Synthesis of 4,5-Dihydrofuran-3-carbonitrile Derivatives with Electron-Rich Alkenes in the Presence of Manganese(III) Acetate

Radical cyclization reactions mediated by manganese(III) acetate were carried out with pi-excessive alkenes (2a-d) and 3-oxopropanenitriles (1a-f) resulting in the formation of 3-cyano-4,5-dihydrofuran derivatives in poor to high yields. A mechanism was proposed for the cyclization reaction. The significance of the study is the formation of the 3-cyano-4,5-dihydrofuran derivatives resembling terfuran, 2-(2-thienyl) furan and 2-(2-benzofuryl) furyl compounds having the fluorescent properties due to a conjugated pi-electron system particularly containing the cyano moeity.