Expedient synthesis of (S)- and (R)-norcoclaurine from (S)- and (R)-norarmepavine [corrected] prepared by the 1-phenylethylurea method

(+/-)-Norarmepavine 3] corrected] prepared by Bischler-Napieralski synthesis afforded, on reaction with (S)-(-)-1-phenylethylisocyanate, ureas 4 and 5 which were separated and purified by crystallization from EtOH and 70% HOAc. Alcoholysis of 4 and 5 with sodium butoxide in n-BuOH afforded (S)-norarmepavine 3a] and (R)-norarmepavine 3b] corrected], 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.