- Mechanism of the Cannizzaro Reaction: Possible Involvement of Radical Intermediates
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The Cannizzaro reaction of benzaldehyde in alkine aqueous dioxan or dioxan alone produces a substantial amount of benzyl alcohol together with the normal product, benzyl alcohol, suggesting a possible partial involvement of radical intermediates.
- Chung, Sung-Kee
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- Weakly Coordinating, Hydroxyl Directed Ruthenium Catalyzed C-H Alkylation of Ubiquitous Benzyl Alcohols with Maleimides
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Benzyl alcohols have been employed as effective coupling partners in Ru-catalyzed C-H functionalization reactions, and their annulation with maleimides then offers efficient synthesis of useful ortho substituted succinimide aromatic aldehydes and ketones. Detailed mechanistic studies have been demonstrated by performing preliminary reactions, deuterium studies, and competitive experiments.
- Dethe, Dattatraya H.,Beeralingappa, Nagabhushana C.,Kumar, Vimlesh
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- Electron-transfer properties of active aldehydes of thiamin coenzyme models, and mechanism of formation of the reactive intermediates
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The active aldehydes 2a-c- derived from the reaction of 3-benzylthiazolium salts (1a+: 3-benzyl-4-methylthiazolium bromide, 1b+: 3-benzyl-4,5-dimethylthiazolium bromide, 1c+: 3-benzylthiazolium bromide) with o-t
- Nakanishi, Ikuo,Itoh, Shinobu,Fukuzumi, Shunichi
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- Generation and IR spectroscopic study of benzyl radical
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The benzyl radical C6H5CH2 has been obtained by gas phase pyrolysis of two different precursors, benzyl bromide and dibenzyl, and studied in an argon matrix at 12 K by IR spectroscopy.Similarly, the deuterosubstituted benzyl radicals, C6H5CD2 and C6D5CH2,
- Baskir, E. G.,Maltsev, A. K.,Korolev, V. A.,Khabashesku, V. N.,Nefedov, O. M.
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- 1H NMR STRUCTURAL STUDY OF 2-PHENYLTHIAZOLIDINE
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Deuteration of 2-phenylthiazolidine, and its complexation with the shift reagent tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato)europium, have been used to study the signals and conformation of the heterocyclic protons and to interpret the 1H NMR spectrum of this 2-substituted thiazolidine.
- Terol, A.,Subra, G.,Fernandez, J. P.,Robbe, Y.,Chapat, J. P.,Granger, R.
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- Phosphine-Catalyzed (3 + 2) Annulation of δ-Acetoxy Allenoates with 2-Sulfonamidomalonate: Synthesis of Highly Substituted 3-Pyrrolines and Mechanistic Insight
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A mild and efficient synthetic protocol for 3-pyrrolines via the phosphine-catalyzed (3 + 2) annulation of δ-acetoxy allenoates with 2-sulfonamidomalonate is reported. The asymmetric version (up to 83% ee) is also achieved by using phosphine (R)-SITCP as
- Wang, Dong,Liu, Wei,Hong, Yang,Tong, Xiaofeng
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- Quantitative production of compound I from a cytochrome P450 enzyme at low temperatures. Kinetics, activation parameters, and kinetic isotope effects for oxidation of benzyl alcohol
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Cytochrome P450 enzymes are commonly thought to oxidize substrates via an iron(IV)-oxo porphyrin radical cation transient termed Compound I, but kinetic studies of P450 Compounds I are essentially nonexistent. We report production of Compound I from cytoc
- Wang, Qin,Sheng, Xin,Horner, John H.,Newcomb, Martin
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- Selective alcohol oxidation with molecular oxygen catalyzed by Os-Cr and Ru-Cr complexes
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The heterobimetallic complexes [Y][M(N)R2(μ-O)2CrO2] (where Y is either N(n-Bu)4+ or PPh4+; M is either Ru or Os; and R is an alkyl or aryl ligand) catalyze the selective oxidation of alcohols with molecular oxygen. The rate of the reaction is higher with a ruthenium-containing complex than with an analogous osmium-containing catalyst. The rate decreases with steric bulk in either the catalyst or substrate. Single-crystal X-ray diffraction studies of [N(n-Bu)4][Ru(N)(CH2SiMe3) 2(μ-O)2CrO2] and [PPh4][Os(N)Me(CH2SiMe3)(μ-O) 2CrO2] show the chromate group coordinated to each nitrido(dialkyl)metal center through two oxo ligands. The oxidation of benzyl alcohol by [N(K-Bu)4][Os(N)(CH2SiMe3) 2(μ-O)2CrO2] was examinined in detail. It is first order in alcohol and substrate, and, when oxygen partial pressure is low, the rate depends directly on the O2 partial pressure. A mechanism in which alcohol coordinates to the osmium center and is oxidized by β-hydrogen elimination is consistent with the data. [N(n-Bu)4] [Os(N)(CH2SiMe3)2(μ-O)2CrO 2] catalyzes the oxidation of dppe with O2 through a different pathway.
