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CC BY-NC-ND 4.0 · SynOpen 2021; 05(01): 36-42
DOI: 10.1055/s-0040-1706022
DOI: 10.1055/s-0040-1706022
letter
Chemoselective Transfer Hydrogenation of α,β-Unsaturated Ketones Catalyzed by Iridium Complexes
Yanping Xia
,
Lu Ouyang
,
Jianhua Liao
,
Xiao Yang
,
The authors thank the National Natural Science Foundation of China (Grant No. 21962004 and 21562004), the Jiangxi Provincial Department of Science and Technology (Grant No. 20192BAB203004), the Fundamental Research Funds for Gannan Medical University (Grant No. QD201810), and the COVID-19 Emergency Project of Gannan Medical University (Grant No. YJ202027) for financial support.
Abstract
Efficient chemoselective transfer hydrogenation of the C=C bond of α,β-unsaturated ketones has been developed, using the iridium complexes containing pyridine-imidazolidinyl ligands as catalysts and formic acid as a hydrogen source. In comparison with organic solvents or H2O as solvent, the mixed solvents of H2O and MeOH are critical for a high catalytic chemoselective transformation. This chemoselective transfer hydrogenation can be carried out in air, which is operationally simple, allowing a wide variety of α,β-unsaturated substrates with different functional groups (electron-donating and electron-withdrawing substituents) leading to chemoselective transfer hydrogenation in excellent yields. The practical application of this protocol is demonstrated by a gram-scale transformation.
Key words
transfer hydrogenation - iridium complex - α,β-unsaturated ketones - formic acid - chemoselective reductionSupporting Information
- Supporting information for this article is available online at https://doi.org/10.1055/s-0040-1706022.
- Supporting Information
Publication History
Received: 29 December 2020
Accepted after revision: 26 January 2020
Article published online:
08 February 2021
© 2020. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)
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- 21 Procedure for the Preparation of 3To a 25.0 mL dried Schlenk tube was added the α,β-unsaturated ketone (2, 0.5 mmol), Ir catalyst (1.0 mol %), HCOOH (10.0 equiv), water (2.0 mL), and MeOH (2.0 mL) successively. The mixture was stirred at room temperature for 12 h under air. After reaction was complete, the mixture was diluted with H2O (15.0 mL), neutralized with saturated aq. NaHCO3, and extracted with EtOAc (3 × 10.0 mL). The combined organic layers were washed with brine (3 × 10.0 mL) and dried over anhydrous MgSO4. After filtration and removal of the EtOAc under vacuum, the crude product was purified by column chromatography on silica gel, eluting with hexane or petroleum ether/ethyl acetate (10:1 to 50:1) to achieve the desired products.1,3-Diphenylpropan-1-one (3aa)12b Yield 90% (94.5 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 8.00 (d, J = 7.8 Hz, 2 H), 7.59 (t, J = 7.3 Hz, 1 H), 7.49 (t, J = 7.7 Hz, 2 H), 7.37–7.22 (m, 5 H), 3.37–3.30 (m, 2 H), 3.14–3.07 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 199.3, 141.3, 136.9, 133.1, 128.6, 128.6, 128.5, 128.1, 126.2, 40.5, 30.2.1-Phenyl-3-(p-tolyl)propan-1-one (3ab)14 Yield 90% (96.3 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.98–7.92 (m, 2 H), 7.55 (t, J = 7.4 Hz, 1 H), 7.45 (t, J = 7.7 Hz, 2 H), 7.13 (q, J = 8.1 Hz, 4 H), 3.31–3.24 (m, 2 H), 3.06–3.00 (m, 2 H), 2.32 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 199.4, 138.2, 136.9, 135.7, 133.1, 129.2, 128.6, 128.3, 128.1, 40.6, 29.7, 21.0.1-Phenyl-3-(m-tolyl)propan-1-one (3ac)2d Yield 86% (95.2 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.96 (d, J = 7.5 Hz, 2 H), 7.55 (t, J = 7.3 Hz, 1 H), 7.45 (t, J = 7.6 Hz, 2 H), 7.19 (t, J = 7.5 Hz, 1 H), 7.04 (dd, J = 13.2, 9.1 Hz, 3 H), 3.33–3.26 (m, 2 H), 3.06–2.99 (m, 2 H), 2.33 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 199.4, 141.3, 138.1, 136.9, 133.1, 129.3, 128.6, 128.5, 128.1, 126.9, 125.4, 40.6, 30.1, 21.4.3-(2-Methoxyphenyl)-1-phenylpropan-1-one (3ad)14 Yield 85% (102 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.97 (d, J = 7.8 Hz, 2 H), 7.53 (t, J = 7.3 Hz, 1 H), 7.43 (t, J = 7.6 Hz, 2 H), 7.23–7.16 (m, 2 H), 6.92–6.81 (m, 2 H), 3.81 (s, 3 H), 3.29–3.22 (m, 2 H), 3.08–3.01 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 200.0, 157.6, 137.0, 132.9, 130.2, 129.6, 128.6, 128.2, 127.6, 120.6, 110.3, 55.2, 39.0, 25.8.3-(4-Chlorophenyl)-1-phenylpropan-1-one (3ae)14 Yield 90% (109.8 mg), colorless oil (88.5–90 °C). 1H NMR (400 MHz, CDCl3): δ = 7.98–7.91 (m, 2 H), 7.56 (t, J = 7.4 Hz, 1 H), 7.45 (t, J = 7.7 Hz, 2 H), 7.28–7.24 (m, 2 H), 7.18 (d, J = 8.4 Hz, 2 H), 3.28 (t, J = 7.5 Hz, 2 H), 3.04 (t, J = 7.5 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.9, 139.7, 136.8, 133.2, 131.9, 129.8, 128.7, 128.6, 128.0, 40.2, 29.4.3-(4-Bromophenyl)-1-phenylpropan-1-one (3af)14 Yield 83% (119.5 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 8.04–7.95 (m, 2 H), 7.58 (dd, J = 10.7, 4.0 Hz, 2 H), 7.48 (t, J = 7.6 Hz, 2 H), 7.35 (dd, J = 7.6, 1.6 Hz, 1 H), 7.27 (td, J = 7.5, 1.1 Hz, 1 H), 7.10 (td, J = 7.7, 1.7 Hz, 1 H), 3.37–3.32 (m, 2 H), 3.24–3.19 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.9, 140.6, 136.8, 133.2, 132.9, 130.8, 128.6, 128.1, 128.0, 127.7, 124.4, 38.6, 30.8.3-(2,3-Difluorophenyl)-1-phenylpropan-1-one (3ag)Yield 81% (99.6 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 8.01–7.95 (m, 2 H), 7.59 (t, J = 7.4 Hz, 1 H), 7.48 (t, J = 7.7 Hz, 2 H), 7.08–6.98 (m, 3 H), 3.34 (t, J = 7.5 Hz, 2 H), 3.15 (t, J = 7.5 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.6, 149.9 (dd, J = 243, 13 Hz), 136.6, 133.2, 130.6 (d, J = 12 Hz), 128.7, 128.0, 125.6 (t, J = 4 Hz), 123.9 (dd, J = 6, 4 Hz), 115.2 (d, J = 17 Hz), 38.6, 23.6.3-(2,3-Dimethylphenyl)-1-phenylpropan-1-one (3ah)Yield 86% (102.3 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 8.00 (d, J = 7.6 Hz, 2 H), 7.59 (t, J = 7.4 Hz, 1 H), 7.49 (t, J = 7.6 Hz, 2 H), 7.11–7.05 (m, 3 H), 3.27 (dd, J = 9.3, 6.5 Hz, 2 H), 3.15–3.08 (m, 2 H), 2.33 (s, 3 H), 2.28 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 199.5, 139.3, 137.1, 136.9, 134.6, 133.1, 128.6, 128.1, 128.1, 126.9, 125.6, 39.6, 28.3, 20.7, 15.1. ESI-HRMS: m/z calcd for C17H19O [M + H]+: 239.1436; found: 239.1433.3-(Furan-2-yl)-1-phenylpropan-1-one (3ai)22a Yield 82% (82 