Synthesis and Application in Catalysis of Planar Chiral (η5-Cyclohexadienyl)tricarbonylmanganese-Based Ligands

Mono- and bidentate ligands (5–8, 15–18, 20, 29–31) have been synthesized in which the phosphinyl group substitutes a (η5-cyclohexadienyl)Mn(CO)3 scaffold. In the case of one of the bidentate ligands, 15, the formation of the corresponding Pd complex was studied. The complex unexpectedly afforded two bimetallic complexes depending on the solvent of the reaction: the neutral complex 33 and the cationic complex 34, whose X-ray structures were established. The catalysts carrying the new ligands demonstrated high activity (99% conversion) in the palladium-catalyzed allylic substitution. The resolution of three of the ligands, 6, 8, and 15, was achieved, and the catalyst with the enantioenriched P–N ligand 15 delivered fairly good enantioselectivity in asymmetric allylic substitution.