Phosgene → Butyl piperazine-1-carboxylate hydrochloride

Participants

Reaction Conditions

Reaction Steps

4-Chlorocarbonyl-1-t.-butoxycarbonylpiperazine can be prepared by the simultaneous additions of solutions of 1-t.-butoxycarbonylpiperazine (40.8 g.) in anhydrous toluene (200 cc.) and of phosgene (11.2 g.) in anhydrous toluene (150 cc.) to anhydrous toluene (100 cc.), the temperature being kept at about -5° C. during this operation. After stirring for 1 hour at 2° C., the 1-t.-butoxycarbonylpiperazine hydrochloride formed during the reaction is filtered off and washed twice with anhydrous toluene (total 200 cc.). The filtrate is evaporated to dryness under reduced pressure (20 mm.Hg.). 4-Chlorocarbonyl-1-t.-butoxycarbonylpiperazine (24.8 g.), which melts at 98° C., is obtained. After the product has been purified by recrystallisation from diisopropyl ether, it melts at 99° C.

Provenance & Evidence