Synthesis of Phosphorus Ligands from Zirconium Reagents. A Useful Approach

The use of several zirconium reagents as the Schwartz reagent [Cp2ZrHCl]n, the dimethylzirconocene Cp2ZrMe2, the zirconocene [Cp2Zr], and the diphenylzirconocene Cp2ZrPh2 allows the synthesis of a variety of new linear and cyclic P-C and P-N ligands. 1,1 diphosphines can be prepared from unsaturated monophosphines. A useful methodology involving ring opening reactions permits the preparation of phosphinite-phosphine and bis-phosphinite ligands. N-functionalized imines and β-diimines substituted with phosphino groups are obtained from cyanophosphines or dinitriles. Carbozirconation of chlorophospha-imine leads to the unprecedented P-metalated iminophosphorane which presents a versatile reactivity towards electrophiles and small unsaturated molecules. Constraint three and four phosphorus cycles can be easily isolated using [Cp2M] (M = Zr or Ti). Interactions between benzynezirconocene and unsaturated phosphines afford numerous methods to prepare linear and cyclic phosphorus reagents. Enantiomerically pure iminophosphines can be synthetized from phosphinozirconocene complexes.