Suzuki-Miyaura Coupling Reaction of Boronic Acids and Ethyl Glyoxylate: Synthetic Access to Mandelate Derivatives

The palladium-catalyzed coupling reaction of arylboronic acids with ethyl glyoxylate provides a straightforward method for the synthesis of mandelic esters. Pd-2(dba)(3)center dot CHCl3 in combination with 2-di-tert-butylphosphanylbiphenyl as the catalytic system and Cs2CO3 as the base were used. The reaction tolerates a wide range of functionalized boronic acids. Mandelic esters were isolated in good-to-excellent yields with a variety of neutral, slightly electron-rich, and slightly electron-poor substituents. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)