Synthesis of new pyridazinone derivatives : 2,6-disubstituted 5-hydroxy-3 (2H) -pyridazinone -4 -carboxylic acid ethyl esters

2,6-Disubstituted 5-hydroxy-3(2 H)-pyridazinone-4-carboxylic acid ethyl esters were synthesized from α-keto esters via an efficient three-step sequence including hydrazone formation, acylation with ethyl malonyl chloride, and subsequent Dieckmann cyclization.