Enantioselective Sulfa-Michael Addition to α,β-Unsaturated γ-Oxoesters Catalyzed by a Metal-Templated Chiral Bronsted Base

The enantioselective addition of aromatic thiols to alpha,beta-unsaturated gamma-oxoesters bearing an imidazole substituent in the delta position and catalyzed by an inert octahedral bis-cyclometalated iridium(III) complex is reported. High enantioselectivity down to catalyst loadings of 0.05mol% is achieved mediated by the formation of well-arranged hydrogen bonds within the ligand sphere of the catalyst after the initial proton transfer. This work highlights the manifold opportunities provided by this metal-templated design strategy in which the metal exerts a purely structural role whereas catalysis occurs through the organic ligand sphere (metal-templated organocatalysis).