- Shapley, Patricia A.,Zhang, Najie,Allen, Jana L.,Pool, Douglas H.,Liang, Hong-Chang
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- Unambiguous and rapid cis/trans assignment of aryl-carboxy disubstituted cyclopropanes using NMR
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It is shown that cis or trans structures of aryl-carboxy disubstituted cyclo propanes can be directly, rapidly and easily determined by 1H NMR with no need of comparing both cis and trans isomers when vicinal coupling constants are in the range
- Solladie-Cavallo, Ariette,Isarno, Thomas
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- An efficient Pd@Pro-GO heterogeneous catalyst for the α, β-dehydrogenation of saturated aldehyde and ketones
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An Efficient Pd@Pro-GO heterogeneous catalyst was developed that can promote the α, β-dehydrogenation of saturated aldehyde and ketones in the yield of 73% ? 92% at mild conditions without extra oxidants and additives. Pd@Pro-GO heterogeneous catalyst was synthesized via two steps: firstly, the Pro-GO was obtained by the esterification reaction between graphene oxide (GO) and N-(tert-Butoxycarbonyl)-L-proline (Boc-Pro-OH), followed by removing the protection group tert-Butoxycarbonyl (Boc), which endowed the proline-functionalized GO with both the lewis acid site (COOH) and the bronsted base site (NH), besides, the pyrrolidine of proline also can form imine with aldehydes to activate these substrates; Second, palladium was dispersed on the proline-functionalized GO (Pro-GO) to obtained heterogeneous catalyst Pd@Pro-GO. Mechanistic studies have shown that the Pd@Pro-GO-catalyzed α,β-dehydrogenation of saturated aldehyde and ketones was realized by an improved heterogeneously catalyzed Saegusa oxidation reaction. Based on the obove characteristics, the Pd@Pro-GO will be widely used in the transition metal catalytic field.
- Pan, Gao-Fei,Wang, Zhe,Chang, Yi-Yuan,Hao, Yue,Wang, Yi-Chen,Xing, Rui-Guang
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supporting information
(2021/12/30)
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- Gold(I)-Catalyzed Reactions between N-(o-Alkynylphenyl)imines and Vinyldiazo Ketones to Form 3-(Furan-2-ylmethyl)-1 H-indoles via Postulated Azallyl Gold and Allylic Cation Intermediates
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This work describes gold-catalyzed additions of vinyldiazo ketones to N-(o-alkynylphenyl)imines to yield 3-(furan-2-ylmethyl)-1H-indoles involving skeletal rearrangement; these new catalytic reactions are applicable to a wide range of substrates. We postu
- Kulandai Raj, Antony Sekar,Narode, Akshay Subhash,Liu, Rai-Shung
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supporting information
p. 1378 - 1382
(2021/03/03)
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- SYNTHESIS OF DEUTERATED ALDEHYDES
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Described are methods for preparing a deuterated aldehyde using N-heterocyclic carbene catalysts in a solvent comprising D2O. The methods may be used to convert a wide variety of aldehydes (e.g., aryl, alkyl, or alkenyl aldehydes) to C-1 deuterated aldehydes under mild reaction conditions without functionality manipulation.
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Paragraph 0011; 00204; 00205-00206; 00208
(2021/03/13)
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- DEUTERATED MK2 PATHWAY INHIBITORS AND METHODS OF USING THE SAME
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The present disclosure provides deuterated pyridinone-pyridinyl compounds and compositions useful in the treatment of p38 MAP Kinase mediated having the structures of Formula (I); wherein the A, B, and R groups are as defined in the detailed description. Methods of inhibition of p38 MAP Kinase activity in a human or animal subject are also provided.
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- Nickel-catalyzed coupling of R2P(O)Me (R = aryl or alkoxy) with (hetero)arylmethyl alcohols
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α-Alkylation of methyldiarylphosphine oxides with (hetero)arylmethyl alcohols was performed under nickel catalysis. Various arylmethyl and heteroarylmethyl alcohols can be used in this transformation. A series of methyldiarylphosphine oxides were alkylated with 30-90% yields. Functional groups on the aromatic rings of methyldiarylphosphine oxides or arylmethyl alcohols including OMe, NMe2, SMe, CF3, Cl, and F groups can be tolerated. The conditions are also suitable for the α-alkylation reaction of dialkyl methylphosphonates.
- Li, Wei-Ze,Wang, Zhong-Xia
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p. 2233 - 2242
(2021/03/24)
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- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
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Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
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supporting information
p. 16865 - 16873
(2021/10/20)
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- Imidazopyrazinone compound as well as preparation method and application thereof
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The invention provides an imidazopyrazinone compound as well as a preparation method and application thereof. The imidazopyrazinone compound structure has the structure shown I, and R. 1 Is phenyl. R2 In the benzyl group, and the compound has at least one D substituent, the D substituent is at R. 1 And/or R2 . The compound has excellent luminescence performance, can be used as a substrate of NanoLuc luminescent system, and is applied to detection and drug detection of luciferase.
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Paragraph 0070; 0097-0099
(2021/10/11)
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- Selective C-H Allylic Oxygenation of Cycloalkenes and Terpenoids Photosensitized by [Cu(Xantphos)(neoc)]BF4
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We present herein for the first time the use of the [Cu(Xantphos)(neoc)]BF4 as a photocatalyst for the selective C-H allylic oxygenation of cycloalkenes into the corresponding allylic hydroperoxides or alcohols in the presence of molecular oxygen. The proposed methodology affords the products at good yields and has also been applied successfully to several bioactive terpenoids, such as geraniol, linalool, β-citronellol, and phytol. A mechanistic study involving also kinetic isotope effects (KIEs) supports the proposed singlet oxygen-mediated reaction. On the basis of the high chemoselectivity and yields and the fast and clean reaction processes observed, the present catalytic system, [Cu(Xantphos)(neoc)]BF4, has also been applied to the synthesis, at a laboratory scale, of the cis-Rose oxide, a well-known perfumery ingredient used in rose and geranium perfumes.
- Kallitsakis, Michael G.,Gioftsidou, Dimitra K.,Tzani, Marina A.,Angaridis, Panagiotis A.,Terzidis, Michael A.,Lykakis, Ioannis N.
