Different pi -deficient arylsulfonyl groups have been studied as candidates for the stabilization of a-sulfonyl esters. The 3,5-bis(trifluoromethyl)phenylsulfonyl group has been shown to be the best substituent for the stereoselective synthesis of E-aconitates by a dialkylation-dehydrosulfinylation integrated process under PTC conditions using K2CO3 as base. (C) 2001 Elsevier Science Ltd. All rights reserved.