In this present paper, we report the efficient, regioselective one-pot synthesis of 5-alkoxy and 5-alkylsulfanylpyrrole-3-carboxylates in high yields via the zinc perchlorate-catalyzed addition of alcohols and thiols to the nitrile carbon of α-cyanomethyl-β-ketoesters followed by annulation. The addition–annulation process is undertaken in aqueous solution to give 4, 5-dihydro-5-oxo-1H-pyrrole-3-carboxylates (pyrrolinones) in good yields. These 4, 5- ...