- Investigating the continuous synthesis of a nicotinonitrile precursor to nevirapine
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2-Chloro-3-amino-4-picoline (CAPIC) is a strategic building block for the preparation of nevirapine, a widely-prescribed nonnucleosidic reverse transcriptase inhibitor for the treatment of HIV-infected patients. A continuous synthesis to the bromo derivative of a CAPIC intermediate, 2-bromo-4- methylnicotinonitrile, that terminates in a dead-end crystallization is described. The route uses inexpensive, acyclic commodity-based raw materials and has the potential to enable lower cost production of nevirapine as well as other value added structures that contain complex pyridines. The route terminates in a batch crystallization yielding high purity CAPIC. This outcome is expected to facilitate regulatory implementation of the overall process.
- Longstreet, Ashley R.,Opalka, Suzanne M.,Campbell, Brian S.,Gupton, B. Frank,McQuade, D. Tyler
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Read Online
- MICROWAVE SPECTRUM OF 1,1'-DIMETHYL-22'-DICYANOETHYLENE
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The microwave spectra of 1,1'-dimethyl-2,2'-dicyanoethylyne and 1,1'-dimethyl-2,2'-dicyanoethylene-d6 have been recorded in the frequency region 18-40 GHz.The measured ground state lines have been fitted to a semi-rigid rotor model.From the resulting six moments of inertia some structural information has been obtained.
- Damiani, D.,Scappini, F.,Lunelli, B.
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Read Online
- Molybdenum hexacarbonyl-catalyzed condensation of malononitrile with ketones and aldehydes
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Molybdenum hexacarbonyl activated with pyridine or morpholine catalyzes the condensation of malononitrile with ketones and aldehydes at 140 C, which leads to alkylidenemalononitriles in 75-100% yield.
- Khusnutdinov,Shchadneva,Mayakova,Oshnyakova,Dzhemilev
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Read Online
- Ylidenemalononitrile enamines as fluorescent "turn-on" indicators for primary amines
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Ylidenemalononitrile enamines undergo rapid amine exchange followed by a cyclization with primary amines to yield fluorescent products with emission intensities as high as 900 times greater than the starting materials. After identifying the fluorescent species by X-ray crystallography, we demonstrate that the rate of amine exchange is substrate dependent and that by simple structural variation the fluorescence can be tuned over the entire visible spectrum. We further demonstrate their potential application in biomolecule labeling.
- Longstreet, Ashley R.,Jo, Minyoung,Chandler, Rebecca R.,Hanson, Kenneth,Zhan, Naiqian,Hrudka, Jeremy J.,Mattoussi, Hedi,Shatruk, Michael,McQuade, D. Tyler
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Read Online
- Preparation of mesoporous carbon nitride materials using urea and formaldehyde as precursors and catalytic application as solid bases
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A series of mesoporous carbon nitride materials have been fabricated using inexpensive and eco-friendly urea and formaldehyde as precursors and mesocellular silica foam (MCF) as a template through a nanocasting approach. Several techniques, including XRD, TEM, elemental analysis, FT-IR, XPS, and CO2-TPD have been applied to characterize the physicochemical properties of the mesoCN materials, and the results show that the materials possess high surface areas (331–355?m2?g?1), relatively concentrated pore size of ca. 6?nm, and abundant and multiple nitrogen-containing species. As heterogeneous base catalysts, mesoCN materials demonstrate high catalytic activity and selectivity in both Knoevenagel condensation and transesterification reactions.
