P-Heterocycles as Ligands in Homogeneous Catalytic Reactions

Homogeneous catalysis reactions of some 3, 4, 5, 6, and 7-membered P-heterocyclic ligands of unprecedented structure, are reviewed. A highly stable polycyclic phosphirane can be synthesized in a few steps from dibenzosuberone, which is found to act as a relatively good electron donor. The radical ring-opening polymerization of methylphosphirane, phosphetane, and phospholane, is found to be the fastest with phosphetanes, reflecting the compromise between the strain in the transition structure and the strain released by the partially broken bond. Phospholes of related structure react readily with maleic acid derivatives such as amides and anhydrides. P-Chloro-2-phospholenes are reacted with amino acid esters, resulting in the corresponding 1-L-α-amino acid derivatives of phospholene oxides as chiral P-N phospholenes.