Reactions of tervalent phosphorus–nitrogen compounds. Part III. Reactions of isocyanates

Abstract

The reactions of N-alkyl phosphoramidites and N-alkyl phosphinous amides with isocyanates usually give rise to insertion products. For example, N-phenyl diphenylphosphinous amide and n-propyl isocyanate give the same product as N-n-propyl diphenylphosphinous amide and phenyl isocyanate. This product is assigned the structure Ph₂PN(Ph)C(O)NHPrⁿ. Dialkyl N-phenyl phosphoramidites and phenyl isocyanate, however, give derivatives of P^V,OO-dialkyl NN-diphenylamidinophosphonates, (RO)₂P(O)C(NPh)NHPh. On the other hand, NN-dialkyl phosphoramidites and NN-dialkylphosphinous amides give dimers and trimers of the isocyanate under the same reaction conditions. These results show the importance of a mobile proton in the formation of insertion and oxidation products. The mechanisms of these reactions are discussed on this basis.