Low Coordinate and Low Valent Phosphorus Intermediates for the Synthesis of Multidentate Ligands and New PN Heterocycles

Abstract

Phosphorus has proven to be a versatile asset in the chemist’s repertoire. Its initial uses as nucleophiles in organic synthesis and ligands in transition metal chemistry is well documented, but more recently, unusual bonding, structures, and reactivity at the P-center have been described. Herein, we report fundamental advancement in organophosphorus chemistry by utilizing monovalent phosphinidenes (R–P) as an intermediate to complex ligand architectures and new heterocyclic scaffolds. Specifically, we synthesized a tetradentate tris(phosphaalkene)phosphine ligand that supports sterically shielded trigonal bipyramidal transition metal complexes and developed a streamlined route to new 10-electron benzazaphospholes that upon dearomatization feature exceedingly long and reactive exocyclic P–X bonds.