- Dual Catalytic Switchable Divergent Synthesis: An Asymmetric Visible-Light Photocatalytic Approach to Fluorine-Containing ?γ-Keto Acid Frameworks
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Herein, we describe a novel and efficient method for constructing a series of fluorine-containing ?γ-keto acid derivatives through combining visible-light photoredox catalysis and chiral Lewis acid catalysis. With this dual catalytic strategy, a variety of chiral ?γ-keto amides containing a gem-difluoroalkyl group and a series of fluorine-containing α,β-unsaturated-?γ-keto esters were successfully constructed with high stereoselectivities, respectively. A series of experiments showed that the chemoselectivity of this process was highly dependent on the fluorine reagents besides the Lewis acid catalysts. This approach facilitates rapid access to ?γ-keto acid derivatives, an important class of precursors for pharmaceuticals, plasticizers, and various other additives.
- Liang, Hui,Xu, Guo-Qiang,Feng, Zhi-Tao,Wang, Zhu-Yin,Xu, Peng-Fei
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- Polarization IR spectra of the hydrogen bond in phenylacetic acid crystals: H/D isotopic effects - Temperature and polarization effects
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This paper deals with experimental studies and with quantitative interpretation of the polarized IR crystalline spectra of phenylacetic acid and of its deuterium isotopomers d2 and d7. The spectra were measured in the νO-H
- Flakus, Henryk T.,Chelmecki, Michal
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- Desulfonylative Electrocarboxylation with Carbon Dioxide
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Electrocarboxylation of organic halides is one of the most investigated electrochemical approaches for converting thermodynamically inert carbon dioxide (CO2) into value-added carboxylic acids. By converting organic halides into their sulfone derivatives, we have developed a highly efficient electrochemical desulfonylative carboxylation protocol. Such a strategy takes advantage of CO2as the abundant C1 building block for the facile preparation of multifunctionalized carboxylic acids, including the nonsteroidal anti-inflammatory drug ibuprofen, under mild reaction conditions.
- Zhong, Jun-Song,Yang, Zi-Xin,Ding, Cheng-Lin,Huang, Ya-Feng,Zhao, Yi,Yan, Hong,Ye, Ke-Yin
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supporting information
p. 16162 - 16170
(2021/09/02)
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- Iron Catalyzed Double Bond Isomerization: Evidence for an FeI/FeIII Catalytic Cycle
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Iron-catalyzed isomerization of alkenes is reported using an iron(II) β-diketiminate pre-catalyst. The reaction proceeds with a catalytic amount of a hydride source, such as pinacol borane (HBpin) or ammonia borane (H3N?BH3). Reactivity with both allyl arenes and aliphatic alkenes has been studied. The catalytic mechanism was investigated by a variety of means, including deuteration studies, Density Functional Theory (DFT) and Electron Paramagnetic Resonance (EPR) spectroscopy. The data obtained support a pre-catalyst activation step that gives access to an η2-coordinated alkene FeI complex, followed by oxidative addition of the alkene to give an FeIII intermediate, which then undergoes reductive elimination to allow release of the isomerization product.
- Woof, Callum R.,Durand, Derek J.,Fey, Natalie,Richards, Emma,Webster, Ruth L.
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supporting information
p. 5972 - 5977
(2021/03/17)
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- Aerobic Oxidative Dehydrogenation of Ketones to 1,4-Enediones
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An efficient and unprecedented strategy for the synthesis of 1,4-enediones from saturated ketones has been developed via palladium-catalyzed oxidative dehydrogenation. The protocol employs molecular oxygen as the sole oxidant and represents an atom- and step-economic process. The approach showed broad substrate scope, good functional group tolerance, and complete E-stereoselectivity. The reaction mechanism has been investigated through deuterium-labeling experiments and intermediate experiments.
