Methyl (<Emphasis Type="Italic">Z</Emphasis>)-3-bromo-3-(4-methylbenzenesulfonyl)prop-2-enoate: Synthesis and reactions with dimethyl malonate and methyl acetoacetate

Bromination–dehydrobromination of methyl (E)-3-(4-methylbenzenesulfonyl)prop-2-enoate gave methyl (Z)-3-bromo-3-(4-methylbenzenesulfonyl)prop-2-enoate whose structure was determined by X-ray analysis. Methyl (Z)-3-bromo-3-(4-methylbenzenesulfonyl)prop-2-enoate behaved as a synthetic equivalent of methyl 3-(4-methylbenzenesulfonyl)prop-2-ynoate in reactions with dimethyl malonate and methyl acetoacetate, which afforded the corresponding Michael adducts, trimethyl 3-(4-methylbenzenesulfonyl)prop-1-ene-1,1,2-tricarboxylate and dimethyl (Z)-2-acetyl-3-(4-methylbenzenesulfonyl)but-2-enedioate, respectively, via nucleophilic attack on the β-position with respect to the sulfonyl group.