- Reactions of α-chloro β-oxo aldehydes with CH-acid anions
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The reactions of α-chloro and α,α-dichloro β-oxo aldehydes with carbanions are accompanied by the cleavage of the carbon-carbon bond in the chloro aldehydes and result in formylation of CH-acids. These electrophiles react with carbanions, which are generated in situ from CH-acids in the presence of AcONa in aprotic solvents, to form polyfunctional hydroxy compounds.
- Guseinov, F. I.
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- Access to α,α-dihaloacetophenones through anodic C[dbnd]C bond cleavage in enaminones
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We have developed a method to synthesize α,α-dihaloketones under electrochemical conditions. In this reaction, the Cl- or Br- is oxidized to Cl2 or Br2 at the anode, which undergoes two-step addition reactions with the N,N-dimethyl enaminone, and finally breaks C[dbnd]C of the N,N-dimethyl enaminone to generate α,α-dihaloketones. The electrosynthesis reaction can be conveniently carried out in an undivided electrolytic cell at room temperature. In addition, various functional groups are compatible with this green protocol which can be applied simultaneously to the gram scale without significantly lower yield.
- Zhang, Zhenlei,Yang, Jiusi,Wu, Kairui,Yu, Renjie,Bu, Jiping,Huang, Zijun,Li, Shaoke,Ma, Xiantao
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supporting information
(2021/12/20)
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- Method for preparing alpha,alpha-dichloroketone under solvent-free condition
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The invention provides a method for synthesizing an alpha,alpha-dichloroketone compound by taking methyl ketone and sulfonyl chloride as raw materials. The method comprises the following steps: heating a reaction mixture of methyl ketone and sulfonyl chloride to 80 DEG C under a dry air condition, stirring for 4-8 hours, after the reaction is finished, removing sulfonyl chloride from the obtained mixture, and carrying out silica gel column chromatography separation by taking ethyl acetate-hexane as an eluent to obtain the alpha,alpha-dichloroketone compound. The synthesis method provided by the invention has the advantages of extremely high chemical reactivity and selectivity, simple and easily available raw materials, low price, simple operation, no need of any catalyst and solvent, reduction of the synthesis cost and the pollution of organic solvents to the environment, greenness, economy and the like.
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Page/Page column 4-5
(2021/06/21)
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- Solvent-free preparation of α,α-dichloroketones with sulfuryl chloride
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An efficient and facile method is reported for the synthesis of a series of α,α-dichloroketones. The direct dichlorination of methyl ketones and 1,3-dicarbonyls using an excess amount of sulfuryl chloride affords the corresponding gem-dichloro compounds in moderate to excellent yields. Moreover, the protocol features high yields, broad substrate scope, and simple reaction conditions without using any catalysts and solvents.
- Tu, Dewei,Luo, Juan,Jiang, Wengao,Tang, Qiang
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supporting information
(2021/09/15)
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- Method for synthesizing mandelic acid
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The invention relates to the technical field of compound preparation, and provides a method for synthesizing mandelic acid, which comprises the following steps: by using styrene as a basic raw material, trichloroisocyanuric acid as a chlorinating agent an
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Paragraph 0032-0033; 0035-0036; 0038-0039; 0041-0042
(2021/02/06)
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- Dichloroacetophenone Derivatives: A Class of Bioconjugation Reagents for Disulfide Bridging
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A mild and biocompatible method for the construction of disulfide bridging in peptides using dichloroacetophenone derivatives is developed. This method is highly selective (chemo, diastereo, regio, etc.) and atom economic and works under biocompatible reaction conditions (metal-free, water, pH 7, rt, etc.).
- Wu, Liu-Hai,Zhou, Shuguang,Luo, Qun-Feng,Tian, Jie-Sheng,Loh, Teck-Peng
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supporting information
p. 8193 - 8197
(2020/11/18)
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- Modular and Chemoselective Strategy for Accessing (Distinct) α,α-Dihaloketones from Weinreb Amides and Dihalomethyllithiums
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The selective transfer of diversely functionalized dihalomethyllithiums (LiCHBrCl, LiCHClI, LiCHBrI, LiCHCl2, LiCHBr2, LiCHFI) to Weinreb amides for preparing gem-dihaloketones in one synthetic operation is reported. The capability of these amides as acylating agents and, the wide availability of dihalomethanes as pronucleophiles, enable a straightforward route to the title compounds under full chemocontrol. No racemization phenomena were evidenced in the case of optically active materials. Additionally, tolerance to sensitive functional groups (esters, amides, halogens, olefins etc.) was uniformly noticed, thus making this conceptually intuitive strategy flexible and tunable by the operator. (Figure presented.).
