Studies on the Syntheses of Benzoquinolizines. V

Synthesis of 1, 3, 4, 6, 11, 11a-Hexahydro-2H-8, 9-dimethoxy-benzo[b]quinolizine

Abstract

1, 3, 4, 6, 11, 11a-Hexahydro-2H-8, 9-dimethoxybenzo[b]quinolizine, synthesized through two different routes, were found to be not entirely identical and the compound was again synthesized by another route, by the condensation-cyclization of α-3, 4-(dimethoxybenzyl) piperidine with formaldehyde and hydrochloric acid. As for the properties of four types of benzoquinolizines synthesized to date, (A) and (B) types obtained by the fusion of isoquinoline and pyridine are stable in the air, and (C) and (D) types formed by the fusion of quinoline and pyridine are somewhat labile. It is interesting in comparison with dibenzoquinolizines that the (B) type compounds have the highest melting point among these compounds.