N-HYDROXYPYRIDINE-2-THIONE CARBAMATES .5. SYNTHESES OF ALKALOID SKELETONS BY AMINIUM CATION RADICAL CYCLIZATIONS

The title radical precursors (PTOC carbamates) were employed as sources of a variety of 5,6-unsaturated aminium cation radicals. 5-Exo radical cyclization followed by trapping by t-BuSH or the PTOC carbamate gave a variety of aklaloid skeletons, typically in good to excellent yields, including pyrrolidines, perhydroindoles, pyrrolizidines, tropanes, 9-azabicyclo[4.2.1]nonanes, 6-azabicyclo [3.2.1]octanes. 6-Exo and 7-endo cyclizations competed in a 6,7-unsaturated system. © 1990.