- Malik, Monika,Pace, Vittorio,Senatore, Raffaele,Touqeer, Saad,Urban, Ernst
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supporting information
p. 5056 - 5061
(2020/10/21)
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- Switchable Synthesis of α,α-Dihalomethyl and α,α,α-Trihalomethyl Ketones by Metal-Free Decomposition of Enaminone C=C Double Bond
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The novel free radical-based cleavage of the enaminone C=C double bond is realized by using N-halosuccinimides (NXS) in the presence of benzoyl peroxide (BPO) with mild heating, enabling the tunable synthesis of α,α-dihalomethyl ketones and α,α,α-trihalomethyl ketones under different reaction conditions. The formation of these divergent products involving featured C=C double bond cleavage requires no any metal reagent, and represents one more practical example on the synthesis of poly halogenated methyl ketones via the functionalization of carbon?carbon bond. (Figure presented.).
- Liu, Yunyun,Xiong, Jin,Wei, Li,Wan, Jie-Ping
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supporting information
p. 877 - 883
(2020/01/24)
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- Electrochemical synthesis of α,α-dihaloacetophenones from terminal alkyne derivatives
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By virtue of electrochemistry, a series of α,α-dihaloacetophenones were easily obtained with good to excellent yields. This electrochemical procedure was taken in a divided cell with constant current in aqueous media. The reaction can be carried out smoothly at room temperature under metal and oxidant free condition, which provides an eco-friendly synthesis for the α,α-dihaloacetophenone derivatives.
- Li, Zhibin,Sun, Qi,Qian, Peng,Hu, Kangfei,Zha, Zhenggen,Wang, Zhiyong
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supporting information
p. 1855 - 1858
(2020/03/10)
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- Oxidative Photochlorination of Electron-Rich Arenes via in situ Bromination
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Electron-rich arenes are oxidatively photochlorinated in the presence of catalytic amounts of bromide ions, visible light, and 4CzIPN as organic photoredox catalyst. The substrates are brominated in situ in a first photoredox-catalyzed oxidation step, followed by a photocatalyzed ipso-chlorination, yielding the target compounds in high ortho/para regioselectivity. Dioxygen serves as a green and convenient terminal oxidant. The use of aqueous hydrochloric acid as the chloride source reduces the amount of saline by-products.
- Düsel, Simon Josef Siegfried,K?nig, Burkhard
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supporting information
p. 1491 - 1495
(2019/04/30)
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- Electrochemical Oxidative Oxydihalogenation of Alkynes for the Synthesis of α,α-Dihaloketones
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An electrochemical oxydihalogenation of alkynes has been developed for the first time. Using this sustainable protocol, a variety of α,α-dihaloketones can be prepared with readily available CHCl3, CH2Cl2, ClCH2CH2Cl, and CH2Br2 as the halogen source under electrochemical conditions at room temperature.
- Meng, Xiangtai,Zhang, Yu,Luo, Jinyue,Wang, Fei,Cao, Xiaoji,Huang, Shenlin
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supporting information
p. 1169 - 1174
(2020/02/04)
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- Preparation method of alpha, alpha-dichloroacetophenone compound
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The invention discloses a preparation method of an alpha, alpha-dichloroacetophenone compound. The preparation method comprises the step of preparing the alpha, alpha-dichloroacetophenone compound ina microchannel reactor by taking an acetophenone compoun
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Paragraph 0020-0028; 0034-0042
(2019/04/27)
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- Iodine-DMSO-promoted divergent reactivities of arylacetylenes
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An unprecedented set of efficient, economical, atom-economic and exceedingly selective I2-DMSO-promoted methods is described for the generation of different structures. The reaction represents the first of its kind, involving the use of different iodine concentrations, temperatures, acids and salt to adjust the selectivity for the synthesis of different alkenes, α-functionalized ketones and α-ketomethylthioesters.
- Rather, Suhail A.,Kumar, Atul,Ahmed, Qazi Naveed
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p. 4511 - 4514
(2019/04/26)
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- Synthesis of Ti-Al binary oxides and their catalytic application for C-H halogenation of phenols, aldehydes and ketones
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Traditional C–H halogenation of organic compounds often requires corrosive agent or harsh condition, and current researches are focused on the use of noble metals as catalyst. In order to give an efficient, benign, activity-adjustable and cost-effective system for halogenation, a series of Ti-Al mixed oxides are prepared as catalyst through sol-gel in this work. Characterizations reveal all catalysts contain more aluminum than titanium, but preparative conditions affect their composition and crystallinity. Monitoring of particle size, zeta potential and UV–vis of preparative solution reveals that formation of catalyst colloids undergoes chemical reaction, affecting catalyst morphology. In halogenation, all catalysts show moderate to high activities, copper chloride proves to be an effective halogen source rather than sodium chloride. The chlorination and bromination are better than iodization, phenol and ketone appear to be more appropriate substrates than aldehyde. Additionally, oxide backbone of catalyst is more durable than its organic components during recycling. This study may provide new catalytic materials for progress of C–H activation.
