Rhodium(CAAC)-Catalyzed Arene Hydrogenation of Benzo-Fused N-Heterocycles to Saturated Building Blocks with an all-cis Configuration

Saturated carbo- and heterocyclic building blocks can be readily obtained by the hydrogenation of aromatic carbo- and heterocycles. Although a variety of methods have been established to accomplish this transformation for simple arenes, the hydrogenation of aromatic N-heterocycles is less explored. We herein report a diastereoselective arene hydrogenation which was applied to an array of benzo-fused N-heterocycles. A total of 48 saturated heterocycles was obtained by hydrogenation in the presence of the rhodium complex ^Cy(CAAC)Rh(cod)Cl in yields of 72–98% with moderate to high diastereoselectivities exhibiting the hydrogen atoms in an all-cis arrangement. The high tolerance towards functional groups enables the formation of valuable saturated products, which offer a starting point for further derivatization. (Figure presented.).