Abstract The pairing of unstabilized nitrogen ylides generated in situ with functionalized thiolesters under ambient conditions resulted in a new intramolecular carbon–carbon bond forming reaction. The scope of the reaction was illustrated with a series of substituted thiolester substrates. This reaction represents a new method for the synthesis of 2- substituted tetrahydrothienyl compounds through a unique 1, 2-thiolate shift. Whereas ...