EXPEDIENT SYNTHESIS OF (S)-NORCOCLAURINE AND (R)-NORCOCLAURINE FROM (S)-ARMEPAVINE AND (R)-ARMEPAVINE PREPARED BY THE 1-PHENYLETHYLUREA METHOD

(±)-Armepavine [3] prepared by Bischler-Napieralski synthesis afforded, on reaction with (S)-(—)-1-phenylethylisocyanate, ureas 4 and 5 which were separated and purified by crystallization from ErOH and 70% HOAc. Alcoholysis of 4 and 5 with sodium butoxide in n-BuOH afforded (S)-armepavine [3a] and (R)-armepavine [3b], respectively. Hplc analysis of ureas prepared from 3a and 3b with (S)-(—)-1-phenylethylisocyanate showed them to be optically pure alkaloids. Refluxing 3a and 3b with 48% HBr afforded the hydrobromide salts of (S)-norcoclaurine [1a] and its (R)-isomer 1b, respectively. © 1990, American Chemical Society. All rights reserved.