- Xu, Jie,Wang, Yue,Shang, Jie-Kun,Ma, Dan,Li, Yong-Xin
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Read Online
- Synthesis of two-dimensional mesoporous carbon nitride under different carbonization temperatures and investigation of its catalytic properties in Knoevenagel condensations
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A two-dimensional mesoporous carbon nitride (MCN-1) material with tunable surface area, pore volume and nitrogen content has been synthesized by using carbon tetrachloride and ethylenediamine as precursors and SBA-15 as a template. The effect of the carbonization temperature on the textural properties, N content and the types of nitrogen species of the MCN-1 samples was also investigated by several characterization techniques. The results reveal that the higher temperature favors the formation of porous structure during the thermal condensation process. In addition, the nitrogen content and the surface N/C ratio in the samples monotonically decrease with the increase of carbonization temperature. The catalytic activity of MCN-1-T is not only related to its surface nitrogen content but also dependent on the structural diversities of the surface nitrogen species. The MCN-1 sample synthesized at 400 °C shows the higher catalytic activity and stability for Knoevenagel condensations. This journal is
- Zhang, Lina,Wang, Hao,Qin, Zhangfeng,Wang, Jianguo,Fan, Weibin
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Read Online
- Observations of tetrel bonding between sp3-carbon and THF
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We report the direct observation of tetrel bonding interactions between sp3-carbons of the supramolecular synthon 3,3-dimethyl-tetracyanocyclopropane (1) and tetrahydrofuran in the gas and crystalline phase. The intermolecular contact is establishedvias-holes and is driven mainly by electrostatic forces. The complex manifests distinct binding geometries when captured in the crystalline phase and in the gas phase. We elucidate these binding trends using complementary gas phase quantum chemical calculations and find a total binding energy of -11.2 kcal mol-1for the adduct. Our observations pave the way for novel strategies to engineer sp3-C centred non-covalent bonding schemes for supramolecular chemistry.
- Alford, Thomas P. J.,Davis, Anthony P.,Domingos, Sérgio R.,Heywood, Victoria L.,Lekanne Deprez, Siebe J.,Mooibroek, Tiddo J.,Roeleveld, Julius J.,Schnell, Melanie,Verhoofstad, Abraham,van der Vlugt, Jarl Ivar
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Read Online
- A bis(heptafulvenyl)-dicyanoethylene thermoswitch with two sites for ring closure
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Suitably functionalized vinylheptafulvenes (VHFs) act as thermoswitches undergoing ring closure to the corresponding dihydroazulenes (DHAs). Here we present the synthesis of a new such thermoswitch incorporating two heptafulvene rings on a dicyanoethylene
- Broman, Soren Lindbaek,Petersen, Anne Ugleholdt,Tortzen, Christian Gregers,Vibenholt, Johan,Bond, Andrew D.,Nielsen, Mogens Brondsted
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Read Online
- Liquid-phase Knoevenagel reactions over modified basic microporous titanosilicate ETS-10
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Al- and Ga-incorporated ETS-10, designated as ETAlS-10 and ETGaS-10, respectively, were synthesized by using P25 titania as a Ti source. The isomorphous substitution of Al and Ga for framework Si at the (4Si) environment was confirmed by 29Si M
- Goa, Yasuhide,Wu, Peng,Tatsumi, Takashi
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Read Online
- Asymmetric organocatalytic vinylogous Michael addition triggered triple-cascade reactions of 2-hydroxycinnamaldehydes and vinylogous nucleophiles: construction of benzofused oxabicyclo[3.3.1]nonane scaffolds
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An organocatalytic vinylogous Michael addition triggered triple-cascade reaction has been developed. 2-Hydroxycinnamaldehydes worked under iminium activation with either acyclic or cyclic ketone-derived α,α-dicyanoalkenes, yielding the benzofused oxabicyclo[3.3.1]nonanes bearing one quaternary stereocenter with excellent stereoselectivities.
- Wu, Hui-Chun,Wang, Chen,Chen, Ying-Han,Liu, Yan-Kai
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supporting information
p. 1762 - 1765
(2021/02/27)
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- Propargylamine-selective dual fluorescence turn-on method for post-synthetic labeling of DNA
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We have developed a propargylamine-selective dual fluorescence turn-on system, using ylidenemalononitrile enamines, for post-synthetic DNA labeling, allowing the direct monitoring of DNA using dual emission in living cells.
