A Platform for the Synthesis of Corynantheine-Type Corynanthe Alkaloids.

Corynantheine-type alkaloids are major components of the Mitragyna speciosa , also known as kratom, that exhibit unique pharmacological activity. However, no universal method to prepare these alkaloids has been reported. Disclosed herein is a catalytic, asymmetric platform that enables rapid access to corynantheine alkaloids. The first enantioselective total synthesis of (-)-corynantheidine pseudoindoxyl is described. The first asymmetric syntheses of (+)-corynoxine and (-)-corynoxine B were also achieved, along with enantioselective syntheses of (-)-corynantheidol and (-)-corynantheidine. Through this work, all series of corynantheine alkaloids including indole, spirooxindole, and pseudoindoxyl can now be accessed in the laboratory, enabling comprehensive biological investigation of kratom alkaloids to be undertaken.