159406-53-8Relevant academic research and scientific papers
Novel tetradentate bisoxazoline ligands from l-serine and β-DDB for asymmetric pinacol coupling reactions of aromatic aldehydes
Wen, Jiwu,Liu, Limin,Zhou, Xiaochun,Hu, Ronghua,Xu, Yaping
, p. 860 - 865 (2013)
A variety of novel hydroxyl-containing tetradentate bisoxazolines were successfully synthesized from natural l-serine and β-DDB. The applications of these ligands in the asymmetric pinacol coupling of aromatic aldehydes revealed that the absolute configurations of the resulting pinacols were entirely dominated by the axial chirality of the biphenyl component and that the bulky substituent adjacent to the hydroxyl group was favorable for achieving both high diastereoselectivities and enantioselectivities. Among the ligands screened, (S,aR,S)-1c exhibited much better asymmetric induction capacity to furnish the (R,R)-pinacols with diastereoselectivities up to 99/1 and with 63-89% enantiomeric excess. A plausible mechanism of the asymmetric pinacol coupling was also suggested.
Horeau amplification in the sequential acylative kinetic resolution of (±)-1,2-diols and (±)-1,3-diols in flow
Brandolese, Arianna,Greenhalgh, Mark D.,Desrues, Titouan,Liu, Xueyang,Qu, Shen,Bressy, Cyril,Smith, Andrew D.
supporting information, p. 3620 - 3627 (2021/05/04)
The sequential acylative kinetic resolution (KR) of C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diols using a packed bed microreactor loaded with the polystyrene-supported isothiourea, HyperBTM, is demonstrated in flow. The sequential KRs of C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diols exploits Horeau amplification, with each composed of two successive KR processes, with each substrate class significantly differing in the relative rate constants for each KR process. Optimisation of the continuous flow set-up for both C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diol substrate classes allowed isolation of reaction products in both high enantiopurity and yield. In addition to the successful KR of C2-symmetric (±)-1,2-syn and (±)-1,3-anti-diols, the application of this process to the more conceptually-complex scenario involving the sequential KR of C1-symmetric (±)-1,3-anti-diols was demonstrated, which involves eight independent rate constants. This journal is
Hydrogen Bonding-Assisted Enhancement of the Reaction Rate and Selectivity in the Kinetic Resolution of d,l-1,2-Diols with Chiral Nucleophilic Catalysts
Fujii, Kazuki,Mitsudo, Koichi,Mandai, Hiroki,Suga, Seiji
supporting information, p. 2778 - 2788 (2017/08/23)
An extremely efficient acylative kinetic resolution of d,l-1,2-diols in the presence of only 0.5 mol% of binaphthyl-based chiral N,N-4-dimethylaminopyridine was developed (selectivity factor of up to 180). Several key experiments revealed that hydrogen bonding between the tert-alcohol unit(s) of the catalyst and the 1,2-diol unit of the substrate is critical for accelerating the rate of monoacylation and achieving high enantioselectivity. This catalytic system can be applied to a wide range of substrates involving racemic acyclic and cyclic 1,2-diols with high selectivity factors. The kinetic resolution of d,l-hydrobenzoin and trans-1,2-cyclohexanediol on a multigram scale (10 g) also proceeded with high selectivity and under moderate reaction conditions: (i) very low catalyst loading (0.1 mol%); (ii) an easily achievable low reaction temperature (0 °C); (iii) high substrate concentration (1.0 M); and (iv) short reaction time (30 min). (Figure presented.).
Asymmetric pinacol coupling of aromatic aldehydes catalyzed by a new titanium-Schiff base complex
Li, You-Gui,Tian, Qing-Shan,Zhao, Jun,Feng, Yan,Li, Min-Jie,You, Tian-Pa
, p. 1707 - 1710 (2007/10/03)
A new Schiff-base with two stereogenic centers has been prepared and its titanium complex applied to catalyze the pinacol coupling of aldehydes, which afforded pinacols in high yield, excellent diastereoselectivities, and high enantioselectivities.
Truly catalytic and enantioselective pinacol coupling of aryl aldehydes mediated by chiral Ti(III) complexes
Chatterjee,Bennur,Joshi
, p. 5668 - 5671 (2007/10/03)
A variety of chiral Ti(IV) complexes were reduced in situ with zinc in acetonitrile. The resulting chiral Ti(III) complexes were found to catalyze the pinacol coupling reaction stereoselectively. The best results were obtained from the Ti-SALEN complex, which was found to be an efficient catalyst at 10 mol % concentration. Various aromatic aldehydes were coupled to obtain chiral hydrobenzoin derivatives with high diastereoselectivity and enantioselectivity. A plausible mechanism is proposed that rationalizes the stereochemical outcome of the reaction.
