Regiospecific electrocyclization of β-arylvinyl ketenimines. Formal syntheses of the alkaloid from marine origin aaptamine

Article abstract of DOI:10.1055/s-1996-4367

Preparation of 6,7-dimethoxy-1-methyl-8-nitroisoquinoline and 6,7-dimethoxy-1-methylisoquinoline, used as precursors in the synthesis of the alkaloid aaptamine, is reported. The method is based on the regiospecific electrocyclization of the appropriate β-arylvinyl ketenimine available by aza-Wittig reaction of the corresponding vinyl iminophosphorane with (trimethylsilyl)ethenone.