A General Organocatalytic Approach toward the Enantioselective Total Synthesis of Indolizidine Based Alkaloids

Four indolizidine based alkaloids (IBAs) have been synthesized in a highly enantioselective, straightforward, and flexible manner. As a key step our previously developed Brønsted acid catalyzed vinylogous Mannich reaction was employed which easily afforded gram amounts of an optically pure central intermediate which can be converted into a wide range of diversely substituted IBAs.