合成路线1

The condensation of dimethylacetone-1,3-dicarboxylate (X) with ethanolamine (XI) yields methyl 3-(methoxycarbonylmethyl)-3-(2-hydroxyethylamino)acrylate (XII), which is cyclized with bromoacetaldehyde diethylacetal (XIII) affording methyl 1-(2-hydroxyethyl)-3-methoxycarbonylpyrrol-2-acetate (XIV). Acylation of (XIV) with methanesulfonyl chloride (XV) and triethylamine in CH2Cl2 yields the corresponding mesylate (XVI), which by treatment with methyl iodide in refluxing acetonitrile is converted into methyl 1-(2-iodoethyl)-3-methoxycarbonylpyrrole-2-acetate (XVII). The cyclization of (XVII) with NaH in DMF yields dimethyl 1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1,7-dicarboxylate (XVIII), which is hydrolyzed with KOH in refluxing methanol - water to the corresponding diacid (XIX). Partial esterification of (XIX) with isopropanol and HCl gives isopropyl 1,2-dihydro-3H-7-carboxypyrrolo[1,2-a]pyrrole-1-carboxylate (XX), which is decarboxylated by heating at 270 C affording isopropyl 1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylate (XXI). Benzoylation of (XXI) with N,N-dimethylbenzamide (XXII) and POCl3 in refluxing CH2Cl2 yields isopropyl 5-benzoyl-1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylate (XXIII), which is finally hydrolyzed with K2CO3 or NaOH in methanol - water.