8.5 Hz, 2 H), 6.78–6.77 (m, 2 H), 6.76 (s, 1 H), 3.77 (s, 3 H), 2.41 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 163.3, 159.1, 158.3, 152.4, 141.3, 138.4, 132.3, 129.8, 128.8, 128.7, 128.6, 126.2, 125.6, 122.5, 113.6, 104.6, 55.3, 21.6.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H20O3Na: 391.1305; found: 391.1295.
#
6-(2-Iodophenyl)-3-(4-methoxyphenyl)-4-phenyl-2H-pyran-2-one (8j)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (15:1 to 8:1) as eluent; yield: 83.1 mg (87% based on 7j: 102.7 mg, 0.200 mmol); 442.8 mg (85% based on 7j: 553.1 mg, 1.08 mmol); yellow crystals; mp 201.2–201.7 °C.
1H NMR (600 MHz, CDCl3): δ = 7.99 (d, J = 7.8 Hz, 1 H), 7.62 (dd, J = 7.8, 1.8 Hz, 1 H), 7.45 (t, J = 7.8 Hz, 1 H), 7.28–7.27 (m, 3 H), 7.21–7.20 (m, 2 H), 7.17 (d, J = 9.0 Hz, 2 H), 7.14 (td, J = 7.8, 1.8 Hz, 1 H), 6.79 (d, J = 9.0 Hz, 2 H), 6.72 (s, 1 H), 3.78 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 163.1, 159.4, 159.3, 151.2, 140.7, 137.8, 137.3, 132.3, 131.5, 130.6, 129.0, 128.8, 128.6, 128.5, 125.8, 123.4, 113.7, 110.4, 95.9, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H17IO3Na: 503.0115; found: 503.0117.
#
3-(4-Methoxyphenyl)-4-phenyl-6-(thiophen-2-yl)-2H-pyran-2-one (8k)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (20:1 to 7:1) as eluent; yield: 31.9 mg (44% based on 7k: 78.7 mg, 0.201 mmol); yellow crystals; mp 191.6–192.3 °C.
1H NMR (600 MHz, CDCl3): δ = 7.66 (d, J = 3.0 Hz, 1 H), 7.45 (d, J = 4.2 Hz, 1 H), 7.28–7.27 (m, 3 H), 7.17–7.16 (m, 2 H), 7.13–7.10 (m, 3 H), 6.76 (d, J = 8.4 Hz, 2 H), 6.65 (s, 1 H), 3.77 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 162.5, 159.1, 153.8, 152.3, 138.0, 135.3, 132.3, 128.8, 128.7, 128.6, 128.5, 127.3, 126.1, 122.4, 113.6, 104.3, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C22H16O3SNa: 383.0712; found: 383.0702.
#
4-Butyl-3-(4-methoxyphenyl)-6-phenyl-2H-pyran-2-one (8l)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (10:1 to 7:1) as eluent; yield: 41.3 mg (61% based on 7l: 74.1 mg, 0.202 mmol); light yellow-green crystals; mp 86.5–86.9 °C.
1H NMR (500 MHz, CDCl3): δ = 7.88–7.87 (m, 2 H), 7.46–7.45 (m, 3 H), 7.23 (d, J = 8.5 Hz, 2 H), 6.97 (d, J = 8.5 Hz, 2 H), 6.66 (s, 1 H), 3.85 (s, 3 H), 2.40 (t, J = 8.0 Hz, 2 H), 1.56–1.50 (m, 2 H), 1.32–1.25 (m, 2 H), 0.84 (t, J = 7.5 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 163.0, 159.4, 158.0, 155.5, 131.7, 131.3, 130.6, 129.0, 126.3, 125.6, 124.1, 114.0, 104.0, 55.4, 33.2, 31.5, 22.6, 13.9.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C22H12O3Na: 357.1461; found: 357.1460.
#
3-(4-Methoxyphenyl)-4-phenyl-6-propyl-2H-pyran-2-one (8m)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (15:1 to 10:1) as eluent; yield: 40.3 mg (62% based on 7m: 72.1 mg, 0.205 mmol); colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.24–7.21 (m, 3 H), 7.11–7.10 (m, 2 H), 7.07 (d, J = 8.5 Hz, 2 H), 6.75 (d, J = 9.0 Hz, 2 H), 6.14 (s, 1 H), 3.76 (s, 3 H), 2.53 (t, J = 7.5 Hz, 2 H), 1.81–1.73 (m, 2 H), 1.02 (t, J = 7.0 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 164.0, 163.3, 159.0, 152.1, 138.0, 132.2, 128.8, 128.6, 128.4, 126.2, 121.8, 113.6, 106.6, 55.3, 35.8, 20.5, 13.7.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C21H20O3Na: 343.1305; found: 343.1314.