- Nguyen, Van Thang,Pandith, Anup,Seo, Young Jun
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supporting information
p. 3199 - 3202
(2020/03/23)
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- Organocatalytic asymmetric vinylogous 1,4-addition of α,α-Dicyanoolefins to chalcones under a bio-based reaction media: Discovery of new Michael adducts with antiplasmodial activity
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The organocatalysed asymmetric vinylogous Michael addition of α,α-dicyanoolefins to α,β-unsaturated aldehydes and ketones have been reported in the last decade, however, chalcones have been poorly explored. Moreover, a considerable part of the publications in this theme still employs undesirable solvents, such as toluene and THF, with concerns related to health and environmental safety. We report herein the use of a bifunctional catalyst derived from a Cinchona alkaloid to perform the enantio- and diastereoselective Michael addition of α,α-dicyanoolefins to chalcones using 2-MeTHF as solvent. The Michael adducts were obtained in moderate to good yields and were evaluated for their antiplasmodial and cytotoxic activity.
- Martelli, Lorena S.R.,Vieira, Lucas C.C.,Paix?o, Márcio W.,Zukerman-Schpector, Julio,de Souza, Juliana O.,Aguiar, Anna Caroline C.,Oliva, Glaucius,Guido, Rafael V.C.,Corrêa, Arlene G.
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supporting information
p. 3530 - 3542
(2019/05/24)
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- Synthesis method of methylene malononitrile compounds
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The invention discloses a synthesis method of methylene malononitrile compounds. According to the method, in the air atmosphere, a ketone compound and malononitrile are taken as raw materials, Ru/C istaken as a catalyst, the raw materials and the catalyst
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Paragraph 0039-0043
(2020/04/02)
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- Pillar[5]arene-based [1]rotaxane: High-yield synthesis, characterization and application in Knoevenagel reaction
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We report a quantitative synthetic strategy of a [1]rotaxane from a representative pseudo[1]rotaxane. The structure of the [1]rotaxane was characterized by 1H NMR, 13C NMR, 2D NMR, mass spectroscopy, and melting point, and its optimized geometry in CHCl3 by theoretical calculation at the B3LYP/6-31G(D) level using the PCM model matched well with 2D NOESY. This [1]rotaxane proves to be a good catalyst for the Knoevenagel reaction in CHCl3, which follows second order kinetics.
- Du, Xu-Sheng,Wang, Chun-Yu,Jia, Qiong,Deng, Rong,Tian, Hua-Sheng,Zhang, Hou-Yu,Meguellati, Kamel,Yang, Ying-Wei
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supporting information
p. 5326 - 5329
(2017/07/07)
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- Increasing global access to the high-volume HIV drug nevirapine through process intensification
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Access to affordable medications continues to be one of the most pressing issues for the treatment of disease in developing countries. For many drugs, synthesis of the active pharmaceutical ingredient (API) represents the most financially important and technically demanding element of pharmaceutical operations. Furthermore, the environmental impact of API processing has been well documented and is an area of continuing interest in green chemical operations. To improve drug access and affordability, we have developed a series of core principles that can be applied to a specific API, yielding dramatic improvements in chemical efficiency. We applied these principles to nevirapine, the first non-nucleoside reverse transcriptase inhibitor used in the treatment of HIV. The resulting ultra-efficient (91% isolated yield) and highly-consolidated (4 unit operations) route has been successfully developed and implemented through partnerships with philanthropic entities, increasing access to this essential medication. We anticipate an even broader global health impact when applying this model to other active ingredients.
- Verghese, Jenson,Kong, Caleb J.,Rivalti, Daniel,Yu, Eric C.,Krack, Rudy,Alcázar, Jesus,Manley, Julie B.,McQuade, D. Tyler,Ahmad, Saeed,Belecki, Katherine,Gupton, B. Frank
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supporting information
p. 2986 - 2991
(2017/07/24)
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- Sterically Demanding Oxidative Amidation of α-Substituted Malononitriles with Amines Using O2
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An efficient amidation method between readily available 1,1-dicyanoalkanes and either chiral or nonchiral amines was realized simply with molecular oxygen and a carbonate base. This oxidative protocol can be applied to both sterically and electronically challenging substrates in a highly chemoselective, practical, and rapid manner. The use of cyclopropyl and thioether substrates support the radical formation of α-peroxy malononitrile species, which can cyclize to dioxiranes that can monooxygenate malononitrile α-carbanions to afford activated acyl cyanides capable of reacting with amine nucleophiles.
