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DOI: 10.1055/s-0040-1719892
Brønsted Acid Catalyzed Direct Annulation of Alkoxyallenes and Naphthols to Chroman Ketals
Financial support from the National Natural Science Foundation of China (21602231, 21772227) and the Natural Science Foundation of Jiangsu Province (Grant No. BK20191197) is gratefully acknowledged.
Abstract
A straightforward Brønsted acid-catalyzed and scalable annulation of alkoxyallenes with simple naphthols was developed, affording chroman ketals in 49–84% yields. The versatile chroman ketals can be easily converted into coumarins by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated oxidation, and a series of 2-substituted chromans via nucleophilic substitutions.
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Biographical Sketches
Maosheng He obtained his master’s degree from Fudan University in June 2017. He is currently a Ph.D. candidate supervised by Prof. Jiang Gaoxi in Organic Chemistry at the University of Chinese Academy of Sciences.
Jinlong Zhang obtained his Ph.D. degree from Lanzhou University in 2015 under the supervision of Prof. Rui Wang, and majored in organic chemistry. After graduation, he moved to Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences as an assistant professor. His research efforts are focused on organic synthesis and asymmetric catalysis.
Cong Zhang obtained her MS degree from Zhengzhou University in 2010. She received her Ph.D degree from the faculty for Chemistry and Pharmacy, Ludwig-Maximilians-Universität München in 2014. She subsequently joined Nanjing Tech University and focuses on computer chemistry for mechanism research.
Hao-Yang Wang received his BSc in chemistry from China Pharmaceutical University, Nanjing in 2000, and obtained his Ph.D. degree from the Shanghai Institute of Organic Chemistry in 2006 under the supervision of Prof. Yin-Long Guo. He then undertook post-doctoral research for two years with Prof. Jürgen O. Metzger at the University Oldenburg, Germany. From 2008, he started to work at the Shanghai Institute of Organic Chemistry. He is focused on developing new MS analysis methods for organic chemistry.
Gaoxi Jiang completed his B.Sc. in 2003 from Peking University, and received his Ph.D. in 2008 from the Shanghai Institute of Organic Chemistry with Prof. Chi-Ming Che (Hong Kong University, HKU). After a short stay at HKU in 2008, he joined Max-Planck-Institut für Kohlenforschung in Germany as a postdoctoral fellow (2009–2011) with Prof. Benjamin List. In 2012, he joined the faculty at the Lanzhou Institute of Chemical Physics. His current research is focused on the development of new synthetic methodologies by asymmetric catalysis.
Exploitation of new reactivity modes and transformations to realize exclusive regioselectivity represents a cutting-edge area of research in organic chemistry. By using this strategy, different kinds of products can be furnished regioselectively from the same set of starting materials, which should provide much more atom- and step-economical protocols to facilitate chemical synthesis. For the primary goal in organic synthesis, chemists have paid tremendous attention to rational reaction model designs based on chemical understanding and wide screening of catalysts.[1] The ability of alkoxyallenes to function as useful π-allyl fragment precursors for transition-metal-catalyzed allylic alkylation to nucleophiles has become a powerful method for carbon–carbon bond formation.[2] Trost, Breit, Rhee, and others have made outstanding contributions in this field.[3] However, these reaction models provided branched allylic product exclusively (Scheme [1a]). Among these, Pd-catalysis exhibited flexible activity and wide substrate tolerance. Mechanistically, for Pd-catalysis, the use of (over)stoichiometric amount of activator is required for the formation of the Pd(II)-hydride species from nucleophiles that trigger the reaction, followed by hydropalladation of the allene to generate the key Pd(π-allyl) complex.[3] In 2015, Cao and co-workers reported a Pd-catalyzed hydroalkoxylation of alkoxyallenes with phenols in the presence of 200 mol% of Et3N to assemble acyclic O,O-acetals (Scheme [1b]).[3d] In 2017, we realized an enantioselective regiodivergent addition of alkoxyallenes to pyrazolones by Pd-catalysis and chiral Brønsted acid, respectively. The former process afforded branched allylic pyrazol-5-ones and the latter gave linear products exclusively (Scheme [1c]).[4] Herein, we disclose a straightforward and scalable Brønsted acid catalyzed annulation of alkoxyallenes with simple naphthols to chroman ketals under very mild reaction conditions (Scheme [1d]). This new metal-free reaction model features a formal CAr–H bond activation at the phenolic hydroxyl ortho-site based on the intrinsic increase in the electrophilicity of phosphoric acid acetal intermediate and its hydrogen-bonding interaction with naphthols. The useful chroman ketal products can be easily converted into coumarins[5] by DDQ-mediated oxidation, and a series of 2-substituted chromans[6] via nucleophilic substitutions, which offers the potential for exploitation of pharmaceutically interesting molecules.
Recently, our group have made a lot of efforts to utilize alkoxyallenes for allylation reactions.[7] As a continuation of our research, the direct reaction between simple alkoxyallenes and naphthols attracted our attention. Initially, naphthol 1a and alkoxyallene 2a were selected to verify the feasibility of this reaction. As shown in Table [1], to our delight, the desired chroman ketal product 3aa was isolated in 83% yield by the treatment of 1a (0.1 mmol) with 2a (0.17 mmol, 1.7 equiv) in the presence of 5.0 mol% diphenylphosphoric acid (PhO)2POOH (PA) as the catalyst in dichloromethane (CH2Cl2) at 25 °C for 8 h (entry 1). Decreasing the loading of alkoxyallene 2a to 0.15 mmol (1.5 equiv) resulted in 73% yield (entry 2); increasing its loading up to 2.0 equivalent did not improve the yield (entry 3). Similar results were obtained when the cyclization reaction was performed in 1,2-dichloroethane or toluene (entries 4 and 5). Other solvents including THF, CH3CN and acetone led to decomposition of 2a (entries 6–8). The use of TsOH or CF3COOH as catalysts instead of PA also gave disappointing results under the optimal reaction conditions, probably because their strong acidity accelerated the decomposition of 2a (entries 9 and 10). Lowering the reaction temperature from 25 to 0 °C was detrimental to the outcome (entry 11).
a Reaction conditions: 1a (0.1 mmol), 2a (0.17 mmol), solvent (1.0 mL), Brønsted acid (5.0 mol%), at 25 °C for 8 h.
b Yield of isolated product.
c 0.15 mmol of 2a was used.
d 0.2 mmol of 2a was used.
e Reaction at 0 °C for 12 h.
