Total synthesis of O-methylandrocymbine by a photo-Pschorr reaction and synthesis of thalifoline

Abstract

The total synthesis of O-methylandrocymbine (4) has been accomplished by photolysis of the diazonium salts (10) and (15) of 6,7-dimethoxy-(11) and 7-benzyloxy-6-methoxy-1-(2-amino-3,4-5-trimethoxyphenethyl)-1,2,3,4-tetrahydr-2-methylisoquinoline (14). On the other hand, pyrolysis of the diazonium salt (15) gave the spiroisoquinoline (32). Moreover, thalifoline (24) was obtained by debenzylation of the by-product (23) in the photolysis and pyrolysis of the latter compound (15).