合成路线1

The cyclization of N-(ethoxycarbonyl)glycine ethyl ester (I) with ethyl acrylate (II) by means of NaH in refluxing benzene gives 4-oxopyrrolidine-1,3-dicarboxylic acid diethyl ester (III), which is selectively decarboxylated with refluxing aqueous 6N HCl yielding 3-oxopyrrolidine-1-carboxylic acid ethyl ester (IV). The Friedlander cyclization of (IV) with 2-aminobenzaldehyde (V) affords the pyrroloquinoline derivative (VI), which is decarboxylated in basic medium to afford 2,3-dihydro-1H-pyrrolo[3,4-b]quinoline (VII). The condensation of (VII) with the furanone derivative (VIII) by means of pyridine in acetonitrile affords the acylated pyrroloquinoline (IX), which is cyclized by means of NaOAc in acetic acid providing the tetracyclic intermediate (X). The dechlorination of (X) with H2 over Pd/C in ethanol affords the expected methyl derivative (XI), which is debenzoylated with sodium methoxide in methanol to give the secondary alcohol (XII). Finally, this compound is oxidized with pyridinium chlorochromate (PCC) in dichloromethane.