The development of the highly diastereoselective and the clean catalytic synthesis of glycidic acid derivatives via Darzens condensation reaction is summarized. The Darzens reaction of alpha-chloroester and nitrile with aromatic aldehydes under mild conditions proceeds in the presence of polystyrene-supported quaternary ammonium salt (polystyrene-supported triethylammonium chloride, Ps-TEAC) as a phase-transfer catalyst (PTC) to give the corresponding cis- and trans-desired products in satisfactory yields. The polymer-supported catalyst can be separated from filtration and reused efficiently. (C) 2004 Elsevier B.V All fights reserved.