synthesis of substituted γ-butyrolactones from cyclopropyl amides mediated by the Lewis acid SnCl4·5H2O is reported. A mechanism involving a tandem ring-opening reaction and intramolecular cyclization reaction is proposed. An efficient one-pot synthesis of substituted γ-butyrolactones from cyclopropyl amides mediated by the Lewis acid SnCl4·5H2O is reported. A mechanism involving a tandem ring-opening reaction