共查询到20条相似文献,搜索用时 15 毫秒
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Yuh-Wern Wu 《中国化学会会志》1996,43(6):507-509
The relative rates for the addition reactions of tert-butyl radical to 2-substituted ally chlorides I have een determined. The correlation of log k/k0, vs. σm gives a ρ mvalue of 3.59 with correlation coefficient of 0.930. When the substituent CH2Cl is excluded, correlation coefficient raises to 0.990 and ρ value becomes 3.39. The large p value and the deviation of relative rate of substituent CH2C1 are discussed. 相似文献
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Annibale Stefani 《Helvetica chimica acta》1973,56(4):1192-1198
The reaction of tris-crotyl-boron with vinylic olefins in the presence of triethyl-aluminium, results in the addition of an α-methylallyl group and an aluminium atom to the double bond, as indicated by the hydrolysis products. The stereochemical aspect of the reaction is discussed and a mechanism is proposed to explain the preferential formation of one diastereoisomer. 相似文献
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Dr. Bo Chen Cheng Fang Prof. Peng Liu Prof. Joseph M. Ready 《Angewandte Chemie (International ed. in English)》2017,56(30):8780-8784
We describe the synthetically useful enantioselective addition of Br−CX3 (X=Cl or Br) to terminal olefins to introduce a trihalomethyl group and generate optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom-transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer-sphere bromine abstraction from a [(bisphosphine)RhIIBrCl] complex by a benzylic radical intermediate. This mechanism appears unprecedented in asymmetric catalysis. 相似文献
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Bertrand Schweitzer‐Chaput Joachim Demaerel Hauke Engler Dr. Martin Klussmann 《Angewandte Chemie (International ed. in English)》2014,53(33):8737-8740
Based on a mechanistic study, we have discovered a Brønsted acid catalyzed formation of ketone radicals. This is believed to proceed via thermally labile alkenyl peroxides formed in situ from ketones and hydroperoxides. The discovery could be utilized to develop a multicomponent radical addition of unactivated ketones and tert‐butyl hydroperoxide to olefins. The resulting γ‐peroxyketones are synthetically useful intermediates that can be further transformed into 1,4‐diketones, homoaldol products, and alkyl ketones. A one‐pot reaction yielding a pharmaceutically active pyrrole is also described. 相似文献
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Luana Cardinale Dr. Mikhail O. Konev Prof. Dr. Axel Jacobi von Wangelin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8239-8243
Functionalization with C1-building blocks are key synthetic methods in organic synthesis. The low reactivity of the most abundant C1-molecule, carbon dioxide, makes alternative carboxylation reactions with CO2-surrogates especially important. We report a photoredox-catalyzed protocol for alkene carbamoylations. Readily accessible 4-carboxamido-Hantzsch esters serve as convenient starting materials that generate carbamoyl radicals upon visible light-mediated single-electron transfer. Addition to various alkenes proceeded with high levels of regio- and chemoselectivity. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8906-8910
We describe the synthetically useful enantioselective addition of Br−CX3 (X=Cl or Br) to terminal olefins to introduce a trihalomethyl group and generate optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom‐transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer‐sphere bromine abstraction from a [(bisphosphine)RhIIBrCl] complex by a benzylic radical intermediate. This mechanism appears unprecedented in asymmetric catalysis. 相似文献
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Abstract: The addition of (N-alkyl-N-alkoxyammine)dimethylaluminum chlorides to nitriles provides a convenient route to little investigated N-alkoxy amidine hydrochlorides. A survey of the scope of this reaction is presented. 相似文献
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Transition-state interatomic distances in the addition of peroxyl radicals to the double bond of olefins are estimated from experimental data (activation energies and rate constants) using a new algorithm combining quantum chemical and parabolic model calculations. An aromatic ring in the α-position with respect to the double bond elongates the ? distance by 0.02 × 10?10 m. Polar groups adjacent to the double bond affect this distance considerably. The geometric parameters of the transition states in the abstraction and addition of peroxyl radicals are compared. 相似文献
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The interaction between CCl4and olefins with different structures is studied in the presence of copper complexes with P-, S-, and N-containing donor ligands. Kinetic and spectroscopic studies show that the ability of olefins to be coordinated to copper complexes governs the rate, the product composition, and the reaction mechanism. Depending on the olefin and the structure of the metal complex, either typical radical-chain reactions or processes without free radicals are observed. 相似文献