Synthesis, coordination study, and catalytic Pauson−Khand reactions of QuinoxP*(CO)4‑μ-alkyne dicobalt complexes

Abstract

The coordination of the P-stereogenic and sterically demanding bisphosphine QuinoxP* to μ-alkyne dicobalt hexacarbonyl complexes was studied experimentally and computationally. Whereas the coordination occurred exclusively in a chelating fashion, the diastereoselectivity was highly substrate dependent. However, it could be explained from the computed structure and energies of the different coordination modes. The fluxional behavior of these complexes was also studied computationally. Their performance as catalysts for the Pauson−Khand reaction was explored, and outstanding reactivity was observed. Although the asymmetric induction was low to moderate, the stereochemical outcome could be mechanistically rationalized. This report provides promising results in terms of reactivity and mechanistic understanding for further developments of highly active chiral catalysts for intermolecular Pauson−Khand reactions.