Encouraged by the optimization results, we first expanded the reaction to gram-scale to evaluate the practical use of the PA-catalyzed direct annulation. Gratifyingly, at 1.15-gram scale of naphthol 1a (8.0 mmol), the yield of 3aa was not decreased significantly, and 1.88 g (81% yield) of 3aa was readily isolated. We then investigated the substrate scope with respect to both naphthols and alkoxyallenes to evaluate the generality of the reaction. As shown in Scheme [2], the reaction could tolerate a wide range of naphthols. For reaction with 2a, besides 1a, both electron-donating and electron-withdrawing substituents at the aromatic rings are applicable to the PA-catalyzed cyclization process, leading to the corresponding products 3ba–ka in good yields of 53–84%. The double cyclizations proceeded smoothly and gave the desired diketal product 3la in 50% yield when 2,6-dinaphthol 1l was employed as the substrate. To our delight, the more challenging 1-naphthols (3m–n) and simple phenol 3o were also reactive, which gave diminished yet promising yields for the assembly of the corresponding products 3ma–oa. Other substituted alkoxyallenes 2b–d including octyl (2c) and cyclohexyl (2d) group were amenable to the reaction conditions, providing 3ab, 3ac and 3ad in 64–81% yields.
As a versatile synthetic block, the chroman ketal products could be conveniently converted into coumarins, chromene and chromans (Scheme [3]). By treatment of ketals with 1,2-dichloro-4,5-dicyanobenzoquinone (DDQ) in toluene heated to 80 °C for 12 h, the coumarins 4a–f were obtained in 58–88% yields. Chromene 5 was isolated in a moderate yield with TsOH as the scavenger of benzyl alcohol, and chroman 6 was afforded in 95% with Et3SiH as the reductant promoted by boron trifluoride ethoxyethane complex (BF3·Et2O). Compound 3aa could also be converted into a series of 2-substituted chromans through Lewis acid promoted nucleophilic substitution reactions. Accordingly, the desired products 7–9 were generated readily in good yields by reaction with nucleophiles TMS-CN, TMS-N3 and 4-bromobenzenethiol in the presence of BF3·Et2O as a Lewis acid (for details, see the experiment section).
Based on the previous reports[3] and on our previous results,[4] [7] we proposed a reaction mechanism. As demonstrated in Scheme [4], alkyoxyallyl phosphate 10, generated by the reaction of PA catalyst with alkoxyallene 2, reacts with naphthol 1a, driven by an intramolecular hydrogen bonding effect via TS-A, to form 11, followed by a fast aromatization to the ene-ether intermediate 12.
The second addition of PA catalyst to 12 should occur to form 2-hydroxynaphthalen-1-yl diphenylphosphate, and an intramolecular substitution reaction takes place via TS-B to release the chroman ketal product 3 with the regeneration of the PA-catalyst. We attempted to detect and isolated the intermediate 12, but failed; the final cyclic product 3 was always obtained, likely due to the extremely facile intramolecular substitution annulation.
In summary, we have described a direct and scalable intermolecular annulation of alkoxyallenes with simple naphthols enabled by Brønsted acid, involving a formal Csp2–H activation that is completely different from the well-developed transition-metal catalysis. A series of useful chroman ketals was readily obtained in good yields under very mild reaction conditions. Moreover, the usefulness of this new method was highlighted by converting the ketal products into a range of interesting coumarin, chromene, and 2-substituted chroman derivatives. Mechanistically, the phosphoric acid catalyst should play dual roles in the cyclic reaction.
All non-aqueous manipulations were performed using standard Schlenk techniques. All reactions were set up under air. Reactions were monitored using thin-layer chromatography (TLC) on silica gel plates. Visualization of the developed plates was performed under UV light (254 nm) or with KMnO4 stain. Silica gel flash column chromatography was performed on SYNTHWARE 40–63 μm silica gel. All NMR spectra were recorded at 400 MHz (1H NMR) or 100 MHz (13C NMR) in CDCl3, methanol-d 4 or DMSO-d 6 solution. 1H NMR spectra were internally referenced to TMS. 13C NMR spectra were internally referenced to the residual solvent signal. Data for 1H NMR spectra are reported as chemical shift (δ, ppm), multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, m= multiplet, br = broad), and coupling constants (J in Hz). High-resolution mass spectra (HRMS) were recorded with a Bruker MicrOTOF-QII mass instrument (ESI). Unless otherwise indicated, starting catalysts and commercially available reagents were used without additional purification.
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Preparation of 3; Typical Procedure
To a mixture of naphthalen-2-ol (144 mg, 1.0 mmol) and diphenyl hydrogen phosphate (12.5 mg, 0.05 mmol) in CH2Cl2 (10 mL) was added ((propa-1,2-dien-1-yloxy)methyl)benzene (248 mg, 1.7 mmol), and stirring was continued for 8 h at room temperature. The reaction mixture was concentrated to give a residue, which was purified by flash chromatography on silica gel (hexane/EtOAc, 180:1) to afford the corresponding pure compound 3.
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Preparation of 4; Typical Procedure
A mixture of 3-(benzyloxy)-2,3-dihydro-1H-benzo[f]chromene (174 mg, 0.6 mmol), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (409 mg, 1.8 mmol) and toluene (6.0 mL) was stirred at 80 °C for 12 h. The reaction mixture was concentrated to give a residue, which was purified by flash chromatography on silica gel (hexane/EtOAc, 30:1) to afford the corresponding pure compound 4.
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Preparation of 5; Typical Procedure
A mixture of 3-(benzyloxy)-2,3-dihydro-1H-benzo[f]chromene (145 mg, 0.5 mmol), methanesulfonic acid (0.15 mL) and N,N-dimethylformamide (1.5 mL) was stirred at 110 °C for 12 h. The reaction mixture was poured into sat. NaHCO3 solution (100 mL) and extracted with EtOAc (50 mL). The separated organic layer was concentrated to give a residue, which was purified by flash chromatography on silica gel (hexane/EtOAc, 200:1) to afford the corresponding pure compound 5.
