Iron-Catalyzed Oxidative C-H Functionalization of Internal Olefins for the Synthesis of Tetrasubstituted Furans.

Tetrasubstituted furans were efficiently synthesized from Fe(OAc)2-catalyzed C-H/C-H cross-dehydrogenative-coupling (CDC) reactions of activated carbonyl methylenes with S,S-functionalized internal olefins, that is, α-oxo ketene dithioacetals and analogues, under oxidative conditions. β-Ketoesters, 1,3-dicarbonyls, β-keto nitrile, and amide derivatives were used as the coupling partners. The resultant alkylthio- and carbonyl-functionalized furans could be further transformed to diverse arylated furan derivatives and furan-fused N-heterocycles, respectively. The control experiments have revealed a radical reaction pathway.