- Su, Peigen,Fan, Chao,Yu, Heng,Wang, Wanqin,Jia, Xin,Rao, Qifan,Fu, Chenxi,Zhang, Donghua,Huang, Benhua,Pan, Cheng,Zheng, Aqun,Sun, Yang
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- Visible-light-promoted oxidative halogenation of alkynes
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In nature, halogenation promotes the biological activity of secondary metabolites, especially geminal dihalogenation. Related natural molecules have been studied for decades. In recent years, their diversified vital activities have been explored for treating various diseases, which call for efficient and divergent synthetic strategies to facilitate drug discovery. Here we report a catalyst-free oxidative halogenation achieved under ambient conditions (halide ion, air, water, visible light, room temperature, and normal pressure). Constitutionally, electron transfer between the oxygen and halide ion is shuttled via simple conjugated molecules, in which phenylacetylene works as both reactant and catalyst. Synthetically, it provides a highly compatible late-stage transformation strategy to build up dihaloacetophenones (DHAPs).
- Li, Yiming,Mou, Tao,Lu, Lingling,Jiang, Xuefeng
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supporting information
p. 14299 - 14302
(2019/12/02)
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- Highly efficient recyclable sol gel polymer catalyzed one pot difunctionalization of alkynes
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Amino-bridged gel polymer P1 was discovered to catalyze alkyne halo-functionalization in excellent yields, regioselectivity, functional group compatibility, and recyclability. We have observed that both aromatic and aliphatic alkynes can be converted to α,α-dihalogenated ketones in the presence of polymer P1 under metal-free conditions at room temperature within a short reaction time.
- Domena, Justin,Chong, Carlos,Johnson, Qiaxian R.,Chauhan, Bhanu P. S.,Xing, Yalan
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supporting information
(2018/08/17)
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- Micelle-Enabled Photoassisted Selective Oxyhalogenation of Alkynes in Water under Mild Conditions
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Using micelles of FI-750-M, visible light, photocatalysts, and inexpensive halogenating reagents, such as N-bromosuccinimide and N-chlorosuccinimde, selective oxyhalogenations of alkynes were achieved in water under very mild conditions. No halogenation at the aromatic rings was detected, and control experiments revealed the radical pathway. The easily conducted protocol exhibited high reproducibility, was readily adjusted to gram scale, and allowed for recycling of reaction medium and catalyst.
- Finck, Lucie,Brals, Jeremy,Pavuluri, Bhavana,Gallou, Fabrice,Handa, Sachin
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p. 7366 - 7372
(2018/07/29)
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- One-pot dichlorinative deamidation of primary β-ketoamides
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An approach to the dichlorinative deamidation of primary β-ketoamides through ketonic cleavage is described, and a series of α,α-dichloroketones were furnished mostly in the presence of TEMPO. Based on control experiments, a mechanism involving tandem dichlorination and deamidation is proposed to interpret the observed reactivity.
- Zheng, Congke,Zhang, Xiaohui,Ijaz Hussain, Muhammad,Huang, Mingming,Liu, Qing,Xiong, Yan,Zhu, Xiangming
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p. 574 - 577
(2017/01/16)
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- α,α-Alkylation-Halogenation and Dihalogenation of Sulfoxonium Ylides. A Direct Preparation of Geminal Difunctionalized Ketones
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A one-pot alkylation–halogenation of ketosulfoxonium ylides in the presence of alkyl halides is described. The method furnishes several gem-difunctionalized haloketones (an alkyl and F, Cl, Br, or I) in good yields. Replacing alkyl halides with a mixture of electrophilic halogen species and various halide anions led to gem-dihalogenated ketones containing a combination of the same or two different halogens. Kinetic isotopic effects as well as reaction kinetic experiments give insight to the mechanism of these reactions.
- Gallo, Rafael D. C.,Ahmad, Anees,Metzker, Gustavo,Burtoloso, Antonio C. B.
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p. 16980 - 16984
(2017/11/27)
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- Ultrasound-assisted tandem reaction of alkynes and trihaloisocyanuric acids by thiourea as catalyst in water
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With water as the sole solvent, a green and efficient method has been developed for the synthesis of various α,α-dihaloketones via ultrasound assisted p-tolylthiourea catalyzed tandem reaction of alkynes with trihaloisocyanuric acids. This synthetic route
- Zhang, Xingyu,Wu, Yundong,Zhang, Ya,Liu, Huilan,Xie, Ziyu,Fu, Shengmin,Liu, Fang
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p. 4513 - 4518
(2017/07/10)
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- Method for removal of methanamide by dichlorination
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A method for removal of methanamide by dichlorination is disclosed, according to the method, a finished product is obtained by removal of methanamide by dichlorination by one-step-reaction of various beta-carbonyl amide derivatives as raw materials, 2,2,6,6-Tetramethylpiperidinooxy (TEMPO) and an alkali as additives and N-chlorosuccinimide as a reagent in a reaction solvent, and then concentration and purification. According to the method, synthesis of an alpha-dichloroacetophenone derivative can be realized for the first time by a method of removal of methanamide by fracturation of carbon-carbon single bond. The method is novel and unique, has certain universality, is mild in reaction conditions, low in requirement of production equipment, and simple in technology, has the advantages of high efficiency, simple operation, high safety, economy and environmentally-friendliness; high-quality diverse alpha-dichloroacetophenone derivative products can be prepared by the method, and the products prepared by the method are important drug synthesis intermediates and material intermediates, can be widely used in the synthesis of heterocycles, unsaturated acids, acetylene alcohols and other compounds and cyclopropanation, and have wide market prospects.
