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1.
A simple and efficient method has been developed for highly diastcreoselective synthesis of trans-1,1-disubstituted-2,6-diarylcyclohexane-4-ones from dibenzalacetone and malononitril with trans-1,2-diaminocyclohexane as catalyst. The substrate 1,5-diaryl-1,4-pentadien-3-ones and active methylene compounds proceeded to give the products with good to excellent yield within a short time. 相似文献
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3-Methylidenechroman-2-ones, or their rearrangement products 3-methylchromen-2-ones, were efficiently synthesized by Michael addition of various nucleophiles to 3-diethoxyphosphorylchromen-2-ones followed by Horner-Wadsworth-Emmons reaction of the adducts with formaldehyde. Relative configuration and conformation of the intermediate adducts were studied using NMR spectroscopy and semiempirical PM3 calculations. 相似文献
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Ivan N. Bardasov Anastasiya U. Alekseeva Denis L. Mihailov Oleg V. Ershov Oleg E. Nasakin Viktor A. Tafeenko 《Tetrahedron letters》2014
The synthesis of 2-(dicyanomethylene)-1,2-dihydropyridine derivatives from the reactions of arylmethylidene derivatives of malononitrile dimers with 1,3-dicarbonyl compounds is described. 相似文献
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BALALAIE Saeed CHADEGANI Fatemeh DARVICHE Fatemeh BIJANZADEH Harnid Reza 《中国化学》2009,27(10):1953-1956
A new and efficient method for the synthesis of 1,8‐dioxo‐9‐aryl‐decahydroacridine derivatives was developed via a one‐pot three component reaction of dimedone, aromatic aldehydes and ammonium acetate in the presence of ammonium chloride, or Zn(OAc)2·2H2O or L‐proline separately in water in the short period of time and high yields. 相似文献
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Enantioselective Organocatalyzed Michael Addition of Isobutyraldehyde to Maleimides in Aqueous Media
Thiourea was introduced into (R,R)-1,2-diphenylethylenediamine as an organocatalyst to promote the reaction between isobutyraldehydes and maleimides. Enantioselective Michael addition reaction was carried out as an eco-friendly method using water as the solvent. As a result of the reaction between isobutyraldehyde and maleimide, ≥97% yield and 99% enantioselectivity were obtained at a low catalyst loading of 0.01 mol%. The solvent effect can be explained by theoretical calculations that indicate the participation of a transition state, in which the CF3 substituent of the catalyst is a hydrogen bond activated by the surrounding water molecules. This discovery enabled the use of low catalyst loading in the organic reactions of chiral substances for pharmaceutical applications. Furthermore, a solvent effect for Michael reaction of the organocatalysts was proposed, and the organic reaction mechanisms were determined through quantum calculations. 相似文献
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Yury V. Tomilov Dmitry N. Platonov Galina P. Okonnishnikova 《Tetrahedron letters》2009,50(40):5605-5608
The mode of reaction of the 1,2,3,4,5,6,7-heptamethoxycarbonylcycloheptatriene with primary amines depends on the reaction conditions and leads to selective formation of N-substituted (heptamethoxycarbonyl)nortrop-2-enes and/or 3-vinylpyridin-2-ones bearing six ester groups. The influence of the solvent on the selectivity of the formation of nortropenes and pyridinones was studied. 相似文献
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The doubly decarboxylative Michael–type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described. 相似文献
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An efficient synthesis of 3,6-disubstituted-4-aroyl-2-pyrones in a single-step reaction through Michael addition of 1,2-diaroylacetylenes with active methylene compounds in the presence of NaH in dimethylsulfoxide at room temperature is reported. The structures have been confirmed by spectral data analyses.