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p. 13503 - 13513
(2021/09/13)
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- Reductive Deuteration of Aromatic Esters for the Synthesis of α,α-Dideuterio Benzyl Alcohols Using D 2O as Deuterium Source
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α,α-Dideuterio benzyl alcohols are important building blocks for the synthesis of deuterium-labeled medicines and agrochemicals. We have developed the first general single-electron transfer reductive deuteration of readily commercially available aromatic
- Luo, Shihui,Weng, Chaoqun,Ding, Yuxuan,Ling, Chen,Szostak, Michal,Ma, Xiaodong,An, Jie
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supporting information
p. 51 - 56
(2020/11/10)
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- An α, α - dideuterium substituted benzyl alcohol compound. Deuterated drug and method for reducing deuteration of benzoate compound
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The invention relates to a method. Α, α-deuterated benzyl alcohol compound and preparation thereofΑ, αThe method for reducing and deuteration - dideuterium-substituted benzyl alcohol compounds is characterized in that the benzoate compound represented by
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Paragraph 0017-0018
(2021/09/08)
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- Trifluorosulfonylation Cascade in Allenols: Stereocontrolled Synthesis of Bis(triflyl)enones
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Herein, we report investigations embodying the first example of reversal of the native regioselectivity in the reaction of allenols with electrophiles. The effortlessness of C?C bond formation, mild reaction conditions, neither catalysts nor light irradiation, and exquisite selectivity, both in terms of functional-group tolerance and chemo-, site-, and stereo-selectivity, converts this trifluorosulfonylation-rearrangement sequence into an appealing protocol for the preparation of novel functionalized enones. The synthetic utility of this method has been validated by the conversion of the initially prepared bis(triflyl)enones into a variety of bis(triflyl)-functionalized molecules such as 1,3-dienes, allylic alcohols, pyrroles, pyrazoles, and chromenes. Besides, DFT calculations have provided a reliable understanding of observed selectivity.
- Lázaro-Milla, Carlos,Macicior, Jon,Yanai, Hikaru,Almendros, Pedro
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supporting information
p. 8983 - 8989
(2020/07/09)
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- Iridium Complex-Catalyzed C2-Extension of Primary Alcohols with Ethanol via a Hydrogen Autotransfer Reaction
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The development of a C2-extension of primary alcohols with ethanol as the C2 source and catalysis by [Cp*IrCl2]2 (where Cp? = pentamethylcyclopentadiene) is described. This new extension system was used for a range of benzylic alcohol substrates and for aliphatic alcohols with ethanol as an alkyl reagent to generate the corresponding C2-extended linear alcohols. Mechanistic studies of the reaction by means of intermediates and deuterium labeling experiments suggest the reaction is based on hydrogen autotransfer.
- Kobayashi, Masaki,Itoh, Satoshi,Yoshimura, Keisuke,Tsukamoto, Yuya,Obora, Yasushi
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p. 11952 - 11958
(2020/10/23)
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- Iron-Catalyzed Amination of Strong Aliphatic C(sp3)-H Bonds
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A concept for intramolecular denitrogenative C(sp3)-H amination of 1,2,3,4-tetrazoles bearing unactivated primary, secondary, and tertiary C-H bonds is discovered. This catalytic amination follows an unprecedented metalloradical activation mechanism. The utility of the method is showcased with the short synthesis of a bioactive molecule. Moreover, an initial effort has been embarked on for the enantioselective C(sp3)-H amination through the catalyst design. Collectively, this study underlines the development of C(sp3)-H bond functionalization chemistry that should find wide application in the context of drug discovery and natural product synthesis.
- Das, Sandip Kumar,Roy, Satyajit,Khatua, Hillol,Chattopadhyay, Buddhadeb
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supporting information
p. 16211 - 16217
(2020/10/26)
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- Photoinduced umpolung addition of carbonyl compounds with α,β-unsaturated esters enables the polysubstituted γ-lactone formation
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We herein report the photoinduced intermolecular umpolung addition of aromatic ketones/aldehydes with α,β-unsaturated esters via ketyl radical intermediates. Following an intramolecular transesterification, a variety of γ-lactone derivatives are readily accessed. Mechanistic investigations demonstrate the significant role of Hantzsch ester, which serves both as the electron and proton donor. This journal is
- Gu, Jia-Yi,Zhang, Wei,Jackson, Seth R.,He, Yan-Hong,Guan, Zhi
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supporting information
p. 13441 - 13444
(2020/11/10)
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- Aryl-Nickel-Catalyzed Benzylic Dehydrogenation of Electron-Deficient Heteroarenes
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This manuscript describes the first practical benzylic dehydrogenation of electron-deficient heteroarenes, including pyridines, pyrazines, pyrimidines, pyridazines, and triazines. This transformation allows for the efficient benzylic oxidation of heteroarenes to afford heterocyclic styrenes by the action of nickel catalysis paired with an unconventional bromothiophene oxidant.
- Zhang, Pengpeng,Huang, David,Newhouse, Timothy R.
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supporting information
p. 1757 - 1762
(2020/02/04)
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- Two Distinct Ag(I)- And Au(I)-Catalyzed Olefinations between α-Diazo Esters and N-Boc-Derived Imines
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Metal-catalyzed reactions between α-diazo esters and imines were well-known to yield aziridine derivatives exclusively. This work reports two new olefination reactions between N-Boc-derived (Boc = tert-Butyloxycarbonyl) imines and α-diazo esters with Ag(I) and Au(I) catalysts, respectively. Our mechanistic studies reveal that these new olefinations involve an initial attack of diazo esters on metal/imine complexes to form Mannich-addition intermediates, which subsequently afford α-aryl-β-aminoacrylates via a Roskamp reaction, or to form β-aryl-β-aminoacrylates via the formation of silver carbenes.