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Paragraph 0020-0049; 0110-0015
(2017/10/12)
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- Water-controlled selective preparation of α-mono or α,α′-dihalo ketones: Via catalytic cascade reaction of unactivated alkynes with 1,3-dihalo-5,5-dimethylhydantoin
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The control of a reaction that can produce multiple products from the same starting material is a highly attractive and challenging concept in organic synthesis. An efficient protocol for the selective synthesis of α-mono or α,α′-dihalo ketones via a water-controlled three-component thiourea-catalyzed cascade reaction of unactivated alkynes, 1,3-dihalo-5,5-dimethylhydantoin and water has been developed. α-Monohaloketones were obtained in aqueous acetone at 45 °C; conversely, α,α′-dihalo ketones were formed with pure water as the sole solvent at room temperature.
- Wu, Chao,Xin, Xiu,Fu, Zhi-Min,Xie, Long-Yong,Liu, Kai-Jian,Wang, Zheng,Li, Wenyi,Yuan, Zhi-Hui,He, Wei-Min
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p. 1983 - 1989
(2017/06/09)
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- Pathways in the Degradation of Geminal Diazides
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The degradation of geminal diazides is described. We show that diazido acetates are converted into tetrazoles through the treatment with bases. The reaction of dichloro ketones with azide anions provides acyl azides, through in situ formation of diazido ketones. We present experimental and theoretical evidence that both fragmentations may involve the generation of acyl cyanide intermediates. The controlled degradation of terminal alkynes into amides (by loss of one carbon) or ureas (by loss of two carbons) is also shown.
- Holzschneider, Kristina,H?ring, Andreas P.,Haack, Alexander,Corey, Daniel J.,Benter, Thorsten,Kirsch, Stefan F.
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p. 8242 - 8250
(2017/08/14)
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- N-Chloro-N-methoxybenzenesulfonamide: A Chlorinating Reagent
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A structurally simple and reactive chlorinating reagent, N-chloro-N-methoxybenzenesulfonamide, was conveniently and economically prepared in high yield. 1,3-Diketones, β-keto esters, benzoyl trifluoroacetones, phenols, anisoles, heteroarenes, and aromatic amines were successfully chlorinated, and the products were obtained in good to high yields.
- Pu, Xiaoqiu,Li, Qingwei,Lu, Zehai,Yang, Xianjin
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supporting information
p. 5937 - 5940
(2016/12/26)
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- Chemoselective Reduction of Trichloromethyl Compounds to gem-Dichloromethyl Groups Following Appel's Reaction Protocol
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A simple and easy reduction of trichloroacetyl compounds following the modification of Appel's reaction protocol, using triphenylphosphine and methanol, afforded the corresponding dichloroacetyl compounds, with the exception of trichloroacetylmorpholine,
- Romero-Reyes, Moises A.,Zaragoza-Galicia, Ivann,Olivo, Horacio F.,Romero-Ortega, Moises
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p. 9515 - 9519
(2016/10/14)
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- Vanadium-catalyzed chlorination under molecular oxygen
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A catalytic chlorination of ketones was performed by using a vanadium catalyst in the presence of Bu4NI and AlCl3 under atmospheric molecular oxygen. This catalytic chlorination could be applied to the chlorination of alkenes to give the corresponding vic-dichlorides. AlCl3 was found to serve as both a Lewis acid and a chloride source to induce the facile chlorination. A combination of Bu4NI and AlI3 in the presence of a vanadium catalyst under atmospheric molecular oxygen induced the iodination of ketones.
- Moriuchi, Toshiyuki,Fukui, Yasuhiro,Kato, Satoshi,Kajikawa, Tomomi,Hirao, Toshikazu
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p. 177 - 180
(2015/03/04)
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- A simple, mild, and efficient method for the preparation of α,α-dichloroketones with DCDMH catalyzed by ammonium chloride
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New process that can selectively prepare α,α-dichloro ketones from various ketones with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) using ammonium chloride as a catalyst is reported. The effects of ammonium salts, solvents, DCDMH, and reaction temperature were investigated. Under the optimal condition, most of α,α-dichlorinated products were selectively obtained in 86-98% yield.