- Li, Jing,Lear, Martin J.,Hayashi, Yujiro
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supporting information
p. 9060 - 9064
(2016/07/26)
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- LOWCOST, HIGH YIELD SYNTHESIS OF NEVIRAPINE
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Improved methods of producing the HIV drug substance, nevirapine are provided. The methods employ a cost effective and high yield synthetic methods for preparing the nevirapine building block 2-chloro-3-amino-4-picoline (CAPIC) and 2-cyclopropyl amino nicotinate (Me-CAN), and improvements in other steps of nevirapine synthesis.
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Page/Page column 19; 20; 21
(2016/12/22)
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- METHODS OF MAKING 2-HALONICOTINONITRILES
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A method of making a 2-halonicotinonitrile comprises reacting an alkylidene nitrile with a C1-compound in an organic solvent and a dehydrating agent. The dehydrating agent substantially retards dimerization of the alkylidene nitrile during the reaction. The enamine intermediate that forms from the reaction is cyclized using a halide donor to make the 2-halonicotinonitrile.
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Paragraph 0054-0060
(2015/03/13)
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- Improved synthesis of mono- and disubstituted 2-halonicotinonitriles from alkylidene malononitriles
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Pyridines with 2,3,4 and/or 5 substitution remain challenging to prepare. Existing strategies to form multisubstituted 2-halonicotinonitriles via enamines suffer from dimerization of the starting alkylidene malononitriles resulting in low yields. Through alteration of reaction conditions, a new high yielding method into enamines was realized by condensing DMF-DMA and alkylidene malononitriles in the presence of substoichiometric acetic anhydride. Cyclization of the resulting enamines under Pinner conditions provided 2-halonicotinonitriles in high overall yields.
- Longstreet, Ashley R.,Campbell, Brian S.,Gupton, B. Frank,McQuade, D. Tyler
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supporting information
p. 5298 - 5301
(2013/11/06)
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- Efficient protocol for knoevenagel condensation in presence of the diazabicyclo[5.4.0]undec-7-ene-water complex
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A simple and efficient protocol for Knoevenagel condensation has been developed in the presence of diazabicyclo[5.4.0]undec-7-ene (DBU)/water complex. A widely range of carbonyl compounds (aliphatic and aromatic aldehydes, ketones) could react smoothly with methylene active ingredients (malononitrile, ethyl cyanoacetate, diethyl malonate and acetylacetone), which can not proceed by conven- tional catalyst. Other significant features of this method include readily work-up, good recyclability of catalytic system and short reaction time.
- Ying, An-Guo,Wu, Cheng-Lin,He, Guang-Hong
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experimental part
p. 653 - 656
(2012/07/28)
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- Facile metal free regioselective transfer hydrogenation of polarized olefins with ammonia borane
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Transfer hydrogenation of polarized olefins bearing strongly electron-withdrawing groups on one side of the double bond was achieved with ammonia borane under mild conditions without using a catalyst. Mechanistic studies proved the character of the direct H transfers proceeding stepwise with a unique hydroboration intermediate and hydride before proton transfer.
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
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supporting information; experimental part
p. 2053 - 2055
(2011/03/22)
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- A simple, efficient and green procedure for Knoevenagel condensation catalyzed by [C4dabco][BF4] ionic liquid in water
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A convenient and rapid method for Knoevenagel condensation has been developed by using DABCO-base ionic liquid catalysts. This method is applicable to a wide range of aromatic/aliphatic/heterocyclic/α,β-unsaturated aldehydes and ketones with active methyl
- Xu, Da-Zhen,Liu, Yingjun,Shi, Sen,Wang, Yongmei
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experimental part
p. 514 - 517
(2010/08/04)
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- CO2 absorbing cost-effective ionic liquid for synthesis of commercially important alpha cyanoacrylic acids: A safe process for activation of cyanoacetic acid
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Cost-effective and carbon dioxide absorbing ionic liquid, tri-(2-hydroxyethyl) ammonium acetate, was shown to perform multiple roles in Knoevenagel condensation. It acted as an environmentally benign solvent, as an activating catalyst for the less reactive cyanoacetic acid and also as a risk reduction medium for the unevenly generated large amount of CO2 gas for large scale reactions. The reaction was scaled up for multi-gram synthesis of commercially important alpha cyanoacrylic acids.
