2-Cyclohexen-1-one → (S)-3-n-butylcyclohexanone

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

(S)-N-methyl-1-phenyl-2-(1-piperidinyl)ethanamine (139.0 mg, 0.638 mmol) was dissolved in dimethyl sulfide (4 mL) and n-butyl lithium (2.5M in hexanes, 0.255 mL, 0.638 mmol) was added to the solution at -65° C. The solution was stirred for 5 min at -65° C., gradually warmed to 0° C. and stirred for 10 min at 0° C. To a second flask was added CuI (81 mg, 0.425 mmol) and 4 mL of dimethyl sulfide. This solution was cooled to -40° C. and treated with n-butyl lithium (0.17 mL, 0.425 mmol). The lithium amide solution in the first flask was cooled to -35° C. and added via canula to the solution of n-BuCu in the second flask. The resulting solution was stirred for 15 min at -35° C., for 10 min at -30° C., and cooled to - 78° C. After 30 min, 2-cyclohexenone (40.8 mg, 0.425 mmol) was added slowly at -78° C. The reaction mixture was quenched after 1 hr by adding 4N NH4Cl (15 mL) at -78° C. and extracted with ether (15 mL). The extract was washed with 1N HCl (15 mL), dried (Na2SO4) and concentrated. The oily residue was purified by column chromatography on silica gel (10:1=hexanes/ethyl acetate) to afford (S)-3-n-butylcyclohexanone (37.1 mg, 57% chemical yield, 83% ee, [α]D =-7.10 (c=1.00, toluene)).

Herkunft & Nachweise