Tetrahedron letters

Chlorosulfonation of 2-acylthiophenes: an examination on the reaction regiochemistry

A Arduini, A Pochini, A Secchi, F Ugozzoli

Index: Arduini, Arturo; Pochini, Andrea; Secchi, Andrea; Ugozzoli, Franco Tetrahedron Letters, 2003 , vol. 44, # 30 p. 5755 - 5757

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Citation Number: 3

Abstract

Chlorosulfonation of thenoyltrifluoroacetone with neat chlorosulfuric acid was found to give a 25: 75 mixture of 3-and 2-chlorosulfonated thenoyltrifluoroacetone isomers in 33% overall yield. The use of dichloromethane as solvent for the chlorosulfonation reaction gave only the 2-chlorosulfonated isomer in 45% yield. On the contrary, the reaction of 2-acetylthiophene with neat chlorosulfuric acid gave only the 3-chlorosulfonated-5-acetylthiophene in 35% ...