- Harnessing Stereospecific Z-Enamides through Silver-Free Cp?Rh(III) Catalysis by Using Isoxazoles as Masked Electrophiles
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The stereospecific synthesis of Z-enamides is described in this paper. For the first time, isoxazoles have been employed as electrophiles in C-H functionalization to afford thermodynamically less stable Z-enamides utilizing salicylaldehydes in an atom- and step-economic fashion. The stereochemistry of enamides might originate from the relative disposition of atoms present in isoxazole and the intramolecular hydrogen bonding. The reaction showed excellent scope as several structurally and electronically diverse salicylaldehydes and isoxazoles reacted efficiently.
- Debbarma, Suvankar,Bera, Sourav Sekhar,Maji, Modhu Sudan
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Read Online
- Photochemistry of 4- and 5- phenyl substituted isoxazoles
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5-Phenylisoxazole (4) and 4-phenylisoxazole (22) underwent phototransposition to 5-phenyloxazole (5) and 4-phenyloxazole (24) respectively. Labeling with deuterium or methyl confirmed that these phototrans-positions occurred via the P4 pathway which involves only interchange of the N2 and C3 ring position. Thus, 4-deuterio-5-phenylisoxazole (4-4d), 4-methyl-5-phenylisoxazole (10), and 5-methyl-4-phenylisoxazole (23) phototransposed to 4-deuterio-5-phenyloxazole (5-4d), 4-methyl-5-phenyloxazole (11), and 5-methyl-4-phenyloxazole (25) respectively. In addition to phototransposition, isoxazoles 4, 10, and 23 also underwent photo-ring cleavage to yield benzoylacetonitrile (9), α-benzoylpropionitrile (15), and aceto-α-phenyl-acetonitrile (26) respectively. Irradiation of 5-phenyl-3-(trifluoromethyl)isoxazole (16) in acetonitrile led to 5-phenyl-2-(trifluoromethyl)oxazole (17), the P4 phototransposition product. Irradiation of 16 in methanol led to a substantial decrease in the yield of 17 and to the formation of a mixture of (E) and (Z)-2-methoxy-2- (trifluoromethyl)-3-benzoylaziridines 18a and 18b.
- Pavlik, James W.,St. Martin, Heather,Lambert, Karen A.,Lowell, Jennifer A.,Tsefrikas, Vikki M.,Eddins, Cheryl K.,Kebede, Naod
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Read Online
- A convenient procedure for transformation of tertiary cyclopropanols into 5-substituted isoxazoles
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Tertiary cyclopropanols, when treated with an excess of amyl nitrite at room temperature, are smoothly converted into dimeric β-nitrosoketones. Heating the methanolic solutions of the latter under reflux gives 5-substituted isoxazoles in good yields. Geor
- Churykau, Dzmitry H.,Kulinkovich, Oleg G.
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Read Online
- Cracking under internal pressure: Photodynamic behavior of vinyl azide crystals through N2release
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When exposed to UV light, single crystals of the vinyl azides 3- azido-1-phenylpropenone (1a), 3-azido-1-(4-methoxyphenyl)propenone (1b), and 3-azido-1-(4-chlorophenyl)propenone (1c) exhibit dramatic mechanical effects by cracking or bending with the release of N2. Mechanistic studies using laser flash photolysis, supported by quantum mechanical calculations, show that each of the vinyl azides degrades through a vinylnitrene intermediate. However, despite having very similar crystal packing motifs, the three compounds exhibit distinct photomechanical responses in bulk crystals. While the crystals of 1a delaminate and release gaseous N2 indiscriminately under paraffin oil, the crystals of 1b and 1c visibly expand, bend, and fracture, mainly along specific crystallographic faces, before releasing N2. The photochemical analysis suggests that the observed expansion is due to internal pressure exerted by the gaseous product in the crystal lattices of these materials. Lattice energy calculations, supported by nanoindentation experiments, show significant differences in the respective lattice energies. The calculations identify critical features in the crystal structures of 1b and 1c where elastic energy accumulates during gas release, which correspond to the direction of the observed cracks. This study highlights the hitherto untapped potential of photochemical gas release to elicit a photomechanical response and motility of photoreactive molecular crystals.
- Shields, Dylan J.,Karothu, Durga Prasad,Sambath, Karthik,Ranaweera, Ranaweera A. A. Upul,Schramm, Stefan,Duncan, Alexander,Duncan, Benjamin,Krause, Jeanette A.,Gudmundsdottir, Anna D.,Naumov, Pan?e
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p. 18565 - 18575
(2020/12/01)
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- Preparation method of isoxazole derivative
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The invention relates to a preparation method of an isoxazole derivative, which comprises the following steps of mixing an propargyl alcohol derivative, a halogen source, an acid and a solvent, and heating to react; adding the hydroxylamine into the react
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Paragraph 0054-0059
(2019/12/02)
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- Copper Photoredox Catalyzed A3’ Coupling of Arylamines, Terminal Alkynes, and Alcohols through a Hydrogen Atom Transfer Process
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The first successful example of the three-component coupling of N-alkylanilines, terminal alkynes, and alcohols was achieved at room temperature by a visible-light-mediated copper-catalyzed photoredox hydrogen-atom transfer process. This method allows pre
- Sagadevan, Arunachalam,Pampana, V. Kishore Kumar,Hwang, Kuo Chu
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supporting information
p. 3838 - 3842
(2019/02/26)
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- A novel synthesis of 5-substituted isoxazoles from propargylic amines and N-hydroxyphthalimide
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A mild and efficient method for the synthesis of 5-substituted isoxazoles through cyclization of propargylic amines with N-hydroxyphthalimide (NHPI) under metal-free conditions was developed.
