Gold(I)-Catalyzed Highly Diastereo- and Enantioselective Cyclization–[4+3] Annulation Cascades between 2-(1-Alkynyl)-2-alken-1-ones and Anthranils

This work reports gold-catalyzed [4+3]-annulations of 2-(1-alkynyl)-2-alken-1-ones with anthranils to yield epoxybenzoazepine products with excellent exo-diastereoselectivity (dr>25:1). The utility of this new gold catalysis is manifested by applicable substrates over a broad scope. More importantly, the enantioselective versions of these [4+3]-cycloadditions have been developed satisfactorily with chiral gold catalysts under ambient conditions (DCM, 0 °C); the ee levels range from 88.0–99.9 %. With DFT calculations, we postulate a stepwise pathway to rationalize the preferable exo-stereoselection.