- Enolate-Based Regioselective Anti-Beckmann C-C Bond Cleavage of Ketones
-
The Baeyer-Villiger or Beckmann rearrangements are established methods for the cleavage of ketone derivatives under acidic conditions, proceeding for unsymmetrical precursors selectively at the more substituted site. However, the fragmentation regioselectivity cannot be switched and fragmentation at the less-substituted terminus is so far not possible. We report here that the reaction of ketone enolates with commercial alkyl nitrites provides a direct and regioselective way of fragmenting ketones into esters and oximes or ω-hydroxyimino esters, respectively. A comprehensive study of the scope of this reaction with respect to ketone classes and alkyl nitrites is presented. Control over the site of cleavage is gained through regioselective enolate formation by various bases. Oxidation of kinetic enolates of unsymmetrical ketones leads to the otherwise unavailable "anti-Beckmann"cleavage at the less-substituted side chain, while cleavage of thermodynamic enolates of the same ketones represents an alternative to the Baeyer-Villiger oxidation or the Beckmann rearrangement under basic conditions. The method is suited for the transformation of natural products and enables access to orthogonally reactive dicarbonyl compounds.
- Jahn, Ullrich,Ma?ek, Tomá?
-
p. 11608 - 11632
(2021/09/02)
-
- A Zirconium Indazole Carboxylate Coordination Polymer as an Efficient Catalyst for Dehydrogenation-Cyclization and Oxidative Coupling Reactions
-
Rational ligand design is crucial for achieving widespread applications of coordination polymers. The preparation, structural characterisation, and catalytic applications of zirconium (IV) coordination polymer (Zr-IDA), which was derived from 1-(carboxymethyl)-1H-indazole-5-carboxylic acid are reported. The Zr-IDA catalyst contains porous and highly crystalline particles with a quasi-spherical morphology around 100 nm in size, and Zr was coordinated with both O and N as shown by FT-IR and XPS measurements. Importantly, the Zr-IDA catalyst shows great activity, selectivity and stability in the oxidative coupling of benzyl cyanides with tert-butyl hydroperoxide to afford tert-butyl peresters, and the dehydrogenation cyclization of o-phenylenediamines with aromatic alcohols to afford 1,2-disubstituted benzimidazole derivatives. Mechanistic investigations were carried out to study these reactions and the developed catalytic system in more detail.
- Sang, Xinxin,Hu, Xinyu,Tao, Rong,Zhang, Yilin,Zhu, Haiyan,Wang, Dawei
-
p. 123 - 129
(2020/02/21)
-
- Ribavirin semi-antigen and artificial antigen and its preparation method and application (by machine translation)
-
The invention relates to ribavirin semi-antigen and artificial antigen and its preparation method and application. The ribavirin semi-antigen having a structure of formula (I) or formula (II) as shown: The ribavirin artificial antigen is represented by t
- -
-
Paragraph 0047-0049; 0051
(2019/04/02)
-
- Introducing efficient palladium catalyzed cross coupling reaction of tertiary alcohols and aroyl chlorides for the synthesis of highly substituted esters
-
Esters are chemical compounds with many practical uses. The common type of esterification is called the Fischer esterification. Another one is by the action of acid chlorides on alcohols but not with tertiary alcohols. The stable carbenium ions formed fro
- Al-Masum, Mohammad,Hira, Arpona,Chrisman, Sara,Nguyen, Ngan T.
-
-
- A fluorobenzene imidazole impurity E preparation method
-
The invention discloses a fluorobenzene imidazole impurity E preparation method. Characterized in that in order to para-benzoic acid as the starting material, after chlorination reaction, esterification reaction, a Friedel-crafts acylation reaction, hydro
- -
-
Paragraph 0060; 0063; 0064
(2019/04/10)
-
- The Conversion of tert-Butyl Esters to Acid Chlorides Using Thionyl Chloride
-
The reaction of tert-butyl esters with SOCl2 at room temperature provides acid chlorides in unpurified yields of 89% or greater. Benzyl, methyl, ethyl, and isopropyl esters are essentially unreactive under these conditions, allowing for the selective conversion of tert-butyl esters to acid chlorides in the presence of other esters.
- Greenberg, Jacob A.,Sammakia, Tarek
-
p. 3245 - 3251
(2017/03/23)
-
- Grignard Reagents on a Tab: Direct Magnesium Insertion under Flow Conditions
-
An on-demand preparation of organomagnesium reagents is presented using a new flow protocol. The risks associated with the activation of magnesium are circumvented by a new on-column initiation procedure. Required amounts of solutions with a precise titration were obtained. Telescoped flow or batch reactions allow access to a diverse set of functional groups.
- Huck, Lena,De La Hoz, Antonio,Díaz-Ortiz, Angel,Alcázar, Jesus
-
supporting information
p. 3747 - 3750
(2017/07/26)
-
- An efficient method for the preparation of: Tert -butyl esters from benzyl cyanide and tert -butyl hydroperoxide under the metal free condition
-
A novel protocol to synthesize tert-butyl esters from benzyl cyanides and tert-butyl hydroperoxide has been successfully achieved. In the presence of tert-butyl hydroperoxide, Csp3-H bond oxidation, C-CN bond cleavage and C-O bond formation proceeded smoothly in one pot under the metal-free condition.
