Stable Gold(III) Catalysts by Oxidative Addition of a Carbon-Carbon Bond

Whereas low-valent late transition metal catalysis has become indispensible for chemical synthesis, homogeneous high-valent transition metal catalysis is underdeveloped, mainly due to the reactivity of high-valent transition metal complexes and the challenges associated with synthesizing them. In this manuscript, we report a mild carbon-carbon bond cleavage reaction by a Au(I) complex that generates a stable Au(III) cationic complex. Complementary to the well-established soft and carbophilic Au(I) catalyst, this Au(III) complex exhibits hard, oxophilic Lewis acidity. This is exemplified by catalytic activation of α,β-unsaturated aldehydes towards selective conjugate additions as well as activation of an unsaturated aldehyde-allene for a [2 + 2] cycloaddition reaction. The origin of the regioselectivity and catalytic activity was elucidated by X-ray crystallographic analysis of an isolated Au(III)-activated cinnamaldehyde intermediate. The concepts revealed in this study provide a strategy for accessing high-valent transition metal catalysis from readily available precursors.