Calcium-mediated Hydrophosphorylation of Organic Isocyanates with Diphenylphosphane Oxide

Abstract

The calcium-mediated addition of diphenylphosphane oxide to organic isocyanates and isothiocyanates yields N-alkyl and N-aryl substituted diphenylphosphorylformamides (E = O, R = iPr, tBu, cHex, Ph, C6H4-4-Br, C6H2-2,4,6-Me3, and Naph) and -thioformamides (E = S, R = iPr, cHex, Ph, and C6H4-4-Me), respectively, of the type Ph2P(O)–C(E)–N(H)R. All derivatives were characterized by IR and NMR spectroscopy as well as X-ray diffraction experiments. The wavenumbers of the N–H stretching modes are smaller for the thio analogues and N-aryl substituents. In the solid state all formamides and thioformamides form dimers by N–H⋯O–P hydrogen bridges. The P–CCE bonds are significantly elongated compared with the P–CPh distances.