Enantioselective Synthesis of P-Chiral (η6-Arene)ruthenium(II) Complexes Using Enantiomerically Pure Orthometalated Palladium(II) Amine Complexes

Enantiomerically pure, rigid, diphosphines [2-(dicyclohexylphosphino)-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene, [2-(diphenylphosphino)-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene, and the amidophosphine [2-(N,N-dimethylamido)-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene were prepared efficiently, by the asymmetric Diels−Alder reactions between dicyclohexylvinylphosphine (DCVP), diphenylvinylphosphine (DPVP), N,N-dimethylacrylamide (DMAA), and 3,4-dimethyl-1-phenylphosphole (DMPP) using chiral organopalladium(II) complexes containing orthopalladated (S)-1-α-(dimethylamino)ethylbenzene, (R)-1-α-(dimethylamino)ethylnaphthalene, or (S)-2-α-(dimethylamino)ethylnaphthalene as the reaction templates. Treatment of the diphosphine complexes with concentrated hydrochloric acid removed the chiral amine auxiliaries from the templates to give chelated dichloropalladium complexes. Then the ligands were displaced from the palladium chloride complexes with cyanide and reacted with [(...