Novel aminophosphonothiophene derivatives from β-keto-δ-carbethoxyphosphonates and phosphineoxides

摘要

The reaction of β-keto-δ-carbethoxyphosphonates and phosphineoxides with active methylene nitriles leads to the corresponding phosphonoalkylidenes. Treatment of these compounds with sulfur, under the classical Gewald reaction conditions, gives a ca. 1:1 mixture of novel aminophosphonothiophene derivatives 3 and 3 ′ . In order to improve the regioselectivity of the reaction, novel conditions have been developed for the Gewald condensation, in which we used an inorganic base NaH in THF as the solvent. These conditions afforded exclusively the 3-regioisomer in good yield.