Diastereoselective synthesis of CF 3 -dihydrobenzofurans by [4+1] annulation of in situ -generated CF 3 - o -quinone methides and sulfur ylides.

An efficient and highly diastereoselective synthesis of CF 3 -dihydrobenzofurans by the reaction of in situ -generated CF 3 - o QMs in the presence of a base with sulphur ylides is put forward. The generality of the present developed method was well studied with diverse substrates to access the corresponding products in excellent yields. The highly reactive CF 3 - o QM has been utilized first time for the annulation reaction.