Chemistry can be defined as the study of matter and the changes it undergoes. You¡¯ll sometimes hear it called the central science because it is the connection between physics and all the other sciences, starting with biology. 791-28-6, Name is Triphenylphosphine oxide, molecular formula is , belongs to chiral-phosphine-ligands compound. In a document, author is Zhong, Hongyu, SDS of cas: 791-28-6.
Cobalt-Catalyzed Asymmetric Hydrogenation of alpha,beta-Unsaturated Carboxylic Acids by Homolytic H-2 Cleavage
The asymmetric hydrogenation of alpha,beta-unsaturated carboxylic acids using readily prepared bis(phosphine) cobalt(0) 1,5-cyclooctadiene precatalysts is described. Di-, tri-, and tetrasubstituted acrylic acid derivatives with various substitution patterns as well as dehydro-a-amino acid derivatives were hydrogenated with high yields and enantioselectivities, affording chiral carboxylic acids including Naproxen, (S)-Flurbiprofen, and a D-DOPA precursor. Turnover numbers of up to 200 were routinely obtained. Compatibility with common organic functional groups was observed with the reduced cobalt(0) precatalysts, and protic solvents such as methanol and isopropanol were identified as optimal. A series of bis(phosphine) cobalt(II) bis(pivalate) complexes, which bear structural similarity to state-of-the-art ruthenium(II) catalysts, were synthesized, characterized, and proved catalytically competent. X-band EPR experiments revealed bis(phosphine)cobalt(II) bis(carboxylate)s were generated in catalytic reactions and were identified as catalyst resting states. Isolation and characterization of a cobalt(II)-substrate complex from a stoichiometric reaction suggests that alkene insertion into the cobalt hydride occurred in the presence of free carboxylic acid, producing the same alkane enantiomer as that from the catalytic reaction. Deuterium labeling studies established homolytic H-2 (or D-2) activation by Co(0) and cis addition of H-2 (or D-2) across alkene double bonds, reminiscent of rhodium(I) catalysts but distinct from ruthenium(II) and nickel(II) carboxylates that operate by heterolytic H-2 cleavage pathways.
Sometimes chemists are able to propose two or more mechanisms that are consistent with the available data. If a proposed mechanism predicts the wrong experimental rate law, however, the mechanism must be incorrect.Welcome to check out more blogs about 791-28-6, in my other articles. SDS of cas: 791-28-6.
Reference:
Phosphine ligand,
,Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate