Two novel indole alkaloids, Kopsiyunnanines A and B, from a Yunnan Kopsia

Two novel indole alkaloids having unusual skeletons were isolated from the aerial part of Yunnan Kopsia arborea. Kopsiyunnanine A (1) is a new class of bisindole alkaloid composed of vallesiachotamine (modified Corynanthe-type) and Aspidospermatan-type alkaloids. Kopsiyunnanine B (2) is a new Corynanthe-type oxindole alkaloid rearranged by D ring rotation.