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Preparation of 6–9; General Procedure
Boron trifluoride diethyl etherate (165 μL, 46% in diethyl etherate, 0.6 mmol) was added to a mixture of 3-(benzyloxy)-2,3-dihydro-1H-benzo[f]chromene (174 mg, 0.6 mmol), triethylsilane (698 mg, 6.0 mmol, for 6), or trimethylsilyl actonitrile (595 mg, 6.0 mmol, for 7), or azidotrimethylsilane (691 mg, 6 mmol, for 8), or 4-bromobenzenethiol (1134 mg, 6 mmol, for 9 with boron trifluoride ethoxyethane 16.5 μL, 46% in ethoxyethane, 0.06 mmol), and CH2Cl2 (6.0 mL) at 0 °C, and stirring was continued for 8 h at room temperature. The reaction mixture was poured into sat. NaHCO3 solution (50 mL) and extracted with EtOAc (50 mL). The separated organic layer was concentrated to give a residue, which was purified by flash chromatography on silica gel (hexane/EtOAc, 200:1) to afford the corresponding pure compound.
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3-(Benzyloxy)-2,3-dihydro-1H-benzo[f]chromene (3aa)
Yield: 1.88 g (81%); white solid; mp 60–62 °C.
1H NMR (400 MHz, CDCl3): δ = 7.84 (d, J = 8.4 Hz, 1 H), 7.76 (d, J = 8.1 Hz, 1 H), 7.64 (d, J = 8.8 Hz, 1 H), 7.52–7.43 (m, 1 H), 7.36–7.20 (m, 6 H), 7.08 (d, J = 8.9 Hz, 1 H), 5.38 (s, 1 H), 4.92–4.63 (m, 2 H), 3.20–3.12 (m, 1 H), 3.11–3.00 (m, 1 H), 2.29–2.22 (m, 1 H), 2.14–2.05 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 149.2, 137.8, 132.8, 129.2, 128.44, 128.41, 127.9, 127.8, 127.7, 126.3, 123.4, 122.1, 119.1, 114.6, 95.8, 69.6, 26.2, 17.3.
HRMS (ESI): m/z [M + Na]+ calcd for C20H18O2Na: 313.1199; found: 313.1201.
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3-(Benzyloxy)-8-methyl-2,3-dihydro-1H-benzo[f]chromene (3ba)
Yield: 256 mg (84%); off-white solid; mp 53–55 °C.
1H NMR (400 MHz, CDCl3): δ = 7.73 (d, J = 8.5 Hz, 1 H), 7.59–7.50 (m, 2 H), 7.34–7.17 (m, 6 H), 7.04 (d, J = 8.9 Hz, 1 H), 5.36 (t, J = 2.9 Hz, 1 H), 4.91–4.61 (m, 2 H), 3.20–3.08 (m, 1 H), 3.07–2.97 (m, 1 H), 2.47 (s, 3 H), 2.28–2.19 (m, 1 H), 2.14–2.02 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 148.6, 137.9, 132.8, 130.9, 129.5, 128.5, 128.4, 127.9, 127.7, 127.5, 127.2, 122.0, 119.0, 114.5, 95.9, 69.6, 26.3, 21.4, 17.3.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O2Na: 327.1361; found: 327.1368.
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3-(Benzyloxy)-8-methoxy-2,3-dihydro-1H-benzo[f]chromene (3ca)
Yield: 266 mg (83%); white solid; mp 107–109 °C.
1H NMR (400 MHz, CDCl3): δ = 7.73 (d, J = 9.0 Hz, 1 H), 7.53 (d, J = 8.7 Hz, 1 H), 7.37–7.18 (m, 5 H), 7.18–7.10 (m, 1 H), 7.10–7.00 (m, 2 H), 5.35 (d, J = 3.2 Hz, 1 H), 4.90–4.61 (m, 2 H), 3.87 (s, 3 H), 3.18–3.06 (m, 1 H), 3.05–2.96 (m, 1 H), 2.26–2.18 (m, 1 H), 2.13–2.01 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 156.0, 147.7, 137.9, 130.2, 128.4, 128.0, 127.9, 127.6, 126.6, 123.6, 119.5, 118.5, 114.9, 107.0, 95.8, 69.6, 55.4, 26.3, 17.4.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O3Na: 343.1310; found: 343.1319.
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3-(Benzyloxy)-8-bromo-2,3-dihydro-1H-benzo[f]chromene (3da)
Yield: 303 mg (82%); white solid; mp 87–89 °C.
1H NMR (400 MHz, CDCl3): δ = 7.89 (d, J = 2.2 Hz, 1 H), 7.69 (d, J = 8.9 Hz, 1 H), 7.53 (d, J = 8.9 Hz, 2 H), 7.35–7.23 (m, 5 H), 7.08 (d, J = 8.9 Hz, 1 H), 5.39 (t, J = 2.5 Hz, 1 H), 4.90–4.64 (m, 2 H), 3.20–3.07 (m, 1 H), 3.06–2.96 (m, 1 H), 2.32–2.20 (m, 1 H), 2.15–2.00 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 149.5, 137.7, 131.4, 130.4, 130.3, 129.4, 128.4, 127.8, 127.7, 126.9, 123.9, 120.2, 117.1, 114.9, 95.8, 69.7, 26.1, 17.2.
HRMS (ESI): m/z [M + Na]+ calcd for C20H17BrO2Na: 391.0310; found: 391.0314.
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3-(Benzyloxy)-8-phenyl-2,3-dihydro-1H-benzo[f]chromene (3ea)
Yield: 290 mg (79%); white solid; mp 118–121 °C.
1H NMR (400 MHz, CDCl3): δ = 7.97 (d, J = 2.0 Hz, 1 H), 7.89 (d, J = 8.7 Hz, 1 H), 7.74 (dd, J = 8.7, 2.0 Hz, 1 H), 7.69 (dd, J = 8.3, 3.3 Hz, 3 H), 7.49–7.43 (m, 2 H), 7.37–7.33 (m, 1 H), 7.31–7.18 (m, 5 H), 7.11 (d, J = 8.9 Hz, 1 H), 5.39 (t, J = 2.8 Hz, 1 H), 4.92–4.63 (m, 2 H), 3.25–3.12 (m, 1 H), 3.12–3.02 (m, 1 H), 2.31–2.21 (m, 1 H), 2.16–2.04 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 149.4, 141.2, 137.8, 136.1, 132.0, 129.5, 128.9, 128.4, 128.1, 127.9, 127.7, 127.3, 127.1, 126.4, 125.9, 122.7, 119.6, 114.6, 95.9, 69.7, 26.3, 17.3.
HRMS (ESI): m/z [M + Na]+ calcd for C26H22O2Na: 389.1518; found: 389.1524.
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3-(Benzyloxy)-2,3-dihydro-1H-benzo[f]chromene-8-carbonitrile (3fa)
Yield: 224 mg (71%); white solid; mp 76–79 °C.
