A Novel Synthesis of α-Methylene-γ-butyrolactones

Abstract A new method is reported for constructing α-methylene-γ-butyrolactone moiety under neutral, anhydrous conditions. Olefin–dibromocarbene adducts were transformed into methyl 1-(dimethylaminomethyl)cyclopropanecarboxylates (3). Treatment of 3 with trimethylsilyl iodide followed by thermolytic distillation of the crude products gave α-methylene-γ-butyrolactones with high regio- and stereo selectivity.