Regioselectivity in the Reaction of Ethyl Diethoxyphosphorylacetate with 1-Aryl-2-haloalkan-1-ones: Effective Synthesis of 4-Aryl-2-diethoxyphosphoryl-4-oxobutanoates
A simple, two-step synthesis of 4,6-disubstituted pyridazin-3(2H)-ones starting from 2-diethoxyphosphoryl-4-oxoalkanoates and hydrazines is described. The intermediate 4-diethoxyphosphoryl-4,5-dihydropyridazin-3(2H)-ones obtained in this way are used in a Horner-Wadsworth-Emmons olefination of aldehydes to give a variety of disubstituted pyridazin-3(2H)-ones.