An intramolecular variant of the modified-Julia olefination was demonstrated by the synthesis of α,β-unsaturated lactones in a mild and (Z)-selective fashion. The lynchpin reagent (benzothiazol-2-sulfonyl) acetic acid was synthesized in a straightforward fashion in 86% overall yield from commercially available 2-mercaptobenzothiazole via conversion to ethyl (benzothiazol-2-ylthio)acetate by base mediated alkylation...