One-pot synthesis of thioethers from indoles and p -quinone methides using thiourea as a sulfur source.

Thiourea is an inexpensive and user friendly sulfur reagent that acts as a sulfur source. A simple and efficient protocol has been developed to access thioethers by reacting indoles with p -quinone methides using thiourea as the sulfur source. In our experiments, the reaction apparently proceeded through an S -(3-indolyl)isothiuronium iodide intermediate and subsequent generation of indolethiol that attacked the 1,6 position of p -quinone methides to give desired thioethers in good to excellent yields.