- Sharma, Yogesh O.,Degani, Mariam S.
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experimental part
p. 526 - 530
(2010/04/23)
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- A convenient and selective one-pot method for the synthesis of monosubstituted secondary alkyl malononitriles
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We have found that α,α-dicyanoalkenes can be efficiently and selectively reduced to α,α-dicyanoalkanes (malononitriles) with NaBH4 in 95% EtOH at 0 °C. In addition, we have determined that the condensation of malononitrile with ketones using absorption alumina as a catalyst can be followed directly, in one pot, by reduction with NaBH 4 in 95% EtOH at 0 °C to provide the monosubstituted secondary alkyl malononitriles in good to excellent yields (42-94%). This procedure provides a convenient alternative to direct alkylation of malononitrile or reduction of α,α-dicyanoalkene intermediates.
- Sammelson, Robert E.,Allen, Mark J.
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p. 543 - 546
(2007/10/03)
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- SYNTHESIS OF 3-AMINO-2-CHLORO-4-METHYLPYRIDINE FROM MALONONITRILE AND ACETONE
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A method for making 3-amino-2-chloro-4-methylpyridine from malononitrile, as depicted in the following reaction scheme.
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- Ammonium acetate-basic alumina catalyzed knoevenagel condensation under microwave irradiation under solvent-free condition
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Ammonium acetate and basic alumina catalyzed efficiently the Knoevenagel condensation of aldehydes and ketones with active methylene compounds under solvent-free condition where olefinic products were obtained in high yields.
- Balalaie, Saeed,Nemati, Navid
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p. 869 - 875
(2007/10/03)
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- Geminal dinitriles and their reactions: I. Hydrolysis of alkylidene- and cycloalkylidenemalononitriles in aqueous medium
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The kinetics of pseudounimolecular hydrolysis of alkylidene- and cycloalkylidenemalononitriles in an aqueous buffer at pH 7 were studied. Correlations between the rate constants and substituent effects were found to fit the Taft-Hancock equation. Electrochemical reduction of alkylidenemalononitriles was studied using 0.2 M tetraethylammonium iodide as supporting electrolyte. The half-wave reduction potentials are related to the substituent constants σ* by the Taft-Zuman equation. Anomalous behavior of 1,1-dicyano-2,3,3-trimethyl-1-butene was observed during the hydrolysis and electrochemical reduction at a dropping mercury electrode.
- Smirnov,Sevast'yanova
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p. 1703 - 1708
(2007/10/03)
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- Synthesis of 3-amino-2-chloro-4-methylpyridine from malononitrile and acetone
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A method for making 3-amino-2-chloro-4-methylpyridine from malononitrile, as depicted in the following reaction scheme.
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- Electrochemical transformation of malononitrile and carbonyl compounds into functionally substituted cyclopropanes: Electrocatalytic variant of the Wideqvist reaction
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Electrolysis of malononitrile and carbonyl compounds in the presence of alkali metal halides in an undivided cell results in the formation of substituted 1,1,2,2-tetracyanocyclopropanes in 60-90% yield. This electrocatalytic variant of the Wideqvist reaction using malononitrile instead of bromomalonitrile was successfully performed. Electrocatalytic transformation of substituted 1,1,2,2-tetracyanocyclopropanes in methanol or ethanol in an undivided cell leads to substituted 2-amino-4,4-dialkoxy-1,5- dicyano-3-azabicyclo[3.1.0]hex-2-enes in 70-95% yields after 0.05-0.10 F/mol of electricity has been passed. (C) 2000 Elsevier Science Ltd.
