Potassium-Mediated Hydrophosphorylation of Heterocumulenes with Diarylphosphane Oxide and Sulfide

The
preparation of the hydrophosphorylation catalysts succeeds via the
metalation of dimesitylphosphane oxide and diphenylphosphane sulfide with potassium hydride in
ethereal solvents such as tetrahydropyran (THP) and tetrahydrofuran
(THF) yielding the tetramers [(thp)­K­(OPMes2)]4 (1a) and [(thf)3{K­(OPMes2)}4] (1b) as well as [(thp)­KSPPh2]∞ (2) with a strand-like structure in the
crystalline state. In ethereal solution these complexes very slowly
degrade into KPAr2 and KE2PAr2 (E
= O, S). The catalytic conversion of iPr-NCE′
(E′ = O, S) and of R-NCN-R (R = iPr, cHex) to the addition products Ar2P­(E)-C­(=E′)-NHR
(Ar = Ph, Mes; E = O, S; E′ = O, S, NR) was studied in the
presence of catalytic amounts of Ar2PEK (Ar = Ph, Mes;
E = O, S). Steric hindrance prevents the addition of dimesitylphosphane
oxide to N,N′-diisopropylcarbodiimide,
whereas diphenylphosphane oxide and sulfide smoothly add to iPr–NCN-iPr yielding
Ph2P­(E)-C­(N-iPr)-NHiPr (E = O, S).