Bimetallic transition metal catalysis is an emerging approach to catalyst development where the presence of two metals centers in a single complex leads to unique reactivity and new reaction mechanisms. Our group recently discovered that 2-phosphinoimidazole ligands can scaffold Pd-Pd, Rh-Rh, and Pt-Pt bimetallic complexes. Here we describe the reactivity of our Pd-Pd complexes in tandem ketone alpha-arylation/annulation reactions to generate substituted naphthalene products in a single transformation. DFT calculations identify the role of the bimetallic catalyst in enabling product formation. In related work, we report that bimetallic Rh(I) complexes enable medium and large N-heterocycle formation (7–15-member rings) via allene hydroamination. Our mechanistic studies confirm the essential role of the bimetallic catalysis in efficient hydroaminations where monometallic Rh catalysts fail to give any cyclization product.

Bimetallic catalysis with 2-phosphinoimidazole-derived Pd–Pd and Rh-Rh complexes

ACS Spring 2022

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