Benzyl-Type Cation Initiated Nucleophilic Substitution on Furan and Thiophene by Using α-EWG Ketene S,S-Acetals as Nucleophiles.

An efficient method for introducing nucleophiles on furan and thiophene has been established via the in situ formation of benzyl-type carbocation, delocalization of the carbocation on heterocyclic ring, and nucleophilic trap of α-EWG ketene S,S-acetal sequence at the 5-position. [ABSTRACT FROM AUTHOR]