Acylation of phosphoryl- and thiophosphorylacetonitriles under phase transfer catalysis conditions and the keto-enol tautomerism of phosphorus-substituted acylacetonitriles

Abstract

A procedure was developed for acylation of phosphoryl- and thiophosphorylacetonitriles under phase transfer catalysis conditions. The reaction in the solid KOH/MeCN system affordedC-acylation products in high yields. In the individual state and in aprotic solvents, these products exist in the enol form (Z isomers) stabilizedvia a strong intramolecular hydrogen bond. In hydroxyl-containing media and in aprotic bipolar solvents, these compounds exist as a mixture of two geometric isomers (E andZ) of the corresponding enols. In this case, theZ isomer exists in two forms, namely, in the cyclic form with an intramolecular hydrogen bond and in the open form stabilized by intermolecular hydrogen bonds with the solvent. The results of X-ray diffraction analysis of both forms ofZ isomers of the compounds containing the phosphoryl and thiophosphoryl groups are discussed.