1007-48-3Relevant articles and documents
A Switchable Catalyst Duo for Acyl Transfer Proximity Catalysis and Regulation of Substrate Selectivity
Goswami, Abir,Gaikwad, Sudhakar,Schmittel, Michael
, p. 2997 - 3001 (2021)
Enzymes are encoded with a gamut of information to catalyze a highly selective transformation by selecting the proper reactants from an intricate mixture of constituents. Mimicking biological machinery, two switchable catalysts with differently sized cavities and allosteric control are conceived that allow complementary size-selective acyl transfer in an on/off manner by modulating the effective local concentration of the substrates. Selective activation of one of two catalysts in a mixture of reactants of similar reactivity enabled upregulation of the desired product.
Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols
Nacsa, Eric D.,MacMillan, David W. C.
, p. 3322 - 3330 (2018)
Nature routinely engages alcohols as leaving groups, as DNA biosynthesis relies on the removal of water from ribonucleoside diphosphates by a radical-mediated "spin-center shift" (SCS) mechanism. Alcohols, however, remain underused as alkylating agents in synthetic chemistry due to their low reactivity in two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide evidence for SCS as a key elementary step, identify the origins of competing reactions, and enable improvements in chemoselectivity by rational photocatalyst design.
Supramolecular Catalysis of Acyl Transfer within Zinc Porphyrin-Based Metal-Organic Cages
Li, Lili,Yang, Linlin,Li, Xuezhao,Wang, Jing,Liu, Xin,He, Cheng
, p. 8802 - 8810 (2021)
To illustrate the supramolecular catalysis process in molecular containers, two porphyrinatozinc(II)-faced cubic cages with different sizes were synthesized and used to catalyze acyl-transfer reactions between N-acetylimidazole (NAI) and various pyridylcarbinol (PC) regioisomers (2-PC, 3-PC, and 4-PC). A systemic investigation of the supramolecular catalysis occurring within these two hosts was performed, in combination with a host-guest binding study and density functional theory calculations. Compared to the reaction in a bulk solvent, the results that the reaction of 2-PC was found to be highly efficient with high rate enhancements (kcat/kuncat = 283 for Zn-1 and 442 for Zn-2), as well as the different efficiencies of the reactions with various ortho-substituted 2-PC substrates and NAI derivates should be attributed to the cages having preconcentrated and preoriented substrates. The same cage displayed different catalytic activities toward different PC regioisomers, which should be mainly attributed to different binding affinities between the respective reactant and product with the cages. Furthermore, control experiments were carried out to learn the effect of varying reactant concentrations and product inhibition. The results all suggested that, besides the confinement effect caused by the inner microenvironment, substrate transfer, including the encapsulation of the reactant and the release of products, should be considered to be a quite important factor in supramolecular catalysis within a molecular container.
Signal amplification and detection via a supramolecular allosteric catalyst
Gianneschi, Nathan C.,Nguyen, SonBinh T.,Mirkin, Chad A.
, p. 1644 - 1645 (2005)
The design of a supramolecular allosteric catalyst system for catalytic signal amplification and detection is presented. The catalyst was switched on by the introduction of an analyte that also behaves as an allosteric activator. Concentrations of Cl- ions as low as 800 nM were catalytically amplified and detected. The signal was transduced via a pH-sensitive fluorescent probe and observed visually using a laboratory, handheld UV lamp and by spectrophotometry. Furthermore, the allosteric effect was quantified using gas chromatography for a range of Cl- concentrations. This three-part detection scheme involving analyte binding, allosteric catalyst activation, and signal transduction represents a new approach to small-molecule detection. Copyright
Cp*Rh-based heterometallic metallarectangles: Size-dependent borromean link structures and catalytic acyl transfer
Huang, Sheng-Li,Lin, Yue-Jian,Hor, T. S. Andy,Jin, Guo-Xin
, p. 8125 - 8128 (2013)
A series of CpRh-based functional metallarectangles have been synthesized from metallaligands. Enlargement of one linker leads to the isolation of two novel Borromean link architectures. All these complexes are intact in solution, as evident from ESI-MS spectroscopic analysis. Arising from the combination of open Cu centers and favorable cavity space, {(CpRh)4(bpe) 2[Cu(opba)·2MeOH]2}4(OTf)·6MeOH shows extraordinary catalytic abilities with high efficiency and wide substrate selectivity in the acyl-transfer reaction.
