Dimethyl sulfoxide mediated elimination reactions in 3-aryl 2,3-dihalopropanoates: Scope and mechanistic insights

Dimethyl sulfoxide (DMSO) efficiently causes the reductive elimination of 3-aryl 2,3-dibromopropanoates to cinnamates with good yield. With 3-phenyl 2,3-dihalopropanoates, debromination is the major pathway providing 3-phenylacrylate derivatives in high yields, whereas dehydrobromination is a competing pathway with thiophene derivatives. H-1 NMR, Br-81 NMR, and MS techniques indicated the formation of brominated-DMSO, MeBr, and HBr as byproducts in this transformation with no evidence for the formation of Br-2. The dual role of DMSO as a nucleophile and bromine scavenger accounts for the products formed in this reaction.