合成路线1

Treatment of methyl pyrrole-2-carboxylate (I) with KOtBu and 18-crown-6 in Et2O, followed by reaction with ethyl iodide (II) in Et2O, yields methyl 1-ethylpyrrole-2-carboxylate (III), which is then subjected to saponification with NaOH to afford carboxylic acid (IV). Condensation of (IV) with beta-alanine benzyl ester p-toluene sulfonate (V) in the presence of diethyl phosphorocyanidate (DEPC) and Et3N in DMF provides benzyl ester (VI), which is then hydrogenated over Pd/C in THF, furnishing carboxylic acid (VII). Cyclization of (VII) with polyphosphoric acid (PPA) affords derivative (VIII), which is then treated with NaH in DMF and alkylated with chloro derivative (IX) in DMF to produce compound (X). Finally, treatment of (X) with hydroxylamine hydrochloride and NaOAc affords the target compound.