- Kardile, Rahul Dadabhau,Liu, Rai-Shung
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supporting information
p. 6452 - 6456
(2019/09/06)
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- Nonbifunctional Outer-Sphere Strategy Achieved Highly Active α-Alkylation of Ketones with Alcohols by N-Heterocyclic Carbene Manganese (NHC-Mn)
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The unusual nonbifunctional outer-sphere strategy was successfully utilized in developing an easily accessible N-heterocyclic carbene manganese (NHC-Mn) system for highly active α-alkylation of ketones with alcohols. This system was efficient for a wide range of ketones and alcohols under mild reaction conditions, and also for the green synthesis of quinoline derivatives. The direct outer-sphere mechanism and the high activity of the present system demonstrate the potential of nonbifunctional outer-sphere strategy in catalyst design for acceptorless dehydrogenative transformations.
- Lan, Xiao-Bing,Ye, Zongren,Huang, Ming,Liu, Jiahao,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 8065 - 8070
(2019/10/11)
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- Iron-Catalyzed Ligand Free α-Alkylation of Methylene Ketones and β-Alkylation of Secondary Alcohols Using Primary Alcohols
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Herein, we demonstrate a general and broadly applicable catalytic cross coupling of methylene ketones and secondary alcohols with a series of primary alcohols to disubstituted branched ketones. A simple and nonprecious Fe2(CO)9 catalyst enables one-pot oxidations of both primary and secondary alcohols to a range of branched gem-bis(alkyl) ketones. A number of bond activations and formations selectively occurred in one pot to provide the ketone products. Coupling reactions can be performed in gram scale and successfully applied in the synthesis of an Alzehimer's drug. Alkylation of a steroid hormone can be achieved. A single catalyst enables sequential one-pot double alkylation to bis-hetero aryl ketones using two different alcohols. Preliminary mechanistic studies using an IR probe, deuterium labeling, and kinetic experiments established the participation of a borrowing-hydrogen process using Fe catalyst, and the reaction produces H2 and H2O as byproducts.
- Alanthadka, Anitha,Bera, Sourajit,Banerjee, Debasis
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p. 11676 - 11686
(2019/10/02)
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- Regioselective deuteration of alcohols in D2O catalysed by homogeneous manganese and iron pincer complexes
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We report a convenient and cost-effective protocol for the regioselective deuteration of primary and secondary alcohols using Earth abundant homogeneous first row transition metal pincer catalysts. D2O is utilized as both a deuterium source and a solvent, allowing for a benign inexpensive process. Depending on the metal selected (Mn or Fe), a high degree of deuterium incorporation was observed selectively either at the α and β position (Mn) or exclusively at the α position (Fe), for primary alcohols. This simple, efficient, and cost-effective protocol for alcohol C-H bond deuteration constitutes a powerful tool for the large scale synthesis of deuterated molecules.
- Kar, Sayan,Goeppert, Alain,Sen, Raktim,Kothandaraman, Jotheeswari,Surya Prakash
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supporting information
p. 2706 - 2710
(2018/07/05)
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- Direct Reduction of Allylic Alcohols Using Isopropanol as Reductant
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The lithium cation-catalyzed direct reduction of allylic alcohols to alkenes using isopropanol as a hydride donor was developed. The hydride transfer of the in situ-generated lithium isopropoxide to an allylic cation is the key process in this transformation. The reaction generates only water and acetone as byproducts, which highlights the synthetic utility of this method. (Figure presented.).
- Sai, Masahiro
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supporting information
p. 3482 - 3487
(2018/09/14)
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- An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
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This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
- Sai, Masahiro
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supporting information
p. 4330 - 4335
(2018/10/15)
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- Selective Actinide-Catalyzed Tandem Proton-Transfer Esterification of Aldehydes with Alcohols for the Production of Asymmetric Esters
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Actinide-catalyzed tandem proton-transfer esterification between aldehydes and alcohols is presented herein for the first time. It represents a novel convenient and external-oxidant-free methodology in the preparation of asymmetric ester compounds. Various kinds of aldehydes and alcohols can be applied to this reaction, affording the corresponding ester product in moderate to high yields. A plausible mechanism was proposed on the basis of the kinetic, stoichiometric, and deuterium-labeling studies.
- Liu, Heng,Eisen, Moris S.
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supporting information
p. 1461 - 1464
(2017/04/28)
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- Transition-Metal-Free Deacylative Cleavage of Unstrained C(sp3)-C(sp2) Bonds: Cyanide-Free Access to Aryl and Aliphatic Nitriles from Ketones and Aldehydes
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A transition-metal-free deacylative C(sp3)-C(sp2) bond cleavage for the synthetically practical oxidative amination of ketones and aldehydes to nitriles is first described, using cheap and commercially abundant NaNO2 as the oxidant and the nitrogen source. Various nitriles bearing aryl, heteroaryl, alkyl, and alkenyl groups could be smoothly obtained from ketones and aldehydes in high yields, avoiding highly toxic cyanides or transition metals.
