Chirality Transfer and Asymmetric Catalysis: Two Strategies toward the Enantioselective Formal Total Synthesis of (+)-Gelsenicine

ABSTRACT: Two strategies are described en route to an enantioselective total synthesis of gelsenicine. One approach centers on a chirality transfer cycloisomerization that ultimately fell short. Separately, an asymmetric catalysis route utilizing bisphosphine-gold-catalyzed cycloisomerization was pursued. A catalytic system was identified that provided a synthetic intermediate in our Gelsemium alkaloid syntheses in high enantiopurity and with absolute configuration determined by electronic circular dichroism, thus representing an enantioselective formal total synthesis of (+)-gelsenicine.

Automated summary

This study describes two strategies for enantioselective total synthesis of gelsenicine. One approach using chirality transfer cyclization fell short, while a separate asymmetric catalysis route utilizing bisphosphine-gold-catalyzed cyclization was pursued. A catalytic system was identified that provided a synthetic intermediate in high enantiopurity, allowing for the enantioselective formal total synthesis of (+)-gelsenicine.