Proton-exchanged montmorillonite-mediated reactions of hetero-benzyl acetates: Application to the synthesis of Zafirlukast
Yang, Lei,Chen, Xuan,Ni, Kaidong,Li, Yuansheng,Wu, Jianhong,Chen, Weilin,Ji, Yin,Feng, Lili,Li, Fei,Chen, Dongyin
supporting information, (2020/06/28)
Proton-exchanged montmorillonite (H-mont) with outstanding surface characteristics can provide abundant acidic sites in the mesopores, and serve as an efficient heterogeneous catalyst for the synthesis of heterocycle-containing diarylmethanes via Friedel-Crafts-like alkylation of (hetero)arenes by heterobenzyl acetates under mild reaction conditions without requiring any additives or an inert atmosphere. Using this strategy, the gram-scale synthesis of indole-containing diarylmethane 13 has been accomplished in good yield for the preparation of Zafirlukast. In addition, H-mont can be applied to the nucleophilic substitution reactions of heterobenzyl acetate 5p with a variety of alcohols and 1,3-dicarbonyl compounds.
Photorelease of Pyridines Using a Metal-Free Photoremovable Protecting Group
Dong, Zaizai,Fang, Xiaohong,Kou, Xiaolong,Tan, Weihong,Tang, Xiao-Jun,Wu, Yayun,Zhang, Zhen,Zhao, Rong,Zhou, Wei
supporting information, p. 18386 - 18389 (2020/08/24)
The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl (DEACM) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research.
Synthetic method of 4-pyridylaldehyde
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Paragraph 0032; 0034; 0039; 0044, (2017/11/18)
The invention relates to the field of organic chemistry, in particular to a synthetic method of 4-pyridylaldehyde. The synthetic method comprises the following steps: 1, taking 4-methyl pyridine as a raw material and obtaining 4-pyridine nitrogen oxide through oxidation reaction under an acidic condition; 2, synthesizing the 4-pyridine nitrogen oxide into acetic acid-4-pyridine methyl ester through acetic anhydride rearrangement; 3, hydrolyzing the acetic acid-4-pyridine methyl ester to obtain 4-pyridine methanol; 4, performing oxidation reaction on the 4-pyridine methanol to obtain the 4-pyridylaldehyde. After the synthetic method is adopted, the 4-methyl pyridine is used as the raw material, and the 4-pyridine methanol is obtained through N-oxidation, rearrangement and hydrolyzation and is further oxidized to obtain the 4-pyridylaldehyde. The synthetic method provided by the invention is high in total yield, low in raw material price, short in reaction time, mild in condition, and simple in process operation.
Base-catalyzed retro-Claisen condensation: A convenient esterification of alcohols via C-C bond cleavage of ketones to afford acylating sources
Xie, Feng,Yan, Fengxia,Chen, Mengmeng,Zhang, Min
, p. 29502 - 29508 (2014/08/05)
The base-catalyzed esterification of alcohols via retro-Claisen condensation has been demonstrated for the first time. A variety of alcohols including aryl- and heteroaryl methanols as well as aliphatic ones underwent efficient acylation to give the ester products in reasonable to good yields upon isolation. Not only conventional 1,3-diketones but also strong electron-withdrawing group containing acetophenones could serve as the acylating suppliers. The synthetic protocol is operationally simple and adaptable to a broad substrate scope. It complements the existed esterification via the retro-Claisen condensation, and enlarges this benign synthetic methodology.
Spinel-type zinc aluminate (ZnAl2O4) nanoparticles prepared by the co-precipitation method: A novel, green and recyclable heterogeneous catalyst for the acetylation of amines, alcohols and phenols under solvent-free conditions
Farhadi, Saeid,Panahandehjoo, Somayeh
scheme or table, p. 293 - 302 (2010/09/04)
Zinc aluminate (ZnAl2O4) nanoparticles with an average particle size of about 8 nm were easily prepared by the co-precipitation method using aqueous ammonia solution as the precipitating agent. This nanosized spinel-type oxide was characterized by TGA, XRD, FT-IR, TEM, and surface area measurement and used as the heterogeneous catalyst for the acetylation reaction. Efficient acetylation of various amines, alcohols and phenols was carried out over ZnAl2O4 nanoparticles using acetic anhydride and/or acetyl chloride as the acetylating agents at room temperature without the use of a solvent. The method is highly selective, allowing the alcoholic hydroxyl group to be protected while the phenolic hydroxyl group remains intact, and the amine group can be acetylated in the presence of the hydroxyl group. This method is fast and has a high yield. It is also clean, safe, cost effective, compatible with substrates that have other functional groups and very suitable for practical organic synthesis. In addition, the catalyst can be reused without significant loss of activity. Indeed, the catalytic activity of the ZnAl2O4 nanoparticles is higher than that of bulk ZnAl2O4.
