Chlorosulfonation of 2-acylthiophenes: an examination on the reaction regiochemistry |
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Authors: | Arturo ArduiniAndrea Pochini Andrea SecchiFranco Ugozzoli |
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Affiliation: | a Dipartimento di Chimica Organica e Industriale dell'Università, Parco Area delle Scienze 17/A, Parma I-43100, Italy b Dipartimento di Chimica Generale e Inorganica Chimica Analitica Chimica Fisica dell'Università, Parco Area delle Scienze 17/A, 43100 Parma, Italy |
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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% yield. The identity of these chlorosulfonated compounds was unambiguously established by NMR techniques and confirmed by the crystal structure determination of the 2-chlorosulfonated isomer. |
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Keywords: | thiophenes chlorosulfonation heterocyclic compounds |
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