Acetic Acid → trans-N-cyclopropyl-2-phenylcyclohexanamine

Participants

Reaction Conditions

Reaction Steps

To a cooled solution of 2.78 ml (40 mmol) of cyclopropylamine and 2.87 ml (50 mmol) of acetic acid, together with 5 g of 3 Å molecular sieves, in 50 ml of methanol, are added 3.5 g (20 mmol) of 2-phenylcyclohexanone. The reaction mixture is stirred for 3.5 hrs at reflux. The reaction mixture is then cooled to 0° C. and 3 g (50 mmol) of sodium cyanoborohydride are slowly added and the reaction mixture is further stirred for 2 hrs at reflux. The cooled reaction mixture is then filtered over a cake of diatomaceous earth. The cake is washed twice by 80 ml of methanol and the combined methanolic extracts are concentrated under vacuum. 100 ml of water are then added to the residue and the pH is ajusted to 12 with a 1 N solution of sodium hydroxyde. The watery layer is extracted with 100 ml of ethyl acetate. The organic layer is washed twice by brine and dried over magnesium sulfate to yield after concentration 3.52 g of a yellow oil. Column chromatography on silica gel (gradient heptane/ethyl acetate) yields 1.0 g (23% yield) of cis-N-cyclopropyl-2-phenylcyclo-hexanamine as a yellow oil (M+H=216) and 1.9 g (44% yield) of trans-N-cyclopropyl-2-phenylcyclohexanamine as a colorless oil (M+H=216).

Provenance & Evidence