Investigations have been conducted to probe the application of diradical cyclization methods in synthetic approaches to members of the erythrina alkaloid family. For this purpose, a series of [[(trimethylsilyl)-methyl] alkenyl]-3, 4-dihydroisoquinolinium perchlorates (5-1 1) have been prepared. These salts have (trimethylsily1) allyl groupings linked via methylene chains of variable lengths to the 1-position of the hydroisoquinolinium cation nucleus and ...