Synthesis of new diphosphine ligands and their application in Pd-catalyzed alkoxycarbonylation reactions

Abstract

Carbocyclic and N-heterocyclic analogues of the industrially applied ligand bis(di-tert-butylphosphinomethyl)benzene (1) have been synthesized in moderate to very good yields. The new ligands are based on benzene, tetralin, lutidine, pyrazine, quinoxaline, and maleimide backbones. Electronic and steric variations of the phosphorous donor sites were performed. As a benchmark reaction, the palladium-catalyzed methoxycarbonylation of 1-octene has been tested. Ester yields up to 64% and high linear selectivities up to 92% were achieved.

Keywords: alkoxycarbonylation; homogenous catalysis; ligands; palladium; phosphine.