- Elinson, Michail N.,Feducovich, Sergey K.,Lizunova, Tatiana L.,Nikishin, Gennady I.
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p. 3063 - 3069
(2007/10/03)
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- Synthesis and oral efficacy of a 4-(butylethylamino)pyrrolo[2,3- d]pyrimidine: A centrally active corticotropin-releasing factor1 receptor antagonist
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The syntheses of a centrally active nonpeptide CRF1 receptor antagonist 2, butylethyl[2,5-dimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo[2,3- d]pyrimidin-4-yl]amine (CP-154,526), and its analogs 11-14 and [3H]-2 are reported. The in v
- Chen, Yuhpyng L.,Mansbach, Robert S.,Winter, Steven M.,Brooks, Elizabeth,Collins, Judith,Corman, Michael L.,Dunaiskis, Audrey R.,Faraci, W. Stephen,Gallaschun, Randall J.,Schmidt, Anne,Schulz, David W.
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p. 1749 - 1754
(2007/10/03)
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- KNOEVENAGEL, WITTIG AND WITTIG-HORNER REACTIONS IN THE PRESENCE OF MAGNESIUM OXIDE OR ZINC OXIDE.
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Alkenes are prepared by Wittig, Knoevenagel and Wittig-Horner reactions in solid-liquid systems, with magnesium oxide or zinc oxide as catalyst.When Wittig-Horner reaction is competitive with Knoevenagel reaction, the catalyst can by modified to give a highly selective reaction : the addition of dimethylsulfoxide on MgO or hexamethylphosphoric triamide on ZnO gives more efficient catalysts for the Wittig-Horner reaction.The addition of a small amount of HgCl2 or CdCl2 on ZnO gives more efficient catalysts for the Knoevenagel reaction.
- Moison, Helene,Texier-Boullet, Francoise,Foucaud, Andre
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p. 537 - 542
(2007/10/02)
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- Reactions retrodieniques - XVIII. Synthese par thermolyse eclair et etude d'allenes fonctionnels reactifs
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The flash thermolysis of anthracenic Diels-Alder adducts leads to the obtention and low temperature spectroscopic characterization (ir, 1H and 13C nmr) of allenes 1-11 (see table 1).Butadienal 1, the simplest α-allenic aldehyde, is thus obtained from its precursors 13, 14 or 17.Thermolysis of the intermediate allylic alcohol 15 gives buta-1,3-dien-2-ol 18, which tautomerizes to methylvinylketone even at -100 deg C.An attempted synthesis of a natural δ-allenic ester, methyl laballenate 19, was undertaken using this method; however, the thermolysis of ester 24 leads via 19 to methyl acrylate and (Z + E) pentadeca-1,3-diene 25, resulting formally from a retroene cleavage of 19.Thermolyses of related esters 26 and 27 give in the same way the corresponding 1,3-dienes.Allenes with gem electron attracting groups are very reactive compounds acting as ketene equivalents in nucleophilic additions and or dipolar cycloadditions.The thermolysis of adducts 28-32, obtained by Knoevenagel condensation of malonic derivatives with ketone 16, leads to the following allenes of this series: 1,1-dicyano-1-methoxycarbonyl propadiene 4, 1,1-bis-(ethoxycarbonyl) propadiene 5 and 1,1-bis-(methoxycarbonyl) propadiene 6.Yields and purity are lower in the case of 3 and 5, owing to the presence of the thermolabile ethoxycarbonyl groups.The possibility of performing nucleophilic additions to the most polymerizable of these allenes: 1,1-dicyanopropadiene 2, is demonstrated by its clean, good yield additions at -50 deg C with methanol, methyl lithium, aniline ir dimethylamine.Allenes O or N-substituted on the allenic carbon are often reactive substances and are known mainly in the case of alkyl ethers and tertiary amines.The flash thermolysis of allylic alcohol 38 gives in good yield propanediol 7 which tautomerizes into acrolein at -50 deg C.Trimethylsilyloxypropadiene 8, 1-trimethylsilyloxybuta-1,2-diene 9 and 3-trimethylsilyloxybuta-1,2-diene 10 could also be obtained from their precursors 40, 44-46.Thermolysis of amine 49 leads in the same way to propadienamine 11, a reactive enamine postulated as a cosmic species and tautomerizing at -65 deg C into 1-azabuta-1,3-diene 50.
