Syntheses and reactivity of novel unsaturated cyclic compounds containing phosphorus atoms

Syntheses and reactivity of some novel unsaturated cyclic four- and five-membered compounds containing phosphorus are described, suggesting the usefulness of 2,4,6-tri-t-butylphenyl (Mes*) as a protecting group. The structure of a 1,3-diphosphacyclobutane-2,4-diyl was confirmed by X-ray crystallography and reactions were conducted to explore the character of the unusual bonding system.