1H NMR (400 MHz, CDCl3): δ = 8.11 (s, 1 H), 7.88 (d, J = 8.8 Hz, 1 H), 7.66 (d, J = 9.0 Hz, 1 H), 7.59 (d, J = 8.8 Hz, 1 H), 7.26 (d, J = 16.8 Hz, 5 H), 7.16 (d, J = 8.9 Hz, 1 H), 5.43 (d, J = 2.8 Hz, 1 H), 4.90–4.68 (m, 2 H), 3.22–3.09 (m, 1 H), 3.09–2.97 (m, 1 H), 2.35–2.24 (m, 1 H), 2.17–2.01 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 151.9, 137.5, 134.6, 134.3, 128.4, 128.3, 128.1, 127.81, 127.8, 127.0, 123.3, 121.0, 119.6, 115.2, 106.6, 96.0, 69.9, 25.9, 17.0.
HRMS (ESI): m/z [M + Na]+ calcd for C21H17NO2Na: 338.1157; found: 338.1164.
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1-(3-(Benzyloxy)-2,3-dihydro-1H-benzo[f]chromen-8-yl)ethan-1-one (3ga)
Yield: 236 mg (71%); white solid; mp 105–107 °C.
1H NMR (400 MHz, CDCl3): δ = 8.38 (d, J = 1.9 Hz, 1 H), 8.04 (dd, J = 8.9, 1.8 Hz, 1 H), 7.92–7.83 (m, 1 H), 7.76 (d, J = 8.8 Hz, 1 H), 7.34–7.24 (m, 5 H), 7.14 (dd, J = 8.9, 2.0 Hz, 1 H), 5.46–5.38 (m, 1 H), 4.91–4.69 (m, 2 H), 3.24–3.13 (m, 1 H), 3.12–3.02 (m, 1 H), 2.70 (s, 3 H), 2.36–2.24 (m, 1 H), 2.16–2.05 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 198.0, 151.6, 137.6, 135.4, 132.3, 130.7, 129.5, 128.4, 128.2, 127.82, 127.76, 124.5, 122.5, 120.1, 115.0, 96.0, 69.8, 26.6, 26.0, 17.2.
HRMS (ESI): m/z [M + Na]+ calcd for C22H20O3Na: 355.1310; found: 355.1321.
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(3-(Benzyloxy)-2,3-dihydro-1H-benzo[f]chromen-8-yl)(phenyl)methanone (3ha)
Yield: 292 mg (74%); colorless oil.
1H NMR (400 MHz, CDCl3): δ = 8.20 (s, 1 H), 8.01–7.89 (m, 2 H), 7.83 (d, J = 7.6 Hz, 2 H), 7.70 (d, J = 8.9 Hz, 1 H), 7.63–7.56 (m, 1 H), 7.54–7.45 (m, 2 H), 7.34–7.21 (m, 5 H), 7.13 (d, J = 8.8 Hz, 1 H), 5.43 (s, 1 H), 4.92–4.67 (m, 2 H), 3.27–3.14 (m, 1 H), 3.14–3.02 (m, 1 H), 2.38–2.23 (m, 1 H), 2.20–2.05 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 196.6, 151.5, 138.3, 137.6, 135.1, 132.6, 132.4, 132.1, 130.0, 129.4, 128.4, 128.3, 128.0, 127.8, 127.7, 126.5, 122.4, 120.1, 115.0, 96.0, 69.8, 26.1, 17.2.
HRMS (ESI): m/z [M + Na]+ calcd for C27H22O3Na: 417.1467; found: 417.1461.
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Methyl 3-(Benzyloxy)-2,3-dihydro-1H-benzo[f]chromene-8-carboxylate (3ia)
Yield: 261 mg (75%); white solid; mp 80–82 °C.
1H NMR (400 MHz, CDCl3): δ = 8.51 (d, J = 2.1 Hz, 1 H), 8.06 (d, J = 8.9 Hz, 1 H), 7.85 (d, J = 8.8 Hz, 1 H), 7.73 (d, J = 8.9 Hz, 1 H), 7.30–7.23 (m, 5 H), 7.12 (d, J = 8.9 Hz, 1 H), 5.41 (d, J = 2.2 Hz, 1 H), 4.89–4.68 (m, 2 H), 3.96 (s, 3 H), 3.24–3.11 (m, 1 H), 3.10–3.00 (m, 1 H), 2.31–2.22 (m, 1 H), 2.14–2.03 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 167.4, 151.3, 137.6, 135.3, 131.5, 129.3, 128.4, 128.3, 127.8, 127.7, 125.8, 125.0, 122.3, 120.0, 114.8, 96.0, 69.8, 52.1, 26.0, 17.2.
HRMS (ESI): m/z [M + Na]+ calcd for C22H20O4Na: 371.1259; found: 371.1267.
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3-(Benzyloxy)-9-methoxy-2,3-dihydro-1H-benzo[f]chromene (3ja)
Yield: 224 mg (70%); white solid; mp 101–103 °C.
1H NMR (400 MHz, CDCl3): δ = 7.65 (d, J = 8.8 Hz, 1 H), 7.56 (d, J = 8.8 Hz, 1 H), 7.38–7.20 (m, 5 H), 7.09 (d, J = 2.2 Hz, 1 H), 7.01 (dt, J = 8.9, 2.4 Hz, 1 H), 6.95 (dd, J = 8.9, 2.2 Hz, 1 H), 5.38 (q, J = 2.5 Hz, 1 H), 4.91–4.64 (m, 2 H), 3.90 (s, 3 H), 3.16–3.05 (m, 1 H), 3.03–2.90 (m, 1 H), 2.30–2.21 (m, 1 H), 2.15–2.04 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 158.3, 149.8, 137.8, 134.1, 130.0, 128.4, 127.9, 127.7, 127.5, 124.5, 116.6, 115.4, 113.6, 101.4, 95.8, 69.6, 55.3, 26.3, 17.5.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O3Na: 343.1310; found: 343.1317.
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3-(Benzyloxy)-5-methoxy-2,3-dihydro-1H-benzo[f]chromene (3ka)
Yield: 170 mg (53%); colorless oil.
