Rhodium-Catalyzed Asymmetric 1,4-Addition of Organoboronic Acids and Their Derivatives to Electron Deficient Olefins

Asymmetric 1,4-arylation and -alkenylation was achieved by use of organoboronic acids or their derivatives in the presence of a rhodium catalyst coordinated with binap ligand. The reaction conditions are unique in that it is usually carried out in an aqueous solvent at 100 °C. The scope of this asymmetric addition is very broad, a,b-unsaturated ketones, esters, 1-alkenylphosphonates, and 1-nitroalkenes being efficiently converted into the corresponding optically active 1,4-addition products with over 95% enantioselectivity. The catalytic cycle is proposed to involve the enantioselective addition of arylor alkenyl-rhodium intermediate to carbon-carbon double bond of the electron deficient olefins as a key step.