- Zheng, Zubiao,Han, Bingbing,Cheng, Peng,Niu, Jiangxiu,Wang, Aidong
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p. 9814 - 9818
(2015/01/09)
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- Steric vs. electronic effects in the Lactobacillus brevis ADH-catalyzed bioreduction of ketones
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Lactobacillus brevis ADH (LBADH) is an alcohol dehydrogenase that is commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, an ethyl or a chloromethyl as a small ketone substituent to the corresponding (R)-alcohols. Herein we have tested a series of 24 acetophenone derivatives differing in their size and electronic properties for their reduction employing LBADH. After plotting the relative activity against the measured substrate volumes we observed that apart from the substrate size other effects must be responsible for the activity obtained. Compared to acetophenone (100% relative activity), other small substrates such as propiophenone, α,α, α-trifluoroacetophenone, α-hydroxyacetophenone, and benzoylacetonitrile had relative activities lower than 30%, while medium-sized ketones such as α-bromo-, α,α-dichloro-, and α,α-dibromoacetophenone presented relative activities between 70% and 550%. Moreover, the comparison between the enzymatic activity and the obtained final conversions using an excess or just 2.5 equiv. of the hydrogen donor 2-propanol, denoted again deviations between them. These data supported that these hydrogen transfer (HT) transformations are mainly thermodynamically controlled. For instance, bulky α-halogenated derivatives could be quantitatively reduced by LBADH even employing 2.5 equiv. of 2-propanol independently of their kinetic values. Finally, we found good correlations between the IR absorption band of the carbonyl groups and the degrees of conversion obtained in these HT processes, making this simple method a convenient tool to predict the success of these transformations. The Royal Society of Chemistry.
- Rodriguez, Cristina,Borzecka, Wioleta,Sattler, Johann H.,Kroutil, Wolfgang,Lavandera, Ivan,Gotor, Vicente
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supporting information
p. 673 - 681
(2014/01/06)
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- Expanding the scope of alcohol dehydrogenases towards bulkier substrates: Stereo- and enantiopreference for α,α-dihalogenated ketones
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Alcohol dehydrogenases (ADHs) were identified as suitable enzymes for the reduction of the corresponding α,α-dihalogenated ketones, obtaining optically pure β,β-dichloro- or β,β-dibromohydrins with excellent conversions and enantiomeric excess. Among the different biocatalysts tested, ADHs from Rhodococcus ruber (ADH-A), Ralstonia sp. (RasADH), Lactobacillus brevis (LBADH), and PR2ADH proved to be the most efficient ones in terms of activity and stereoselectivity. In a further study, two racemic α-substituted ketones, namely α-bromo- α-chloro- and α-chloro-α-fluoroacetophenone were investigated to obtain one of the four possible diastereoisomers through a dynamic kinetic process. In the case of the brominated derivative, only the (1R)-enantiomer was obtained by using ADH-A, although with moderate diastereomeric excess (>99 % ee, 63 % de), whereas the fluorinated ketone exhibited a lower stereoselectivity (up to 45 % de). Bulking up: A series of β,β-dihalohydrins are obtained through alcohol dehydrogenase (ADH) catalyzed bioreduction of the synthesized α,α-dihalogenated ketones. Two racemic acetophenone derivatives are also subjected to this protocol to obtain stereoenriched alcohols through dynamic kinetic resolution (DKR).
- Kedziora, Kinga,Bisogno, Fabricio R.,Lavandera, Ivan,Gotor-Fernandez, Vicente,Montejo-Bernardo, Jose,Garcia-Granda, Santiago,Kroutil, Wolfgang,Gotor, Vicente
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p. 1066 - 1072
(2014/05/06)
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- Direct conversion of alcohols to α-chloro aldehydes and α-chloro ketones
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Direct conversion of primary and secondary alcohols into the corresponding α-chloro aldehydes and α-chloro ketones using trichloroisocyanuric acid, serving both as stoichiometric oxidant and α-halogenating reagent, is reported. For primary alcohols, TEMPO has to be added as an oxidation catalyst, and for the transformation of secondary alcohols (TEMPO-free protocol), MeOH as an additive is essential to promote chlorination of the intermediary ketones.
- Jing, Yuanyuan,Daniliuc, Constantin G.,Studer, Armido
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supporting information
p. 4932 - 4935
(2015/04/27)
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- Efficient partial hydrogenation of trichloromethyl to gem-dichloromethyl groups in platinum on carbon-catalyzed system
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While gem-dichloromethyl groups can be directly synthesized by the mono-dechlorination of the corresponding trichloromethyl groups, the suppression control of the over-reduction to form chloromethyl or methyl functionalities is quite difficult. We have established the efficient and widely applicable mono-dechlorination method of the trichloromethyl groups to form the corresponding gem-dichloromethyl groups using platinum on carbon in dimethylacetamide as a specific solvent at 25 °C under a hydrogen atmosphere. The mono-dechlorination of the α,α,α- trichloromethylcarbonyl groups smoothly proceeded by the use of platinum on carbon as a catalyst in a highly chemoselective manner, while the efficient mono-dechlorination of the alkyl- and aryl-trichloromethyl groups required the combined use of Bu3SnH.
