Enantioselective catalysis of Suzuki reaction with planar-chiral CN-palladacycles: competition of two catalytic cycles

Abstract

The investigations of the catalysis of atroposelective Suzuki reaction with chiral CN-palladacycles showed that two competing catalytic cycles operate in this process, the relative contributions of each of them depend on the structure of the catalyst and reaction conditions. The reactions in aprotic medium at reduced temperature predominantly follow the pathway, in which the structure of palladacycle was retained, thus providing enantioselectivity up to 53% ee, when a nonmetallocene planar-chiral iminate CN-dimer was used as the catalyst. The structure of the μ-iodide cyclopalladated CN-dimer recovered upon reaction completion was confirmed by X-ray diffraction and spectroscopic studies of its triphenylphosphine derivative.