#
6-Isopropyl-3-(4-methoxyphenyl)-4-phenyl-2H-pyran-2-one (8n)[16]
Prepared by TP C; purified by silica gel column chromatography using PE/EtOAc (15:1 to 10:1) as eluent; yield: 34.9 mg (73% based on 7n: 52.8 mg, 0.150 mmol); light yellow crystals; mp 136.7–137.5 °C.
1H NMR (500 MHz, CDCl3): δ = 7.24–7.23 (m, 3 H), 7.12–7.11 (m, 2 H), 7.07 (d, J = 8.5 Hz, 2 H), 6.75 (d, J = 8.5 Hz, 2 H), 6.13 (s, 1 H), 3.76 (s, 3 H), 2.85–2.79 (m, 1 H), 1.31 (d, J = 7.0 Hz, 6 H).
13C NMR (125 MHz, CDCl3): δ = 168.1, 163.9, 159.0, 152.3, 138.2, 132.2, 128.8, 128.6, 128.4, 126.3, 122.0, 113.6, 104.3, 55.3, 32.8, 20.4.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C21H20O3Na: 343.1305; found: 343.1306.
#
6-(tert-Butyl)-3-(4-methoxyphenyl)-4-phenyl-2H-pyran-2-one (8o)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (20:1 to 15:1) as eluent; yield: 54.2 mg (81% based on 7o: 73.7 mg, 0.201 mmol); light yellow crystals; mp 150.6–151.3 °C.
1H NMR (500 MHz, CDCl3): δ = 7.25–7.24 (m, 3 H), 7.12–7.11 (m, 2 H), 7.08 (d, J = 8.5 Hz, 2 H), 6.75 (d, J = 8.5 Hz, 2 H), 6.17 (s, 1 H), 3.76 (s, 3 H), 1.35 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 170.2, 163.7, 159.0, 152.1, 138.4, 132.2, 128.8, 128.5, 128.4, 126.3, 121.8, 113.6, 103.3, 55.3, 36.2, 28.1.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C22H22O3Na: 357.1461; found: 357.1453.
#
6-Cyclohexyl-3-(4-methoxyphenyl)-4-phenyl-2H-pyran-2-one (8p)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (15:1 to 10:1) as eluent; yield: 49.5 mg (68% based on 7p: 78.7 mg, 0.201 mmol); light yellow crystals; mp 191.7–192.5 °C.
1H NMR (500 MHz, CDCl3): δ = 7.24–7.23 (m, 3 H), 7.11–7.10 (m, 2 H), 7.07 (d, J = 8.5 Hz, 2 H), 6.74 (d, J = 8.5 Hz, 2 H), 6.10 (s, 1 H), 3.76 (s, 3 H), 2.50–2.45 (m, 1 H), 2.07–2.04 (m, 2 H), 1.87–1.85 (m, 2 H), 1.75–1.73 (m, 1 H), 1.51–1.44 (m, 2 H), 1.40–1.32 (m, 2 H), 1.28–1.20 (m, 1 H).
13C NMR (125 MHz, CDCl3): δ = 167.5, 163.9, 159.0, 152.3, 138.3, 132.2, 128.8, 128.6, 128.4, 126.3, 121.9, 113.6, 104.6, 55.3, 42.3, 30.7, 26.0, 25.9.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H24O3Na: 383.1618; found: 383.1610.
#
3-(4-Methoxyphenyl)-6-phenyl-2H-pyran-2-one (8q)
[CAS Reg. No. 17372-50-8]
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (15:1 to 8:1) as eluent; yield: 36.1 mg (63% based on 7q: 63.4 mg, 0.204 mmol); yellow-green crystals; mp 169.9–170.7 °C.
1H NMR (600 MHz, CDCl3): δ = 7.88–7.86 (m, 2 H), 7.70 (d, J = 8.4 Hz, 2 H), 7.53 (d, J = 7.2 Hz, 1 H), 7.48–7.45 (m, 3 H), 6.97 (d, J = 8.4 Hz, 2 H), 6.78 (d, J = 6.6 Hz, 1 H), 3.85 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 161.7, 160.0, 159.2, 139.1, 131.4, 130.7, 129.5, 129.0, 127.3, 125.5, 125.4, 114.0, 102.0, 55.5.
