Different addition modes of cyclopentadiene and furan at methylidene(thio)hydantoins

Abstract

3-Methylidene-5-phenylhydantoin and 3-methylidene-5-phenylthiohydantoin react with cyclopentadiene forming spirocyclic Diels–Alder adducts. In contrast, their reactions with furan in the presence of AlCl3 give the products of the furan α-amidoalkylation.