Selective Arene Hydrogenation for Direct Access to Saturated Carbo‐ and Heterocycles

Arene hydrogenation provides direct access to saturated carbo‐ and heterocycles and thus its strategic application may be used to shorten synthetic routes. This powerful transformation is widely applied in industry and is expected to facilitate major breakthroughs in the applied sciences. The ability to overcome aromaticity while controlling diastereo‐, enantio‐, and chemoselectivity is central to the use of hydrogenation in the preparation of complex molecules. In general, the hydrogenation of multisubstituted arenes yields predominantly the cis isomer. Enantiocontrol is imparted by chiral auxiliaries, Brønsted acids, or transition‐metal catalysts. Recent studies have demonstrated that highly chemoselective transformations are possible. Such methods and the underlying strategies are reviewed herein, with an emphasis on synthetically useful examples that employ readily available catalysts. From simplicity, complexity: Modern arene hydrogenation methods provide direct access to complex saturated carbo‐ and heterocycles by controlling the diastereo‐, enantio‐, and chemoselectivity. The hydrogenation of multisubstituted arenes generally yields predominantly the cis isomer. Enantiocontrol may be imparted by chiral auxiliaries, Brønsted acids, or transition‐metal catalysts. The chemoselectivity can often be controlled by optimization of the catalyst and reaction conditions.