科研之友
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摘要
A novel and expedient cascade strategy has been demonstrated for the synthesis of fused benzo‐aza‐oxa‐[5‐6‐5] tetracycles in high yields and diastereoselectivities (up to 20?:?1 dr). The strategy was fulfilled through palladium‐catalyzed oxidative convergent assembly of functionally divergent anilines and 3‐butenoic acid with five chemical bonds constructed. Coupled with control experiments and deuterium labelled studies, DFT calculations were performed for the proposed mechanism. The utility of the illustrated strategy is emphasized by gram‐scale syntheses, late‐stage functionalization, and the transformation to a key core of natural products such as martinellic acid and seneciobipyrrolidine.(#br)A fused benzo‐aza‐oxa‐[5‐6‐5] tetracycle was concisely constructed via Pd‐catalyzed cascade cyclization with readily available anilines and 3‐butenoic acid. Five chemical bonds and a fused tricycle were formed in one step. This strategy offers an option for synthesizing the common core of natural products martinelline, martinellic acid, seneciobipyrrolidine and incargranine?B. Experimental and computational studies shed light on the mechanism.
