ON THE REACTION BETWEEN ALKYL ISOCYANIDES AND 3-BENZYLIDENE-2,4-PENTANEDIONE - A CONVENIENT SYNTHETIC ROUTE TO DENSELY FUNCTIONALIZED FURANS

Alkyl isocyanides undergo a formal [1 + 4] cycloaddition reaction with 3-benzylidene-2,4-pentanedione yielding multiply functionalized furan ring systems in fairly high yields. The H-1 NMR spectrum of 4-acetyl- 2-(N-benzylamino)-5-methyl-3-phenylfuran shows an AB pattern for the b enzylic methylene protons as a result of a restricted rotation about t he bond between the acetyl group and the furan ring, thus giving rise to perpendicular disymmetric planes.