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Melika Hadjebi Mehri S. Hashtroudi Hamid Reza Bijanzadeh Saeed Balalaie 《Helvetica chimica acta》2011,94(3):382-388
The four‐component reaction of dimethyl acetylenedicarboxylate (=dimethyl but‐2‐ynedioate; DMAD), aromatic aldehydes, and malononitrile (=propanedinitrile) leads to polyfunctionalized 1,4‐dihydropyridine derivatives. The reaction proceeds at room temperature and in the presence of a catalytic amount (20%) of (NH4)2HPO4 as a base in aqueous media. 相似文献
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Indium-mediated addition of allyl bromide to 1,1-dicyano-2-arylethenes gives Michael addition products in aqueous media with good yields. The reaction need neither any activation nor in inert atmosphere. 相似文献
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Ethyl 4-(trifluoromethyl)-2-vinylthiazole-5-carboxylate was utilized as a precursor to ethyl 4-(trifluoromethyl)-2-(aminoethyl)thiazole-5-carboxylate analogs via Michael-like addition of various secondary amines. Reactions employed 1.2 equiv of amine, and the products were isolated by solvent removal and acid/base extraction. Use of primary amines was also investigated. 相似文献
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Tanaka M Nakamura K Iwado T Sato T Okada M Sue K Iwamura H Hiaki T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(2):606-612
Cyclotrimerization of 1‐phenyl‐2‐propyn‐1‐one in pressurized hot water gave 1,3,5‐tribenzoylbenzene in one pot in 65 % yield after 7 min at 200 °C, or in 74 % yield after 60 min at 150 °C. The reaction did not take place in the absence of water, and added base promoted the reaction at 250 °C, suggesting a mechanism of three‐consecutive Michael addition reactions. The reaction rates increased with temperature, but the yield of 1,3,5‐tribenzoylbenzene decreased at the expense of formation of acetophenone as a side product at higher temperatures. p‐Methyl and p‐chloro‐substituents on the phenyl ring retarded and enhanced the reaction, respectively. A mechanism involving the enol of benzoylacetaldehyde at a branching point of the pathway leading to 1,3,5‐tribenzoylbenzene and acetophenone was suggested. 相似文献
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《Tetrahedron》2003,59(4):481-492
The synthesis of the new dienes N-substituted 2,3,4,5-tetrahydrobenzoxazol-2-ones 8a-8c is described, through a one-step convergent process from 1,2-cyclohexanedione (7a) and the corresponding isocyanates 2a-2c. The presence of electron-donor substituents in the aryl ring of the isocyanate gave rise to the exclusive formation of the captodative olefins 10. Diene 8a proved to be reactive and stereoselective in Diels-Alder additions with a cyclic olefin. The reaction with acetylenic dienophiles yielded the 2,3-dihydrobenzoxazol-2-ones 21 and 24, as the products of sequential [4+2] cycloaddition and retro-Diels-Alder reactions. Methyl vinyl ketone (22) underwent regio- and stereoselective tandem Diels-Alder and Michael additions to give propellane 29a. Evidence of an endo π-pyramidalization of the central double bond of adduct 19 would rationalize the exo stereoselection in the formation of 29a. The regioselectivity in these reactions has been rationalized in terms of FMO theory by ab initio calculations. 相似文献
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Bin Tan Di Zhu Lihong Zhang Pei Juan Chua Xiaofei Zeng Guofu Zhong Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(12):3842-3848
A facile and highly stereoselective construction of heavily functionalized chiral tetrahydronaphthalene skeletons fused with an oxazolidine moiety has been developed. The process involves an organocatalytic tandem Michael/nitrone formation/intramolecular [3+2] nitrone–olefin cycloaddition in aqueous media. Using rationally designed substrates, the reaction conditions have been optimized and the one‐pot process has been applied to a series of nitroolefin acrylates and aldehydes. The N‐hydroxyphenylamine component used in the second step has also been varied. The stereochemistry of one product has been verified by an X‐ray crystal structure determination. The water used in the strategy not only constitutes an environmentally benign solvent, but also helps to improve the reactivity and stereoselectivity. 相似文献
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A Facile and Efficient One‐Pot Electrochemical Synthesis of Thiazole Derivatives in Aqueous Solution 下载免费PDF全文
Mohsen Ameri Ali Amoozadeh Alireza Asghari Davood Nematollahi Mohammad Bakherad 《Helvetica chimica acta》2015,98(2):210-223
In the present work, the electrooxidation of hydroquinones 1a and 1b , and catechols 1c and 1d was studied in the presence of rhodanine ( 3 ) as nucleophile in a mixture of EtOH and phosphate buffer solution as ‘green’ media using cyclic voltammetry and controlled‐potential coulometry. The results indicated that the corresponding p‐ and o‐quinones formed from the hydroquinones and catechols, respectively, participate in Michael addition reaction to yield new thiazole derivatives. The electrochemical syntheses of these new thiazole derivatives were performed successfully at three graphite rod electrodes in undivided cells in good‐to‐excellent yields at room temperature without any catalyst. 相似文献