1H NMR (400 MHz, CDCl3): δ = 7.78 (d, J = 7.8 Hz, 1 H), 7.68 (d, J = 7.5 Hz, 1 H), 7.40–7.32 (m, 2 H), 7.25 (dd, J = 13.6, 4.6 Hz, 5 H), 7.03 (s, 1 H), 5.56 (d, J = 2.9 Hz, 1 H), 4.92–4.66 (m, 2 H), 4.02–3.93 (m, 3 H), 3.24–3.12 (m, 1 H), 3.11–3.02 (m, 1 H), 2.35–2.22 (m, 1 H), 2.16–2.02 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 149.3, 141.0, 137.9, 129.2, 128.3, 127.9, 127.7, 127.6, 127.0, 124.1, 124.0, 121.9, 116.0, 104.9, 96.0, 77.3, 69.8, 55.8, 25.9, 17.1.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O3Na: 343.1310; found: 343.1315.
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2,8-Bis(benzyloxy)-2,3,4,8,9,10-hexahydrochromeno[6,5-f]chromene (3la)
Yield: 226 mg (50%); white solid; mp 189–191 °C.
1H NMR (400 MHz, CDCl3): δ = 7.68 (d, J = 9.1 Hz, 2 H), 7.32–7.20 (m, 10 H), 7.11 (d, J = 9.1 Hz, 2 H), 5.38 (d, J = 2.7 Hz, 2 H), 4.91–4.62 (m, 4 H), 3.23–3.11 (m, 2 H), 3.10–3.01 (m, 2 H), 2.32–2.20 (m, 2 H), 2.15–2.04 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 147.6, 137.8, 128.4, 128.3, 127.9, 127.6, 121.8, 119.1, 115.4, 95.7, 69.5, 26.4, 17.5.
HRMS (ESI): m/z [M + Na]+ calcd for C30H28O4Na: 475.1885; found: 475.1887.
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2-(Benzyloxy)-6-methoxy-3,4-dihydro-2H-benzo[h]chromene (3ma)
Yield: 212 mg (66%); white solid; mp 66–68 °C.
1H NMR (400 MHz, CDCl3): δ = 8.24–8.06 (m, 2 H), 7.54–7.38 (m, 2 H), 7.32–7.21 (m, 5 H), 6.48 (s, 1 H), 5.48 (t, J = 2.9 Hz, 1 H), 4.94–4.65 (m, 2 H), 3.93 (s, 3 H), 3.21–3.00 (m, 1 H), 2.79–2.65 (m, 1 H), 2.24–2.13 (m, 1 H), 2.13–2.03 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 149.4, 140.2, 137.9, 128.4, 127.9, 127.6, 126.1, 126.0, 125.3, 125.0, 121.8, 120.9, 115.7, 105.3, 95.9, 69.5, 55.8, 26.6, 21.4.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O3Na: 343.1310; found: 343.1318.
#
3-(Benzyloxy)-6,10-dimethyl-2,3-dihydrobenzo[h]indeno[2,1-f]chromen-13(1H)-one (3na)
Yield: 206 mg (49%); red oil.
1H NMR (400 MHz, CDCl3): δ = 8.21 (dd, J = 8.8, 3.4 Hz, 1 H), 7.91 (s, 1 H), 7.68 (dd, J = 7.8, 3.4 Hz, 1 H), 7.35–7.24 (m, 7 H), 7.18 (dd, J = 7.6, 2.1 Hz, 1 H), 5.53 (d, J = 2.9 Hz, 1 H), 4.94–4.74 (m, 2 H), 3.48–3.34 (m, 1 H), 3.33–3.18 (m, 1 H), 2.52 (s, 3 H), 2.33 (s, 3 H), 2.26–2.14 (m, 1 H), 2.13–2.02 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 196.1, 147.3, 142.1, 137.7, 137.4, 136.2, 135.1, 134.3, 129.3, 128.7, 128.4, 128.4, 127.71, 127.7, 127.67, 126.4, 124.5, 124.3, 122.0, 121.7, 116.1, 97.0, 70.0, 26.0, 22.2, 21.1, 17.4.
HRMS (ESI): m/z [M + Na]+ calcd for C29H24O3Na: 443.1623; found: 443.1619.
#
2-(Benzyloxy)-6-methoxychromane (3oa)
Yield: 173 mg (64%); white solid; mp 67–69 °C.
1H NMR (400 MHz, CDCl3): δ = 7.38–7.23 (m, 5 H), 6.77 (d, J = 8.8 Hz, 1 H), 6.69 (dd, J = 8.8, 3.0 Hz, 1 H), 6.61 (d, J = 2.9 Hz, 1 H), 5.28 (t, J = 2.8 Hz, 1 H), 4.74 (dd, J = 74.3, 12.1 Hz, 2 H), 3.74 (s, 3 H), 3.09–2.92 (m, 1 H), 2.70–2.52 (m, 1 H), 2.13–2.02 (m, 1 H), 2.00–1.87 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 153.7, 145.9, 137.9, 128.4, 127.8, 127.6, 123.3, 117.6, 114.0, 113.3, 95.8, 69.3, 55.7, 26.4, 20.8.
HRMS (ESI): m/z [M + Na]+ calcd for C17H18O3Na: 293.1148; found: 293.1147.
#
3-((4-Methoxybenzyl)oxy)-2,3-dihydro-1H-benzo[f]chromene (3ab)
Yield: 205 mg (64%); white solid; mp 67–69 °C.
1H NMR (400 MHz, CDCl3): δ = 7.83 (d, J = 8.4 Hz, 1 H), 7.76 (d, J = 8.1 Hz, 1 H), 7.64 (d, J = 8.9 Hz, 1 H), 7.52–7.43 (m, 1 H), 7.38–7.31 (m, 1 H), 7.27–7.18 (m, 2 H), 7.09 (d, J = 8.9 Hz, 1 H), 6.86–6.78 (m, 2 H), 5.36 (t, J = 2.9 Hz, 1 H), 4.84–4.58 (m, 2 H), 3.76 (s, 3 H), 3.21–3.09 (m, 1 H), 3.09–2.99 (m, 1 H), 2.29–2.17 (m, 1 H), 2.14–2.02 (m, 1 H).
13C NMR (101 MHz, CDCl3): δ = 159.3, 149.3, 132.8, 129.8, 129.6, 129.3, 128.4, 127.8, 126.3, 123.4, 122.1, 119.1, 114.6, 113.8, 95.6, 69.3, 55.3, 26.3, 17.3.
HRMS (ESI): m/z [M + Na]+ calcd for C21H20O3Na: 343.1310; found: 343.1313.
#
3-(Octyloxy)-2,3-dihydro-1H-benzo[f]chromene (3ac)
Yield: 253 mg (81%); colorless oil.