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.99–7.95 (m, 2 H), 7.56 (t, J = 7.4 Hz, 1 H), 7.45 (t, J = 7.7 Hz, 2 H), 7.33–7.28 (m, 1 H), 6.30–6.25 (m, 1 H), 6.05 (d, J = 3.1 Hz, 1 H), 3.35–3.31 (m, 2 H), 3.11–3.07 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.7, 154.8, 141.1, 136.8, 133.2, 128.6, 128.1, 110.3, 105.3, 36.9, 22.5.1-Phenyl-3-(thiophen-2-yl)propan-1-one (3aj)22b Yield 80% (86.4 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.98–7.93 (m, 2 H), 7.55 (t, J = 7.4 Hz, 1 H), 7.45 (t, J = 7.6 Hz, 2 H), 7.11 (dd, J = 5.1, 0.9 Hz, 1 H), 6.91 (dd, J = 5.0, 3.5 Hz, 1 H), 6.85 (d, J = 3.1 Hz, 1 H), 3.38–3.33 (m, 2 H), 3.31–3.26 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.6, 143.9, 136.8, 133.2, 128.7, 128.1, 126.9, 124.7, 123.4, 40.6, 24.2.1-(4-Fluorophenyl)-3-phenylpropan-1-one (3ba)2d Yield 88% (100.3 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.99–7.93 (m, 2 H), 7.32–7.18 (m, 5 H), 7.09 (t, J = 8.6 Hz, 2 H), 3.25 (t, J = 7.7 Hz, 2 H), 3.05 (t, J = 7.6 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 197.6, 165.7 (d, J = 253 Hz), 141.2, 133.3 (d, J = 2 Hz), 130.7 (d, J = 9 Hz), 128.60, 128.5 (d, J = 14 Hz), 126.2, 115.7 (d, J = 22 Hz), 40.4, 30.1. ESI-HRMS: m/z calcd for C15H14OF [M + H]+: 229.1029; found: 229.1030.1-(4-Chlorophenyl)-3-phenylpropan-1-one (3bb)2d Yield 84% (102.5 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.91–7.86 (m, 2 H), 7.42 (d, J = 8.5 Hz, 2 H), 7.31–7.20 (m, 5 H), 3.26 (dd, J = 10.0, 5.3 Hz, 2 H), 3.06 (dd, J = 10.0, 5.2 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.0, 141.1, 139.5, 135.2, 129.5, 128.9, 128.,6 128.4, 126.2, 40.4, 30.1.1-(4-Bromophenyl)-3-phenylpropan-1-one (3bc)2d Yield 83% (119.5 mg), yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.84 (d, J = 8.5 Hz, 2 H), 7.61 (d, J = 8.5 Hz, 2 H), 7.36–7.22 (m, 5 H), 3.29 (t, J = 7.7 Hz, 2 H), 3.09 (t, J = 7.6 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.2, 141.1, 135.6, 131.9, 129.6, 128.6, 128.4, 128.3, 126.3, 40.4, 30.1.3-Phenyl-1-[4-(trifluoromethyl)phenyl]propan-1-one (3bd)2d Yield 80% (111.2 mg), yellow oil. 1H NMR (400 MHz, CDCl3): δ = 8.07 (d, J = 8.2 Hz, 2 H), 7.74 (d, J = 8.3 Hz, 2 H), 7.36–7.22 (m, 5 H), 3.35 (t, J = 7.6 Hz, 2 H), 3.11 (t, J = 7.6 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 198.2, 140.9, 139.5, 134.6 (q, J = 33 Hz), 128.6, 128.4, 128.4, 126.3, 125.7 (q, J = 4 Hz), 123.5 (q, J = 258 Hz), 40.8, 29.9.1-(3-Bromo-4-fluorophenyl)-3-phenylpropan-1-one (3be)Yield 87% (133.1 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 8.19 (dd, J = 6.6, 2.1 Hz, 1 H), 7.92 (ddd, J = 8.5, 4.7, 2.1 Hz, 1 H), 7.36–7.30 (m, 2 H), 7.28–7.18 (m, 4 H), 3.28 (t, J = 7.6 Hz, 2 H), 3.09 (t, J = 7.6 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 196.5, 162.0 (d, J = 244 Hz), 140.9, 134.4 (d, J = 3 Hz), 134.0 (d, J = 1 Hz), 129.2 (d, J = 8 Hz), 128.6, 128.4, 126.3, 116.7 (d, J = 23 Hz), 109.9 (d, J = 22 Hz), 40.4, 30.0. ESI-HRMS m/z calcd for C15H13OBrF [M + H]+: 307.0134; found: 307.0135.1-(4-Nitrophenyl)-3-phenylpropan-1-one (3bf)22c Yield 81% (103.3 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 8.32 (d, J = 8.8 Hz, 2 H), 8.11 (d, J = 8.8 Hz, 2 H), 7.36–7.30 (m, 2 H), 7.27 (dd, J = 11.1, 4.1 Hz, 3 H), 3.37 (t, J = 7.6 Hz, 2 H), 3.12 (t, J = 7.5 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 197.7, 150.3, 141.3, 140.6, 129.1, 128.7, 128.4, 126.4, 123.9, 41.0, 29.9.3-Phenyl-1-(p-tolyl)propan-1-one (3bg)2d Yield 90% (100.8 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.90 (d, J = 8.2 Hz, 2 H), 7.36–7.23 (m, 7 H), 3.34–3.28 (m, 2 H), 3.13–3.07 (m, 2 H), 2.44 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 198.9, 143.9, 141.4, 134.4, 129.3, 128.6, 128.5, 128.2, 126.1, 40.4, 30.3, 21.7.1-(4-Methoxyphenyl)-3-phenylpropan-1-one (3bh)14 Yield 92% (110.4 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.72 (dd, J = 7.7, 1.7 Hz, 1 H), 7.51–7.46 (m, 1 H), 7.28 (dq, J = 21.7, 7.4 Hz, 5 H), 7.06–6.97 (m, 2 H), 3.91 (s, 3 H), 3.37–3.31 (m, 2 H), 3.09–3.03 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 201.8, 158.6, 141.8, 133.5, 130.4, 128.5, 128.4, 128.3, 125.9, 120.7, 111.5, 55.5, 45.5, 30.5.3-Phenyl-1-(thiophen-2-yl)propan-1-one (3bi)12b Yield 87% (94.0 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.72 (d, J = 3.8 Hz, 1 H), 7.65 (d, J = 4.9 Hz, 1 H), 7.36–7.27 (m, 4 H), 7.24 (t, J = 7.5 Hz, 1 H), 7.14 (t, J = 4.3 Hz, 1 H), 3.29–3.24 (m, 2 H), 3.13–3.08 (m, 2 H). 13C NMR (100 MHz, CDCl3): δ = 192.2, 144.2, 141.0, 133.6, 131.9, 128.6, 128.5, 128.1, 126.3, 41.2, 30.4.1-(Furan-2-yl)-3-phenylpropan-1-one (3bj)12b Yield 81% (89.1 mg), pale yellow oil. 1H NMR (400 MHz, CDCl3): δ = 7.59 (d, J = 0.9 Hz, 1 H), 7.34–7.19 (m, 6 H), 6.54 (dd, J = 3.5, 1.6 Hz, 1 H), 3.21–3.16 (m, 2 H), 3.07 (dd, J = 9.7, 5.3 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 188.5, 152.7, 146.4, 141.0, 128.5, 128.4, 126.2, 117.1, 112.2, 40.2, 30.0.1-(Naphthalen-1-yl)-3-phenylpropan-1-one (3bk)14 Yield 93% (120.9 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 8.60 (d, J = 8.5 Hz, 1 H), 8.01 (d, J = 8.2 Hz, 1 H), 7.91 (d, J = 7.9 Hz, 1 H), 7.85 (d, J = 7.2 Hz, 1 H), 7.64–7.55 (m, 2 H), 7.50 (t, J = 7.7 Hz, 1 H), 7.31 (dq, J = 12.0, 7.3 Hz, 5 H), 3.42 (t, J = 7.7 Hz, 2 H), 3.18 (t, J = 7.6 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 203.6, 141.2, 136.0, 134.0, 132.6, 130.2, 128.6, 128.5, 128.5, 127.9, 127.5, 126.5, 126.2, 125.8, 124.4, 43.9, 30.6.(E)-5-Phenyl-1-(2,6,6-trimethylcyclohex-2-en-1-yl)pent-1-en-3-one (3bl)Yield 78% (110.0 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.36–7.18 (m, 7 H), 6.15 (d, J = 16.3 Hz, 1 H), 2.96 (td, J = 14.1, 6.9 Hz, 4 H), 2.08 (t, J = 6.0 Hz, 2 H), 1.76 (s, 3 H), 1.65 (d, J = 2.8 Hz, 1 H), 1.49 (d, J = 5.6 Hz, 2 H), 1.07 (s, 6 H). 13C NMR (100 MHz, CDCl3): δ = 199.7, 142.5, 141.4, 136.2, 136.0, 130.5, 128.5, 128.4, 126.1, 42.2, 39.7, 34.1, 33.6, 30.4, 28.8, 21.8, 18.9. ESI-HRMS m/z calcd for C20H27O [M + H]+: 283.2062; found: 283.2064.1,5-Diphenylpentan-3-one (3bm)22d Yield 76% (90.4 mg), colorless oil. 1H NMR (400 MHz, CDCl3): δ = 7.31 (t, J = 7.4 Hz, 4 H), 7.22 (dd, J = 17.0, 7.3 Hz, 6 H), 2.93 (t, J = 7.6 Hz, 4 H), 2.75 (dd, J = 9.7, 5.5 Hz, 4 H). 13C NMR (100 MHz, CDCl3): δ = 209.2, 141.0, 128.5, 128.3, 126.1, 44.5, 29.8
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