First total synthesis of the β-carboline alkaloids trigonostemine A, trigonostemine B and a new synthesis of pityriacitrin and hyrtiosulawesine

Abstract

The total synthesis of four natural products, trigonostemine A, trigonostemine B, pityriacitrin, and hyrtiosulawesine was accomplished. The key intermediates, variously substituted 1-formyl-β-carbolines, were prepared in five steps via a novel synthetic approach using readily available starting materials. These formyl derivatives were then further transformed, providing a general route for the synthesis of the four title alkaloids. The method reported herein represents the first total synthesis of the two trigonostemines and a new pathway to pityriacitrin and hyrtiosulawesine.