New approaches to polysubstituted pyrroles and pyrrolinones from α-cyanomethyl-β-ketoesters

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 alpha-cyanornethyl-beta-ketoesters followed by annulation. The addition-annulation process is undertaken in aqueous solution to give 4,5-dihydro-5-oxo-1H-pyrrole-beta-carboxylates (pyrrolinones) in good yields. These 4,5-dihydro-5-oxo-1H-pyrrole-3-carboxylates are also obtained by the hydrolysis of 5-alkoxypyrrole-3-carboxylates. (c) 2006 Elsevier Ltd. All rights reserved.