共查询到20条相似文献,搜索用时 15 毫秒
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Patil H. S. Nikalje M. D. Chopade A. U. Chopade M. U. 《Russian Journal of Organic Chemistry》2021,57(4):611-618
Russian Journal of Organic Chemistry - Asymmetric reduction of homobenzylic ketones was achieved through the use of chiral spiroborate ester catalyst. The catalyst is applicable for both analytical... 相似文献
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Yarabally R Girish Kanchipura R Raghavendra Dasappa Nagaraja Kothanahally S Sharath Kumar Sheena Shashikanth 《中国化学》2015,33(2):181-184
An efficient, inexpensive and simple method for the reduction of various α,β‐unsaturated ketones to corresponding saturated ketones using tosyl hydrazide as a hydrogen donor in DMF using calcium oxide powder has been reported. A variety of enones underwent reduction without forming undesirable side products. High chemoselectivity, broad functional group tolerance and good yields are the noteworthy features of this protocol. 相似文献
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Polarity‐Reversed Allylations of Aldehydes,Ketones, and Imines Enabled by Hantzsch Ester in Photoredox Catalysis 下载免费PDF全文
Li Qi Prof. Dr. Yiyun Chen 《Angewandte Chemie (International ed. in English)》2016,55(42):13312-13315
The polarity reversal (umpolung) reaction is an invaluable tool for reversing the chemical reactivity of carbonyl and iminyl groups, which subsequent cross‐coupling reactions to form C?C bonds offers a unique perspective in synthetic planning and implementation. Reported herein is the first visible‐light‐induced polarity‐reversed allylation and intermolecular Michael addition reaction of aldehydes, ketones, and imines. This chemoselective reaction has broad substrate scope and the engagement of alkyl imines is reported for the first time. The mechanistic investigations indicate the formation of ketyl (or α‐aminoalkyl) radicals from single‐electron reduction, where the Hantzsch ester is crucial as the electron/proton donor and the activator. 相似文献
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Eleven structurally different α, β-unsaturated ketones were subjected to the Clemmensen reduction under anhydrous conditions using amalgamated zinc, hydrogen chloride in a solution of ethyl ether, and acetic anhydride. In all cases but one the formation of cyclopropyl acetates was observed. 4-Methyl-3-penten-2-one, methyl vinyl ketone, 2-isopropylidene-1-cyclopentanone, and 2-cyclohepten-1-one led to substituted cyclopropyl acetates. Stereospecific reactions were found with 2-ethylidene-1-cyclopentanone, 2-benzylidene-1-cyclohexanone, and methyl 1-cyclohexenyl ketone, whereas 3-penten-2-one, 3-methyl-3-buten-2-one, and 2-methyl-2-cyclohexen-1-one afforded mixtures of the isomeric cyclopropyl acetates. These results are interpreted in terms of the intital formation of an allylic anion which undergoes electrocyclic closure. A stereospecific course is followed when geometric constraints permitted. Exceptions are discussed. 相似文献
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The polarity reversal (umpolung) reaction is an invaluable tool for reversing the chemical reactivity of carbonyl and iminyl groups, which subsequent cross‐coupling reactions to form C−C bonds offers a unique perspective in synthetic planning and implementation. Reported herein is the first visible‐light‐induced polarity‐reversed allylation and intermolecular Michael addition reaction of aldehydes, ketones, and imines. This chemoselective reaction has broad substrate scope and the engagement of alkyl imines is reported for the first time. The mechanistic investigations indicate the formation of ketyl (or α‐aminoalkyl) radicals from single‐electron reduction, where the Hantzsch ester is crucial as the electron/proton donor and the activator. 相似文献
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R. A. Gadzhili A. G. Aliev R. A. Nadzhafova R. I. Ibragimov 《Chemistry of Heterocyclic Compounds》2005,41(8):1009-1012
The reaction of 3-chloro-2-halo-1-propenyl ketones with β-aminocrotonic acid ethyl ester leads to the formation of ethyl esters
of 6-alkyl(aryl, benzyl, cyclohexyl)-4-chloromethyl-2-methylnicotinic acids. It was established that at increased temperatures
