2-Cyclohexen-1-one, 5-methyl- → (S,S)-3-n-butyl-5-methylcyclohexanone

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

(S)-N-methyl-1-phenyl-2-(1-piperidinyl)ethanamine (345.0 mg, 1.58 mmol) was dissolved in ether (12 mL) and n-butyllithium (2.5M in hexanes, 0.63 mL, 1.575 mmol) was added to the solution at -65° C. The solution was stirred for 5 min at -65° C., warmed to 0° C. and stirred for 10 min at 0° C. To a second flask was added CuI (251 mg, 1.32 mmol) and 10 mL of diethyl ether. This solution was cooled to -40° C. and treated with n-butyl lithium (0.53 mL, 1.323 mmol). The 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, 5-methyl-2-cyclohexenone (290 mg, 2.64 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 (20 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 (ether/pentane=1/8 followed by ether/pentane=1/5) to afford (S,S)-3-n-butyl-5-methylcyclohexanone (176 mg, 79% chemical yield, 39% ee, [α]D =5.5 (c=1.00, benzene)) and (R)-5-methyl-2-cyclohexenone (78 mg, 54% chemical yield, 28% ee, [α]D =22.8 (c=4.00, acetone)).

Herkunft & Nachweise