To investigate the stereoselectivity of noscapine and its derivatives obtained via Bischler-Napieralski reaction, five pairs of phthalideisoquinoline enantiomers 3, 4a, 4b, 5a, 5b were synthesized with 1-isobenzofurancarboxamide,1,3-dihydro-4,5-dimethoxy-N-[2-(7-methoxy-1,3-benzodio xol- 5-yl)ethyl]-3-oxo- (1) and 1-isobenzofurancarboxamide,N-[2-(1,3-benzodioxol-5-yl)ethyl]-1,3-dihydro-4,5- dimethoxy-3-oxo- (2), via two process including Bischler-Napieralski reaction and reduction of sodium borohydride. (±)-α-Narcotine and (±)-β-hydrastine were prepared through N-methylation reaction from 3 and 5a. The phthalideisoquinoline synthesized via this methods has stereoselectivity. We got pairs of erythro isomers predominantly, and found small amounts of threo configuration products. The steric hindrance on 8-substituent group of intermediate products 3,4-tetrahydroisoquinoline (M) caused the stereoselectivity in the process of reduction with sodium borohydride.

Key words: narcotine, phthalideisoquinoline, Bischler-Napieralski reaction, stereoselectivity