#
3-(2,3-Dihydrobenzofuran-5-yl)-4-phenyl-6-(p-tolyl)-2H-pyran-2-one (8r)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (20:1 to 10:1) as eluent; yield: 63.0 mg (83% based on 7r: 82.6 mg, 0.200 mmol); yellow crystals; mp 184.7–185.3 °C.
1H NMR (500 MHz, CDCl3): δ = 7.79 (d, J = 8.0 Hz, 2 H), 7.28–7.26 (m, 5 H), 7.20–7.18 (m, 2 H), 7.12 (s, 1 H), 6.82 (d, J = 8.0 Hz, 1 H), 6.78 (s, 1 H), 6.59 (d, J = 8.5 Hz, 1 H), 4.54 (t, J = 8.5 Hz , 2 H), 3.14 (t, J = 8.5 Hz, 2 H), 2.41 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 163.4, 159.7, 158.1, 152.3, 141.2, 138.4, 131.2, 129.8, 128.8, 128.6, 128.5, 127.5, 126.8, 125.9, 125.6, 122.8, 109.0, 104.6, 71.5, 29.7, 21.6.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C26H20O3Na: 403.1305; found: 403.1298.
#
3-(2,4-Dimethoxyphenyl)-4,6-diphenyl-2H-pyran-2-one (8s)
Prepared by TP D; purified by silica gel column chromatography using PE/EtOAc (10:1 to 6:1) as eluent; yield: 63.0 mg (96% based on 7s: 82.3 mg, 0.198 mmol); yellow oil.
1H NMR (500 MHz, CDCl3): δ = 7.91–7.90 (m, 2 H), 7.46–7.45 (m, 3 H), 7.26–7.25 (m, 3 H), 7.20–7.19 (m, 2 H), 7.00 (d, J = 8.0 Hz, 1 H), 6.83 (s, 1 H), 6.42 (dd, J = 8.5, 1.5 Hz, 1 H), 6.37 (d, J = 1.5 Hz, 1 H), 3.78 (s, 3 H), 3.55 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 162.8, 161.1, 158.4, 158.1, 153.4, 138.5, 132.3, 131.8, 130.6, 129.0, 128.6, 128.2, 128.0, 125.7, 120.4, 116.0, 104.8, 104.7, 99.0, 55.4.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C25H20O4Na: 407.1254; found: 407.1244.
#
Methyl 2-(2,3-Dihydrobenzofuran-5-yl)-2-oxoacetate (10b)
[CAS Reg. No. 1565941-34-5]
Synthesized according to the literature.[15] Purified by silica gel column chromatography using PE/EtOAc (10:1 to 6:1) as eluent; yield: 667.7 mg (53% based on 5-acetyl-2,3-dihydrobenzofuran: 1.00 g, 6.60 mmol); light yellow solid; mp 67.5–68.7 °C.
1H NMR (500 MHz, CDCl3): δ = 7.90 (d, J = 1.5 Hz, 1 H), 7.86 (dd, J = 8.5, 2.0 Hz, 1 H), 6.85 (d, J = 8.5 Hz, 1 H), 4.70 (t, J = 9.0 Hz, 2 H), 3.96 (s, 3 H), 3.27 (d, J = 9.0 Hz, 2 H).
#
One-Pot Synthesis of 2-Pyrone 8a
To a stirred solution of 9a (104.1 mg, 0.500 mmol, 1.0 equiv) and methyl p-methoxybenzoylformate (10a; 118.8 mg, 0.612 mmol, 1.2 equiv) in DCM (5.0 mL) cooled at –78 °C was added dropwise P(NMe2)3 (115.0 μL, 0.633 mmol, 1.3 equiv) via a microsyringe. Upon complete addition of P(NMe2)3, the solution was slowly warmed to rt and vigorously stirred at rt. Upon completion of the reaction as monitored by TLC (ca. 12 h), TfOH (133.0 μL, 1.504 mmol, 3.0 equiv) was added dropwise via microsyringe to the solution at 0 °C. The reaction mixture was warmed to rt and then heated at 45 °C until the reaction was completed as monitored by TLC, which was then cooled to rt and neutralized with sat. aq NaHCO3. The mixture was extracted with DCM (3 × 25 mL). The combined organics were washed with brine, dried (anhyd Na2SO4), filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel eluting with PE/EtOAc (15:1 to 10:1, v/v) to afford 2-pyrone 8a as yellow-green crystals; yield: 144.1 mg (81%).
