Studies on the reaction of trityl derivatives with H‐phosphonate diesters: Their relevance to the synthesis of 4‐pyridylphosphonates

Transesterification of diphenyl H‐phosphonate with tritanol in pyridine afforded equimolar amounts of phenyl H‐phosphonate monoester and diphenyl 4‐pyridylphosphonate as the only phosphorus‐containing species. Using ³¹P NMR spectroscopy a plausible reaction pathway for the observed transformation was proposed and some of the postulated intermediates were identified. These studies also enabled us to develop an efficient protocol for the formation of diphenyl and diethyl 4‐pyridylphosphonates from the corresponding H‐phosphonate diesters under mild reaction conditions. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 492–499, 1999     

Stereospecific synthesis of P-epimeric (Rp1, Rp2)-bis-[O-l-menthylphenylphosphonothionyl] diselenide. A new variant of the stereoselective Staudinger reaction

An efficient procedure is described that leads to pure (S_P)- O -l-menthylphenylthiophosphinate. The absolute configuration of this diastereomer was assigned by chemical correlation and confirmed by X-ray crystallography. The reaction of the isomer with phenyl azide, leading to amidate, is a new variant of the stereoselective Staudinger reaction. Addition of elemental selenium to the (S_P)-thiophosphinate led to diastereomeric O-l-menthylphenylselenophosphonothioic acid, which was finally oxidized to the diastereomeric (R_P1,R_P2)-bis-[O-l-menthylphenylphosphonothionyl] diselenide. The diselenide structure was unambiguously confirmed by ³¹P NMR spectroscopy.