- Sawama, Yoshinari,Imanishi, Takahiro,Nakatani, Ryosuke,Fujiwara, Yuta,Monguchi, Yasunari,Sajiki, Hironao
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p. 4540 - 4546
(2014/06/10)
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- Laccase/TEMPO-mediated system for the thermodynamically disfavored oxidation of 2,2-dihalo-1-phenylethanol derivatives
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An efficient methodology to oxidize β,β-dihalogenated secondary alcohols employing oxygen was achieved in a biphasic medium using the laccase from Trametes versicolor/TEMPO pair, providing the corresponding ketones in a clean fashion under very mild conditions. Moreover, a chemoenzymatic protocol has been applied successfully to deracemize 2,2-dichloro-1-phenylethanol combining this oxidation with an alcohol dehydrogenase-catalyzed bioreduction. the Partner Organisations 2014.
- Kedziora, Kinga,Diaz-Rodriguez, Alba,Lavandera, Ivan,Gotor-Fernandez, Vicente,Gotor, Vicente
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supporting information
p. 2448 - 2453
(2014/05/06)
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- K 2S 2O 8-mediated difunctionalization of C≡C bonds in water: A simple and efficient approach to α, α -dihaloacetophenones from phenylacetylenes and NaX
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A novel K2S2O8-mediated oxy-1,1-dihalogenation of alkynes with NaX in the presence of water has been developed, affording α,α-dihaloacetophenones in moderate to good yields. The advantages of this reaction are mild reaction conditions, operational simplicity, and use of pure water as reaction medium. A plausible reaction mechanism is proposed on the basis of mechanistic studies.
- Wang, Jing-Yu,Jiang, Qing,Guo, Can-Cheng
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supporting information
p. 3130 - 3138
(2015/10/12)
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- Halocarbocyclization versus dihalogenation: Substituent directed iodine(iii) catalyzed halogenations
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The nucleophilicity of the substituents in iodobenzene pre-catalysts have a huge impact on product selectivity in iodine(iii) triggered halogenations, steering the reactivity from solely carbocyclizations towards dihalogenations. Utilizing this catalyst-dependent reactivity a diastereo- and chemoselective dihalogenation method was established allowing the conversion of structurally and electronically diverse unsaturated compounds in excellent yields.
- Stodulski, Maciej,Goetzinger, Alissa,Kohlhepp, Stefanie V.,Gulder, Tanja
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supporting information
p. 3435 - 3438
(2014/03/21)
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- Bronsted acidic ionic liquid accelerated halogenation of organic compounds with N-halosuccinimides (NXS)
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The Bronsted-Acidic ionic liquid 1-methyl-3-(4-sulfobutyl) imidazolium triflate [BMIM(SO3H)][OTf] was demonstrated to act efficiently as solvent and catalyst for the halogenation of activated organic compounds with N-halosuccinimides (NXS) under mild conditions with short reaction times. Methyl aryl ketones were converted into a-halo and a,a-dihaloketones, depending on the quantity of NXS used. Ketones with activated aromatic rings were selectively halogenated, however in some cases mixtures of a-halogenated ketone and ring-halogenated ketones were obtained. Activated aromatics were regioselectively ring halogenated to give mono- and dihalo-substituted products. The [BMIM(SO3H)][OTf] ionic liquid (IL-A) was successfully reused eight times in a representative monohalogenation reaction with no noticeable decrease in efficiency. An effective halogenation scale-up in this IL is also presented. The reactivity trend and the observed chemo- and regioselectiivities point to an ET process in these IL-promoted halofunctionalization reactions.
- Vrazic, Dejan,Jereb, Marjan,Laali, Kenneth K.,Stavber, Stojan
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- A new and efficient method for the synthesis of α,α- dihaloketones by oxyhalogenation of alkynes using oxone-KX (X = Cl, Br, or I)
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A simple and efficient method for the preparation of α,α- dichloroketones, α,α-dibromoketones, and α,α- diiodoketones by oxyhalogenation of alkynes using oxone and KX (X = Cl, Br, or I) is described.
- Madabhushi, Sridhar,Jillella, Raveendra,Mallu, Kishore Kumar Reddy,Godala, Kondal Reddy,Vangipuram, Venkata Sairam
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supporting information
p. 3993 - 3996
(2013/07/25)
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- Aromatic substitution in ball mills: Formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
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Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed. The Royal Society of Chemistry.
