67081-98-5Relevant academic research and scientific papers
NOVEL COMPOUNDS
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Page/Page column 58, (2022/03/07)
The invention relates to compounds of formula (I) and to their use in treating or preventing an inflammatory disease or a disease associated with an undesirable immune response: wherein R, R1, R2 and RB are as defined herein.
2,2′-Bipyridine-α,α′-trifluoromethyl-diol ligand: Synthesis and application in the asymmetric Et2Zn alkylation of aldehydes
Lauzon, Samuel,Ollevier, Thierry
supporting information, p. 11025 - 11028 (2021/11/03)
A chiral 2,2′-bipyridine ligand (1) bearing α,α′-trifluoromethyl-alcohols at 6,6′-positions was designed in five steps affording either the R,R or S,S enantiomer with excellent stereoselectivities, i.e. 97% de, >99% ee and >99.5% de, >99.5% ee, respectively. The key step for reaching high levels of stereoselectivity was demonstrated to be the resolution of the α-CF3-alcohol using (S)-ibuprofen as the resolving agent. An initial application for the 2,2′-bipyridine-α,α′-CF3-diol ligand was highlighted in the ZnII-catalyzed asymmetric ethylation reaction of aromatic, heteroaromatic, and aliphatic aldehydes. Synergistic electron deficiency and steric hindrance properties of the newly developed ligand afforded the corresponding alcohols in good to excellent yields (up to 99%) and enantioselectivities (up to 95% ee). As observed from single crystal diffraction analysis, the complexation of the 2,2′-bipyridine-α,α′-CF3-diol ligand generates an unusual hexacoordinated ZnII.
Novel non-metal catalyst for catalyzing asymmetric hydrogenation of ketone and alpha, beta-unsaturated ketone
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Paragraph 0162-0167, (2021/04/26)
The invention discloses a novel non-metal catalyst for catalyzing asymmetric hydrogenation of ketone and alpha, beta-unsaturated ketone. The preparation method of a chiral alcohol compound shown as formula IV comprises the following step of: reacting a ketone compound shown as formula V with hydrogen under the catalysis of tri(4-hydrotetrafluorophenyl)boron and a chiral oxazoline compound to obtain the chiral alcohol compound shown as the formula IV; the preparation method of a chiral tetralone compound shown as formula VI comprises the following step of: under the catalysis of tri(4-hydrotetrafluorophenyl)boron and a chiral oxazoline compound, reacting an alpha, beta-unsaturated ketone compound shown as formula VII with hydrogen to obtain the chiral tetralone compound shown as the formula VI. The method has the advantages of easy synthesis of raw materials, mild reaction conditions, simple operation, high stereoselectivity and the like, the ee value of the product is up to 92%, and the yield is up to 99%.
Enantioselective Addition of Diethylzinc to Aromatic Aldehydes Using Novel Thiophene-Based Chiral Ligands
Aydin, A. E.
, p. 901 - 909 (2020/07/03)
Abstract: Chiral norephedrine-derived β-amino alcohols with a thiophene moiety were synthesized from thiophene carbaldehydes (methyl- or ethyl-substituted) and chiral amino alcohols, such as both enantiomers of norephedrine and 2-aminopropanol. The synthesized ligands were applied to the catalytic asymmetric addition of diethylzinc to aldehydes to obtain optically active alcohols with a high conversion (92%) and excellent enantioselectivities (ee up to 99%). The highest enantioselectivity (ee 99%) was obtained with p-trifluorobenzaldehyde as the substrate containing the strongly electron-acceptor CF3 group.
Asymmetric Hydrogenation of Ketones and Enones with Chiral Lewis Base Derived Frustrated Lewis Pairs
Du, Haifeng,Feng, Xiangqing,Gao, Bochao,Meng, Wei
supporting information, p. 4498 - 4504 (2020/02/05)
The concept of frustrated Lewis pairs (FLPs) has been widely applied in various research areas, and metal-free hydrogenation undoubtedly belongs to the most significant and successful ones. In the past decade, great efforts have been devoted to the synthesis of chiral boron Lewis acids. In a sharp contrast, chiral Lewis base derived FLPs have rarely been disclosed for the asymmetric hydrogenation. In this work, a novel type of chiral FLP was developed by simple combination of chiral oxazoline Lewis bases with achiral boron Lewis acids, thus providing a promising new direction for the development of chiral FLPs in the future. These chiral FLPs proved to be highly effective for the asymmetric hydrogenation of ketones, enones, and chromones, giving the corresponding products in high yields with up to 95 % ee. Mechanistic studies suggest that the hydrogen transfer to simple ketones likely proceeds in a concerted manner.
