4358-88-7Relevant articles and documents
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Ojima,I. et al.
, p. 1889 - 1892 (1974)
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One-step room-temperature synthesis of [Al]MCM-41 materials for the catalytic conversion of phenylglyoxal to ethylmandelate
Wang, Zichun,Jiang, Yijiao,Rachwalik, Rafal,Liu, Zhongwen,Shi, Jeffrey,Hunger, Michael,Huang, Jun
, p. 3889 - 3896 (2013)
Mesoporous [Al]MCM-41 materials with nSi/nAl ratios of 15 to 50 suitable for the direct catalytic conversion of phenylglyoxal to ethylmandelate have been successfully synthesized at room temperature within 1 h. The surface areas and pore sizes of the obtained [Al]MCM-41 materials are in the ranges of 1005-1246 m2 g-1 and 3.44-3.99 nm, respectively, for the different nSi/nAl ratios. For all [Al]MCM-41 catalysts, most of the Al species were tetrahedrally coordinated with Si in the next coordination sphere of atoms. 1H and 13C magic-angle spinning NMR spectroscopic investigations indicated that the acid strength of the SiOH groups on these [Al]MCM-41 catalysts and the density of these surface sites are enhanced with increasing Al content in the synthesis gels. These surface sites with enhanced acid strength were found to be catalytically active sites for phenylglyoxal conversion. The [Al]MCM-41 material with nSi/nAl=15 showed the highest phenylglyoxal conversion (93.4 %) and selectivity to ethylmandelate (96.9 %), whereas the [Al]MCM-41 material with nSi/nAl=50 reached the highest turnover frequency (TOF=99.3 h-1). This is a much better catalytic performance than that of a dealuminated zeolite Y (TOF=1.7 h-1) used as a reference catalyst, which is explained by lower reactant transport limitations in mesoporous materials than that in the microporous zeolite. Mesopores flex their catalytic muscles: Mesoporous [Al]MCM-41 materials with nSi/nAl ratios of 15 to 50 suitable for the direct catalytic conversion of phenylglyoxal to ethylmandelate were successfully synthesized at room temperature within 1 h. Copyright
Tunable System for Electrochemical Reduction of Ketones and Phthalimides
Chen, Gong,Qiao, Tianjiao,Wang, Yaxin,Zhang, Jian,Zhao, Jianyou
supporting information, p. 3297 - 3302 (2021/10/14)
Herein, we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without the need for stoichiometric external reductants. By utilizing NaN3 as the electrolyte and graphite felt as both the cathode and the anode, we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N3/HN3 cycle operated as a hydrogen atom shuttle, which was critical for reduction of the carbonyl groups to methylene groups.
Exploiting Cofactor Versatility to Convert a FAD-Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
Xu, Jian,Peng, Yongzhen,Wang, Zhiguo,Hu, Yujing,Fan, Jiajie,Zheng, He,Lin, Xianfu,Wu, Qi
supporting information, p. 14499 - 14503 (2019/09/17)
Cyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild-type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α-keto ester, but with poor yield and stereoselectivity. Structure-guided, site-directed mutagenesis drastically improved the catalytic carbonyl-reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α-keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild-type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
