In organic chemistry, atoms other than carbon and hydrogen are generally referred to as heteroatoms. The most common heteroatoms are nitrogen, oxygen and sulfur. Now I present to you an article called Mechanism study on asymmetric Michael addition reaction between alkynone and α-angelica lactone catalyzed by chiral N, N’-dioxide-Sc(III) complex, published in 2020-09-15, which mentions a compound: 591-12-8, mainly applied to butenolide alkynone scandium catalyst Michael addition mechanism bond order, Recommanded Product: 5-Methylfuran-2(3H)-one.
The reaction mechanism and enantioselectivity of asym. Michael addition reaction between alkynone (R1) with α-angelica lactone (R2) catalyzed by chiral N, N’-dioxide-Sc(III) complex were investigated at the M06/6-31G(d,p) (acetonitrile, SMD) level. The α-angelica lactone substrate could isomerize to the active enolized form in the presence of Sc(OTf)3 reagent, assisted by the counter trifluoromethanesulfonate anion OTf-. The alkynone substrate and enolized angelica lactone (or its anion) coordinated to Sc(III) center of N,N’-dioxide-Sc(III) complex catalyst simultaneously, forming a high active hexacoordinate-Sc(III) complex. The catalytic reaction occurred via a two-step mechanism, in which C2-Cγ bond formation was predicted to be the chirality-controlling step as well as the rate-determining step, affording predominant S-enantiomer. The counterion OTf- facilitated C-H construction as a proton-shuttle, producing mainly E-configuration product observed in experiment The steric repulsion from the ortho-substituent of amide moiety as well as the chiral backbone of N, N’-dioxide-Sc(III) catalyst played the key role for chiral induction in the asym. reaction. The less destabilizing Pauli repulsion and more stabilizing attractive interaction, especially the orbital interaction, along the si-face attack pathway enhanced the enantiodifference of the two competing pathways for high enantioselectivity. The energy barriers for E/Z isomerization of S or R-enantiomer assisted by HOTf was as high as 34.6-35.0 kcal mol-1, indicating that the product with Z-conformation was difficult to be obtained. These results were in good agreement with exptl. observations.
If you want to learn more about this compound(5-Methylfuran-2(3H)-one)Recommanded Product: 5-Methylfuran-2(3H)-one, you may wish to communicate with the author of the article,or consult the relevant literature related to this compound(591-12-8).
Reference:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia