Synthesis of Chiral Bis-MOP-type Diphosphines. Chelating Effect in Nickel-catalyzed Phosphination

Chiral his-MOP-type diphosphines with alkyl and pyridyl bridges connecting the two binaphthyl units have been synthesized via [NiCl2(dppe)]-assisted phosphination of the corresponding aryl triflates. The effect of the amount of the nickel complex on the reaction yield was investigated. Catalytic and even stoichiometric amounts of the complex proved to be insufficient to promote an efficient phosphination, but the use of an excess of the metal complex provides good yields.