Reaction of Alkyl(dialkoxyphosphoryl)alkanimidates with Phenyl Isothiocyanate

A slow reaction of C-phosphorylated imidates with phenyl isothiocyanate proceeds selectively via nucleophilic addition by the carbon-nitrogen double bond, involving the = N-H group, to form thiourea derivatives in yields of up to 77%. The reaction accelerates in the presence of triethylamine. Reaction kinetics were studied. It was found the the rate constants vary in parallel with basicity (pK_a) of the starting imidates.