Studies on the syntheses of heterocyclic compounds. Part CCCLXXXIII. A total synthesis of (–)(–)-OO-dimethylcurine

Abstract

Cyclisation of the amide prepared by condensation of 5-bromo-3,4-dimethoxyphenethylamine with methyl 3-bromo-4-methoxyphenylacetate gave a 3,4-dihydroisoquinoline, reduction of which, followed by an Eschweiler–Clarke reaction, afforded a tetrahydroisoquinoline. An Ullmann reaction then gave a mixture of the diastereoisomeric racemates of OO-dimethylcurine (I), tetrandrine (III), and the bisbenzylisoquinolinyl ether (IV). A total synthesis of (–)(–)-OO-dimethylcurine (II) was achieved by a similar route.