反应详情

Mixed Homocuprate (C3H7C≡CCuR)Li. A solution of 1-pentyne (0.07 mL, 0.70 mmol) in dry Et2O (2 mL) was treated with n-BuLi (0.44 mL of a 1.6M solution, 0.70 mmol) at 0° C. and stirred for 10 min. A solution of copper (I) iodide/tri-n-butylphosphine complex (CuI.Bu3P, 0.27 g, 0.69 mmol) in dry THF (1 mL) was added. The yellow, homogeneous solution was warmed to room temperature and stirred for 10 min. Concurrently, trans-1-lithio-3-trimethylsilyloxy-1-octene (51) was prepared by addition of n-BuLi (0.41 mL of a 1.6M solution, 0.65 mmol) to a solution of the vinyltin 49 (0.38 g, 0.77 mmol) in dry THF (3 mL) at -78° C. and stirring for 20 min at -78° C. (Although reagent 49 was contaminated with 15% of other isomers, only the desired isomer was appreciably transmetallated under the reaction conditions.) To this solution was added the initially described organocopper solution, and the yellow heterogeneous mixture was stirred at -78° C. for 45 min. A solution of enone(±)-1 (0.090 g, 0.58 mmol) in dry Et2O (2 mL) was added, and the mixture stirred at -78° C. for 30 min and at -30° C. for 1 h. The reaction mixture was quenched with 20% aqueous ammonium sulfate (5 mL) and poured into Et2O (10 mL) and water (5 mL). Extraction with two 15-mL portions of Et2O, drying of the combined ether extracts over Na2SO4, and concentration by rotary evaporation afforded the crude, trimethylsilyl-protected product 57, which could be purified by flash chromatography (50:1 hexane/EtOAc) to yield 57 as a mixture of two diastereomers: IR (neat) 2990(w), 2960 (s), 2935 (s), 2860, 1760 (s), 1460 (w), 1382, 1373, 1250, 1210, 1155, 1060 (s), 970, 840 (s), cm-1 ; 1H NMR (CDCl3) δ 5.54 (m, J1 =15.6 Hz, J2 =5.1 Hz, 2H), 4.61 (d, J=5.3 Hz, H10), 4.19 (dd, J1 =5.3 Hz, J2 =0.6 Hz, H11), 4.04 (m, H15), 3.11 (m, H12), 2.85 (dddd, J1 =18.2 Hz, J2 = 8.5 Hz, J3 =2.6 Hz, J4 =0.7 Hz, H8), 2.24 (br d, J=18.2 Hz, H8), 1.52-1.14 (m, 8H), 1.46 (s, 3H), 1.36 (s, 3H), 0.89 (t, J=7.0 Hz, 3H), 0.10 (s, 9H); 13C NMR (CDCl3) δ 213.19, 135.70, 128.11, 112.41. 81.79*, 77.93, 72.73*, 39.16, 38.61*, 38.00, 31.65, 26.81, 25.04, 24.89, 22.50, 13.92, 0.22 (*denotes a doublet due to the presence of two diastereomers). Generally, it was found to be more efficient to deprotect the crude 57 prior to purification. The crude product 57 was stirred in MeOH (10 mL) at 0° C. and a catalytic amount of K2CO3 was added. The reaction mixture was stirred at 0° C. for 15 min and at room temperature for 1.5 h. The mixture was concentrated by rotary evaporation, dissolved in diethyl ether (20 mL), washed twice with water (20 mL), dried over Na2SO4, and concentrated by rotary evaporation to give, after flash chromatography with 3:1 hexane/EtOAc, 58 (0.078 g, 48%) (, a colorless oil as a mixture of two diastereomers: IR (neat) 3470 (br), 2990, 2930 (s), 2860, 1757 (s), 1455, 1405, 1380, 1370, 1210, 1150, 1060, 970, 850, 805 (w), cm-1 ; 1H NMR (CDCl3) δ 5.62 (dd, J1 =15.8 Hz, J2 =6.2 Hz, H14), 5.53 (dd, J1 =15.8 Hz, J2 =5.6 Hz, H13), 4.60 (d, J=5.1 Hz, H10), 4.18 (t, J=5.1 Hz, H11), 4.04 (q, J=5.8 Hz, H15), 3.08 (t, J=7.2 Hz, H12), 2.82 (dd, J1 =18.2 Hz, J2 =8.5 Hz, H8), 2.22 (br d, J=18.2 Hz, H8), 1.93 (br, --OH), 1.58-1.13 (m, 8H), 1.41 (s, 3H), 1.32 (s, 3H), 0.86 (t, J=7.0 Hz, 3H); 13C NMR (CDCl3) δ 213.06, 135.11, 129.22, 112.39, 81.60, 77.81, 72.14, 39.15*, 38.67, 37.18, 31.55, 26.71, 24.90, 24.80, 22.43, 13.87; high resolution mass spectrum, m/e 282.1826 (calcd for C16H26O4, 282.1831). Anal. calcd for C16H26O4 : C, 68.05; H, 9.28. Found: C, 68.39; H, 9.31.

1. stirringstirred for 10 min
2. customonly the desired isomer was appreciably transmetallated under the reaction conditions
3. stirringthe yellow heterogeneous mixture was stirred at -78° C. for 45 min
4. stirringthe mixture stirred at -78° C. for 30 min and at -30° C. for 1 h
5. customThe reaction mixture was quenched with 20% aqueous ammonium sulfate (5 mL)
6. additionpoured into Et2O (10 mL) and water (5 mL)
7. extractionExtraction with two 15-mL portions of Et2O
8. dry with materialdrying of the combined ether
9. concentrationextracts over Na2SO4, and concentration by rotary evaporation
10. customafforded the crude, trimethylsilyl-protected product 57, which
11. customcould be purified by flash chromatography (50:1 hexane/EtOAc)