- Schmidt, Robert,Stolle, Achim,Ondruschka, Bernd
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p. 1673 - 1679
(2013/02/22)
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- Decarboxylative bromination of cinnamic acids by 2-iodoxybenzoic acid with tetrabutylammonium bromide
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The decarboxylative bromination of cinnamic acids using the hypervalent iodine reagent 2-iodoxybenzoic acid with tetrabutylammonium bromide is described, providing good to excellent yields of bromostyrenes. Bromostyrenes are useful coupling components in a wide range of transition metal-catalysed coupling reactions.
- Han, Jianlei,Wei, Yuping
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body text
p. 247 - 248
(2012/09/22)
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- One-step conversion of acetophenones to α-haloacetophenone dimethyl acetals using DCDMH/DBDMH and molecular sieve in methanol
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Using DCDMH/DBDMH as N-halo reagent, piperidine as catalyst, and 4-A molecular sieve as water-removing agent, α-haloacetophenone dimethyl acetals were directly obtained from the solvent of methanol. As to the substrates with electronwithdrawing groups, the conversions were 80-100%. Copyright Taylor & Francis Group, LLC.
- Zhou, Bin,Chen, Zizhan,Zheng, Zubiao,Han, Bingbing,Zou, Xinzhuo
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experimental part
p. 1445 - 1453
(2012/04/17)
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- Platinum on carbon-catalyzed precise reduction control of trichloromethyl to Geminal-dichloromethyl groups
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Geminal-dichloromethyl derivatives could be efficiently synthesized by the highly chemoselective platinum on carbon-catalyzed mono-dechlorination of trichloromethyl substrates in dimethylacetamide (DMA) as a specific solvent at 25 °C under a hydrogen atmosphere. Copyright
- Imanishi, Takahiro,Fujiwara, Yuta,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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p. 771 - 776
(2012/06/30)
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- N-Halosuccinimide/SiCl4 as general, mild and efficient systems for the α-monohalogenation of carbonyl compounds and for benzylic halogenation
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Combinations of N-halosuccinimide and tetrachlorosilane in acetonitrile were found to be efficient systems for the selective α-monohalogenation of carbonyl compounds as well as for benzylic halogenation under mild conditions.
- Salama, Tarek A.,Novák, Zoltán
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experimental part
p. 4026 - 4029
(2011/08/09)
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- α-Halogenation of carbonyl compounds: Halotrimethylsilane-nitrate salt couple as an efficient halogenating reagent system
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A mixture of chloro/bromotrimethylsilane and nitrate salt is found to be an effective reagent system for the α-chlorination/bromination of carbonyl compounds. The reaction occurs under mild conditions yielding the products in moderate to good yields.
- Prakash, G.K. Sxurya,Ismail, Rehana,Garcia, Jessica,Panja, Chiradeep,Rasul, Golam,Mathew, Thomas,Olah, George A.
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experimental part
p. 1217 - 1221
(2011/03/22)
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- Selective 1,2-dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides
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1,2-Dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides can be selectively realized through using different reaction conditions. α,β-Dihalo alkenes were obtained exclusively using THF as solvent without using any catalyst, while α,α
- Liu, Jinhua,Li, Wenjuan,Wang, Chao,Li, Yao,Li, Zhiping
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supporting information; experimental part
p. 4320 - 4323
(2011/09/12)
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- Addition of halide to π-bond directly from aqueous NaX solution: A general strategy for installation of two different functional groups
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Activation of π-bond with organic Lewis acid and cationic surfactant mediated direct transfer of halides to alkyne and alkene are demonstrated to afford α,α-dihaloketones and other valuable synthons with outstanding selectivities.
- Pandit, Palash,Gayen, Krishnanka S.,Khamarui, Saikat,Chatterjee, Nirbhik,Maiti, Dilip K.
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supporting information; experimental part
p. 6933 - 6935
(2011/08/06)
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- Simple and efficient methods for selective preparation of α-mono or α,α-dichloro ketones and β-ketoesters by using DCDMH
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New processes that can selectively prepare α-mono or α,α-dichloro ketones and β-ketoesters using 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) are reported. Using silica gel as the catalyst and methanol as the solvent and heating for 1 h under reflux, α-monochlorinated products were selectively obtained in 86-98% yield. However using a deep eutectic solvent (choline chloride: p-TsOH = 1:1) as the solvent and stirring for 45 min at room temperature, α,α- dichlorinated products were selectively obtained in 86-95% yield.
- Chen, Zizhan,Zhou, Bin,Cai, Huihua,Zhu, Wei,Zou, Xinzhuo
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experimental part
p. 275 - 278
(2010/04/22)
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- Cu(OTf)2-catalyzed α-halogenation of ketones with 1,3-dichloro-5,5'-dimethylhydantoin and N-bromosuccinimide
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Copper(II) triflate catalyses efficiently the α-halogentaion of aryl or alkyl ketones with l.3-diehloro-5.5'-dimethylhydantoin and N-bromosuccinimde to give the corresponding α,α-dichloroketones and α-bromoketones in high yield with excellent product selectivity.
