反应详情

The chloride (B) (38.6 g) was added to a solution of sodium iodide (55.7 g) in acetone (1 litre) and the solution was allowed to stand overnight. Hexane (500 ml) was added and the precipitated solid was removed by filtration. The filtrate was concentrated and the residue partitioned between water (500 ml) and hexane (500 ml). The organic phase was separated, washed with saturated sodium thiosulphate solution (500 ml) and saturated sodium chloride solution (2×500 ml), and dried (MgSO4). The solvent was removed by evaporation and the residual liquid distilled under vacuum to give (2E)-4-cyclohexyl-1-iodobut-2-ene (C) as a dark liquid (44.9 g), b.p. 80°-85° C. at 0.15 mm Hg; NMR: 0.8-1.8(complex m, 11H), 1.9(t, 2H), 3.9(m, 2H), 5.7(m, 2H). (iii) A 1.6M solution of butyllithium in hexane (93.9 ml) was added dropwise over 30 minutes to a stirred solution of diisopropylamine (21.9 ml) in dry tetrahydrofuran (THF) (200 ml) at 0° C. under an atmosphere of argon. The temperature was maintained at 0° C. for 30 minutes and then the solution was cooled to -40° C. A solution of (4S)-4-benzyl-3-(3-methylbutyryl)oxazolidin-2-one (31.3 g) (obtained as described in Tetrahedron. 1987, 44, 5525) in dry THF (70 ml) was added dropwise over 30 minutes. The solution was kept at -40° C. for 30 minutes and then the temperature was allowed to rise to 0° C. A solution of iodide (C) (39.0 g) in dry THF (75 ml) was added dropwise over 30 minutes, and then the solution was stirred at 0° C. for 1 hour. Saturated sodium chloride solution (250 ml) was added and the mixture was extracted with ether (3×250 ml). The extracts were washed with saturated sodium chloride solution (2×250 ml) and dried (MgSO4). The solvent was removed by evaporation and the residue was purified by flash chromatography, eluting with ethyl acetate/hexane (8:92 v/v), to give (4s)-4-benzyl-3-[(2S,4E)-6-cyclohexyl-2-isopropylhex-4-enoyl]oxazolidin-2-one (A) (34.5 g) as a clear oil; NMR: 0.8 -1.2(complex m, 12H), 1.6(m, 6H), 1.85(t, 1H), 2.0(m, 2H), 2.35(m, 2H), 2.6(m, 1H), 3.3(dt, 1H), 3.8(m, 1H), 4.1(d, 1H), 4.7(m, 1H), 5.4(m, 2H), 7.3(m, 5H); mass spectrum (+ve FAB), 398 (M+H+); 22 [α]436 +45.8 (c, 1.04, CHCl3). ##STR1##

1. customthe precipitated solid was removed by filtration
2. concentrationThe filtrate was concentrated
3. customthe residue partitioned between water (500 ml) and hexane (500 ml)
4. customThe organic phase was separated
5. washwashed with saturated sodium thiosulphate solution (500 ml) and saturated sodium chloride solution (2×500 ml)
6. dry with materialdried (MgSO4)
7. customThe solvent was removed by evaporation
8. distillationthe residual liquid distilled under vacuum