#
Pd-Catalyzed Intramolecular Cross-Coupling of 8g;[10] 10-Methoxy-3-phenyl-1H-dibenzo[f,h]isochromen-1-one (11)
Crushed K2CO3 (55.5 mg, 0.402 mmol, 2.0 equiv), 8g (88.8 mg, 0.205 mmol, 1.0 equiv), Pd(OAc)2 (2.8 mg, 0.012 mmol, 6 mol%), and PCy3·HBF4 (7.9 mg, 0.021 mmol, 10 mol%) were placed in a 25 mL Schlenk tube equipped with a high vacuum valve and a magnetic stir bar in a glovebox. The tube was moved to a Schlenk line from the glovebox and degassed N,N-dimethylacetamide (2.0 mL) was added. The reaction mixture was heated to 130 °C. Upon completion of the reaction as monitored by TLC (12 h), the heat source was removed, and the reaction mixture was allowed to cool. The crude mixture was then loaded directly onto silica gel and purified by flash chromatography on silica gel eluting with PE/DCM (3:1 to 1:3, v/v) to afford 11 as yellow-green crystals; yield: 62.8 mg (87%); mp 203.1–204.2 °C.
1H NMR (600 MHz, CDCl3): δ = 9.78 (d, J = 9.0 Hz, 1 H), 8.61 (d, J = 8.4 Hz, 1 H), 8.41 (d, J = 8.4 Hz, 1 H), 8.02–8.00 (m, 3 H), 7.79 (t, J = 7.8 Hz, 1 H), 7.72–7.69 (m, 2 H), 7.53–7.47 (m, 3 H), 7.36 (dd, J = 8.0, 2.4 Hz, 1 H), 4.02 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 161.8, 158.9, 155.0, 137.5, 132.9, 132.1, 132.0, 130.4, 130.1, 129.5, 129.1, 127.6, 127.0, 125.6, 125.1, 123.7, 123.1, 117.2, 113.6, 105.1, 97.8, 55.6.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C24H16O3Na: 375.0992; found: 375.0994.
#
Sonogashira Coupling of 8j with Phenylacetylene; 3-(4-Methoxyphenyl)-4-phenyl-6-[2-(phenylethynyl)phenyl]-2H-pyran-2-one (12)
A mixture of 8j (385.5 mg, 0.803 mmol, 1.0 equiv), phenylacetylene (106.0 μL, 0.966 mmol, 1.2 equiv), Pd(PPh3)2Cl2 (12.5 mg, 0.0178 mmol, 2 mol%), and CuI (9.0 mg, 0.047 mmol, 6 mol%) in Et3N (3.0 mL) and THF (3.0 mL) was stirred overnight at 80 °C. The heat source was removed and the reaction mixture was allowed to cool. The solvent was evaporated and the residue was purified by flash chromatography on silica gel eluting with PE/DCM (1:1 to 0:1, v/v) to afford 12 as yellow solid; yield: 247.0 mg (68%); mp 193.5–194.4 °C.
1H NMR (600 MHz, CDCl3): δ = 8.02 (d, J = 7.8 Hz, 1 H), 7.68 (d, J = 7.8 Hz, 1 H), 7.63 (s, 1 H), 7.48 (t, J = 7.8 Hz, 1 H), 7.43 (t, J = 7.8 Hz, 1 H), 7.33–7.30 (m, 3 H), 7.26–7.23 (m, 3 H), 7.18–7.16 (m, 6 H), 6.78 (d, J = 8.4 Hz, 2 H), 3.78 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 163.3, 159.2, 156.2, 151.8, 138.2, 134.2, 132.7, 132.3, 131.6, 129.8, 128.94, 128.89, 128.8, 128.6, 128.5, 128.3, 126.0, 123.4, 122.7, 120.7, 113.6, 109.9, 95.4, 88.5, 55.3.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C32H22O3Na: 477.1461; found: 477.1462.
#
TfOH-Promoted Intramolecular Hydroarylation of 12
In a dry Schlenk tube equipped with a high vacuum valve and a stir bar, 12 (90.5 mg, 0.199 mmol, 1.0 equiv) was dissolved in DCM (2.0 mL). TfOH (71.0 μL, 0.800 mmol, 4.0 equiv) was added dropwise via a microsyringe to the solution at rt. The reaction mixture was then heated at 45 °C overnight, which was then cooled to rt and neutralized with sat. aq NaHCO3. The mixture was extracted with DCM (3 × 20 mL). The combined organic extracts were washed with brine, dried (anhyd Na2SO4), filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel eluting with PE/EtOAc (20:1 to 9:1, v/v) to afford 13 as light yellow solid; yield: 67.2 mg (74%) and a light yellow solid of the mixture of 13 and 14 (ratio = 3:7); yield: 17.3 mg; total yield of 13: 72.4 mg (80%); yield of 14: 12.1 mg (13%).
