Several synthetic routes towards 3-aryl-7,8-dimethoxyisoquinolines were investigated to provide intermediates for berbines and benzo-[c]-phenanthridines. A facile synthesis of 3-aryl-7,8-dioxygenated isocoumarins was obtained by conversions to isoquinoline derivatives were unsuccessful. A novel route to an benzylaminophenyl-acetaldehyde dimethyl acetal was accomplished, with subsequent ring closure to a 3-siryl-7,8-dimethoxyisoquinoline. The preparation of dissymmetrically substituted desoxy-benzoins was briefly investigated and, through the intermediate conversion of a desoxybenzoin to a 3-aryl-8-hydroxy-7-methoxy-isoquinoline, the alkaloid Berberastine was synthesized.
|Date of Award||1973|