1H NMR (400 MHz, CDCl3): δ = 7.83 (d, J = 8.4 Hz, 1 H), 7.75 (d, J = 8.1 Hz, 1 H), 7.62 (d, J = 8.9 Hz, 1 H), 7.51–7.43 (m, 1 H), 7.37–7.27 (m, 1 H), 7.06 (d, J = 8.9 Hz, 1 H), 5.29 (t, J = 3.0 Hz, 1 H), 3.83 (dt, J = 9.7, 6.8 Hz, 1 H), 3.59 (dt, J = 9.7, 6.7 Hz, 1 H), 3.19–2.97 (m, 2 H), 2.28–2.15 (m, 1 H), 2.14–2.01 (m, 1 H), 1.57–1.49 (m, 2 H), 1.29–1.11 (m, 10 H), 0.83 (t, J = 7.0 Hz, 3 H).
13C NMR (101 MHz, CDCl3): δ = 149.4, 132.8, 129.2, 128.4, 127.7, 126.2, 123.3, 122.0, 119.1, 114.5, 97.0, 68.4, 31.8, 29.6, 29.3, 29.2, 26.4, 26.0, 22.6, 17.5, 14.1.
HRMS (ESI): m/z [M + Na]+ calcd for C21H28O2Na: 335.1987; found: 335.1991.
#
3-(Cyclohexyloxy)-2,3-dihydro-1H-benzo[f]chromene (3ad)
Yield: 209 mg (74%); white solid; mp 46–48 °C.
1H NMR (400 MHz, CDCl3): δ = 7.84 (d, J = 8.4 Hz, 1 H), 7.75 (d, J = 8.1 Hz, 1 H), 7.62 (d, J = 8.8 Hz, 1 H), 7.51–7.43 (m, 1 H), 7.37–7.29 (m, 1 H), 7.04 (d, J = 8.9 Hz, 1 H), 5.44 (dd, J = 3.6, 2.5 Hz, 1 H), 3.86–3.72 (m, 1 H), 3.21–2.97 (m, 2 H), 2.24–2.13 (m, 1 H), 2.12–2.02 (m, 1 H), 2.00–1.91 (m, 1 H), 1.81–1.69 (m, 2 H), 1.66–1.58 (m, 1 H), 1.54–1.44 (m, 1 H), 1.35–1.14 (m, 5 H).
13C NMR (101 MHz, CDCl3): δ = 149.6, 132.8, 129.1, 128.4, 127.6, 126.2, 123.2, 122.0, 119.2, 114.4, 95.2, 75.7, 33.5, 32.1, 26.9, 25.7, 24.2, 24.1, 17.6.
HRMS (ESI): m/z [M + Na]+ calcd for C19H22O2Na: 305.1512; found: 305.1511.
#
3H-Benzo[f]chromen-3-one (4a)[5a]
Yield: 98.9 mg (84%); off-white solid; mp 115–117 °C.
1H NMR (400 MHz, DMSO-d 6): δ = 8.88 (d, J = 9.7 Hz, 1 H), 8.50 (d, J = 8.4 Hz, 1 H), 8.16 (d, J = 9.0 Hz, 1 H), 8.04 (d, J = 8.1 Hz, 1 H), 7.77–7.70 (m, 1 H), 7.66–7.59 (m, 1 H), 7.54 (d, J = 9.0 Hz, 1 H), 6.63 (d, J = 9.7 Hz, 1 H).
13C NMR (101 MHz, DMSO-d 6): δ = 160.4, 153.7, 140.71, 133.6, 130.3, 129.22, 129.20, 128.7, 126.5, 122.6, 117.2, 115.7, 113.3.
HRMS (ESI): m/z [M + Na]+ calcd for C13H8O2Na: 219.0422; found: 219.0425.
#
8-Bromo-3H-benzo[f]chromen-3-one (4b)
Yield: 140 mg (85%); off-white solid; mp 210–212 °C.
1H NMR (400 MHz, DMSO-d 6): δ = 8.84 (d, J = 9.8 Hz, 1 H), 8.44 (d, J = 9.0 Hz, 1 H), 8.30 (s, 1 H), 8.13 (d, J = 9.0 Hz, 1 H), 7.81 (d, J = 9.0 Hz, 1 H), 7.59 (d, J = 9.1 Hz, 1 H), 6.64 (d, J = 9.7 Hz, 1 H).
13C NMR (101 MHz, DMSO-d 6): δ = 160.2, 153.8, 140.5, 132.6, 131.6, 131.4, 131.0, 128.0, 125.2, 119.6, 118.5, 116.3, 113.5.
HRMS (ESI): m/z [M + Na]+ calcd for C13H7BrO2Na: 296.9527; found: 296.9533.
#
8-Phenyl-3H-benzo[f]chromen-3-one (4c)
Yield: 144 mg (88%); yellow solid; mp 133–135 °C.
1H NMR (400 MHz, DMSO-d 6): δ = 8.89 (d, J = 9.7 Hz, 1 H), 8.56 (d, J = 8.8 Hz, 1 H), 8.33 (s, 1 H), 8.23 (d, J = 9.0 Hz, 1 H), 8.02 (d, J = 8.7 Hz, 1 H), 7.84 (d, J = 7.7 Hz, 2 H), 7.59–7.51 (m, 3 H), 7.48–7.40 (m, 1 H), 6.63 (d, J = 9.8 Hz, 1 H).
13C NMR (101 MHz, DMSO-d 6): δ = 160.4, 153.8, 140.8, 139.7, 138.0, 133.9, 130.8, 129.5, 128.4, 128.2, 127.6, 127.4, 126.6, 123.5, 117.6, 115.9, 113.2.
HRMS (ESI): m/z [M + Na]+ calcd for C19H12O2Na: 295.0735; found: 295.0738.
#
8-Methoxy-3H-benzo[f]chromen-3-one (4d)
Yield: 82.8 mg (61%); yellow solid; mp 162–164 °C.
1H NMR (400 MHz, CDCl3): δ = 8.39 (d, J = 9.8 Hz, 1 H), 8.09 (d, J = 9.1 Hz, 1 H), 7.85 (d, J = 9.1 Hz, 1 H), 7.40 (d, J = 9.0 Hz, 1 H), 7.33 (dd, J = 9.2, 2.6 Hz, 1 H), 7.20 (d, J = 2.6 Hz, 1 H), 6.54 (d, J = 9.7 Hz, 1 H), 3.94 (s, 3 H).
13C NMR (101 MHz, CDCl3): δ = 161.0, 157.8, 152.4, 139.0, 131.8, 131.6, 123.8, 122.8, 120.4, 117.4, 115.8, 113.2, 107.5, 55.5.
