A Modular and Divergent Strategy for Dibenzo[b,f]oxepine Natural Products: Total Syntheses of Pacharin, Bauhiniastatins 1–4, and Bauhinoxepins C–J and Structural Revision of Bauhinoxepin F

Abstract

We report the development of synthetic routes to representative Bauhinia family natural products, including pacharin, bauhiniastatins 1–4, and bauhinoxepins C–J. The key transformation involves a one-pot aldol condensation/S_NAr sequence to efficiently construct the dibenzo[b,f]oxepine core. Subsequently, a cyano group, employed as a reactive handle in the aldol reaction, was removed via decyanation. Through diverse functional group transformations, a total of 28 Bauhinia family analogs were successfully synthesized, including the originally misassigned bauhinoxepin F (3d). In addition, the structure of bauhinoxepin F was subsequently revised based on our synthetic studies.