Asymmetric synthesis of α,β-epoxysulfones via phase-transfer catalytic Darzens reaction

Described is the asymmetric synthesis of alpha,beta-epoxysulfones by the catalytic phase-transfer Darzens reaction of chloromethyl phenyl sulfone with various aromatic aldehydes in the presence of the cinchona alkaloid-derived chiral phase-transfer catalysts bearing N-2,3,4-trifluorobenzyl moiety. The trans-(alpha R,beta R)-epoxysulfones were obtained in good chemical yields (81-95%) with high enantioselectivities (up to 97% ee) in the presence of N-(2,3,4-trifluorobenzyl) quinidinium bromide. (c) 2007 Elsevier Ltd. All rights reserved.