- Ge, Jing-Jie,Yao, Chuan-Zhi,Wang, Mei-Mei,Zheng, Hong-Xing,Kang, Yan-Biao,Li, Yadong
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supporting information
p. 228 - 231
(2016/02/03)
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- Rhodium-Catalyzed Intramolecular C-H Bond Activation with Triazoles: Preparation of Stereodefined Pyrrolidines and Other Related Cyclic Compounds
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On treatment of triazoles having an N-sulfonyl-protected benzylamine moiety with [Rh2(C7H15CO2)4], intramolecular C-H bond insertion takes place at the benzylic position to give cis-N-sulfonyl-2-aryl-3-[(sulfonylimino)methyl]pyrrolidines in good yields and with highly stereoselectivities. Analogously, the similar treatment of triazoles having an ether or even an alkyl moiety affords 2-alkyl- or 2-aryl-3-[(sulfonylimino)methyl]tetrahydrofurans or a 2-alkyl-3-[(sulfonylimino)methyl]cyclopentane in good yields. Three is a magic number: On treatment of triazoles with [Rh2(C7H15CO2)4], the rhodium catalyst plays three roles, denitrogenation, C-H bond activation, and stereoselective cyclization, providing a new method for heterocycle synthesis. Intramolecular C-H bond insertion takes place at the benzylic position to give pyrrolidines and related heterocycles in good yields.
- Senoo, Masato,Furukawa, Ayana,Hata, Takeshi,Urabe, Hirokazu
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supporting information
p. 890 - 895
(2016/01/16)
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- Synthesis of 2-acylphenol and flavene derivatives from the ruthenium-catalyzed oxidative c-h acylation of phenols with aldehydes
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The cationic ruthenium hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4- has been found to be an effective catalyst for the oxidative C-H coupling reaction of phenols with aldehydes to give 2-acylphenol compounds. The coupling of phenols with α,β-unsaturated aldehydes selectively gives the flavene derivatives. The catalytic method mediates direct oxidative C-H coupling of phenol and aldehyde substrates without using any metal oxidants or forming wasteful byproducts. A cationic ruthenium hydride complex catalyzes the oxidative C-H coupling of phenols with aldehydes to form 2-acylphenol and flavene derivatives.
- Lee, Hanbin,Yi, Chae S.
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supporting information
p. 1899 - 1904
(2015/03/18)
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- Ruthenium-Catalyzed Deuteration of Alcohols with Deuterium Oxide
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The catalytic properties of a series of ruthenium complexes for H/D exchange between D2O and alcohols were studied. The catalytic activity of the ruthenium complexes and the regioselectivity of the H/D exchange reactions were found to be dependent on the auxiliary ligands. While ruthenium η6-cymene complexes such as [(η6-cymene)RuCl(NH2CH2CH2NTs)]Cl, (η6-cymene)RuCl2/NH2CH2CH2OH, and (η6-cymene)Ru{(S,S)-NHCHPhCHPhNTs} catalyzed regioselective deuteration of alcohols with D2O at the β-carbon positions only, octahedral ruthenium complexes such as RuCl2(2-NH2CH2Py)(PPh3)2 (2-NH2CH2Py = 2-aminomethylpyridine) and RuCl2(NH2CH2CH2NH2)(PPh3)2 catalyzed regioselective H/D exchange reactions of D2O with alcohols at both the α- and β-carbon positions of alcohols. The H/D exchange reactions proceed through reversible dehydrogenation of alcohols and hydrogenation of carbonyl compounds involving hydride species and H/D exchange among D2O and carbonyl and hydride species. The different regioselectivities of the H/D exchange reactions can be related to the relative ease of H/D exchange of ruthenium hydride intermediates with D2O. (Chemical Equation Presented).
- Bai, Wei,Lee, Ka-Ho,Tse, Sunny Kai San,Chan, Ka Wing,Lin, Zhenyang,Jia, Guochen
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p. 3686 - 3698
(2015/08/24)
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- Oxidative Coupling of Terminal Alkynes with Aldehydes Leading to Alkynyl Ketones by Using Indium(III) Bromide
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An indium(III)-promoted direct acylation of terminal alkynes using aldehydes leading to ynones was developed. In contrast to the previous addition reactions of alkynes to aldehydes, which provide propargylic alcohols, the oxidative coupling proceeded exclusively to afford alkynyl ketones. The products were likely generated through an Oppenauer oxidation of the indium propargylic alkoxide species by excess amounts of aldehydes.
- Ogiwara, Yohei,Kubota, Masahito,Kurogi, Kotaro,Konakahara, Takeo,Sakai, Norio
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supporting information
p. 18598 - 18600
(2016/01/25)
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- Unsymmetrical diarylmethanes by ferroceniumboronic acid catalyzed direct friedel-crafts reactions with deactivated benzylic alcohols: Enhanced reactivity due to ion-pairing effects
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The development of general and more atom-economical catalytic processes for Friedel-Crafts alkylations of unactivated arenes is an important objective of interest for the production of pharmaceuticals and commodity chemicals. Ferroceniumboronic acid hexafluoroantimonate salt (1) was identified as a superior air- and moisture-tolerant catalyst for direct Friedel-Crafts alkylations of a variety of slightly activated and neutral arenes with stable and readily available primary and secondary benzylic alcohols. Compared to the use of classical metal-catalyzed alkylations with toxic benzylic halides, this methodology employs exceptionally mild conditions to provide a wide variety of unsymmetrical diarylmethanes and other 1,1-diarylalkane products in high yield with good to high regioselectivity. The optimal method, using the bench-stable ferroceniumboronic acid salt 1 in hexafluoroisopropanol as cosolvent, displays a broader scope compared to previously reported catalysts for similar Friedel-Crafts reactions of benzylic alcohols, including other boronic acids such as 2,3,4,5-tetrafluorophenylboronic acid. The efficacy of the new boronic acid catalyst was confirmed by its ability to activate primary benzylic alcohols functionalized with destabilizing electron-withdrawing groups like halides, carboxyesters, and nitro substituents. Arene benzylation was demonstrated on a gram scale at up to 1 M concentration with catalyst recovery. Mechanistic studies point toward the importance of the ionic nature of the catalyst and suggest that factors other than the Lewis acidity (pKa) of the boronic acid are at play. A SN1 mechanism is proposed where ion exchange within the initial boronate anion affords a more reactive carbocation paired with the non-nucleophilic hexafluoroantimonate counteranion.
