Synthesis of 2-(2-phenylethenyl) substituted 4,5-dihydrofurans by regioselective addition of 1,3-dicarbonyl compounds to dienes promoted by cerium(IV) ammonium nitrate

Radical addition of 1,3-dicarbonyl compounds to conjugated dienes in the presence of cerium(IV) ammonium nitrate in THF produced 4,5-dihydrofurans in good to excellent yields. All radical additions occurred on the terminal double bond as regioselective. Two different dihydrofurans were obtained from the reaction of 1-phenyl-1,3-butanedione with 1-phenyl-1,3-butadiene and 3-methyl-1-phenyl-1,3-butadiene. All compounds were characterised by IR, H-1, C-13-NMR and HRMS spectra.