Reaction of Tricoordinate Phosphorus Compounds with Organophosphorus Pseudohalogens. 1. Desulfurization and Deoxygenation of Oxophosphoranesulfenyl Chlorides. Scope and Mechanism

Article abstract of DOI:10.1021/jo00044a035

The reaction of oxophosphoranesulfenyl chlorides RR'P(O)SCl 2 with P^III compounds has been investigated.Its mechanistic features have been elucidated by variable-temperature 31P NMR spectroscopy and stereochemical changes at P^IV and P^III phosphorus centers.These studies show that in all cases phosphonium intermediates containing the sulfur bridge >P(O)-S-P(+)<-Cl(-) are formed.Depending on electronic and steric factors and reaction conditions, this primary phosphonium salt either decomposes by nucleophilic attack of the chloride counterion on the phosphoryl center (desulfurization pathway) or is transformed into the isomeric phosphonium salt >P(S)-O-P(+)<-Cl(-).The latter decomposes by the attack of the chloride anion on the thiophosphoryl center (deoxygenation pathway). 31P NMR studies fully corroborated the observed stereochemical changes.