SYNTHESIS AND REACTIVITY OF METHYLENE BRIDGED DIPHOSPHORYL COMPOUNDS

An improved high-yield Arbusov-type synthesis for diphosphorylmethanes with different substituents on both phosphorus atoms (4, 5, 7) by the reaction of isopropyl diphenylphosphinite or diisopropyl phenylphosphonite with diisopropyl bromomethylphosphonate (1) or isopropyl phenyl-bromomethylphosphinate (2), respectively, is described. 1 and 2 are available in yields of about 50% by the reaction of an excess of methylene bromide with triisopropylphosphite or diisopropyl phenylphosphonite, respectively. The metalation of the symmetrical and unsymmetrical diphosphorylmethanes 3-8 with NaH in toluene yields the corresponding carbanionic salts 3A-8A. Their structure und reactivity are investigated by means of P-31 NMR spectroscopy and Horner-reactions with benzaldehyde. Regioselective monomethylation at the central carbon atom of 3-7 is performed using the phasetransfer technique. With exception of the phosphono-phosphinate derivative t4, on this way the appropriate 1,1-diphosphorylethanes 13 and 15-17 are obtained in high yield.