- Chen, Xiuling,Li, Yan,Wu, Minghu,Guo, Haibing,Jiang, Longqiang,Wang, Jian,Sun, Shaofa
-
p. 102023 - 102027
(2016/11/09)
-
- A direct and sustainable synthesis of tertiary butyl esters enabled by flow microreactors
-
Tertiary butyl esters find large applications in synthetic organic chemistry. A straightforward method for the direct introduction of the tert-butoxycarbonyl group into a variety of organic compounds has been developed using flow microreactor systems. The resultant flow process was more efficient, versatile and sustainable compared to the batch.
- Degennaro, Leonardo,Maggiulli, Daniela,Carlucci, Claudia,Fanelli, Flavio,Romanazzi, Giuseppe,Luisi, Renzo
-
supporting information
p. 9554 - 9557
(2016/08/01)
-
- A mesoporous organosilica grafted Pd catalyst (MOG-Pd) for efficient base free and phosphine free synthesis of tertiary butyl esters via tertiary-butoxycarbonylation of boronic acid derivatives without using carbon monoxide
-
A mesoporous organosilica grafted palladium(ii) catalyst was synthesized and characterized using various spectroscopic techniques. Its catalytic activity was evaluated for the synthesis of tertiary butyl esters via tert-butoxycarbonylation of boronic acid
- Ghosh, Kajari,Molla, Rostam Ali,Iqubal, Md. Asif,Islam
-
p. 3540 - 3551
(2015/06/25)
-
- Modulators of methyl modifying enzymes, compositions and uses thereof
-
Agents for modulating methyl modifying enzymes, compositions and uses thereof are provided herein.
- -
-
Page/Page column 252; 253
(2015/12/26)
-
- Preparation of tert-butyl esters via Pd-catalyzed tert-butoxycarbonylation of (hetero)aryl boronic acid derivatives
-
A novel protocol to synthesize tert-butyl esters from boronic acids or boronic acid pinacol esters and di-t-butyl dicarbonate has been successfully achieved. The cross-coupling reactions can produce up to 94% yields by using palladium acetate and triphenylphosphine as catalyst system, dioxane as a solvent. Moreover, a wide range of substrates including benzenes, pyridines, and quinolines boronic acids or boronic acid pinacol esters can fit with this system as well.
- Wu, Yusheng,Li, Xinjian,Zou, Dapeng,Zhu, Helong,Wang, Yaping,Li, Jingya,Wu, Yangjie
-
supporting information
p. 1836 - 1839
(2014/05/06)
-
- MODULATORS OF METHYL MODIFYING ENZYMES, COMPOSITIONS AND USES THEREOF
-
Agents for modulating methyl modifying enzymes, compositions and uses thereof are provided herein
- -
-
Paragraph 00564; 00565
(2013/06/05)
-
- Synthesis of functionalized aryl fluorides using organolithium reagents in flow microreactors
-
Flow on: Flow microreactors enable the generation of aryl lithium compounds and subsequent electrophilic fluorination with NFSI and N-fluorosultam. The reaction can be successfully accomplished to synthesize various aryl fluorides involving an electron-withdrawing, an electron-donating, and a sterically hindered functional group in good yields. Copyright
- Nagaki, Aiichiro,Uesugi, Yuki,Kim, Heejin,Yoshida, Jun-Ichi
-
supporting information
p. 705 - 708
(2013/05/08)
-
- An efficient method for the preparation of tertiary esters by palladium-catalyzed alkoxycarbonylation of aryl bromides
-
The palladium-catalyzed alkoxycarbonylation of aryl bromides is described for the efficient preparation of tertiary esters. The protocol proved compatible with a wide variety of functionalized (hetero)aromatic bromides, as well as several different sterically hindered tertiary alcohols, affording the alkoxycarbonylated products in high yields. Finally, the formation of aromatic trityl esters is discussed.
- Xin, Zhuo,Gogsig, Thomas M.,Lindhardt, Anders T.,Skrydstrup, Troels
-
supporting information; experimental part
p. 284 - 287
(2012/02/16)
-
- Derivative of a fibrinolytic enzyme
-
A derivative of a fibrinolytic enzyme in which the catalytic site on the enzyme which is responsible for fibrinolytic activity is blocked by a specific immuno-globulin or fragment thereof linked thereto by a reversible linking group and directed against a
- -
-
-
- p-Fluorobenzoyl Chloride for Characterization of Active Hydrogen Functional Groups by Fluorine-19 Nuclear Magnetic Resonance Spectrometry
-
The base-catalyzed reactions of p-fluorobenzoyl chloride provide a convenient method for (19)F NMR analysis of alcohols, phenols, carboxylic acids, amines, and thiols.The (19)F chemical shift and yield data for p-fluorobenzoyl derivatives for nearly 100 compounds are presented.The yield data for these p-fluorobenzoyl derivatives suggest a simple, and in many cases, quantitative method for introducing a fluorine tagging group.The (19)F chemical shifts indicate a wide chemical shift range (ca. 10 ppm) for a large number of compounds.Furthermore, most chemical classes (e.g., phenols, alcohols, etc.) have fairly well resolved chemical shift regions.
- Spratt, M. P.,Dorn, H. C.
-
p. 2038 - 2043
(2007/10/02)
-
