Total Synthesis of Pyrrolnitrin. IV. Synthesis of Ethyl 3-Aryl-5-methyl-2-pyrrolecarboxylate. (3)

Treatment of the crude-enamine (IV), prepared from 1-(3-chlorophenyl)-1, 3-butanedione (II) and diethyl aminomalonate (III), with sodium ethoxide gave ethyl 3-(3-chlorophenyl)-5-methyl-2-pyrrolecarboxylate (VI) and ethyl 2-(3-chlorophenyl)-4-methyl-5-pyrrolecarboxylate (VII'), whose structures were confirmed by other synthetic methods. Mechanism of above reaction and ultraviolet absorption spectra of these pyrrole derivatives were discussed.