The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature. HPLC of Formula: C10H20O, 7540-51-4, Name is (S)-3,7-Dimethyloct-6-en-1-ol, SMILES is C/C(C)=CCC[C@H](C)CCO, in an article , author is Burrows, Lauren C., once mentioned of 7540-51-4.
The narrow substrate scope of the asymmetric Pauson-Khand reaction (PKR) presently limits its synthetic utility. We recently reported an example of an enantioselective PKR with a precursor not comprising a 1,6-enyne by using a cationic Rh(I) catalyst and a chiral monodentate phosphorous ligand. Herein, the mechanisms and ligand effects on the reactivity and selectivity of enyne PKRs using Rh(I) metal complexes with three different ligands ((R)-BINAP, (S)-MonoPhos, or CO) are examined experimentally and computationally. A correlation between experiments and DFT calculations is demonstrated. The PKR with the bidentate ligand (R)-BINAP is fast and shows a low calculated Gibbs free energy of activation (Delta G double dagger) for the oxidative cyclization step; the monodentate ligand, (S)-MonoPhos, affords a much slower reaction with a higher Delta G double dagger; and using the CO-only Rh complex, the reaction is very slow with a high Delta G double dagger. A linear relationship between the enantiomeric excess of (S)-MonoPhos and the PKR product suggests that the active Rh catalyst involves a single ligand. The absolute configuration of the product afforded by each of these ligand-bound catalysts is determined by DFT calculations and confirmed by vibrational circular dichroism spectroscopy. Transition-state structures for the oxidative cyclization step show that the chiral induction is controlled by steric interactions between the phenyl groups of the (R)-BINAP ligand or the methyl groups of the (S)-MonoPhos ligand and an alkenyl hydrogen of the enyne. DFT calculations revealed two competing oxidative cyclization pathways involving either four- or five-coordinated Rh(I) species. The preferred mechanism and the enantioselectivity are affected by the ligand, the substrate, and CO concentration. Incorporating experimental temperature and CO concentration into the Gibbs free-energy calculations proved crucial for obtaining agreement with experimental results.
But sometimes, even after several years of basic chemistry education, it is not easy to form a clear picture on how they govern reactivity! 7540-51-4, you can contact me at any time and look forward to more communication. HPLC of Formula: C10H20O.
Reference:
Chiral Catalysts,
,Chiral catalysts – SlideShare