- Zhao, Bao-Yin,Zhang, Xing-Long,Guo, Rui-Li,Wang, Meng-Yue,Gao, Ya-Ru,Wang, Yong-Qiang
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supporting information
p. 1216 - 1221
(2021/02/20)
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- Oxidation of Alkynyl Boronates to Carboxylic Acids, Esters, and Amides
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A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)?B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.
- Li, Chenchen,Li, Ruoling,Zhang, Bing,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 10913 - 10917
(2020/05/25)
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- Nickel-Catalyzed Electrochemical Reductive Relay Cross-Coupling of Alkyl Halides to Aryl Halides
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A highly regioselective Ni-catalyzed electrochemical reductive relay cross-coupling between an aryl halide and an alkyl halide has been developed in an undivided cell. Various functional groups are tolerated under these mild reaction conditions, which pro
- Fang, Ping,Jiao, Ke-Jin,Liu, Dong,Ma, Hong-Xing,Mei, Tian-Sheng,Qiu, Hui
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supporting information
p. 6520 - 6524
(2020/01/24)
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- Enantioselective Copper(I)/Chiral Phosphoric Acid Catalyzed Intramolecular Amination of Allylic and Benzylic C?H Bonds
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Radical-involved enantioselective oxidative C?H bond functionalization by a hydrogen-atom transfer (HAT) process has emerged as a promising method for accessing functionally diverse enantioenriched products, while asymmetric C(sp3)?H bond amination remains a formidable challenge. To address this problem, described herein is a dual CuI/chiral phosphoric acid (CPA) catalytic system for radical-involved enantioselective intramolecular C(sp3)?H amination of not only allylic positions but also benzylic positions with broad substrate scope. The use of 4-methoxy-NHPI (NHPI=N-hydroxyphthalimide) as a stable and chemoselective HAT mediator precursor is crucial for the fulfillment of this transformation. Preliminary mechanistic studies indicate that a crucial allylic or benzylic radical intermediate resulting from a HAT process is involved.
- Ye, Liu,Tian, Yu,Meng, Xiang,Gu, Qiang-Shuai,Liu, Xin-Yuan
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supporting information
p. 1129 - 1133
(2019/12/12)
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- Nickel-Catalyzed Allylic C(sp2)–H Activation: Stereoselective Allyl Isomerization and Regiospecific Allyl Arylation of Allylarenes
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Stereoselective allyl isomerization and regiospecific allyl arylation reactions of allylarenes with a catalytic system comprising nickel(II) with an aryl Grignard reagent were studied. Both reactions are triggered by allylic internal C(sp2)–H activation by in-situ-formed Ni0, which is inserted into the C–H bond at the 2-position of the allyl moiety without a directing group. The isomerization of allylarene to 1-propenylarene favors the E isomer and proceeds with quantitative conversion. The arylation takes place through oxidative cross-coupling of allylarenes with excess Grignard reagent. It occurs regiospecifically at the position of C(sp2)–H activation and represents a new method for the synthesis of 1,1-disubstituted olefins. The results of deuterium labeling experiments reveal an alkenyl/alkyl mechanism involving allylic internal C(sp2)–H activation and multiple intermolecular 1,2-, 1,3-, and 2,3-hydride shifts. These methods represent new approaches to the functionalization of olefins, and the mechanistic investigations could be helpful for the discovery and design of new strategies for olefin functionalization.
- Wu, Qiang,Wang, Lanlan,Jin, Rizhe,Kang, Chuanqing,Bian, Zheng,Du, Zhijun,Ma, Xiaoye,Guo, Haiquan,Gao, Lianxun
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supporting information
p. 5415 - 5422
(2016/11/22)
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- Development of a QuEChERS-Based Stable-Isotope Dilution LC-MS/MS Method to Quantitate Ferulic Acid and Its Main Microbial and Hepatic Metabolites in Milk
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Forage plants of the Poaceae family are grown as pasturage or used for the production of hay, straw, corn stover, etc. Although ferulic acid contents of grasses are generally high, the amount of ingested ferulic acid differs depending on the type of forage, resulting in varying contents of ferulic acid and its microbial and hepatic metabolites in milk. Concentrations and patterns of these metabolites may be used as markers to track different forages in livestock feeding. Therefore, we developed a stable isotope dilution assay to quantitate ferulic acid, 12 ferulic acid-based metabolites, p-coumaric acid, and cinnamic acid in milk. Because most analytes were not commercially available as stable isotope labeled standard compounds, they were synthesized as 13C- or deuterium-labeled standard compounds. A modification of the QuEChERS method, a Quick, Easy, Cheap, Effective, Rugged, and Safe approach usually applied to analyze pesticides in plant-based products, was used to extract the phenolic acids from milk. Determination was carried out by LC-ESI-MS/MS in scheduled multiple reaction monitoring modus. By using three different milk samples, the applicability of the validated approach was demonstrated.
- Waterstraat, Martin,Hildebrand, Andreas,Rosler, Margit,Bunzel, Mirko
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p. 8667 - 8677
(2016/11/29)
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- DEUTERATED BENZYLBENZENE DERIVATIVES AND METHODS OF USE
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Provided are compounds having an inhibitory effect on sodium-dependent glucose cotransporter SGLT. The invention also provides pharmaceutical compositions, methods of preparing the compounds, synthetic intermediates, and methods of using the compounds, independently or in combination with other therapeutic agents, for treating diseases and conditions that are affected by SGLT inhibition.
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Page/Page column 208; 209; 210
(2010/04/03)
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- SUBSTITUTED 4-AMINO-PIPERIDINES
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The present invention relates to new substituted 4-amino-piperidine opioid receptor modulators, pharmaceutical compositions thereof, and methods of use thereof
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Page/Page column 20
(2010/02/17)
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- Secondary α-Deuterium Kinetic Isotope Effects Signifying a Polar Transition State in the Thermolysis of Ring-Substituted tert-Butyl Phenylperacetates
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Several ring-substituted tert-butyl phenylperacetates (YC6H4CH2CO3But) and their deuterated versions (YC6H4CD2CO3But) were prepared (Y: p-OCH3, p-CH3, p-H, and p-NO2). Thermolyses at 80°C in CDCl3 showed excellent first-order kinetics. The rates have been measured as kYH × 104 and kYD × 104 s-1: 11.9 and 9.20 (p-OCH3), 2.64 and 2.22 (p-CH3), 1.06 and 0.93 (p-H), 0.164 and 0.156 (p-NO2). Hammett correlations were derived to yield ρYH+ = -1.17 and ρYD+ = -1.12. However, better Hammett plots were obtained with three points (p-OCH3, p-CH3, and p-H) showing ρYH+ = -1.35 and ρYD+ = -1.28. SDKIE was calculated as 1.293 (p-OCH3), 1.189 (p-CH3), 1.140 (p-H), and 1.051 (p-NO2), showing substantial substituent effects. Values of kYH/kYD for p-NO2 showed little temperature dependence. Hammett correlations and SDKIE were derived from the same kinetic entity that is the bond cleavage.
- Kim, Sung Soo,Tuchkin, Alexey
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p. 3821 - 3824
(2007/10/03)
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- Raney Co-Al Alloy, an Efficient Catalyst for the Selective Incorporation of Deuterium Atoms at the Benzylic Position of Aromatic Compounds
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By using Raney Co-Al in 20% Na2CO3-D2O solution, deuterium atoms can be selectively incorporated into the benzylic position of aromatic compounds in high deuterium content.