- Mo, Xiaobin,Yakiwchuk, Joshua,Dansereau, Julien,Adam McCubbin,Hall, Dennis G.
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supporting information
p. 9694 - 9703
(2015/08/18)
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- Diastereoselective synthesis of α-(aminomethyl)-γ-butyrolactones via a catalyst-free aminolactonization
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An auto-catalytic domino reaction, presumably involving an aza-Michael reaction, proton transfer, and lactonization, furnishing α-(aminomethyl)-γ-butyrolactones in near quantitative yields and excellent diastereoselectivity is described.
- Ramachandran, P. Veeraraghavan,Nicponski, Daniel R.
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supporting information
p. 15216 - 15219
(2015/01/08)
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- Mechanism of copper(I)/TEMPO-catalyzed aerobic alcohol oxidation
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Homogeneous Cu/TEMPO catalyst systems (TEMPO = 2,2,6,6- tetramethylpiperidine-N-oxyl) have emerged as some of the most versatile and practical catalysts for aerobic alcohol oxidation. Recently, we disclosed a (bpy)CuI/TEMPO/NMI catalyst system
- Hoover, Jessica M.,Ryland, Bradford L.,Stahl, Shannon S.
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supporting information
p. 2357 - 2367
(2013/03/28)
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- Mechanistic borderline of one-step hydrogen atom transfer versus stepwise Sc3+-coupled electron transfer from benzyl alcohol derivatives to a non-heme iron(IV)-oxo complex
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The rate of oxidation of 2,5-dimethoxybenzyl alcohol (2,5-(MeO) 2C6H3CH2OH) by [Fe IV(O)(N4Py)]2+ (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2- pyridyl)methylamine) was enhanced significantly in the presence of Sc(OTf) 3 (OTf- = trifluoromethanesulfonate) in acetonitrile (e.g., 120-fold acceleration in the presence of Sc3+). Such a remarkable enhancement of the reactivity of [FeIV(O)(N4Py)] 2+ in the presence of Sc3+ was accompanied by the disappearance of a kinetic deuterium isotope effect. The radical cation of 2,5-(MeO)2C6H3CH2OH was detected in the course of the reaction in the presence of Sc3+. The dimerized alcohol and aldehyde were also produced in addition to the monomer aldehyde in the presence of Sc3+. These results indicate that the reaction mechanism is changed from one-step hydrogen atom transfer (HAT) from 2,5-(MeO)2C6H3CH2OH to [Fe IV(O)(N4Py)]2+ in the absence of Sc3+ to stepwise Sc3+-coupled electron transfer, followed by proton transfer in the presence of Sc3+. In contrast, neither acceleration of the rate nor the disappearance of the kinetic deuterium isotope effect was observed in the oxidation of benzyl alcohol (C6H5CH2OH) by [FeIV(O)(N4Py)]2+ in the presence of Sc(OTf) 3. Moreover, the rate constants determined in the oxidation of various benzyl alcohol derivatives by [FeIV(O)(N4Py)]2+ in the presence of Sc(OTf)3 (10 mM) were compared with those of Sc 3+-coupled electron transfer from one-electron reductants to [Fe IV(O)(N4Py)]2+ at the same driving force of electron transfer. This comparison revealed that the borderline of the change in the mechanism from HAT to stepwise Sc3+-coupled electron transfer and proton transfer is dependent on the one-electron oxidation potential of benzyl alcohol derivatives (ca. 1.7 V vs SCE).
- Morimoto, Yuma,Park, Jiyun,Suenobu, Tomoyoshi,Lee, Yong-Min,Nam, Wonwoo,Fukuzumi, Shunichi
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p. 10025 - 10036
(2012/10/29)
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- A model reaction assesses contribution of H-tunneling and coupled motions to enzyme catalysis
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To assess the contribution of physical features to enzyme catalysis, the enzymatic reaction has to be compared to a relevant uncatalyzed reaction. While such comparisons have been conducted for some hydrolytic and radical reactions, it is most challenging for biological hydride transfer and redox reactions in general. Here, the same experimental tools used to study the H-tunneling and coupled motions for enzymatic hydride transfer between two carbons were used in the study of an uncatalyzed model reaction. The enzymatic oxidations of benzyl alcohol and its substituted analogues mediated by alcohol dehydrogenases were compared to the oxidations by 9-phenylxanthylium cation (PhXn+). The PhXn+serves as an NAD+ model, while the solvent, acetonitrile, models the protein environment. Experimental comparisons included linear free energy relations with Hammett reaction constant (ρ) of zero versus -2.7; temperature-independent versus temperature-dependent primary KIEs; deflated secondary KIEs with deuteride transfer (i.e., primary-secondary coupled motion) versus no coupling between secondary KIEs and H- or D-transfer; and large versus small secondary KIEs for the enzymatic versus uncatalyzed alcohol oxidation. Some of the differences may come from differences in the order of microscopic steps between the catalyzed versus uncatalyzed reactions. However, several of these comparative experiments indicate that in contrast to the uncatalyzed reaction the transition state of the enzymatic reaction is better reorganized for H-tunneling and its H-donor is better rehybridized prior to the C-H→C transfer. These findings suggest an important role for these physical features in enzyme catalysis.