HRMS (ESI): m/z [M + Na]+ calcd for C14H10O3Na: 249.0528; found: 249.0523.
#
9-Methoxy-3H-benzo[f]chromen-3-one (4e)
Yield: 103 mg (76%); off-white solid; mp 171–173 °C.
1H NMR (400 MHz, DMSO-d 6): δ = 8.93 (d, J = 9.8 Hz, 1 H), 8.06 (d, J = 8.9 Hz, 1 H), 7.93 (d, J = 8.9 Hz, 1 H), 7.84 (d, J = 2.4 Hz, 1 H), 7.35 (d, J = 8.9 Hz, 1 H), 7.24 (dd, J = 8.9, 2.4 Hz, 1 H), 6.58 (d, J = 9.7 Hz, 1 H), 3.98 (s, 3 H).
13C NMR (101 MHz, DMSO-d 6): δ = 160.6, 159.9, 154.4, 141.3, 133.3, 131.2, 130.8, 125.5, 118.2, 114.8, 114.4, 112.6, 102.5, 56.1.
HRMS (ESI): m/z [M + Na]+ calcd for C14H10O3Na: 249.0528; found: 249.0522.
#
6-Methoxy-5,6-dihydro-2H-chromen-2-one (4f)
Yield: 61.3 mg (58%); brown solid; mp 102–104 °C.
1H NMR (400 MHz, CDCl3): δ = 7.66 (d, J = 9.5 Hz, 1 H), 7.26 (d, J = 8.7 Hz, 1 H), 7.11 (dd, J = 9.0, 2.8 Hz, 1 H), 6.92 (d, J = 2.9 Hz, 1 H), 6.43 (d, J = 9.5 Hz, 1 H), 3.85 (s, 3 H).
13C NMR (101 MHz, CDCl3): δ = 161.0, 156.1, 148.5, 143.2, 119.4, 119.2, 117.9, 117.1, 110.1, 55.8.
HRMS (ESI): m/z [M + Na]+ calcd for C10H8O3Na: 199.0371; found: 199.0374.
#
1H-Benzo[f]chromene (5)
Yield: 46.5 mg (51%); orange oil.
1H NMR (400 MHz, CDCl3): δ = 7.77 (d, J = 7.9 Hz, 1 H), 7.72–7.60 (m, 2 H), 7.56–7.48 (m, 1 H), 7.44–7.34 (m, 1 H), 7.06 (d, J = 8.9 Hz, 1 H), 6.58 (dt, J = 6.3, 2.0 Hz, 1 H), 5.11 (dt, J = 6.7, 3.5 Hz, 1 H), 3.65 (dd, J = 3.5, 2.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 148.6, 140.3, 132.3, 130.4, 128.3, 128.0, 126.5, 124.1, 122.4, 118.0, 111.6, 100.6, 20.7.
HRMS (ESI): m/z [M + Na]+ calcd for C13H10ONa: 205.0629; found: 205.0627.
#
2,3-Dihydro-1H-benzo[f]chromene (6)
Yield: 105 mg (95%); off-white solid.
1H NMR (400 MHz, CDCl3): δ = 7.84–7.69 (m, 2 H), 7.59 (d, J = 8.9 Hz, 1 H), 7.51–7.42 (m, 1 H), 7.37–7.28 (m, 1 H), 7.03 (d, J = 8.9 Hz, 1 H), 4.28–4.19 (m, 2 H), 3.03 (t, J = 6.6 Hz, 2 H), 2.22–2.07 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 152.6, 133.3, 129.0, 128.4, 127.6, 126.3, 123.2, 121.8, 119.1, 113.8, 66.2, 22.3, 21.3.
HRMS (ESI): m/z [M + Na]+ calcd for C13H12ONa: 207.0785; found: 207.0788.
#
2,3-Dihydro-1H-benzo[f]chromene-3-carbonitrile (7)
Yield: 66.5 mg (53%); white solid; mp 89–91 °C.
1H NMR (400 MHz, CDCl3): δ = 7.83–7.74 (m, 2 H), 7.66 (d, J = 8.9 Hz, 1 H), 7.56–7.49 (m, 1 H), 7.44–7.36 (m, 1 H), 7.07 (d, J = 8.9 Hz, 1 H), 5.15 (t, J = 4.5 Hz, 1 H), 3.27 (dt, J = 16.0, 7.9 Hz, 1 H), 3.16 (dt, J = 17.0, 5.5 Hz, 1 H), 2.42 (dt, J = 7.8, 5.0 Hz, 2 H).
13C NMR (101 MHz, CDCl3): δ = 149.4, 132.6, 129.7, 128.6, 128.5, 126.9, 124.3, 122.0, 118.5, 117.4, 113.0, 63.2, 25.4, 18.7.
HRMS (ESI): m/z [M + H]+ calcd for C14H12NO: 210.0913; found: 210.0915.
#
3-Azido-2,3-dihydro-1H-benzo[f]chromene (8)
Yield: 83.8 mg (62%); off-white solid; mp 57–59 °C.
1H NMR (400 MHz, CDCl3): δ = 7.86–7.72 (m, 2 H), 7.65 (d, J = 8.9 Hz, 1 H), 7.54–7.45 (m, 1 H), 7.42–7.32 (m, 1 H), 7.11 (d, J = 8.9 Hz, 1 H), 5.71 (t, J = 3.4 Hz, 1 H), 3.05 (t, J = 6.8 Hz, 2 H), 2.20–2.04 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 149.0, 132.6, 129.5, 128.5, 128.2, 126.6, 123.9, 122.0, 118.8, 113.8, 85.8, 25.8, 17.2.
HRMS (ESI): m/z [M + H – N2]+ calcd for C13H12NO: 198.0913; found: 198.0915.
#
3-((4-Bromophenyl)thio)-2,3-dihydro-1H-benzo[f]chromene (9)
Yield: 209 mg (94%); white solid; mp 74–76 °C.
1H NMR (400 MHz, CDCl3): δ = 7.81 (d, J = 8.4 Hz, 1 H), 7.76 (d, J = 8.1 Hz, 1 H), 7.64 (d, J = 8.9 Hz, 1 H), 7.54–7.46 (m, 1 H), 7.43 (d, J = 8.5 Hz, 2 H), 7.39–7.32 (m, 3 H), 7.04 (d, J = 8.9 Hz, 1 H), 5.77 (t, J = 3.9 Hz, 1 H), 3.25–3.07 (m, 2 H), 2.54–2.32 (m, 2 H).
