Synthesis of Novel Fused Systems Derived from 4-Spiro-Fused 6,7-Dimethoxy-1-(ethoxycarbonyl)dihydroisoquinolines

Abstract

Ethyl esters of 4-spiro-fused 6,7-dimethoxydihydroisoquinoline-1-carboxylatic acids were reduced to the corresponding 1-(hydroxymethyl)tetrahydroisoquinolines. The latter were cyclized with Formalin to form oxazoloisoquinolines, which were then recyclized into tetrahydropyranoisoquinolines by treatment with hydrobromic and concentrated hydrochloric acids. Spiro-fused 1-(hydroxymethyl)isoquinoline-6,7-diols were reacted with dibromoethane to obtain the corresponding dioxinoisoquinolines.