2078-14-0Relevant articles and documents
Trimethylsilyl Esters as Novel Dual-Purpose Protecting Reagents
Chen, Jyun-Siao,Huang, Po-Hsun,Hsieh, Ya-Chi,Liu, Jen-Wei,Hsu, Hsiao-Lin,Zhang, Kai-Min,Wu, Ren-Tsung,Chang, Ting-Shuo,Liu, Yu-Hao,Wu, Hsin-Ru,Luo, Shun-Yuan
supporting information, p. 754 - 762 (2021/12/02)
Trimethylsilyl esters, AcOTMS, BzOTMS, TCAOTMS, etc., are inexpensive and chemically stable reagents that pose a negligible environmental hazard. Such compounds prove to serve as efficient dualpurpose reagents to respectively achieve acylation and trimethylsilylation of alcohols under acidic or basic conditions. Herein, a detailed study on protection of various substrates and new methodological investigations is described.
A simple and efficient room temperature silylation of diverse functional groups with hexamethyldisilazane using CeO2 nanoparticles as solid catalysts
Anbu, Nagaraj,Vijayan, Chellappa,Dhakshinamoorthy, Amarajothi
, (2019/06/08)
In this study, a mild and efficient method is developed for the silylation of diverse functional groups using CeO2 nanoparticles (n-CeO2) as solid catalysts with hexamethyldisilazane (HMDS) as silylating agent at room temperature. Alcohols, phenols and acids are silylated to their respective silyl derivatives with faster reaction rate while amines and thiols required relatively longer reaction time. Moreover, the solid catalyst is easily be separated from the reaction mixture and recycled more than five times without any obvious decay in its activity. Powder X-ray diffraction (XRD), transmission electron microscope (TEM), UV–vis diffuse reflectance spectra (UV-DRS) and Raman analyses revealed identical structural integrity, particle size, absorption edge and valence state for the reused solid compared to the fresh solid catalyst.
Synthesis of trimethylsilyl carboxylates by HMDS under solvent-free conditions
Jereb, Marjan,Lakner, Janja
, p. 5713 - 5723 (2016/08/23)
A broad set of structurally different carboxylic acids were transformed into their trimethylsilyl esters with HMDS in a practically completely solvent-free process, while a catalytic amount of iodine was required in some cases. The process has several advantages over the known methods: untreated reactants, air atmosphere, mild and neutral conditions, no evolution of hydrogen halide, no need of an additional base, low amount of waste, completely without chromatography, low consumption of energy, and operational simplicity.
Fe(TAML)Li/(diacetoxyiodo)benzene-mediated oxidation of alcohols: Evidence for mild and selective C-O and C-C oxidative cleavage in lignin model transformations
Napoly, Francois,Jean-Gerard, Ludivine,Goux-Henry, Catherine,Draye, Micheline,Andrioletti, Bruno
, p. 781 - 787 (2014/03/21)
A novel combination of Fe(TAML)Li and (diacetoxyiodo)- benzene for the oxidation of primary and secondary alcohols at 25 °C in acetone is reported. In view of the interesting ability of this system to selectively cleave specific types of C-C bonds of elaborated alcohols, the application of this novel combination to the oxidative cleavage of lignin model molecules was investigated. Considering the numerous supported versions of the oxidant as well as the mild conditions employed, the developed methodology appears to be a promising lignin depolymerization strategy.
Investigation of the substrate range of CYP199A4: Modification of the partition between hydroxylation and desaturation activities by substrate and protein engineering
Bell, Stephen G.,Zhou, Ruimin,Yang, Wen,Tan, Adrian B. H.,Gentleman, Alexander S.,Wong, Luet-Lok,Zhou, Weihong
, p. 16677 - 16688 (2013/03/28)
The cytochrome P450 enzyme CYP199A4, from Rhodopseudomonas palustris HaA2, can efficiently demethylate 4-methoxybenzoic acid. It is also capable of oxidising a range of other related substrates. By investigating substrates with different substituents and ring systems we have been able to show that the carboxylate group and the nature of the ring system and the substituent are all important for optimal substrate binding and activity. The structures of the veratric acid, 2-naphthoic acid and indole-6-carboxylic acid substrate-bound CYP199A4 complexes reveal the substrate binding modes and the side-chain conformational changes of the active site residues to accommodate these larger substrates. They also provide a rationale for the selectivity of product oxidation. The oxidation of alkyl substituted benzoic acids by CYP199A4 is more complex, with desaturation reactions competing with hydroxylation activity. The structure of 4-ethylbenzoic acid-bound CYP199A4 revealed that the substrate is held in a similar position to 4-methoxybenzoic acid, and that the C β C-H bonds of the ethyl group are closer to the heme iron than those of the Cα (3.5 vs. 4.8 A?). This observation, when coupled to the relative energies of the reaction intermediates, indicates that the positioning of the alkyl group relative to the heme iron may be critical in determining the amount of desaturation that is observed. By mutating a single residue in the active site of CYP199A4 (Phe185) we were able to convert the enzyme into a 4-ethylbenzoic acid desaturase. Engineering a P450 desaturase: The substrate range of CYP199A4 from Rhodopseudomonas palustris was investigated. The partition between the hydroxylation and desaturation activities of 4-ethylbenzoic acid was studied by changing the substrate and by mutation. The activity of CYP199A4 with 4-ethylbenzoic acid was changed to a desaturase by a single mutation at F185. Copyright
Dealkylation of esters via treatment with N-(trimethylsilyl) diethylamine and methyl iodide
Yamamoto, Yasushi,Shimizu, Hideaki,Hamada, Yoshitaka
, p. 119 - 122 (2007/10/03)
A method for the conversion of esters to carboxylic acids has been reported. Reaction of methyl o-methoxybenzoate with N-(trimethylsilyl)diethylamine and methyl iodide, followed by hydrolysis, afforded o-methoxybenzoic acid with a 94% yield based on 96% conversion. Methyl esters of not only aromatic acids but also aliphatic acids were converted to the corresponding acids with high yields. A combination of N-(trimethylsilyl)dimethylamine and methyl iodide was also effective to give p-methylbenzoic acid with a 85% yield based on 90% conversion from the corresponding methyl ester.
Syntheses with N-Trimethylsilylheteroarylium Salts: Reactions with Aldehydes, Ketones and Carboxylic Acids. Comparison of Reactivity with Analogous N-Acylheteroarylium Salts
Anders, Ernst,Stankowiak, Achim,Riemer, Roland
, p. 931 - 934 (2007/10/02)
N-Trimethylsilylheteroarylium salts 2 can be characterized as efficient silylating reagents for carbonyl compounds (5 or 8) and carbonic acids 11, their reactivity is comparable to that of N-acylheteroarylium salts 1.In some cases (depending on the nature of the substrates), their silylating power can be stronger than the acylating power of comparable salts 1.This will be demonstrated in the case of enolizable examples of 5 and 8.
