Dimolybdenum Catalysis: Deoxygenative Coupling of Aldehydes

Described herein is the first example of dimolybdenum-catalyzed deoxygenative coupling of aldehydes using pinacol as a benign reductant. Both homocoupling and heterocoupling were successfully achieved. This facile protocol enables the rapid construction of a collection of symmetrical and unsymmetrical alkenes, including bioactive stilbenes, Pterostilbene, and DMU-211, with high (E)-selectivity. Detailed mechanistic studies revealed the involvement of a Mo2(OAc)4-carbene intermediate. UV/vis spectral analysis showed that the dinuclear molybdenum, rather than the mononuclear molybdenum, was the active catalytic species.