Versatile synthesis of 4-methylidenepyrazolidin-3-ones using a Horner-Wadsworth-Emmons approach

Abstract

A new, versatile method for the synthesis of, so far unknown, variously substituted 4-methylidenepyrazolidin-3-ones as potential cytotoxic agents is described. Target compounds were synthesized from the corresponding 4-diethoxyphosphorylpyrazolidin-3-ones which were used as Horner-Wadsworth- Emmons -reagents for the olefination of formaldehyde. 4-Phosphorylpyrazolidin-3- ones were, in turn, obtained starting from the sodium salt of ethyl 2-diethoxyphosphoryl-3-hydroxy-2-propenoate, ethyl 2-acyl-2- diethoxyphosphorylacetates, or 3-methoxy-2-diethoxyphosphorylacrylate and monosubstituted or 1,2-disubstituted hydrazines. © Georg Thieme Verlag Stuttgart · New York.