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.
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.
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.
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.