7473-98-5Relevant articles and documents
Generation and reactivity of phenylhydroxycarbenes in solution
Keul, Felix,Mardyukov, Artur,Schreiner, Peter R.
supporting information, (2022/01/19)
We provide evidence for the first successful generation of phenylhydroxycarbene and 4-trifluoromethylphenylhydroxycarbene in solution. The carbene tautomers of the corresponding benzaldehyde derivatives had been prepared under cryogenic matrix-isolation conditions before but their reactivity, apart from a prototypical quantum mechanical tunneling [1,2]-H-shift reaction, had not been studied. Here our strategy is to employ suitable carbene precursors for the McFadyen–Stevens reaction, to generate the parent and the para-CF3-substituted phenylhydroxycarbenes, and to react them with benzaldehyde or acetone in a highly facile, allowed six-electron carbonyl-ene reaction toward the corresponding α-hydroxy ketones. Our findings are supported by computations at the DLPNO-CCSD(T)/cc-pVQZ//B3LYP/def2-TZVP level of theory.
1,5,7-Triazabicyclo[4.4.0]dec-5-ene Enhances Activity of Peroxide Intermediates in Phosphine-Free α-Hydroxylation of Ketones
Wang, Yongtao,Lu, Rui,Yao, Jia,Li, Haoran
supporting information, p. 6631 - 6638 (2021/02/05)
The critical role of double hydrogen bonds was addressed for the aerobic α-hydroxylation of ketones catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), in the absence of either a metal catalyst or phosphine reductant. Experimental and theoretical investigations were performed to study the mechanism. In addition to initiating the reaction by proton abstraction, a more important role of TBD was revealed, that is, to enhance the oxidizing ability of peroxide intermediates, allowing DMSO to be used rather than commonly used phosphine reductants. Further characterizations with nuclear Overhauser effect spectroscopy (NOESY) confirmed the presence of double hydrogen bonds between TBD and the ketone, and kinetic studies suggested the attack of dioxygen on the TBD-enol adduct to be the rate-determining step. This work should encourage the application of TBD as a catalyst for oxidations.
Preparation method of photoinitiator
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, (2021/10/13)
The invention discloses a preparation method of a photoinitiator. The preparation method comprises the following steps: acid chloride required for Fries reaction, aluminum trichloride and a solvent are mixed and then subjected to a Fourier reaction with benzene. Fries reaction intermediate purification method The Fourier reaction intermediate is mixed with chlorine for chlorination reaction, and the product of the chlorination reaction is subjected to gas-liquid separation to separate the gas. Reaction Section Step and The product purification step results in a photoinitiator finished product. To the technical scheme of the invention, the advantages of the traditional process of producing the photoinitiator are combined with the characteristics of the microchannel reactor to realize continuous preparation, the productivity can be improved, the production risk is reduced, the manpower and equipment investment are reduced, and the cost is further reduced.
Competitive Desulfonylative Reduction and Oxidation of α-Sulfonylketones Promoted by Photoinduced Electron Transfer with 2-Hydroxyaryl-1,3-dimethylbenzimidazolines under Air
Hasegawa, Eietsu,Nakamura, Shyota,Oomori, Kazuki,Tanaka, Tsukasa,Iwamoto, Hajime,Wakamatsu, Kan
, p. 2556 - 2569 (2021/02/27)
Desulfonylation reactions of α-sulfonylketones promoted by photoinduced electron transfer with 2-hydroxyarylbenzimidazolines (BIH-ArOH) were investigated. Under aerobic conditions, photoexcited 2-hydroxynaphthylbenzimidazoline (BIH-NapOH) promotes competitive reduction (forming alkylketones) and oxidation (producing α-hydroxyketones) of sulfonylketones through pathways involving the intermediacy of α-ketoalkyl radicals. The results of an examination of the effects of solvents, radical trapping reagents, substituents of sulfonylketones, and a variety of hydroxyaryl- and aryl-benzimidazolines (BIH-ArOH and BIH-Ar) suggest that the oxidation products are produced by dissociation of α-ketoalkyl radicals from the initially formed solvent-caged radical ion pairs followed by reaction with molecular oxygen. In addition, the observations indicate that the reduction products are generated by proton or hydrogen atom transfer in solvent-caged radical ion pairs derived from benzimidazolines and sulfonylketones. The results also suggest that arylsulfinate anions arising by carbon-sulfur bond cleavage of sulfonylketone radical anions act as reductants in the oxidation pathway to convert initially formed α-hydroperoxyketones to α-hydroxyketones. Finally, density functional theory calculations were performed to explore the structures and properties of radical ions of sulfonylketones as well as BIH-NapOH.
Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey–Seebach Reaction
Crespi, Stefano,Donabauer, Karsten,K?nig, Burkhard,Murugesan, Kathiravan,Rozman, Ur?a
supporting information, p. 12945 - 12950 (2020/09/23)
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C?H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
Preparation method of alpha-hydroxyketone photoinitiator
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Paragraph 0043-0045, (2019/07/04)
The invention provides a preparation method of an alpha-hydroxyketone photoinitiator. The preparation method comprises the steps of taking a ketone compound and a trihalomethyl-substituted benzene anda derivative thereof as raw materials, enabling the raw materials to react under the action of a polar solvent and a metal catalyst to form a halogenated intermediate in one step, and hydrolyzing theobtained product under the action of an alkali metal hydroxide aqueous solution and a phase transfer catalyst to obtain the alpha-hydroxyketone photoinitiator. The operation is simple, the reaction step is short, no Lewis acid catalyst is used in the reaction, the pollution is small, the catalyst can be recycled, by-products are less, the cost is low, and a variety of products can be produced bythe same method.
Ultrasonic preparation method for alpha-hydroxyketones
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Paragraph 0028; 0031, (2019/05/11)
The invention relates to the technical field of organic synthesis, and concretely relates to an ultrasonic preparation method for alpha-hydroxyketones. Ketones and peroxide which are used as raw materials undergo an ultrasonic reaction in the presence of an organic solvent to prepare the alpha-hydroxyketones. The preparation method provided by the invention avoids the use of halogens with high toxicity and high risks in the reaction process to avoid the risk of the product not meeting the requirements of the regulations due to the introduction of the halogens in the reaction process, and alsohas the advantages of low cost of the overall process, shortening of the cycle of batch production, simplicity in process operation and easiness in achieving of large-scale production.
Expedient preparation of active pharmaceutical ingredient ketamine under sustainable continuous flow conditions
Kassin, Victor-Emmanuel H.,Gérardy, Romaric,Toupy, Thomas,Collin, DIégo,Salvadeo, Elena,Toussaint, Fran?ois,Van Hecke, Kristof,Monbaliu, Jean-Christophe M.
supporting information, p. 2952 - 2966 (2019/06/18)
A robust three-step continuous flow procedure is presented for the efficient and sustainable preparation of active pharmaceutical ingredient ketamine. The procedure relies on the main assets of continuous flow processing, starts from commercially available chemicals, utilizes low toxicity reagents and a FDA class 3 solvent under intensified conditions. The procedure features a unique hydroxylation step with molecular oxygen, a fast imination relying on triisopropyl borate and a thermolysis employing Montmorillonite K10 as a heterogeneous catalyst, all three steps being performed in ethanol. The three individual steps can be run independently or can be concatenated, thus providing a compact yet efficient setup for the production of ketamine. The scalability of the critical hydroxylation step was assessed in a commercial pilot continuous flow reactor. The process can also be adapted for the preparation of ketamine analogs. A thorough computational study on the backbone rearrangement of the cyclopentylphenylketone scaffold under thermal stress rationalizes the experimental selectivity and the various experimental observations reported herein.
Preparing method of photoinitiator 2-methyl-2-hydroxy-1-phenylacetone
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Page/Page column 4-6, (2019/04/30)
The invention discloses a preparing method of a photoinitiator 2-methyl-2-hydroxy-1-phenylacetone. The preparing method comprises the steps of conducting acylation reaction on isobutyric acid and phosphorus trichloride, after the reaction is completed, introducing hydrogen chloride gas to make the intermediate state reaction complete, obtaining 2-chloride-2-methyl propionylchloride through chlorination reaction, conducting Friedel-Crafts reaction with benzene in the presence of a catalyst to obtain 2-chloride-2-methyl-1-phenylpropane-1-ketone, and finally after alkaline hydrolysis, washing anddistillation, obtaining the photoinitiator 1173. According to the preparing method, hydrogen chloride is introduced into the acylation step, so that the reaction yield is increased, and byproduct odors are reduced; meanwhile, chlorination reaction of a conventional technology is conducted one step in advance, the production cost of the conventional technology is reduced, and thus the product hasmarket competitiveness.
Process for preparing photoinitiator 1173
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Paragraph 0039; 0044; 0045; 0048, (2018/12/14)
The invention discloses a process for preparing a photoinitiator 1173 (2-hydroxy-2-methyl-1-phenyl-1-acetone). The process comprises the following steps: a procedure of preparing ketone at a high temperature, namely liquefying and mixing benzoic acid and isobutyric acid so as to obtain a reaction mixed liquid, preheating the reaction mixed liquid, contacting with a metallic salt catalyst, carryingout dehydration at a high temperature of 300-500 DEG C so as to remove carbon dioxide to prepare ketone, thereby obtaining isobutyryl benzene; and a procedure of one-pot method chlorination alkalinehydrolysis, namely by taking the isobutyryl benzene, carbon tetrachloride and sodium hydroxide as reagents and tetrabutylammonium bromide as a phase change catalyst, carrying out a one-pot method chlorination and alkaline hydrolysis reaction, thereby obtaining the 2-hydroxy-2-methyl-1-phenyl-1-acetone. The process disclosed by the invention is high in selectivity, and safe and environment-friendly.