- Liu, Qi,Zhao, Yu,Hammann, Blake,Eilers, James,Lu, Yun,Kohen, Amnon
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experimental part
p. 6825 - 6833
(2012/09/25)
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- Et3N-promoted tandem ring-opening reaction of N-tosylaziridines with terminal alkynoates: A straightforward synthesis of functionalized enamines
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A tandem ring-opening reaction of N-tosylaziridines with terminal alkynoates promoted by Et3N has been described. A variety of N-tosylaziridines reacted with terminal alkynoates to give functionalized enamines in moderate to good yields under s
- Meng, Ling-Guo,Wang, Lei
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supporting information; experimental part
p. 3242 - 3244
(2012/04/11)
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- Discovery of a metalloenzyme-like cooperative catalytic system of metal nanoclusters and catechol derivatives for the aerobic oxidation of amines
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We have discovered a new class of cooperative catalytic system, consisting of heterogeneous polymer-immobilized bimetallic Pt/Ir alloyed nanoclusters (NCs) and 4-tert-butylcatechol, for the aerobic oxidation of amines to imines under ambient conditions. After optimization, the desired imines were obtained in good to excellent yields with broad substrate scope. The reaction rate was determined to be first-order with respect to the substrate and catechol and zero-order for the alloyed Pt/Ir NC catalyst. Control studies revealed that both the heterogeneous NC catalyst and 4-tert-butylcatechol are essential and act cooperatively to facilitate the aerobic oxidation under mild conditions.
- Yuan, Hao,Yoo, Woo-Jin,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information
p. 13970 - 13973
(2012/10/29)
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- Hydrogen abstraction from H-donor substrates by the 6-CF 3-benzotriazol-N-oxyl radical (TFNO)
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The aminoxyl radical 6-trifluoromethyl-benzotriazol-N-oxyl (TFNO) has been generated from the parent hydroxylamine 6-CF3-1-hydroxy-benzotriazole (TFBT) by one-electron oxidation with a CeIV salt and characterized by spectrophotometry and cyclic voltammetry (CV). Rate constants of H-abstraction (kH) by TFNO from a number of H-donor benzylic substrates have been determined spectrophotometrically in MeCN solution at 25°C. A radical H-atom transfer (HAT) route of oxidation is substantiated for TFNO by several pieces of evidence. The kinetic data also testify the relevance of stereoelectronic effects upon the HAT reactivity of TFNO.
- Tadesse, Mahelet Aweke,Galli, Carlo,Gentili, Patrizia
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body text
p. 529 - 538
(2012/04/23)
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- Hydrogen atom abstraction reactions from tertiary amines by benzyloxyl and cumyloxyl radicals: Influence of structure on the rate-determining formation of a hydrogen-bonded prereaction complex
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A time-resolved kinetic study on the hydrogen atom abstraction reactions from a series of tertiary amines by the cumyloxyl (CumO?) and benzyloxyl (BnO?) radicals was carried out. With the sterically hindered triisobutylamine, comparable hydrogen atom abstraction rate constants (kH) were measured for the two radicals (kH(BnO ?)/kH(CumO?) = 2.8), and the reactions were described as direct hydrogen atom abstractions. With the other amines, increases in kH(BnO?)/kH(CumO ?) ratios of 13 to 2027 times were observed. kH approaches the diffusion limit in the reactions between BnO? and unhindered cyclic and bicyiclic amines, whereas a decrease in reactivity is observed with acyclic amines and with the hindered cyclic amine 1,2,2,6,6-pentamethylpiperidine. These results provide additional support to our hypothesis that the reaction proceeds through the rate-determining formation of a C-H/N hydrogen-bonded prereaction complex between the benzyloxyl α-C-H and the nitrogen lone pair wherein hydrogen atom abstraction occurs, and demonstrate the important role of amine structure on the overall reaction mechanism. Additional mechanistic information in support of this picture is obtained from the study of the reactions of the amines with a deuterated benzyloxyl radical (PhCD2O?, BnO?- d2) and the 3,5-di-tert-butylbenzyloxyl radical.
- Salamone, Michela,Dilabio, Gino A.,Bietti, Massimo
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supporting information; scheme or table
p. 6264 - 6270
(2011/10/08)
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- Application of Mitsunobu reagents to redox Isomerization of CF 3-containing propargylic alcohols to (E)-α,β-enones
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Isomerization of CF3-containing secondary propargylic alcohols proceeds with excellent E selectivity by treatment with Mitsunobu reagents, tris- (p-methoxyphenyl)phosphine (TMPP), and 1,1′-(azodicarbonyl) dipiperidine (ADDP) in the presence of phenol.
- Watanabe, Yohsuke,Yamazaki, Takashi
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supporting information; experimental part
p. 1957 - 1960
(2011/06/20)
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- INDANONE INHIBITORS OF ACETYLCHOLINESTERASE
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The present invention relates to new indanone inhibitors of acetylcholinesterase, pharmaceutical compositions thereof, and methods of use thereof.
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Page/Page column 17
(2010/06/19)
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- Collision-induced loss of AgH from Ag+ adducts of alkylamines, aminocarboxylic acids and alkyl benzyl ethers leads exclusively to thermodynamically favored product ions
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The loss of AgH from [M + Ag]+ precursor ions of tertiary amines, aminocarboxylic acids and aryl alkyl ethers is examined by deuterium labeling combined with collision activation (CA) dissociation experiments. It was possible to demonstrate tha
- Schaefer, Mathias,Dreiocker, Frank,Budzikiewicz, Herbert
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experimental part
p. 278 - 284
(2009/07/11)
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- The mechanism for the rhodium-catalyzed decarbonylation of aldehydes: A combined experimental and theoretical study
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The mechanism for the rhodium-catalyzed decarbonylation of aldehydes was investigated by experimental techniques (Hammett studies and kinetic isotope effects) and extended by a computational study (DFT calculations). For both benzaldehyde and phenyl acetaldehyde derivatives, linear Hammett plots were obtained with positive slopes of +0.79 and +0.43, respectively, which indicate a buildup of negative charge in the selectivity-determining step. The kinetic isotope effects were similar for these substrates (1.73 and 1.77 for benzaldehyde and phenyl acetaldehyde, respectively), indicating that similar mechanisms are operating. A DFT (B3LYP) study of the catalytic cycle indicated a rapid oxidative addition into the C(O)-H bond followed by a rate-limiting extrusion of CO and reductive elimination. The theoretical kinetic isotope effects based on this mechanism were in excellent agreement with the experimental values for both substrates, but only when migratory extrusion of CO was selected as the rate-determining step.
