Platinum-catalyzed reductive coupling of activated alkenes under hydrogenation conditions

The Pt complex generated from PtCl2, PR3, and SnCl2 catalyzes the reductive coupling of activated alkenes under environmentally benign hydrogenation conditions. Various bis-enones participated in the intramolecular cyclization, forming the desired cyclization products in moderate to good yield. Intermolecular reductive coupling of the enone and the aldehyde provided the coupling product in good yield. This methodology illustrates the first use of platinum complexes in hydrogen-mediated couplings of activated alkenes.