Sterically protected organophosphorus compounds of unusual structures

The character of bis(2,4,6-tri-tert-butylphenyl)diphosphene is described experimentally and theoretically. The diphosphene is stabilized by steric protection and the structure can be characterized by spectroscopic as well as crystallographic analyses. Theoretical calculation on the diphosphene strongly suggests that the P=P bond is an isolated double bond and that the P–C bonds are single covalent bond. The reactivity has been investigated including photolysis, oxidation, sulfurization, selenation, transition-metal complex formation, and carbene addition. Plausible mechanistic scheme for the reaction of the diphosphene with 3,4,5,6-tetrachlorocyclohexa-3,5-diene-1,2-dione (or tetrachloro-o-benzoquinone) to a pentavalent spiro product is discussed based on the product analysis.

P-chiral 1-phosphanorbornenes: from asymmetric phospha-Diels–Alder reactions towards ligand design and functionalisation

A building set for chiral phosphorus. The principle of stereotopic face differentiation is successfully applied to a PC bond. A divergent ligand synthesis is feasible after reduction of the chiral auxiliary.