Pyridone analogues of tetrahydroisoquinolines and protoberberines from mimosine and mimosinamine

Abstract

Several pyrido[1,2-a]piperazines and their N-methyl derivatives have been prepared. These pyridine analogues of the 1,2,3,4-tetrahydroisoquinolines were formed by condensation of carbonyl compounds with mimosine and mimosinamine in the absence of an acid catalyst. A Mannich reaction converted one of these compounds, 1-(3,4-dimethoxybenzyl)-9-hydroxy-1,2,3,4-tetrahydro-8H-pyrido[1,2-a]- pyrazin-8-one, into a pyridone analogue of the tetrahydroprotoberberine caseadine.