98-53-3Relevant articles and documents
Nature chooses rings: Synthesis of silicon-containing macrocyclic peroxides
Arzumanyan, Ashot V.,Novikov, Roman A.,Terentev, Alexander O.,Platonov, Maxim M.,Lakhtin, Valentin G.,Arkhipov, Dmitry E.,Korlyukov, Alexander A.,Chernyshev, Vladimir V.,Fitch, Andrew N.,Zdvizhkov, Alexander T.,Krylov, Igor B.,Tomilov, Yury V.,Nikishin, Gennady I.
, p. 2230 - 2246 (2014)
The reactions of 1,2-bis(dimethylchlorosilyl)ethane (1), 1,2-bis(dimethylchlorosilyl)ethene (6), and 1,2-bis(dimethylchlorosilyl)ethyne (7) with gem-bis(hydroperoxides) 2a-h and 1,1-bis(hydroperoxy)bis(cycloalkyl) peroxides 4a-c were found to proceed in an unusual way. Thus, the reactions do not give the expected polymeric peroxides; instead, they produce cyclic silicon-containing peroxides containing 2, 4, or 6 silicon atoms in the ring: 9- (3a-h), 12- (5a-c), 18- (8, 12), 24- (9, 10), 27- (13), and 36-membered (11) compounds. The size of the rings produced in the reactions increases in the series 1,2-bis(dimethylchlorosilyl)ethane 1H, 13C, and 29Si NMR spectroscopy, X-ray diffraction, elemental analysis, and high-resolution mass spectrometry. The yields vary from 77 to 95%. Structures of the larger-size rings (18-, 24-, 27-, and 36-membered peroxides) were confirmed by 1H, 13C, and 29Si NMR spectroscopy using 2D (COSY, HSQC, and HMBC), 2D DOSY 1H, 3D 1H- 29Si HMBC-DOSY NMR experiments, and elemental analysis.
Efficient Aliphatic C-H Oxidation and C═C Epoxidation Catalyzed by Porous Organic Polymer-Supported Single-Site Manganese Catalysts
Wang, Bingyang,Lin, Jin,Sun, Qiangsheng,Xia, Chungu,Sun, Wei
, p. 10964 - 10973 (2021/09/08)
Bioinspired manganese complexes have emerged over recent decades as attractive catalysts for a number of selective oxidation reactions. However, these catalysts still suffer from oxidative degradation. In the present study, we prepared a series of porous Mn-N4 catalysts in which the catalytic units are embedded in the skeleton of porous organic polymers (POPs). These POP-based manganese catalysts demonstrated high reactivity in the oxidation of aliphatic C-H bonds and the asymmetric epoxidation of olefins. Furthermore, these catalysts could be readily recycled and reused due to their heterogeneous nature. Morphological characterization revealed that the Mn-N4 complex was individually distributed over a porous polymer network. Remarkably, the nature of the single-site catalyst prevented oxidative degradation during the reaction. The present work has thus developed a successful approach for bioinspired single-site manganese catalysts in which the oxidation reaction is confined to a specific channel in an enzyme-like mode.
Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
supporting information, p. 9925 - 9937 (2021/06/30)
A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
supporting information, p. 10005 - 10013 (2021/07/19)
The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
Highly Selective Hydrogenation of Phenols to Cyclohexanone Derivatives Using a Palladium@N-Doped Carbon/SiO2Catalyst
Sheng, Xueru,Wang, Chao,Wang, Wentao
supporting information, p. 2425 - 2431 (2021/11/16)
A new palladium-based heterogeneous material was synthesized by means of immobilization of Pd(OAc)2/1,10-phenanthroline on commercially available SiO2and subsequent pyrolysis at 600 °C for 2 h in air, namely, a Pd@N-doped carbon/SiO2catalyst. The obtained catalyst was studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) techniques, and was effectively applied in the highly selective hydrogenation of phenols to give the corresponding cyclohexanone derivatives with 93-98% yields at 100 °C under 0.4 MPa H2in EtOH. It was demonstrated that introducing nitrogen could effectively promote the Pd dispersion and enhance the electronic interaction of Pd, both of which facilitate the improvement of the catalytic activity and selectivity. The likely reaction pathway was outlined to elucidate the selective hydrogenation mechanism according to experimental results.
Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
supporting information, p. 21176 - 21182 (2020/09/17)
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
Hamada, Shohei,Sugimoto, Koichi,Elboray, Elghareeb E.,Kawabata, Takeo,Furuta, Takumi
, p. 5486 - 5490 (2020/07/24)
The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
Electrochemistry Broadens the Scope of Flavin Photocatalysis: Photoelectrocatalytic Oxidation of Unactivated Alcohols
Zhang, Wen,Carpenter, Keith L.,Lin, Song
supporting information, p. 409 - 417 (2019/11/25)
Riboflavin-derived photocatalysts have been extensively studied in the context of alcohol oxidation. However, to date, the scope of this catalytic methodology has been limited to benzyl alcohols. In this work, mechanistic understanding of flavin-catalyzed oxidation reactions, in either the absence or presence of thiourea as a cocatalyst, was obtained. The mechanistic insights enabled development of an electrochemically driven photochemical oxidation of primary and secondary aliphatic alcohols using a pair of flavin and dialkylthiourea catalysts. Electrochemistry makes it possible to avoid using O2 and an oxidant and generating H2O2 as a byproduct, both of which oxidatively degrade thiourea under the reaction conditions. This modification unlocks a new mechanistic pathway in which the oxidation of unactivated alcohols is achieved by thiyl radical mediated hydrogen-atom abstraction.
Base-free oxidation of alcohols enabled by nickel(ii)-catalyzed transfer dehydrogenation
Ye, Danfeng,Liu, Zhiyuan,Sessler, Jonathan L.,Lei, Chuanhu
supporting information, p. 11811 - 11814 (2020/10/13)
An efficient nickel(ii)-catalyzed transfer dehydrogenation oxidation of alcohols is reported that relies on cyclohexanone as the formal oxidant and does not require the use of an external base. The synthetic utility of this protocol is demonstratedviathe facile oxidation of structurally complicated natural products.
Spiroxamine and synthesis method thereof
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Paragraph 0060-0061; 0068-0072; 0077-0078; 0084-0087; 0091, (2021/01/04)
The invention belongs to the field of compound synthesis, and discloses spiroxamine and a synthesis method thereof. According to the synthesis method, 3-(N-ethyl-N-propylamine)-1, 2-propylene glycol and p-tert-butyl cyclohexanone are synthesized; the 3-(N-ethyl-N-propylamine)-1, 2-propylene glycol, p-tert-butyl cyclohexanone and xylene are fully stirred and uniformly mixed; concentrated sulfuric acid is dropwise added; heating and reflux dehydration, cooling, pH value adjustment and standing for layering are performed to obtain an upper organic phase layer and a lower water layer; and the upper organic phase layer is purified, so that the spiroxamine is obtained. The content of the synthesized 3-(N-ethyl-N-propylamine)-1, 2-propylene glycol is 99% or above, and the conversion rate of the synthesized 3-(N-ethyl-N-propylamine)-1, 2-propylene glycol is 95% or above; the spiroxamine is synthesized from the 3-(N-ethyl-N-propylamine)-1, 2-propylene glycol and p-tert-butyl cyclohexanone. Thesynthesis method is simple and low in cost; the content of the synthesized spiroxamine reaches 98.3% or above, and the yield reaches 91% or above.
