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131.
132.
A Cu(OTf)2-catalyzed simple synthetic approach for highly substituted 1-alkoxy imidazole has been described. This protocol involves (3 + 2) cycloaddition of oximino carbenoids with organo nitriles. This method has wide substrate scope and tolerates alkyl, aryl, substituted aryl, vinyl, and ester nitriles. 相似文献
133.
Schareina T Zapf A Mägerlein W Müller N Beller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(21):6249-6254
A general protocol for the cyanation of aryl halides with the nontoxic cyanide source K4[Fe(CN)6] using copper catalysis and a ligand system based on 1-alkylimidazoles is presented. The advantages of this system are the high selectivity, a unique substrate range, easy handling, and inexpensive reagents. 相似文献
134.
Dr. Alessa Hinzmann Dr. Tobias Betke Prof. Dr. Yasuhisa Asano Prof. Dr. Harald Gröger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5313-5321
While belonging to the most fundamental functional groups, nitriles represent a class of compound that still raises challenges in terms of an efficient, cost-effective, general and, at the same time, sustainable way for their synthesis. Complementing existing chemical routes, recently a cyanide-free enzymatic process technology based on the use of an aldoxime dehydratase (Oxd) as a biocatalyst component has been developed and successfully applied for the synthesis of a range of nitrile products. In these biotransformations, the Oxd enzymes catalyze the dehydration of aldoximes as readily available substrates to the nitrile products. Herein, these developments with such enzymes are summarized, with a strong focus on synthetic applications. It is demonstrated that this biocatalytic technology has the potential to “cross the bridge” between the production of fine chemicals and pharmaceuticals, on one hand, and bulk and commodity chemicals, on the other. 相似文献
135.
C. Wade Downey Alice Y.-K. Lee John R. Goodin Courtney J. Botelho William M. Stith 《Tetrahedron letters》2017,58(36):3496-3499
(Trimethylsilyl)acetonitrile reacts smoothly with dimethyl acetals in the presence of stoichiometric trimethylsilyl trifluoromethanesulfonate (TMSOTf) to yield β-methoxynitriles. The ideal substrates for this reaction are acetals derived from aromatic aldehydes. Elimination to the corresponding α,β-unsaturated nitriles is observed as the major product in the case of electron-rich acetals. A mechanistic hypothesis that includes isomerization of the silylnitrile to a nucleophilic N-silyl ketene imine is presented. 相似文献
136.
Cyano‐Schmittel Cyclization through Base‐Induced Propargyl‐Allenyl Isomerization: Highly Modular Synthesis of Pyridine‐Fused Aromatic Derivatives
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Xu You Xin Xie Haoyi Chen Yuxue Li Yuanhong Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18699-18705
The cyano‐Schmittel cyclization of in situ‐generated cyano‐allenes has been carried out. The DFT calculation results suggest that the diradical pathway plays a major role in this cyclization. The reactions can be conveniently performed in a one‐pot manner through cascade Sonogashira coupling of terminal cyano‐ynes with organic halides, followed by base‐promoted propargyl‐allenyl isomerization/cyclization, leading to an efficient access to pyridine‐fused polycyclic architectures. In particular, a large variety of aryl or heteroaryl rings such as furans, thiophenes and pyridines can be incorporated into the follow‐up cyano‐Diels–Alder reactions, highlighting the great synthetic utility of this chemistry. 相似文献
137.
Synthesis of 6‐Aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles by the Cu‐Catalyzed Reaction of 2‐(2‐Bromophenyl)‐1H‐indoles with CH2(CN)2
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Kazuhiro Kobayashi Kosuke Ezaki Daisuke Hanioka Ippei Nozawa 《Helvetica chimica acta》2015,98(2):179-183
A series of 6‐aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles 4 have been prepared by treatment of 2‐(2‐bromophenyl)‐1H‐indoles 1 , available from 1‐(2‐bromophenyl)ethanones or 1‐(2‐bromophenyl)propan‐1‐ones by using Fischer indole synthesis, with propanedinitrile in the presence of a catalytic amount of CuBr and an excess of K2CO3 in DMSO at 100°. 相似文献
138.
Copper‐Catalyzed Cyanomethylation of Allylic Alcohols with Concomitant 1,2‐Aryl Migration: Efficient Synthesis of Functionalized Ketones Containing an α‐Quaternary Center
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Dr. Ala Bunescu Dr. Qian Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (International ed. in English)》2015,54(10):3132-3135
A copper‐catalyzed alkylation of allylic alcohols by alkyl nitriles with concomitant 1,2‐aryl migration was developed. Formation of the alkyl nitrile radical was followed by its intermolecular addition to alkenes and the migration of a vicinal aryl group with the concomitant generation of a carbonyl functionality to complete the domino sequence. Mechanistic studies suggested that 1,2‐aryl migration proceeded through a radical pathway (neophyl rearrangement). The protocol provided an efficient route to functionalized ketones containing an α‐quaternary center. 相似文献
139.
Dr. Shachar Klaiman Prof. Dr. Lorenz S. Cederbaum 《Angewandte Chemie (International ed. in English)》2015,54(36):10470-10473
Lowering the activation energy of a chemical reaction is an essential part in controlling chemical reactions. By attaching a single electron, a barrierless path for the cis–trans isomerization of maleonitrile on the anionic surface is formed. The anionic activation can be applied in both reaction directions, yielding the desired isomer. We identify the microscopic mechanism that leads to the formation of the barrierless route for the electron‐induced isomerization. The generalization to other chemical reactions is discussed. 相似文献
140.
The synthetic utility of N-triflylimidazole as an in situ reagent for facile, high yielding, synthesis of various aliphatic, aromatic, and heteroaromatic nitriles from the corresponding aldoximes has been demonstrated. With benzaldoximes, in the presence of certain substitutents (2-F; 2-OMe; 3-CF3; 2-Me-5-F) a different course of reaction was observed, leading instead to novel 1:1 aldoxime-bis(N-triflyl)imidazole covalent adducts, in which the aldoxime oxygen atom is bonded to the imidazole C-2 ring carbon. For these aldoximes, conversion to nitrile could be effected by reaction with Tf2O in the absence of imidazole. The molecular structure of the adduct formed from 2-methyl-5-fluoro-benzaldoxime was confirmed by X-ray analysis. Plausible mechanisms for the formation of 1:1 covalent adducts have been considered. Various attempts to isolate such adducts via the reaction of an authentic sample of bis(N-triflyl)imidazolium trifate with aldoxime were unsuccessful. Remarkably, whereas isolated benzaldoxime adducts undergo deprotonation/methylation with NaH/MeI, an authentic sample of bis(N-triflyl)imidazolium triflate did not undergo H/Me exchange under these conditions. These transformations are discussed. 相似文献