Iridium-Catalyzed Asymmetric Hydrogenation of 2<i>H</i>‑Chromenes: A Highly Enantioselective Approach to Isoflavan Derivatives

A highly efficient (aS)-Ir/In-BiphPHOX-catalyzed asymmetric hydrogenation of substituted 2H-chromenes and substituted benzo­[e]­[1,2]­oxathiine 2,2-dioxides is described. A series of 2H-chromenes and benzo­[e]­[1,2]­oxathiine 2,2-dioxides were hydrogenated to give the target products in high yields (92–99%) with excellent enantioselectivities (up to 99.7% ee) using our catalytic system. This reaction provides a direct and efficient method for the construction of chiral benzo six-membered oxygen-containing compounds.