Structural and configurational relationships 'metal complex–substrate–product' in asymmetric catalytic hydrogenation, hydrosilylation and cross-coupling reactions

The central chirality of the metal atom and configurational relations in asymmetric reactions catalysed by metal complexes

“…10, 52 ± 56 Similar dependences were found for hydrosilylation, 10, 55 cross-coupling 10,57,58 and allylic alkylation 59 on Rh, Ni, Pd, etc. complexes.…”

“…Presumably, the reaction mechanism depends on the nature of the catalytic complex with different phosphine ligands. However, the similarity of the dependences of the product configuration on the structure of the catalytic complex 10 (see Section II) is rather in favour of a single mechanism.…”

“…Configurational models in asymmetric homogeneous catalysis Knowles 30 who studied the hydrogenation of a-acetamidoacrylic acid in the presence of the Rh ± dipamp complex (1) recommended that the so-called quadrant diagram was used to determine the efficient and non-efficient coordination variants of an enamide in a hypothetical transition complex. 6,10 This diagram is based on the arrangement of the phosphine phenyl groups (with the edge or the plane facing the viewer) in the precursor of the catalytic complex as established by X-ray diffraction spectroscopy. 31 According to this diagram, the substituents of a coordinated substrate that fall into the quadrants blocked by the phenyl groups of the ligand turned edgewise to the viewer encounter with a greater steric hindrance.…”

“…For example, the octant projections of bis(diphenylphosphine) complexes were obtained on the basis of data on the l-and d-as well as l-and d-twist-chair conformations of five-and sevenmembered rhodium chelate complexes. 10 This projection shows only axial phenyl substituents. They fall completely into the corresponding octants, whereas the equatorial substituents lie at the border between two opposite octants.…”

Recent developments in enantioselective cobalt-catalyzed transformations

“…The asymmetric hydrogenation of alkenes has found numerous applications in pharmaceutical and agrochemical industries. In most cases, it is catalyzed by metals such as ruthenium, rhodium or iridium [40]. Replacing these expensive and toxic elements with more abundant and environmentally compatible transition metals, such as cobalt, is attractive.…”