共查询到20条相似文献,搜索用时 15 毫秒
1.
Dr. Pei Chui Too Guo Hao Chan Dr. Ya Lin Tnay Prof. Hajime Hirao Prof. Shunsuke Chiba 《Angewandte Chemie (International ed. in English)》2016,55(11):3719-3723
Sodium hydride (NaH) is widely used as a Brønsted base in chemical synthesis and reacts with various Brønsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with unprecedented and unique hydride‐donor chemical reactivity. 相似文献
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《Helvetica chimica acta》2018,101(5)
A new and concise protocol for selective reduction of N,N‐dimethylamides into aldehydes was established using sodium hydride (NaH) in the presence of sodium iodide (NaI) under mild reaction conditions. The present protocol with the NaH‐NaI composite allows for reduction of not only aromatic and heteroaromatic but also aliphatic N,N‐dimethylamides with wide substituent compatibility. Retention of α‐chirality in the reduction of α‐enantioriched amides was accomplished. Use of sodium deuteride (NaD) offers a new step‐economical alternative to prepare deuterated aldehydes with high deuterium incorporation rate. The NaH‐NaI composite exhibits unique chemoselectivity for reduction of N,N‐dimethylamides over ketones. 相似文献
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Zonghan Hong Derek Yiren Ong Dr. Subas Kumar Muduli Dr. Pei Chui Too Guo Hao Chan Dr. Ya Lin Tnay Prof. Shunsuke Chiba Dr. Yusuke Nishiyama Prof. Hajime Hirao Prof. Han Sen Soo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7108-7114
Sodium hydride (NaH) has been commonly used as a Brønsted base in chemical syntheses, while it has rarely been employed to add hydride (H?) to unsaturated electrophiles. We previously developed a procedure to activate NaH through the addition of a soluble iodide source and found that the new NaH–NaI composite can effect even stereoselective nucleophilic hydride reductions of nitriles, imines, and carbonyl compounds. In this work, we report that mixing NaH with NaI or LiI in tetrahydrofuran (THF) as a solvent provides a new inorganic composite, which consists of NaI interspersed with activated NaH, as revealed by powder X‐ray diffraction, and both solid‐state NMR and X‐ray photoelectron spectroscopies. DFT calculations imply that this remarkably simple inorganic composite, which is comprised of NaH and NaI, gains nucleophilic hydridic character similar to covalent hydrides, resulting in unprecedented and unique hydride donor chemical reactivity. 相似文献
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过渡金属盐促进的纳米氢化钠对硝基的还原反应 总被引:2,自引:0,他引:2
研究了在过渡金属盐促进下,纳米尺寸的活性氢化钠对硝基化合物的还原反应.结果表明,过渡金属盐的存在,使纳米氢化钠(NaH*)的还原活性进一步增强,硝基苯的转化率在较短时间内就超过90%.镍盐对生成苯胺的选择性最好(100%),其次是锰盐.不同纳米碱金属氢化物对硝基苯还原的活性和生成苯胺的选择性顺序为NaH*>KH*>LiH*.几种硝基化合物的反应结果表明,NaH*-镍盐是硝基还原生成芳胺有效的复合还原剂 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(7):1866-1870
A simple protocol for hydrodebromination and ‐deiodination of halo(hetero)arenes was enabled by sodium hydride (NaH) in the presence of lithium iodide (LiI). Mechanistic studies showed that an unusual concerted nucleophilic aromatic substitution operates in the present process. 相似文献
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Andrew S. S. Wilson Chiara Dinoi Michael S. Hill Mary F. Mahon Laurent Maron Emma Richards 《Angewandte Chemie (International ed. in English)》2020,59(3):1232-1237
A molecular calcium hydride effects the two electron reduction of polyaromatic hydrocarbons, including naphthalene (E0=?3.1 V). 相似文献
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Reduction of Phosphine Oxide by Using Chlorination Reagents and Dihydrogen: DFT Mechanistic Insights
Dr. Hui Zhu Dr. Zheng-Wang Qu Prof. Dr. Stefan Grimme 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(18):4670-4672
Extensive DFT calculations provide detailed mechanistic insights into the metal-free reduction of phosphine oxide Ph3P=O by using chlorination reagents O=CClX (X=COCl, Cl, OCCl3 and Ph) and H2. Fast electrophilic attack to the P=O group oxygen atom is favored by exergonic CO2 release to form phosphonium Ph3PCl+ and chloride Cl−, which may slowly cleave H2 by an unstable HPh3PCl complex yielding Ph3PH+ and Cl− ions in solution. Moderate heating is required to accelerate the slow H2-activation step and to eliminate HCl to form phosphine Ph3P instead of Ph3PH+Cl− salt as the desired product. Though partially quenched by Ph3P (and reactant Ph3P=O if present), borane B(2,6-F2C6H3)3 can be still combined with Cl− and Ph3P as reactive frustrated Lewis pair (FLP) catalysts. 相似文献
