Reactions of trico-ordinate phosphorus compounds with phosphorus pseudohalogens. Part 2. Pentaco-ordinate intermediates in the reaction of o-phenylene neopentyl phosphite with diethoxyoxophosphoranesulfenyl chloride

Reaction between oxophosphoranesulfenyl chloride 1(R = R′= EtO) and o-phenylene neopentyl phosphite 4 takes predominantly the deoxygenation course, yielding the phosphorochloridothioate 7 and the phosphate 8. Formation of minor products 5 and 6 corresponding to the desulfurization pathway, and low-temperature 31P NMR observations, are rationalized by proposing phosphoranephosphonium equilibria which are shifted towards phosphorane structures 9, 13, 11. These results supplement our earlier studies on desulfurization and deoxygenation of compound 1 with tricoordinate phosphorus compounds and add new evidence for phosphonium–phosphorane equilibria.