Chemoselective 1,2‐Reduction and Regiodivergent Deuteration of Chromium‐Bound Arenes

Abstract

Herein, a general strategy for chemo‐ and regioselective 1,2‐reduction of chromium‐bound arenes was developed, thus providing rapid access to 1,3‐cyclohexadienes. Selective arene activation via π‐complexation along with the use of mild hydride Ph3SiH can overcome the inherently low reactivity of arene π‐bonds while tolerating various reduction‐sensitive functional groups. Its versatility further enables a regiodivergent deuteration. Using different sequences of (non)deuterated hydride and acid reagents, the deuterated positions as well as the degrees of deuterium incorporation can be controlled precisely, which leads to a large and previously inaccessible chemical space for 1,3‐cyclohexadiene isotopologues. A reasonable mechanism was proposed based on intermediate capture and control experiments. The synthetic value of this selective 1,2‐reduction was demonstrated in the formal total synthesis of (±)‐galanthamine and (±)‐lycoramine.