Dicyclohexylcarbodiimide → Difenoximide

Participants

Reaction Steps

24.5 Grams of 1-(3-cyano-3,3-diphenylpropyl)-4-phenylpiperidine-4-carboxylic acid are dissolved in 225 ml. of redistilled N,N-dimethylformamide by warming to about 60°C. To the warm solution were added, with stirring, 9.0 grams of recrystallized N-hydroxysuccinimide, followed by 12.4 grams of dicyclohexylcarbodiimide. A precipitate appears upon cooling to room temperature. The suspension is stirred at room temperature under anhydrous conditions for about 36 hours, then is cooled to approximately 5°C. and is filtered to remove the precipitate. The filtrate is diluted with approximately 400 ml. of ethyl acetate and 200 ml. of water. The organic layer is then separated and washed three times with water, solid sodium chloride being added as needed to break the emulsion formed. The solution is dried over anhydrous sodium sulfate and partially concentrated until a precipitate forms. Filtration and recrystallization of the precipitate from a mixture of tetrahydrofuran and isopropyl ether affords N-[1-(3-cyano-3,3-diphenylpropyl)-4-phenylpiperidine-4-carbonyloxy]succinimide, melting at about 156.5°-157.5°C. This product has the formula ##SPC3##

Provenance & Evidence