#
3-(4-Methoxyphenyl)-4,5-diphenyl-2H-benzo[h]chromen-2-one (13)
Light yellow solid; mp 210.9–211.6 °C.
1H NMR (500 MHz, CDCl3): δ = 8.74–8.72 (m, 1 H), 7.84–7.82 (m, 1 H), 7.68–7.66 (m, 2 H), 7.49 (s, 1 H), 6.93–6.92 (m, 7 H), 6.79–6.72 (m, 3 H), 6.67–6.65 (m, 4 H), 3.71 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 161.2, 158.7, 152.7, 151.6, 141.4, 138.4, 136.6, 133.5, 132.0, 130.3, 129.8, 129.2, 128.0, 127.5, 127.4, 127.30, 127.26, 127.2, 126.4, 126.3, 123.0, 122.7, 114.7, 113.2, 55.2.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C32H22O3Na: 477.1461; found: 477.1462.
#
(E)-5-Benzylidene-3-(4-methoxyphenyl)-4-phenylindeno[1,2-b]pyran-2(5H)-one (14)
Light yellow solid.
1H and 13C NMR data were recorded for a 30:70 mixture of 13 and 14.
1H NMR (500 MHz, CDCl3): δ = 8.01 (s, 1 H), 7.85 (d, J = 9.0 Hz, 1 H), 7.74 (d, J = 7.5 Hz, 2 H), 7.54 (t, J = 7.5 Hz, 2 H), 7.46 (t, J = 7.5 Hz, 1 H), 7.37 (t, J = 7.5 Hz, 1 H), 7.33–7.28 (m, 3 H), 7.11–7.10 (m, 2 H), 7.05 (t, J = 7.5 Hz, 1 H), 7.01–6.97 (m, 3 H), 6.72 (d, J = 8.5 Hz, 2 H), 3.75 (s, 3 H).
13C NMR (150 MHz, CDCl3): δ = 160.7, 158.7, 152.1, 151.5, 138.8, 136.4, 134.2, 131.9, 131.4, 130.4, 130.0, 129.5, 129.3, 129.2, 128.9, 128.6, 128.3, 128.2, 127.4, 125.9, 125.5, 114.6, 113.3, 55.2.
HRMS (ESI-TOF): m/z [M + Na]+ calcd for C32H22O3Na: 477.1461; found: 477.1466.
#
#
Conflict of Interest
The authors declare no conflict of interest.
Supporting Information
- Supporting information for this article is available online at https://doi-org.accesdistant.sorbonne-universite.fr/10.1055/a-1526-7839.
- Supporting Information
-
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- 5a Liu J, Liu R, Wei Y, Shi M. Trends Chem. 2019; 1: 779
- 5b De N, Yoo EJ. ACS Catal. 2018; 8: 48
- 5c Special Issue: Chemistry of Donor-Acceptor Cyclopropanes and Cyclobutanes: Reissig H.-U, Werz DB. Isr. J. Chem. 2016; 56: 365-577
- 5d Grover HK, Emmett MR, Kerr MA. Org. Biomol. Chem. 2015; 13: 655
- 5e Novikov RA, Tomilov YV. Mendeleev Commun. 2015; 25: 1
- 5f Schneider TF, Kaschel J, Werz DB. Angew. Chem. Int. Ed. 2014; 53: 5504
- 5g Cavitt MA, Phun KH, France S. Chem. Soc. Rev. 2014; 43: 804
- 5h De Nanteuil F, De Simone F, Frei R, Benfatti F, Serrano E, Waser J. Chem. Commun. 2014; 50: 10912
- 5i Reissig HU, Zimmer R. Chem. Rev. 2003; 103: 1151
- 5j Werz DB, Biju AT. Angew. Chem. Int. Ed. 2020; 59: 3385
- 5k Xia Y, Liu X, Feng X. Angew. Chem. Int. Ed. 2020; 60: 9192
- 5l Pirenne V, Muriel B, Waser J. Chem. Rev. 2021; 121: 227
- 5m Augustin AU, Werz DB. Acc. Chem. Res. 2021; 54: 1528
- 6 Shao J, Luo Q, Bi H, Wang SR. Org. Lett. 2021; 23: 459
- 7a Li G.-Q, Dai L.-X, You S.-L. Org. Lett. 2009; 11: 1623
- 7b Sathishkannan G, Srinivasan K. Adv. Synth. Catal. 2014; 356: 729
- 7c Zhu Y, Gong Y. J. Org. Chem. 2015; 80: 490
- 8a Yin D, Liu H, Lu C.-D, Xu Y.-J. J. Org. Chem. 2017; 82: 3252