- Jagdale, Arun R.,Chouthaiwale, Pandurang V.,Sudalai, Arumugam
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experimental part
p. 1424 - 1430
(2010/02/28)
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- Synthesis and reactivity of fluorous and nonfluorous aryl and alkyl iodine(III) dichlorides: New chlorinating reagents that are easily recycled using biphasic protocols
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Fluorous aryl and alkyl iodine(III) dichlorides of the formulas (R fn(CH2)3)2C6H 3ICl2 (Rfn ) CF3(CF 2)n-1; n ) 8 for 3,5-disubstituted and n ) 6, 8, 10 for 2,4-disubstituted) and RfnCH2ICl2 (n ) 8, 10) are prepared in 71-98% yields by reactions of Cl2 and the corresponding fluorous iodides. These are effective reagents for the conversions of cyclooctene to trans-1,2-dichlorocyclooctene, anisole to 4-chloro- and 2-chloroanisole, 4-tert-butylphenol to 2-chloro-4-tert-butylphenol, PhCOCH 2COPh to PhCOCHClCOPh, and PhCOCH3 to PhCOCH2Cl and PhCOCHCl2 (CH3CN, rt to 40°C, 100-64% conversions). The chlorinated products and fluorous iodide coproducts are easily separated by organic/fluorous liquid/liquid biphase workups. The latter are obtained in 97-90% yields and reoxidized with Cl2. Analogous chlorinations are conducted with 3-Cl2IC6H4COOH (16) and 4,4'-Cl2IC6H4C6H 4ICl2. With the former, the products and coproduct 3-IC6H4COOH (91-85% recoveries) are easily separated by organic/aqueous NaHCO3 liquid/ liquid biphase workups. The coproduct from the latter, 4,4'-IC6H4C6H4I, is insoluble in common organic solvents, allowing separation by liquid/solid phase workups (91-89% recoveries). The effect of the structure of the iodine(III) dichloride upon reactivity is analyzed in detail. The fluorous systems with Rf8 substituents are generally superior, but 16 is more reactive and gives higher selectivities.
- Podgorsek, Ajda,Jurisch, Markus,Stavber, Stojan,Zupan, Marko,Iskra, Jernej,Gladysz, John A.
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body text
p. 3133 - 3140
(2009/08/15)
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- Halogenation of ketones with N-halosuccinimides under solvent-free reaction conditions
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Several aryl substituted ketones, cyclic ketones, 1,3-diketones and a β-ketoamide were halogenated with N-halosuccinimides under solvent-free reaction conditions (SFRC) at various temperatures (20-80 °C), whereas less enolized ketones required the presence of an acid catalyst (p-toluenesulfonic acid, PTSA). Bromination of substituted acetophenones obeys first order kinetics v=kBr[ketone] and the following correlation with the keto-enol equilibrium constant: log kBr=0.3pKE+C1, less enolized substrates being more reactive; the moderate positive charge developed in the rate determining step was confirmed by the Hammett correlation (ρ=-0.5). On the other hand, in cyclic ketones an opposite relation was observed: log kBr=-0.6pKE+C2, indicating higher reactivity of substrates with higher enolization constant (KE). The important role of the nature of the solvent (MeCN, MeOH) in preorganization of the ketone-NBS-PTSA mixture prior to SFRC bromination was found.
- Pravst, Igor,Zupan, Marko,Stavber, Stojan
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p. 5191 - 5199
(2008/09/21)
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- Synthesis of 2-chloro-2-imidoylaziridines via aza-darzens-type reaction of 3,3-dichloro-1-azaallylic anions and N-(arylsulfonyl)imines
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3,3-Dichloro-1-azaallylic anions, generated by deprotonation of α,α-dichloroketimines 10 with lithium diisopropylamide, reacted with N-sulfonylaldimines 7 to produce the Mannich-type products N-[2,2-dichloro-3- (N-alkylimino)-1,3-diarylpropyl]benzenesulfo
- Giubellina, Nicola,Mangelinckx, Sven,Toernroos, Karl W.,De Kimpe, Norbert
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p. 5881 - 5887
(2007/10/03)
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- A convenient and efficient synthesis of 1-aryl-2,2-dichloroethanones
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1-Arylethanones are readily chlorinated with an aqueous HCl-H 2O2 system using ethanol as a cosolvent. The reaction prceeds rapidly and results in selective conversion of 1-arylethanones into 1-aryl-2,2-dichloroethanones in yields of 48-89%, depending on the nature of the substituent in the aryl group.
- Terent'ev, Alexander O.,Khodykin, Sergey V.,Troitskii, Nikolay A.,Ogibin, Yuri N.,Nikishin, Gennady I.
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p. 2845 - 2848
(2007/10/03)
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