摘要：Surfactant-type protonic acid-promoted intramolecular cyclization of functionalized allylsilanes was studied in water for the synthesis of α-methylene-γ-lactone compounds. ω-Formyl-β-(acetoxymethyl)allylsilane afforded carbocyclic compounds in good yields, while the cyclization product was not obtained from the corresponding β-ethoxycarbonyl derivative. It was found that ( Z )-β-(acetoxymethyl)allylsilane predominantly afforded the cis -product, while ( E )-β-(acetoxymethyl)allylsilane afforded both cis - and trans -products at a ratio of almost 1 : 1. The stereoselectivity of the cyclization reaction was almost the same as a protonic acid-promoted reaction in CH2Cl2 and was explained by an interaction between the C(Si)–C(alkene) bond and the carbonyl moiety. The cyclization products were converted to α-methylene-γ-lactone compounds.
