Asymmetric addition of arylboronic acids to glyoxylate catalyzed by a ruthenium/Me-BIPAM complex

The enantioselective synthesis of a-hydroxy esters by ruthenium-catalyzed 1,2-addition of arylboronic acids to tert-butyl glyoxylate is described. The use of RuCl2(PPh3)(3) with (R, R)-Me-BIPAM gave optically active mandelic acids of up to 99% ee. Addition of a fluoride salt such as potassium fluoride (KF) or caesium fluoride (CsF) was effective for achieving high enantioselectivities.