Stereoselective intramolecular acylation of γ′-benzoyloxyphosphine oxides with an internal chlorotrimethylsilane trap: isolation of silylated tetrahedral intermediates

The kinetic products of the intramolecular acylation of γ′-benzoyloxyphosphine oxides were revealed by conducting the reaction in the presence of an internal trapping agent. A high level of stereocontrol over the formation of both the stereogenic centre α to phosphorus and the hemiacetal centre was observed. The stereochemistry of the products was determined by X-ray crystallography and 1H NMR and the stereoselectivity of the reaction is explained in terms of the known structure and configurational instability of lithiated phosphine oxides.