the compounds obtained are partially converted into the corresponding dihydrofuro[3,4-c]pyridines.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1184–1188, August, 2005. 相似文献
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Ren-Lin Zheng Xiu-Xiu Zeng Hai-Yun He Jun He Sheng-Yong Yang Luo-Ting Yu 《合成通讯》2013,43(10):1521-1531
An improved synthesis of 6-aryl-3-cyanopyridine-2-(1H)-thiones utilizing enaminones as starting materials catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) was described. Moreover, a convenient one-pot conversion of aryl ketones to 6-aryl-3-cyanopyridine-2-(1H)-thiones was also developed in moderate to good yields (up to 80%). 相似文献
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Condensates 4–6 undergo reductive dimerization with Sm in THF containing aqueous NH4Cl to produce 7–9, whereas with Zn under similar reaction condition 3–5 produce 10–12. 相似文献
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Stephan Enthaler Dr. Björn Eckhardt Shigeyoshi Inoue Dr. Elisabeth Irran Dr. Matthias Driess Prof. Dr. 《化学:亚洲杂志》2010,5(9):2027-2035
In the present study, the zinc‐catalyzed hydrosilylation of various ketones to give their corresponding alcohols has been examined in detail. Diethyl zinc that can be modified by easily accessible phenol ligands allows the efficient reduction of various aryl and alkyl ketones. By using a practical in situ catalyst, excellent turnover frequencies up to 1000 h?1 and a broad functional group tolerance were achieved. 相似文献
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Jun-Jie Tian Zhao-Ying Yang Xin-Shen Liang Ning Liu Chen-Yu Hu Xian-Shuang Tu Xiang Li Prof. Dr. Xiao-Chen Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18610-18614
Herein, we report that highly chemoselective and enantioselective reduction of 2-vinyl-substituted pyridines has been achieved for the first time. The reaction, which uses chiral spiro-bicyclic bisboranes as catalysts and HBpin and an acidic amide as reducing reagents, proceeds through a cascade process involving 1,4-hydroboration followed by transfer hydrogenation of a dihydropyridine intermediate. The retained double bond in the reduction products permits their conversion to natural products and other useful heterocyclic compounds by simple transformations. 相似文献
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Reduction of aldehydes using decaborane (B10H14) in an aqueous solution gave the corresponding alcohol chemoselectively in good to high yields. 相似文献
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Stevan W. Djuri Richard B. Herbert Frederick G. Holliman 《Journal of heterocyclic chemistry》1985,22(5):1425-1428
A novel procedure for the chemoselective reduction of 2-acyl-1H-indole-3-carboxaldehydes has been developed. Low temperature lithium triethylborohydride reduction affords the indol-2-yl carbinol whilst sodium cyanoborohydride reduction in acetic acid affords the 3-hydroxymethyl analogs. Both processes are high yield, and provide access to intermediates of potential utility for indole alkaloid synthesis. 相似文献
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Poor solubility of Hantzsch ester is used as indicator in the reduction of methylidene malononitrile. The Knoevenagel reaction is integrated to develop a reductive alkylation of malononitrile with aryl and aliphatic aldehyde as the carbonyl substrate. 相似文献
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Catalytic hydrogenation of 2‐cyano‐2‐(2‐nitrophenyl)acetates bearing an electron withdrawing substituent to the nitrile, using Hantzsch ester catalyzed by Pd/C, affords 2‐aminoindoles in good to excellent yields. 相似文献
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A series of aldehydes and ketones were reduced by potassium borohydride in an ionic liquid/water ([bmim]PF6/H2O) biphasic system to afford corresponding alcohol with high purity in excellent yields. The ionic liquid/water biphasic system could promote the chemoselectivity and the substituents such as nitro group and chlorine remained intact. Aromatic ketones were not as active as aromatic aldhydes and cyclic ketones owing to their higher steric hindrance. The ionic liquid could be recycled and reused. This protocol has notable advantages of no need of phase transfer catalyst and organic solvents, mild conditions, simple operation, short reaction time, ease work-up, high yields and recycling of the ionic liquid. 相似文献