Some rearrangements of trivalent phosphorus compounds.

The rearrangements of both three-and four-coordinated phosphorus compounds are reviewed. The thermal rearrangements of alk-2-enyl diphenylphos- phinites and alk-2-enyldiphenylphosphines have been studied. The rearrangements probably proceed via five-membered and four- membered cyclic transition states respectively. Also Included are further examples of the rearrangement of the intermediates formed from the addition of trivalent phosphorus compounds, possessing a group capable of stabilising an anion, to aromatic aldehydes and ketones. The neighbouring group effect of trivalent phosphorus compounds is reviewed followed by studies attempting to confirm the effect (if any) of trivalent phosphorus compounds undergoing participation via a three-meinbered cyclic phosphonium intermediate. Following a brief review on the preparation and properties of vinylphosphorus compounds, the preparation and reactions of l-phenylvinyldiphenylphosphine are discussed. These reactions are concerned with the ability of the o-phenyl group to stabilise an incipient phosphorane.