- Hakiki, Abdelhak,Ripoll, Jean-Louis,Thuillier, Andre
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p. 911 - 920
(2007/10/02)
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- Knoevenagel Condensation in the Heterogenous Phase Using AlPO4-Al2O3 as a New Catalyst
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The Knoevenagel condensation of several aldehydes and ketones was carried out at room temperature on an AlPO4-Al2O3 catalyst and in the absence of solvent (dry reaction), using malononitrile and ethyl cyanoacetate as the acidic methylene reagents.Only the
- Cabello, Jose A.,Campelo, Juan M.,Garcia, Angel,Luna, Diego,Marinas, Jose M.
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p. 5195 - 5197
(2007/10/02)
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- KNOEVENAGEL CONDENSATION CATALYSED BY ALUMINIUM OXIDE.
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The Knoevenagel condensation of carbonyl compounds with active methylene compounds was readily carried out with aluminium oxide as catalyst.
- Texier-Boullet, Francoise,Foucaud, Andre
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p. 4927 - 4928
(2007/10/02)
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- THE WAVELENGTH- AND SOLVENT-DEPENDENT PHOTOCHEMISTRY OF 1,1-DICYANO-2-METHYL-4-PHENYLBUT-1-ENE; REACTION FROM TWO EXCITED STATES
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1,1-Dicyano-2-methyl-4-phenylbut-1-ene ( 4 ), on u.v. irradiation in solution, yields two products, 3,3-dicyano-2-methyl-4-phenylbut-1-ene ( 5 ) and 1-dicyanomethyl-1-methylindane ( 6 ).The photoreaction is dependent both on solvent polarity and on the excitation wavelength.A long-wavelength band in the absorption spectrum of ( 4 ), not present in the spectra of its isolated chromophores, is attributed to an intramolecular charge-transfer interaction.THe unusual dependence on solvent and wavelength is explained in terms of a reaction mechanism in which ( 5 ) is formed from a delocalised excited state, with a staggered conformation, and ( 6 ) from a charge-transfer excited state, with an eclipsed conformation.
- Cookson, Richard C.,Sadler, David E.,Salisbury, Kingsley
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p. 774 - 782
(2007/10/02)
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- A Synthesis of Pyrroloquinazolinones, Indoloquinazolinones, Pyrrolothienopyrimidinones, Benzothienopyrrolopyrimidinones and 6H-Cycloheptathienopyrrolopyrimidinones
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α-Cyano-γ-halo-crotonnitriles (1) synthesized (e.g. via Knoevenagel reaction and by subsequent halogenation) react with primary arylamines (2) to substituted 1-aryl-2-amino-3-cyano-pyrroles (3).We found that the reaction yields pyrroloquinazolin-5-
- Suesse, M.,Johne, S.
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p. 647 - 653
(2007/10/02)
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- Synthesis of Norbornanones with a Geminal Dimethyl Group
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The synthesis of gem-dimethylnorbornanones is described.One synthetic pathway after a Diels-Alder reaction involves the transformation of the nitro group into the oxo group with subsequent methylation into the geminal dimethyl product.A shorter way by -cycloaddition of cyclopentadiene with a suitable dimethylated dienophile (e.g. 2-methyl-1-nitropropene) failed, probably by steric hindrance of the dienophile. 7-Oxanorbornanones with a gem -dimethyl group could not be prepared.A second synthetic approach to gem-dimethylnorbornanones is opened by Lewis acid catalyzed rearrangement of cyclohexenylcarbaldehydes. - Keywords: Camphenilone; Diels-Alder reaction; Homonorbornanone; α-Methylation of carbonyls; Nef-reaction; Norepifenchone
- Buchbauer, Gerhard,Dworan, Erich
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p. 1165 - 1174
(2007/10/02)
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