Regioselective Synthesis of the 5,6-Dihydro-4H-furo[2,3-c]pyrrol-4-one Skeleton: A New Class of Compounds

We hereby report the first preparation of the 5,6-dihydro-4H-furo[2.3-c]pyrrol-4-one (3) and its derivatives starting from methyl 3-(methoxycarbonyl)furnan-2-acetate (8). The ester functionality connected to the methylene group was regiospecifically converted to the desired monohydrazide 9. Conversion of 9 into the acyl azide In followed by Curtius rearrangement gave the corresponding isocyanate derivative 11 (Scheme 2). Reaction of 11 with different nucleophiles produced urethane and urea derivatives (Scheme 3). Intramolecular cyclization reactions provided the target compounds (Scheme 5). Removal of the amine-protecting group formed the title compound 3.