- Ester-Substituted Electron-Poor Alkenes for Cycloaddition-Retroelectrocyclization (CA-RE) and Related Reactions
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We report the reactions of electron-deficient alkenes, tetrasubstituted by carboxylic ester and cyano groups, with electron-rich (dimethylamino)phenyl-substituted alkynes. Mono- or diester-substituted alkenes exclusively undergo the [2+2] cycloaddition-retroelectrocyclization (CA-RE) reaction, well established for multicyanated ethenes, whereas tri- and tetraester-substituted alkenes also undergo a [4+2] hetero-Diels-Alder (HDA) reaction with a third product being formed, presumably by a [3+2] cycloaddition reaction followed by rearrangement. Electrochemical studies revealed cathodic shifts of the first reduction potential of the buta-1,3-dienes obtained from the CA-RE reaction as cyano groups are substituted for ester moieties. Post-CA-RE functionalization of the ester-substituted buta-1,3-dienes by transesterification, diazonium chemistry, and cross-coupling is described. The formation of a pharmacologically interesting pyrazolopyran illustrates the synthetic utility of ester-substituted CA-RE products.
- Reekie, Tristan A.,Donckele, Etienne J.,Ruhlmann, Laurent,Boudon, Corinne,Trapp, Nils,Diederich, Fran?ois
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- Copper-Catalyzed Regio- and Stereoselective Iodocyanation and Dicyanation of Alkynes with Cyanogen Iodide
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anti-Selective iodocyanation and dicyanation of various internal alkynes has been developed by means of a simple copper catalyst system. The selectivity of the products was switched by tuning the reaction conditions. Mechanistic studies have revealed all of the stepwise pathways including diiodide formation, selective monocyanation, and second cyanation processes.
- Sakata, Naoki,Sasakura, Kohei,Matsushita, Gaku,Okamoto, Kazuhiro,Ohe, Kouichi
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supporting information
p. 3422 - 3425
(2017/07/15)
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- An unexpected reaction of diethyl phosphite with electron-deficient dialkyl dicyanofumarates
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Diethyl phosphite reacts with both dimethyl dicyanofumarate and dicyanomaleate in boiling 1,2-dichloroethane to yield, after chromatographic workup, a 1:1-mixture of the corresponding meso- and dl-dicyanosuccinates. The analogous transformation was observed in the cases of diethyl and diisopropyl dicyanofumarates. A reaction pathway via initial formation of a P-C bond followed by its hydrolytic cleavage is proposed.
- Mlostoń, Grzegorz,Celeda, Ma?gorzata,Heimgartner, Heinz
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p. 207 - 210
(2016/02/18)
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- Cyclopropanation of electron-deficient alkenes with activated dibromomethylene compounds mediated by lithium iodide or tetrabutylammonium salts
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Reactions of electron-deficient alkenes with dibromomethylene compounds activated by cyano and ester groups were promoted by LiI or tetrabutylammonium bromide to afford the corresponding cyclopropanes in high yields.
- Kawai, Daisuke,Kawasumi, Katsuaki,Miyahara, Tsukasa,Hirashita, Tsunehisa,Araki, Shuki
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scheme or table
p. 10390 - 10394
(2010/02/28)
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- Remote-control photoswitching using NIR light
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(Chemical Equation Presented) Near-infrared (NIR) light is used to toggle photoswitches back and forth between their two isomers even though the chromophores do not significantly absorb this type of light. The reactions are achieved through a "remote control" process by using photon up-converting hexagonal NaYF4 nanocrystals doped with lanthanide ions. These nanoparticles absorb 980 nm light and convert it to wavelengths that can be used to trigger the photoswitches offering a practical means to potentially achieve 3D-data storage, drug-delivery, and photolithography.
- Carling, Carl-Johan,Boyer, John-Christopher,Branda, Neil R.
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supporting information; body text
p. 10838 - 10839
(2009/12/04)
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- Reversible Diels-Alder reactions for the generation of dynamic combinatorial libraries
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(Chemical Equation Presented) Condensation reactions between various dienes and dienophiles have been screened for reversibility. Functionalized fulvenes, bearing in particular biological groups, and cyanolefins have been found to react rapidly and reversibly, in the temperature range from -10 to +50°C. These results pave the way for the development of dynamic combinatorial libraries based on reversible Diels-Alder chemistry.
- Boul, Peter J.,Reutenauer, Philippe,Lehn, Jean-Marie
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- 3,4-Dicyanomaleic anhydride, a new dienophile
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Thermolysis of 2,3-dicyano-bicylo[2,2,1]hept-5-ene-2,3-dicarboxylic anhydride (6) at 580-590°C or of 3,4,5,6-tetraazidophthalic anhydride (9) at 110°C affords 3,4-dicyanomaleic anhydride (1).
- Friedrich, Klaus,Zimmer, Ralph
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body text
p. 757 - 759
(2011/10/11)
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- Potassium fluoride on alumina: Oxidative coupling of acidic carbon compounds with diiodine
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Diiodine reacts at room temperature with activated methylene compounds in the presence of potassium fluoride on alumina and saturated dimers, unsaturated dimers or trimers were formed according to the stoechiometry of the reaction. The reactions were improved by using ultrasound activation.
- Villemin,Alloum
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p. 3169 - 3179
(2007/10/02)
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- A Convenient Synthesis of Dialkyl (E)-2,3-Dicyanobutendioates
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Dialkyl (E)-2,3-dicyanobutendioates 4, potentially useful intermediates for the synthesis of a wide variety of heterocyclic compounds, are conveniently prepared by the reaction of alkyl bromocyanoacetates 2 with potassium thiocyanate in acetonitrile followed by treatment with water.The starting alkyl bromocyanoacetates are prepared by the photochemical reaction of the appropriate alkyl cyanoacetate with bromine in carbon tetrachloride.
- Yamada, Yoichi,Yasuda, Heinosuke
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p. 768 - 770
(2007/10/02)
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- Reactions of Monoprotic Thioureas with Ethyl α-Chloroacetoacetate, Ethyl Bromomalonate, and Ethyl Bromocyanoacetate
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N,N,-Dialkyl-N'-arylthioureas (1) with ethyl α-chloroacetoacetate, furnished dialkylamine hydrochlorides, aryl isothiocyanates, 2-arylimino-1,3-oxathioles (2), 2-arylimino-3-aryl Δ4-thiazolines (3), diarylthioureas (9), and carbonyl sulphide.With ethyl bromomalonate the products were dialkylamine hydrobromides, aryl isothiocyanates, 2-arylimino-3-arylthiazolidin-4-ones (11), and diarylthioureas (9).Ethyl bromocyanoacetate gave an ethyl cyanothio>acetate (13).Compound (13) with triethylamine gave the starting thiourea (1) and diethyl dicyanofumarate.
- Singh, Harjit,Ahuja, Amarjit S.,Malhotra, Nageshwar
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p. 653 - 656
(2007/10/02)
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