272458-63-6Relevant articles and documents
Asymmetric cross-coupling of racemic α-bromo esters with aryl Grignard reagents catalyzed by cyclopropane-based bisoxazolines cobalt complexes
Liu, Feipeng,Bian, Qinghua,Mao, Jianyou,Gao, Zidong,Liu, Dan,Liu, Shikuo,Wang, Xueyang,Wang, Yu,Wang, Min,Zhong, Jiangchun
, p. 663 - 669 (2016)
Four new cyclopropane-based bisoxazolines were synthesized and applied to cobalt-catalyzed cross-coupling reactions between racemic α-bromo esters and aryl Grignard reagents. The reaction afforded a series of chiral α-arylalkanoic esters with high yields and good enantioselectivities (up to 93% yield, 92:8 er). This research focuses on the cross-coupling between racemic α-bromopropanoate and p-isobutylphenyl Grignard reagent's which provides ibuprofen ester efficiently. Furthermore, ibuprofen ester 7e was transformed into (S)-ibuprofen (99:1 er) via hydrolysis and recrystallization.
2,2′-Bipyridine-α,α′-trifluoromethyl-diol ligand: Synthesis and application in the asymmetric Et2Zn alkylation of aldehydes
Lauzon, Samuel,Ollevier, Thierry
, 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.
Lipase-immobilized magnetic chitosan nanoparticles for kinetic resolution of (R,S)-ibuprofen
Siodmiak, Tomasz,Ziegler-Borowska, Marta,Marszall, Michal Piotr
, p. 7 - 14 (2013/10/22)
Chitosan (CS)-poly[N-benzyl-2-(methacryloxy)-N,N-dimethylethanaminium bromide] coated magnetic nanoparticles were prepared by co-precipitation method via epichlorohydrin CS cross-linking reaction and were used in the kinetic resolution of (R,S)-ibuprofen by enantioselective esterification. Enzyme immobilized onto the surface of the new magnetic supports with the use of N-(3- dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysulfo-succinimide sodium salt (sulfo-NHS) procedure demonstrated high catalytic activity that enabled us to obtain (S)-methyl ester of ibuprofen with high enantioselectivity (E = 50.6). The chiral compounds that resulted from the application of magnetic nanoparticles were analyzed with the use of chiral stationary phases. It should be emphasized that the main advantage of the support is the possibility to magnetically recovery and effective separation (even up to 5 s) from the reaction mixture with the use of magnet. The properties of magnetic particles allow for better optimization and may reduce the total costs of the esterification reaction of ibuprofen. Moreover, the application of lipase-immobilized magnetic supports enables to maintain high enantioselective activity after repeated use.
