Dicarboximidophosphonothioates derived from a variety of five-membered ring dicarboximides and containing alkoxy, alkylamine, alkylthio, aryloxy, or alkyl groups attached to phosphorus have been prepared, principally by the novel reaction of cyclic anhydrides with phosphoramidothioates and sodium hydride. The reaction of phthalic anhydride with 0, O-diethyl phosphoramidothioate and sodium hydride to form 0, Odiethyl ...