- Tsukinoki, Takehito,Ishimoto, Keiko,Mukumoto, Mamoru,Suzuki, Michio,Kawaji, Takatoshi,Nagano, Yoshiaki,Tsuzuki, Hirohisa,Mataka, Shuntaro,Tashiro, Masashi
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- Intermediates in the ene reactions of singlet oxygen and N-phenyl-1,2,4-triazoline-3,5-dione with olefins
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The reaction between singlet oxygen and cis- and trans-2-butene-1,1,1-d3 has been studied. The product isotope effects (k(H)/k(D)) were found to be 1.38 and 1.25, respectively. Similarly, N-phenyl-1,2,4-triazoline-3,5-dione (PTAD) reacts readily with these substrates and shows isotope effects that are larger (5.36, 1.29) but in the same direction. 2-Methyl-1-propene-3,3,3-d3 is unreactive with singlet oxygen but reacts easily with PTAD with a product isotope effect of 1.25. The intermolecular (kinetic) and intramolecular (product) isotope effects on the reactions of singlet oxygen with cis-1,4-diphenyl-2-butene were found to be 1.07 and 1.50, respectively. cis-Butene is 18 times more reactive with singlet oxygen than the trans isomer. Ene reactions for both singlet oxygen and PTAD probably proceed through the reversible formation of an intermediate with structural requirements similar to a perepoxide or aziridinium imide, respectively.
- Orfanopoulos,Smonou,Foote
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p. 3607 - 3614
(2007/10/02)
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- Collision-induced Dissociations of Aryl-substituted Alkoxide Ions. Losses of Dihydrogen and Rearrangement Processes
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The ion PhCH2O- undergoes competitive losses of H., H2, CH2O, and C6H6 upon collisional activation.The loss of H2 occurs mainly to form (C6H4)-CHO, and ab initio calculations suggest the reaction proceeds by the stepwise m
- Raftery, Mark J.,Bowie, John H.,Sheldon, John C.
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p. 563 - 570
(2007/10/02)
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- Preparation of deuterium labelled styrenes and divinylbenzenes
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Specifically deuteriated styrenes (1-d, 2,2'-d2, and ring labelled), perdeuteriostyrene, and specifically deuteriated divinylbenzenes (1,1'-d2 2,2,2',2'-d4, and ring labelled) have been prepared by transforming suitably labelled phenylacetic (hydride or d
- Werstiuk, Nick Henry,Timmins, George
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p. 1072 - 1076
(2007/10/02)
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- Hydrogen Transfer Reactions, 7. Regio- and Stereoselectivity in the Dehydrogenation Steps during Homogeneously Catalysed Hydrogen Transfer
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In the disproportionation of 1,2-dihydronaphthalene catalysed by metal complexes, especially by the Wilkinson catalyst (7), the elimination occurs in two steps.The abstraction of the first hydrogen proceeds with but a small preference for the 2-position - in contrast to dehydrogenations via hydride transfer.The second hydrogen is removed highly stereospecifically from the vicinal cis-position, the acceptor being cis-hydrogenated.Intermolecular H/D-scrambling may occur via allyl hydrido complexes.
- Gessner, Uwe,Heesing, Albert
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p. 2593 - 2606
(2007/10/02)
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- MECHANISMS OF FREE-RADICAL REACTIONS. XIII. MECHANISM AND SELECTIVITY OF THE FREE-RADICAL HALOGENATION OF ALKYL AROMATIC HYDROCARBONS WITH FLUOROALKYL SUBSTITUENTS
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The free-radical chlorination and bromination of 1-fluoro-2-arylethanes and 1,1,1-trifluoro-2-arylethanes was studied by the method of competing reactions.In all cases a good correalation between log krel and the Brown ?+ constants was observed.The variation of the selectivity in the transition from one reaction series to the other indicates that two independent factors which determine the reactivity (the change in the dissociation energy of the C-H bond and the polar effect of the substituents) have a simultaneous effect.
- Dneprovskii, A. S.,Eliseenkov, E. V.,Mil'tsov, S. A.
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p. 317 - 324
(2007/10/02)
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- Hydrogen Transfer Reactions, Part 2. Radical Mechanism of Thermal Disproportionation of 1,2-Dihydronaphthalene
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In the thermal disproportionation of 1,2-dihydronaphthalene (1) both hydrogen abstraction and addition are stereo-unspecific radical reactions.An electrocyclic mechanism was excluded.
- Heesing, Albert,Muellers, Wolfgang
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