A one-step synthesis of 5-alkoxypyrrole-3-phosphonates is presented starting from suitable alpha-cyanomethyl-beta-ketophosphonates. The key step in the synthesis involves a one-pot addition and heteroannulation sequence. The zinc perchlorate-catalyzed addition of alcohols to the nitrile carbon of alpha-cyanomethyl- beta-ketophosphonates followed by annulation furnished 5-alkoxypyrrole-3-phosphonates. The addition-annulation process is carried out in the presence of water and 4,5-dihydro-5-oxo-1H-pyrrole-3-phosphonates (pyrrolinones) are obtained in good yields. (C) 2007 Elsevier Ltd. All rights reserved.