13C NMR (101 MHz, CDCl3): δ = 149.4, 133.8, 133.2, 132.8, 132.0, 129.5, 128.5, 128.1, 126.6, 123.8, 122.0, 121.8, 119.2, 113.8, 83.1, 27.3, 19.1.
HRMS (ESI): m/z [M – H]+ calcd for C19H14BrOS: 368.9943; found: 368.9946.
#
#
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/s-0040-1719892.
- Supporting Information
-
References
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- 1b Dauth A, Love JA. Chem. Rev. 2011; 111: 2010
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- 2b Zimmer R, Reissig H.-U. Chem. Soc. Rev. 2014; 43: 2888
- 2c Bras JL, Muzart J. Chem. Soc. Rev. 2014; 43: 3003
- 2d Muñoz MP. Chem. Soc. Rev. 2014; 43: 3164
- 2e Brasholz M, Reissig H.-U, Zimmer R. Acc. Chem. Res. 2009; 42: 45
- 2f Ma S. Chem. Rev. 2005; 105: 2829
- 3a Yang Z, Wang Z. Angew. Chem. Int. Ed. 2021; 60: 27288
- 3b Jang D.-J, Lee S, Lee J, Moon D, Rhee YH. Angew. Chem. Int. Ed. 2021; 60: 22166
- 3c Zheng J, Nikbakht A, Breit B. ACS Catal. 2021; 11: 3343
- 3d Jiang L, Jia T, Wang M, Liao J, Cao P. Org. Lett. 2015; 17: 1070
- 3e Lim W, Kim J, Rhee YH. J. Am. Chem. Soc. 2014; 136: 13618
- 3f Kim H, Lim W, Im D, Kim DG, Rhee YH. Angew. Chem. Int. Ed. 2012; 51: 12055
- 3g Kim H, Rhee YH. J. Am. Chem. Soc. 2012; 134: 4011
- 3h Trost BM, Xie J, Sieber JD. J. Am. Chem. Soc. 2011; 133: 20611
- 3i Trost BM, Jäkel C, Plietker B. J. Am. Chem. Soc. 2003; 125: 4438
- 3j Trost BM, Simas AB. C, Plietker B, Jäkel C, Xie J. Chem. Eur. J. 2005; 11: 7075
- 3k Trost BM, Xie J. J. Am. Chem. Soc. 2006; 128: 6044
- 3l Trost BM, Xie J. J. Am. Chem. Soc. 2008; 130: 6231
- 4 Zhou H, Wei Z, Zhang J, Yang H, Xia C, Jiang G. Angew. Chem. Int. Ed. 2017; 56: 1077
- 5a Harvey RG, Cortez C, Ananthanarayan TP, Sanford S. J. Org. Chem. 1988; 53: 3936
- 5b Cao D, Liu Z, Verwilst P, Koo S, Jangjili P, Kim JS, Lin W. Chem. Rev. 2019; 119: 10403
- 5c Santos-Figueroa LE, Moragues ME, Climent E, Agostini A, Martínez-Máñez R, Sancenón F. Chem. Soc. Rev. 2013; 42: 3489
- 6 Pratap R, Ram VJ. Chem. Rev. 2014; 114: 10476
For reviews, see:
Corresponding Authors
Publication History
Received: 01 December 2021
Accepted after revision: 20 December 2021
Article published online:
14 February 2022
© 2022. Thieme. All rights reserved
Georg Thieme Verlag KG
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-
References
- 1a Ahn S, Hong M, Sundararajan M, Ess DH, Baik MH. Chem. Rev. 2019; 119: 6509
- 1b Dauth A, Love JA. Chem. Rev. 2011; 111: 2010
- 1c Transition Metals in Organic Synthesis: A Practical Approach. Gibson SE. Oxford University Press; Oxford: 1997
- 2a Blieck R, Taillefer M, Monnier F. Chem. Rev. 2020; 120: 13545
- 2b Zimmer R, Reissig H.-U. Chem. Soc. Rev. 2014; 43: 2888
- 2c Bras JL, Muzart J. Chem. Soc. Rev. 2014; 43: 3003
- 2d Muñoz MP. Chem. Soc. Rev. 2014; 43: 3164
- 2e Brasholz M, Reissig H.-U, Zimmer R. Acc. Chem. Res. 2009; 42: 45
- 2f Ma S. Chem. Rev. 2005; 105: 2829
- 3a Yang Z, Wang Z. Angew. Chem. Int. Ed. 2021; 60: 27288
- 3b Jang D.-J, Lee S, Lee J, Moon D, Rhee YH. Angew. Chem. Int. Ed. 2021; 60: 22166
- 3c Zheng J, Nikbakht A, Breit B. ACS Catal. 2021; 11: 3343
- 3d Jiang L, Jia T, Wang M, Liao J, Cao P. Org. Lett. 2015; 17: 1070
- 3e Lim W, Kim J, Rhee YH. J. Am. Chem. Soc. 2014; 136: 13618
- 3f Kim H, Lim W, Im D, Kim DG, Rhee YH. Angew. Chem. Int. Ed. 2012; 51: 12055
- 3g Kim H, Rhee YH. J. Am. Chem. Soc. 2012; 134: 4011
- 3h Trost BM, Xie J, Sieber JD. J. Am. Chem. Soc. 2011; 133: 20611
- 3i Trost BM, Jäkel C, Plietker B. J. Am. Chem. Soc. 2003; 125: 4438
- 3j Trost BM, Simas AB. C, Plietker B, Jäkel C, Xie J. Chem. Eur. J. 2005; 11: 7075
- 3k Trost BM, Xie J. J. Am. Chem. Soc. 2006; 128: 6044
- 3l Trost BM, Xie J. J. Am. Chem. Soc. 2008; 130: 6231
- 4 Zhou H, Wei Z, Zhang J, Yang H, Xia C, Jiang G. Angew. Chem. Int. Ed. 2017; 56: 1077
- 5a Harvey RG, Cortez C, Ananthanarayan TP, Sanford S. J. Org. Chem. 1988; 53: 3936
- 5b Cao D, Liu Z, Verwilst P, Koo S, Jangjili P, Kim JS, Lin W. Chem. Rev. 2019; 119: 10403
- 5c Santos-Figueroa LE, Moragues ME, Climent E, Agostini A, Martínez-Máñez R, Sancenón F. Chem. Soc. Rev. 2013; 42: 3489
- 6 Pratap R, Ram VJ. Chem. Rev. 2014; 114: 10476
For reviews, see:
