Methanol → (4S)-1-benzyloxycarbonyl-4-hydroxy-1,2,3,4-tetrahydroquinoline

Participants

Reaction Steps

To a mixture of 0.5 mL of (R)-2-methyl-CBS-oxazaborolidine solution and 3 mL of dichloromethane was added dropwise 0.07 mL of 1.0M borane-dimethylsulfide complex at 25° C., and the mixture was stirred at the same temperature for 15 minutes. To the solution was added dropwise a solution of 141 mg of 1-benzyloxycarbonyl-4-oxo-1,2,3,4-tetrahydroquinoline in 2.5 mL of dichloromethane over about 10 minutes. Furthermore, to the reaction solution were added 0.07 mL of 1.0M borane-dimethylsulfide complex and a solution of 141 mg of 1-benzyloxycarbonyl-4-oxo-1,2,3,4-tetrahydroquinoline in 2.5 mL of dichloromethane alternately with total 4 times. To the reaction solution was added dropwise 1 mL of methanol, and the reaction solution was concentrated. To the resulting residue were added 10 mL of dichloromethane and 10 mL of phthalate buffer (pH4.0), and the aqueous layer was removed, and then water was added. The organic layer was separated, dried over magnesium sulfate, and then filtered, and the filtrate was concentrated. The resulting residue was purified by column chromatography on silica gel (solvent; n-hexan/ethyl acetate=4/1) to give 559 mg of (4S)-1-benzyloxycarbonyl-4-hydroxy-1,2,3,4-tetrahydroquinoline (yield: 99%, optical purity: 96% ee).

Provenance & Evidence