ENDOCYCLIC RESTRICTION TEST - APPLICATIONS TO TRANSFERS OF OXYGEN FROM NITROGEN AND FROM SULFUR TO PHOSPHORUS(III)

The geometries allowed for formal transfers of oxygen to the phosphoru s(III) of a phosphine from a nitrone, an O-acetylhydroxylamine, and a sulfoxide have been evaluated by the endocyclic restriction test. Inve stigations of the conversions of 1 to 2, 16 to 17, and 28 to 29, by is otopic labeling, substituent effect, and kinetic and spectroscopic exp eriments, reveal the operation of different mechanisms for each of the se transfers. For 1, oxygen addition to phosphorus is the preferred me chanism. In the case of 16, the mechanism involves nucleophilic displa cement of oxygen from nitrogen by phosphorus to give 26 followed by ox ygen addition to phosphorus. In acetic acid, the oxygen is added to 26 from water in the workup whereas in toluene the oxygen is provided by the acetate produced by the displacement. For 28, either addition by oxygen of the sulfoxide to activated phosphorus or addition by phospho rus to sulfur of the sulfoxide precedes oxygen transfer.