Simple and efficient protocol for the synthesis of novel dihydro-1H-pyrano[2,3-c]pyrazol-6-ones via a one-pot four-component reaction

Ba(OH)(2) catalyzed simple and efficient one-pot four-component reaction of Meldrums acid, ethyl acetoacetate, hydrazine hydrate, and aromatic aldehydes to give 3-methyl-4-aryl-4,5-dihydro-1H-pyrano[2,-3c]pyrazol-6-ones in refluxing water is reported. The yields are high and the reactions go to completion in 1-2 h. (C) 2012 Elsevier Ltd. All rights reserved.