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Dr. Ibrahim Yildiz 《Chemphyschem》2023,24(20):e202300431
D-Arginine dehydrogenase from Pseudomonas aeruginosa (PaDADH) is an amine oxidase which catalyzes the conversion of D-arginine into iminoarginine. It contains a non-covalent FAD cofactor that is involved in the oxidation mechanism. Based on substrate, solvent, and multiple kinetic isotope effects studies, a stepwise hydride transfer mechanism is proposed. It was shown that D-arginine binds to the active site of enzyme as α-amino group protonated, and it is deprotonated before a hydride ion is transferred from its α-C to FAD. Based on a mutagenesis study, it was concluded that a water molecule is the most likely catalytic base responsible from the deprotonation of α-amino group. In this study, we formulated computational models based on ONIOM method to elucidate the oxidation mechanism of D-arginine into iminoarginine using the crystal structure of enzyme complexed with iminoarginine. The calculations showed that Arg222, Arg305, Tyr249, Glu87, His 48, and two active site water molecules play key roles in binding and catalysis. Model systems showed that the deprotonation step occurs prior to hydride transfer step, and active site water molecule(s) may have participated in the deprotonation process. 相似文献
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Sepideh Sharif Dr. Michael J. Rodriguez Dr. Yu Lu Dr. Michael E. Kopach Dr. David Mitchell Dr. Howard N. Hunter Prof. Michael G. Organ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(57):13099-13103
NaBHT (sodium butylated hydroxytoluene), a hindered and soluble base for the efficient arylation of various base-sensitive amines and (hetero)aryl halides has been found to have an unanticipated role as a hydride donor to reduce (hetero)aryl halides and allylic acetates. Mechanistic studies have uncovered that NaBHT, but not BHT, can deliver multiple hydrides through oxidation of the benzylic methyl group in NaBHT to the aldehyde. Further, performing the reduction with NaBHT-d20 has revealed that the redox-active benzylic position is not the only hydride donor site from NaBHT with one hydride in three coming, presumably, from the tert-butyl groups. The reduction works well under mild conditions and, incredibly, only consumes 20 percent of the NaBHT in the process; the remaining 80 percent can be readily recovered in pure form and reused. This, combined with the low cost of the material in ton-scale quantity, makes it practical and attractive for wider use in industry at scale. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(39):11969-11973
A method for the nucleophilic amination of methoxy arenes was established by using sodium hydride (NaH) in the presence of lithium iodide (LiI). This method offers an efficient route to benzannulated nitrogen heterocycles. Mechanistic studies showed that the reaction proceeds through an unusual concerted nucleophilic aromatic substitution. 相似文献
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《Angewandte Chemie (International ed. in English)》2017,56(43):13275-13278
A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4‐dioxane as reagents and 1,10‐phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism. 相似文献
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Nanometric sodium hydride (NaH*) possesses a large specific surface area. Its chemical reactivity is in orders of magnitude higher than that of the conmercial one. After heat treatment at 2ll℃, the specific surface area of NaH* becomes smaller whereas its chemical reactivity is even higher. This fact indicates that the specific surface area of NaH* particles is an important but not the only factor for its high reactivity. NaH treated at (400℃, 6h) still retains a specific surface area of 30m2 g-1 and gives fairly high chemical reactivity. 相似文献
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提出了带有不同取代基的茂钛配合物与纳米氢化钠(NaH)组成的高活性加氢催化剂,在常温常压下,取代茂钛配合物TiCl2/NaH对1-己烯的加氢反应有极高的初始活性,TOFmax达到110molH2/(molTi.s),催化转换数达到22200molH2/(molTi)。该催化体系对底物有明显的专一选择性,只有端烃才能发生加氢反应,且无民构化副反应发生,纳米氢化钠的助剂作用是该催化体系高活性关键因素。 相似文献
16.
