Base induced chiral substituted furans and imidazoles from carbohydrate-derived 2-haloenones

Chiral substituted furans and imidazoles are key intermediates to access biologically important molecules. We describe herein a catalyst/ligand free cascade Michael-type addition/intramolecular cyclization/carbohydrate-ring opening of 2-haloenones with 1,3-dicarbonyl compounds or amidines utilizing K₂CO₃/DMSO at ambient temperature that provides a straightforward approach to a variety of optically active (poly)hydroxy furans and imidazoles containing multiple stereocenters with good yield and excellent regioselectivity. The furan intermediates provide efficient access to synthetically valuable substituted α-benzyloxyvinyl ketones. The NMR spectrum of the substituted 2-methylfurans shows an unusual long-range (⁵J_H-H) ¹H-¹H COSY cross-peak between C₂-CH₃ and C₄-H signals.