Observation of hyperpositive non-linear effect in catalytic asymmetric organozinc additions to aldehydes
Geiger, Yannick,Achard, Thierry,Maisse-Fran?ois, Aline,Bellemin-Laponnaz, Stéphane
supporting information, p. 1250 - 1256 (2020/07/25)
Asymmetric amplification is a phenomenon that is believed to play a key role in the emergence of homochirality in life. In asymmetric catalysis, theoretical and experimental models have been investigated to provide an understanding of how chiral amplification is possible, in particular based on non-linear effects. Interestingly, it has been proposed a quarter century ago that chiral catalysts, when not enantiopure might even be more enantioselective than their enantiopure counterparts. We show here that such hyperpositive non-linear effect in asymmetric catalysis is indeed possible. An in-depth study into the underlying mechanism was carried out, and the scheme we derive differs from the previous proposed models.
Chiral zinc amidate catalyzed additions of diethylzinc to aldehydes
Zhang, Jinxia,Li, Shasha,Zheng, Xinxin,Li, Hongjie,Jiao, Peng
supporting information, p. 1913 - 1917 (2019/06/24)
A series of bifunctional spiro ligands bearing “carboxamide–phosphine oxide” groups and ethylzinc carboxamidates from these ligands as catalysts for Et2Zn additions to aldehydes were reported. Excellent yields were obtained with moderate ee′s in Et2Zn additions to benzaldehyde derivatives, implying effectiveness of our newly designed catalytic structures as well as mediocre stereocontrol by these chiral ligands. Possible transition states were suggested based on the crystal structures of two ligands.
Noscapine Derivatives as New Chiral Catalysts in Asymmetric Synthesis: Highly Enantioselective Addition of Diethylzinc to Aldehydes
Mohebbi, Maryam,Bararjanian, Morteza,Ebrahimi, Samad N.,Smie?ko, Martin,Salehi, Peyman
, p. 1841 - 1848 (2018/02/14)
Noscapine, a natural alkaloid, has never been used as a parent scaffold in chiral induction. The first examples of noscapinoid compounds as efficient catalysts in asymmetric synthesis are now reported. Three derivatives of noscapine were synthesized from its reaction with different Grignard reagents. Asymmetric addition of diethylzinc to aldehydes was performed in the presence of these catalysts in high yields and good to excellentees.
Chiral 2-(2-hydroxyaryl)alcohols (HAROLs) with a 1,4-diol scaffold as a new family of ligands and organocatalysts
Dilek, ?mer,Tezeren, Mustafa A.,Tilki, Tahir,Ertürk, Erkan
supporting information, p. 268 - 286 (2017/12/06)
Efficient and modular syntheses of chiral 2-(2-hydroxyaryl)alcohols (HAROLs), novel 1,4-diols carrying one phenolic and one alcohol hydroxyl group, have been developed which led to generation of a small library of structurally diverse HAROLs in enantiomerically pure form. Of the different HAROLs examined, a HAROL based on the indan backbone exhibited the highest activity and enantioselectivity in the 1,2-addition of certain organometallic compounds to aldehydes in the presence of Ti(OiPr)4 (up to 97% y, 88% ee) and performed as a hydrogen-bond donor organocatalyst in the Morita-Baylis-Hillman reaction, promoted by trialkylphosphines.
New C2-symmetric six-membered carbene ligands for asymmetric diethylzinc addition of arylaldehydes
Zhou, Bihui,Li, Zijing,Yang, Chen,Li, Linlin,Fan, Limei,Huang, Hongxia,Li, Jie
, p. 1 - 10 (2018/06/27)
A series of new six-membered NHC precursors were prepared by simply esterification of their parent compounds. Their applicability in asymmetric diethylzinc addition of arylaldehydes has been demonstrated and the corresponding secondary alcohol was obtained with good yields and moderate enantioselectivities. (Figure pressented)