Oleg I. Kolodiazhnyi 《Phosphorus, sulfur, and silicon and the related elements》2014,189(7-8):1102-1131
AbstractThis article describes the asymmetric synthesis of chiral organophosphorus compounds using methods of enantioselective hydride reduction and hydrogenation of corresponding unsaturated compounds. Many applications in stereoselective synthesis with reference to updated literature findings as well as the author's original research are discussed. The uses of chiral organophosphorus compounds in some asymmetric transformations leading to the formation of phosphorus analogues of important natural compounds were also presented. 相似文献
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Grant J. Sherborne Avetik G. Gevondian Ignacio Funes‐Ardoiz Amit Dahiya Christoph Fricke Franziska Schoenebeck 《Angewandte Chemie (International ed. in English)》2020,59(36):15543-15548
Selective C –C couplings are powerful strategies for the rapid and programmable construction of bi‐ or multiaryls. To this end, the next frontier of synthetic modularity will likely arise from harnessing the coupling space that is orthogonal to the powerful Pd‐catalyzed coupling regime. This report details the realization of this concept and presents the fully selective arylation of aryl germanes (which are inert under Pd0/PdII catalysis) in the presence of the valuable functionalities C?BPin, C?SiMe3, C?I, C?Br, C?Cl, which in turn offer versatile opportunities for diversification. The protocol makes use of visible light activation combined with gold catalysis, which facilitates the selective coupling of C?Ge with aryl diazonium salts. Contrary to previous light‐/gold‐catalyzed couplings of Ar–N2+, which were specialized in Ar–N2+ scope, we present conditions to efficiently couple electron‐rich, electron‐poor, heterocyclic and sterically hindered aryl diazonium salts. Our computational data suggest that while electron‐poor Ar–N2+ salts are readily activated by gold under blue‐light irradiation, there is a competing dissociative deactivation pathway for excited electron‐rich Ar–N2+, which requires an alternative photo‐redox approach to enable productive couplings. 相似文献
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One-pot etherification reaction of aromatic and some aliphatic carbonyl compounds with organic halides in the presence of sodium hydride as a reducing reagent proceeded smoothly in dioxane, a polar solvent with higher boiling point, to provide desired ethers in moderate to high yields. 相似文献
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Cobalt‐Catalyzed Oxidase C−H/N−H Alkyne Annulation: Mechanistic Insights and Access to Anticancer Agents 下载免费PDF全文
Ruhuai Mei Hui Wang Svenja Warratz Prof. Stuart A. Macgregor Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6759-6763
Cp*‐free cobalt‐catalyzed alkyne annulations by C?H/N?H functionalizations were accomplished with molecular O2 as the sole oxidant. The user‐friendly oxidase strategy proved viable with various internal and terminal alkynes through kinetically relevant C?H cobaltation, providing among others step‐economical access to the anticancer topoisomerase‐I inhibitor 21,22‐dimethoxyrosettacin. DFT calculations suggest that electronic effects control the regioselectivity of the alkyne insertion step. 相似文献