SYNTHESIS OF 2-KETO-4-PHOSPHORYLBUTYRIC ACIDS AND THEIR DERIVATIVES

Article abstract of DOI:10.1007/BF00958265

The Claisen condensation of 3-phosphorylated propionitriles with diethyl oxalate has been examined.The product of the condensation of 3-(methylethoxyphosphinyl)propionitrile, following hydrolysis, has been shown to be the enol form (Z-isomer) of 4-(methylhydroxyphosphinyl)-3-cyano-2-ketobutyric acid.On crystallization from water, the other isomers (the E-isomer of the enol or the keto-forms) were not isolated.Distillation of the products of silylation of the reaction mixture with hexamethyldisilazane gave both geometric isomers of the enol (Z and E).In aqueous solution, the enol gradually cyclizes to give 2-hydroxy-3-(methylhydroxyphosphinyl)citraconimide.