Coreximine and Related Compounds. III. : The Formation of Coreximine Isomers under Eschweiler-Clarke's Conditions : Studies on the Syntheses of Heterocyclic Compounds. CLXIV.

Abstract

The 3, 4-dihydroisoquinoline compound (XII), obtained by the Bischler-Napieralski reaction of the amide (XI), was derived to the 1, 2, 3, 4-tetrahydroisoquinoline compound (XIII) and debenzylated to 1-(4-hydroxy-3-methoxybenzyl)-6-methoxy-1, 2, 3, 4-tetrahydroisoquinolin-7-ol (II). The free base of XII was very labile and easily changed to 1-benzoylisoquinoline (XIV) which was submitted to the Clemmensen reduction to obtain II. In order to obtain 1-(4-hydroxy-3-methoxybenzyl)-6-methoxy-2-methyl-7-hydroxy-1, 2, 3, 4-tetrahydroisoquinoline (I), II was submitted to the Eschweiler-Clarke reaction and an unexpected cyclization to the dibenzoquinolizine base occurred, forming XV, a kind of isomer of coreximine. Methylation of XV with diazomethane gave (±)-norcoralydine (XVI), while treatment of II with sodium borohydride and formaldehyde solution resulted in normal N-methylation to form I.