PALLADIUM CATALYZED INSERTION OF CARBON-MONOXIDE INTO BENZYL-TETRAHYDROISOQUINOLINES - A NEW SYNTHESIS OF BERBINE ALKALOIDS

A new total synthesis of the berbine alkaloid ring system was achieved, [these compounds have pharmacological activity]. Pd catalyzed insertion of CO into the 1-(2-bromobenzyl)-substituted-1,2,3,4-tetrahydroisoquinolines by the use of catalytic amounts of palladium diacetate and triphenylphosphine in the presence of tri-n-butylamine yielded the berbin-8-ones which, on reduction with lithium aluminum hydride gave the berbines (.+-.)-berbine, (.+-.)-2,3-dimethoxyberbine, (.+-.)-xylopinine and (.+-.)-pseudoepitetrahydroberbine.