A family of -macrocyclic diphosphines: modular, stereoselective synthesis and application in catalytic CO/ethylene coupling.

A family of -macrocyclic diphosphines was prepared in just three steps from white phosphorus and commercial materials using a modular synthetic approach. Alkylation of bicyclic diphosphane 3,4,8,9-tetramethyl-1,6-diphosphabicyclo(4.4.0)deca-3,8-diene, or P(dmb), produced phosphino-phosphonium salts [R-P(dmb)]X, where R is methyl, benzyl and isobutyl, in yields of 90-96%. Treatment of these salts with organolithium or Grignard reagents yielded symmetric and unsymmetric macrocyclic diphosphines of the form -1-R-6-R'-3,4,8,9-tetramethyl-2,5,7,10-tetrahydro-1,6-DiPhospheCine, or R,R'-DPC, in which R' is methyl, cyclohexyl, phenyl or mesityl, in yields of 46-94%. Alternatively, symmetric diphosphine Cy-DPC was synthesized in 74% yield from the dichlorodiphosphine ClP(dmb). As a first application, these -macrocyclic diphosphines were used as ligands in the nickel-catalyzed synthesis of acrylate from CO and ethylene, for which they showed promising catalytic activity.