Studies on Tetrahydroisoquinolines. XII. An Alternative Synthesis of (±)-Bracteoline, (±)-Isoboldine, (±)-N-Methyllaurotetanine, and Their Related Aporphines

Abstract

By the treatment of the p-quinol acetate (Xa) and (Xb) with trifluoroacetic acid, (±)-10-benzyloxy-1-hydroxy-2, 9-dimethoxyaporphine (XIa) and (±)-9-benzyloxy-1-hydroxy-2, 10-dimethoxyaporphine (XIb) were given in good yield, respectively. Furthermore, XIa and XIb were converted to (±)-bracteoline (XIIa) and (±)-isoboldine (XIIb) by catalytic debenzylation, or to (±)-10-hydroxy-1, 2, 9-trimethoxyaporphine (XIVa) and (±)-N-methyllaurotetanine (XIVb) by methylation and successive debenzylation, respectively.