Heterobimetallic Catalysis: Platinum-Gold-Catalyzed Tandem Cyclization/C-X Coupling Reaction of (Hetero)Arylallenes with Nucleophiles.

Heterobimetallic catalysis offers new opportunities for reactivity and selectivity but still presents challenges, and only a few metal combinations have been explored so far. Reported here is a Pt-Au heterobimetallic catalyst system for the synthesis of a family of multi-heteroaromatic structures through tandem cyclization/C-X coupling reaction. Au-catalyzed 6-endo-cyclization takes place as the first fast step. Pt-Au clusters are proposed to be responsible for the increased reactivity in the second step, that is, the intermolecular nucleophilic addition which occurs through an outer-sphere mechanism by hybrid homogeneous-heterogeneous catalysis.