- 8b Fauduet H, Burgada R. Synthesis 1980; 642
- 8c Romanova IP, Bogdanov AV, Mironov VF, Shaikhutdinova GR, Larionova OA, Latypov SK, Bal-andina AA, Yakh-varov DG, Gubaidullin AT, Saifina AF, Sinyashin OG. J. Org. Chem. 2011; 76: 2548
- 8d Zhang J, Hao J, Huang Z, Han J, He Z. Chem. Commun. 2020; 56: 10251
- 9a Venkatesh C, Singh PP, Ila H, Junjappa H. Eur. J. Org. Chem. 2006; 5378
- 9b Nguyen TN, Nguyen TS, May JA. Org. Lett. 2016; 18: 3786
- 10a Węcławski MK, Tasior M, Hammann T, Cywiński PJ, Gryko DT. Chem. Commun. 2014; 50: 9105
- 10b Węcławski MK, Deperasińska I, Banasiewicz M, Young DC, Leniak A, Gryko DT. Chem. Asian J. 2019; 14: 1763
- 10c Xue W, Wang D, Li C, Zhai Z, Wang T, Liang Y, Zhang Z. J. Org. Chem. 2020; 85: 3689
- 11a Campeau L.-C, Parisien M, Leblanc M, Fagnou K. J. Am. Chem. Soc. 2004; 126: 9186
- 11b Campeau L.-C, Parisien M, Jean A, Fagnou K. J. Am. Chem. Soc. 2006; 128: 581
- 12a Zhang J, Li S, Qiao Y, Peng C, Wang X.-N, Chang J. Chem. Commun. 2018; 54: 12455
- 12b Hsiao H.-C, Annamalai P, Jayakumar J, Sun S.-Y, Chuang S.-C. Adv. Synth. Catal. 2021; 363: 1695
- 13 Armstrong A, Baxter CA, Lamont SG, Pape AR, Wincewicz R. Org. Lett. 2007; 9: 351
- 14a Minatti A, Zheng X, Buchwald SL. J. Org. Chem. 2007; 72: 9253
- 14b Komatsuki K, Kozuma A, Saito K, Yamada T. Org. Lett. 2019; 21: 6628
- 15 Tan P, Wang H, Wang SR. Org. Lett. 2021; 23: 2590
- 16 CCDC 2083287 (8n) contains the supplementary crystallographic data for this paper. The data can be
obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures.
For selective recent examples:
For selective recent examples:
Corresponding Author
Publication History
Received: 19 May 2021
Accepted after revision: 10 June 2021
Accepted Manuscript online:
10 June 2021
Article published online:
08 July 2021
© 2021. Thieme. All rights reserved
Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany
-
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- 5f Schneider TF, Kaschel J, Werz DB. Angew. Chem. Int. Ed. 2014; 53: 5504
- 5g Cavitt MA, Phun KH, France S. Chem. Soc. Rev. 2014; 43: 804
- 5h De Nanteuil F, De Simone F, Frei R, Benfatti F, Serrano E, Waser J. Chem. Commun. 2014; 50: 10912
- 5i Reissig HU, Zimmer R. Chem. Rev. 2003; 103: 1151
- 5j Werz DB, Biju AT. Angew. Chem. Int. Ed. 2020; 59: 3385
- 5k Xia Y, Liu X, Feng X. Angew. Chem. Int. Ed. 2020; 60: 9192
- 5l Pirenne V, Muriel B, Waser J. Chem. Rev. 2021; 121: 227
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- 14b Komatsuki K, Kozuma A, Saito K, Yamada T. Org. Lett. 2019; 21: 6628
- 15 Tan P, Wang H, Wang SR. Org. Lett. 2021; 23: 2590
- 16 CCDC 2083287 (8n) contains the supplementary crystallographic data for this paper. The data can be
obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures.
For selective recent examples:
For selective recent examples: