Metal-Free C-S Bond Formation in Elemental Sulfur and Cyclobutanol Derivatives: The Synthesis of Substituted Thiophenes.

A general approach for the metal-free synthesis of thiophenes by -cyclobutanols and elemental sulfur has been developed. This protocol provides a strategy for constructing multisubstituted thiophene derivatives via C-S bond formation under air. This reaction shows good functionality tolerance under the reaction conditions, and the mechanism is validated by control experiments and density functional theory calculations.