10.1007/s11178-008-3011-6

Abstract

A number of cyclic diphosphites were synthesized on the basis of an accessible diol, 1,3 : 1′,3′-di-Obenzylidenedipentaerythritol. The resulting diphosphites were converted into complex covalent and coordination organophosphorus compounds.We recently synthesized first representatives of complete esters derived from dipentaerythritol and phosphorous acid and estimated prospects in their application as ligands for the preparation of coordination compounds of platinum subgroup metals [1]. While developing studies in this line, we made an attempt to build up structurally related systems containing only two phosphite moieties located symmetrically with respect to the central ether oxygen atom. For this purpose we examined phosphorylation of 1,3 : 1′,3′-di-O-benzylidenedipentaerythritol (I) as a mixture of configurational isomers. A procedure for the synthesis of compound I was developed by us previously [2]. As phosphorylating agents we used accessible di-and trimethylene phosphorochloridites II-IV which are highly reactive at 0°C in the system dioxane-pyridine. The yield of target phosphites V-VII ranged from 59 to 80% (Scheme 1). The progress of the reactions was monitored by 31 P NMR spectroscopy (δ P 122-133 ppm). Diphosphites V-VII were purified by passing solutions of the crude products through a layer of silica gel. All tervalent phosphorus compounds V-VII were stable on storage at room temperature in an inert atmosphere. Among these, compounds VI and VII were the most stable.The 1 H NMR spectra of phosphites V-VII contained signals from all protons present in the assumed structures. Compounds V-VII displayed in the spectra signals from methylene protons at δ 3.30-3.39 ppm, a broadened singlet from the CHC 6 H 5 protons at δ 5.45 ppm, aromatic proton signals in the region δ 7.36-7.47 ppm, and doublets from the CH 2 OP protons at δ 4.