- Fristrup, Peter,Kreis, Michael,Palmelund, Anders,Norrby, Per-Ola,Madsen, Robert
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p. 5206 - 5215
(2008/12/22)
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- Alcohols for the α-alkylation of methyl ketones and indirect aza-wittig reaction promoted by nickel nanoparticles
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Nickel nanoparticles have been found to activate primary alcohols used for the α-alkylation of ketones or in indirect aza-Wittig reactions. These processes involve hydrogen transfer from the alcohol to the intermediate α,β-unsaturated ketone or imine, respectively. All these reactions are carried out in the absence of any ligand, hydrogen acceptor or base under mild reaction conditions. For the first time nickel is employed as a potential alternative to noble-metal-based catalysts in both reactions. A reaction mechanism is proposed on the basis of some deuteration experiments. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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experimental part
p. 4908 - 4914
(2009/05/27)
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- A mechanistic study of the chromium(II)-mediated transformations of trichloromethyl alkyls and carbinols: evidence for carbene, carbyne, and carbenoid intermediates
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Using CrCl2 in THF at room temperature, trichloromethyl carbinols and trichloromethylalkanes are readily transformed to the highly reactive α-chlorocarbenes, carbynes and α-chloro-α-chromium(III) vinylidene carbenoids. A mechanistic study is carried out to determine the nature of the intermediates.
- Bejot, Romain,Tisserand, Steve,Li, De Run,Falck,Mioskowski, Charles
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p. 3855 - 3858
(2008/02/02)
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- An unprecedented rearrangement in collision-induced mass spectrometric fragmentation of protonated benzylamines
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The collision-induced dissociation (CID) mass spectra of several protonated benzylamines are described and mechanistically rationalized. Under collision-induced decomposition conditions, protonated dibenzylamine, for example, loses ammonia, thereby forming an ion of m/z 181. Deuterium labeling experiments confirmed that the additional proton transferred to the nitrogen atom during this loss of ammonia comes from the ortho positions of the phenyl rings and not from the benzylic methylene groups. A mechanism based on an initial elongation of a C-N bond at the charge center that eventually cleaves the C-N bond to form an ion/neutral complex of benzyl cation and benzylamine is proposed to rationalize the results. The complex then proceeds to dissociate in several different ways: (1) a direct dissociation to yield a benzyl cation observed at m/z 91; (2) an electrophilic attack by the benzyl cation within the complex on the phenyl ring of the benzylamine to remove a pair of electrons from the aromatic sextet to form an arenium ion, which either donates a ring proton (or deuteron when present) to the amino group forming a protonated amine, which undergoes a charge-driven heterolytic cleavage to eliminate ammonia (or benzylamine) forming a benzylbenzyl cation observed at m/z 181, or undergoes a charge-driven heterolytic cleavage to eliminate diphenylmethane and an immonium ion; and (3) a hydride abstraction from a methylene group of the neutral benzylamine to the benzylic cation to eliminate toluene and form a substituted immonium ion. Corresponding benzylamine and dibenzylamine losses observed in the spectra of protonated tribenzylamine and tetrabenzyl ammonium ion, respectively, indicate that the postulated mechanism can be widely applied. The postulated mechanisms enabled proper prediction of mass spectral fragments expected from protonated butenafine, an antifungal drug. Copyright
- Bialecki, Jason,Ruzicka, Josef,Attygalle, Athula B.
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p. 1195 - 1204
(2007/10/03)
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- Ruthenium catalyzed deuterium labelling of α-carbon in primary alcohol and primary/secondary amine in D2O
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Primary alcohols and primary/secondary amines are labelled with D atom at α-position regioselectively by means of deuterium oxide and ruthenium catalyst. Copyright
- Takahashi, Masaaki,Oshima, Koichiro,Matsubara, Seijiro
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p. 192 - 193
(2007/10/03)
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- Direct access to ketones from aldehydes via rhodium-catalyzed cross-coupling reaction with potassium trifluoro(organo)borates
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A direct cross-coupling reaction of aromatic aldehydes with potassium trifluoro(organo)borates afforded ketones in high yields and under mild conditions in the presence of a rhodium catalyst and acetone. This new reaction, involving a formal aldehyde C-H bond activation, is believed to proceed via a Heck-type mechanism followed by hydride transfer to acetone. Copyright
- Pucheault, Mathieu,Darses, Sylvain,Genet, Jean-Pierre
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p. 15356 - 15357
(2007/10/03)
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- Assay for the enantiomeric analysis of [2H1]-fluoroacetic acid: Insight into the stereochemical course of fluorination during fluorometabolite biosynthesis in Streptomyces cattleya
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A sensitive method for the configurational analysis of (R)- and (S)-[2H1]-fluoroacetate has been developed using 2H{1H}-NMR in a chiral liquid crystalline solvent. This has enabled biosynthetic experiments to be
- O'Hagan, David,Goss, Rebecca J. M.,Meddour, Abdelkrim,Courtieu, Jacques
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p. 379 - 387
(2007/10/03)
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