Convenient synthesis of functionalized α-methylenebutano-4-lactams or lactones

α-Alkylidene-γ-lactams and lactones are the active constituents of many natural and synthetic compounds exhibiting pronounced biological properties. They are able to act as Michael acceptors in the reaction with thiol groups of bionucleophiles or can readily form [2 + 2] cycloadducts with DNA bases. We have developed concise synthetic approaches towards exemplary representatives of α-methylene models that hinges upon the preliminary assembly of the lactam and lactone template. Subsequent installation of the methylidene by a metallation/alkylation/elimination sequence completed the elaboration of the racemic title compounds. The presence of a quaternary carbon center bearing the carboxylate function precluded the undesirable isomerization leading to the corresponding endocyclic unsaturated analogues.