Phosphoryl isocyanates XYP(O)NCO show high reactivity and serve as initial compounds for the synthesis of various types of compounds of potential practical interest: phosphorylated urethanes, ureas, heterocyclic compounds, etc. Although isocyanates of such a type have been known since the mid-twentieth century, no versatile and efficient method of their synthesis from available and cheap initial reagents has hitherto been invented. The reaction of phosphoryl chlorides XYP(O)Cl with sodium cyanate 1 could be used as such a method; however, whereas this method makes it possible to obtain phosphonyl and phosphinyl isocyanates in satisfactory yields, in the reaction of NaOCN with chlorophosphates, either no corresponding isocyanates are obtained or their yields are low 2 [1]. This result can be explained by the lower reactivity of chlorophosphates as compared with chlorophosphonates and chlorophosphinates in S N 2( P ) reactions [5]. In this case, the problem may be solved by activating the phosphoruscontaining component, for example, by means of an appropriate catalyst.In this work, we propose a general efficient catalytic method of synthesis of various types of phosphoryl isocyanates, which increases the possibilities for designing various nitrogen-containing organophosphorus compounds.It was previously found in our laboratory that the phosphorylation of weakly nucleophilic polyfluorinated alcohols with chlorophosphates was catalyzed by some metal salts showing Lewis acid properties [6]. The most probable mechanism of the catalyst action is activation of the phosphorylating agent due to complexation of the metal cation with phosphoryl oxygen.If activation of such a kind really takes place, these metal salts, in principle, should also catalyze other reactions of nucleophilic substitution of the chlorine atom at the tetrahedral phosphorus atom, in particular, the reaction of chlorophosphates with sodium cyanate.In our study, diphenyl chlorophosphate ( Ia , R = R' = PhO) and bis(2,2,2-trifluoroethyl) chlorophosphate ( Ib , R = R' = CF 3 CH 2 O ), the simplest representatives of diaryl and bis(polyfluoroalkyl) chlorophosphates, were used as phosphorylating agents; the reaction medium used was anhydrous acetonitrile, an available and simple-to-dry polar aprotic solvent with a high dissolving power that is inert toward the initial phosphoryl chlorides and the phosphoryl isocyanates ( II ) resulting from the reaction.The best catalyst is expected to be a metal salt showing simultaneously high efficiency and solubility in the given reaction medium. According to our studies of the catalytic phosphorylation of polyfluoroalkanols with phosphorus acid chlorides, anhydrous Group I and II metal chlorides-LiCl, CaCl 2 , and MgCl 2 3 -showed the highest efficiency [6]. Since MgCl 2 turned out to be significantly more soluble than the other salts in the system acetonitrile-chlorophosphate Ia or Ib , we used this salt as a catalyst.In this work, we studied the reaction of chlorophosphates Ia and Ib with a twofold excess of NaOCN at ...
