p-Toluenesulfonic acid → (trans)-N-benzyl-N-[3-(3,4-dimethoxyphenyl) cyclohexyl]amine

Participants

Reaction Steps

3-(3,4-Dimethoxyphenyl)cyclohexanone (6.90 g) and benzylamine (3.16 g) were refluxed for 1.5 hours in benzene (150 ml) in the presence of para-toluenesulfonic acid (630 mg), using a Dean-Stark apparatus while removing the water generated. After distilling off the benzene under reduced pressure, it was dissolved in methanol (120 ml) while cooling on ice, sodium borohydride (1.12 g) was gradually added and the mixture was stirred at room temperature for an hour. After concentrating the reaction solution, water was added, extraction was performed with chloroform, and the solution was washed with saturated sodium bicarbonate water and saturated saline. After drying with anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure to produce a light yellow oily substance which was then separated and purified by silica gel column chromatography (n-hexane:ethyl acetate=5:1→1:1→1:2), to give 3.16 g of (trans)-N-benzyl-N-[3-(3,4-dimethoxyphenyl) cyclohexyl]amine (33.2% yield) and 3.09 g of (cis)-N-benzyl-N-[3-(3,4-dimethoxyphenyl)cyclohexyl]amine (32.4% yield).

Provenance & Evidence