- Zhang, Yicheng,Chen, Wei,Jia, Xueshun
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supporting information
p. 2181 - 2183
(2018/05/08)
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- Difluoromethylthiolation of Phenols and Related Compounds with a HF2CSO2Na/Ph2PCl/Me3SiCl System
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A novel HF2CSO2Na/Ph2PCl/Me3SiCl system is disclosed for the late-stage direct difluoromethylthiolation of Csp2 and Csp3 nucleophiles. Difluoromethylthiolation of phenols and naphthols proceeded nicely under this system to regioselectively provide corresponding SCF2H compounds in good yields. Other substrates such as indoles, pyrroles, pyrazoles, enamines, ketones, and β-keto esters were also transformed to corresponding SCF2H products in good yields. The late-stage direct difluoromethylthiolation of a number of natural products and pharmaceutically attractive molecules was also achieved.
- Huang, Zhongyan,Matsubara, Okiya,Jia, Shichong,Tokunaga, Etsuko,Shibata, Norio
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supporting information
p. 934 - 937
(2017/02/26)
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- TEMPO-catalyzed synthesis of 5-substituted isoxazoles from propargylic ketones and TMSN3
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A novel and efficient TEMPO-catalyzed synthesis of 5-substituted isoxazoles from propargylic ketones and TMSN3via a radical mechanism process is described. This methodology provides an easy access to a variety of useful 5-substituted isoxazoles
- He, Yan,Xie, Yu-Yang,Wang, Ying-Chun,Bin, Xiao-Min,Hu, Da-Chao,Wang, Heng-Shan,Pan, Ying-Ming
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p. 58988 - 58993
(2016/07/06)
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- Tandem synthesis of 3-halo-5-substituted isoxazoles from 1-copper(I) alkynes and dihaloformaldoximes
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A tandem synthesis of 3-halo-5-substituted isoxazoles has been developed from 1-copper(I) alkynes and dihaloformaldoximes under base-free conditions. Thus, 1,3-dipolar cycloaddition and all its drawbacks can now be avoided completely.
- Chen, Wenwen,Wang, Bo,Liu, Nan,Huang, Dayun,Wang, Xinyan,Hu, Yuefei
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p. 6140 - 6143
(2015/01/09)
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- One-pot oxidation and rearrangement of propargylamines and in situ pyrazole synthesis
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Reported here are procedures for a one-pot oxidation and rearrangement of propargylamines to synthesize enaminones, with supporting mechanistic studies. Also reported are the extended one-pot syntheses of pyrazoles, including celecoxib and various heterocyclic compounds.
- Chen, Jinshan,Properzi, Roberta,Uccello, Daniel P.,Young, Jennifer A.,Dushin, Russell G.,Starr, Jeremy T.
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p. 4146 - 4149
(2014/09/29)
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- A novel synthesis of 1,2,4-oxadiazoles and isoxazoles
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A novel synthesis of 1,2,4-oxadiazoles and isoxazoles is described by utilizing the reactions between amidoximes and α,β-alkynic aldehydes and/or ketones. Conjugate addition products, obtained from amidoximes and α,β-alkynic aldehydes and/or ketones, afford 1,2,4-oxadiazoles and isoxazoles when treated with bases and acids, respectively. 1,2,4-Oxadiazoles can also be synthesized directly from amidoximes and α,β-alkynic aldehydes in a one-pot manner under basic conditions. The reactions are general for a variety of starting compounds and tolerate the presence of aryl, heteroaryl and alkyl groups.
- Kivrak, Arif,Zora, Metin
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p. 817 - 831
(2014/01/23)
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- Propylphosphonic anhydride (T3P): A remarkably efficient reagent for the one-pot transformation of aromatic, heteroaromatic, and aliphatic aldehydes to nitriles
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Propylphosphonic anhydride has been demonstrated to be an efficient reagent for the transformation of aromatic, heteroaromatic, and aliphatic aldehydes to respective nitriles in excellent yields. This procedure offers simple and one-pot access to nitriles and highlights the synthetic utility of T3P as a versatile reagent in organic chemistry. Georg Thieme Verlag Stuttgart - New York.
- Augustine, John Kallikat,Atta, Rajendra Nath,Ramappa, Balakrishna Kolathur,Boodappa, Chandrakantha
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experimental part
p. 3378 - 3382
(2010/03/03)
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- Reaction of β-dimethylaminovinyl ketones with hydroxylamine: A simple and useful method for synthesis of 3- and 5-substituted isoxazoles
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(Chemical Equation Presented) The regioselective synthesis of 3- and 5-substituted-isoxazoles from the reaction of β-dimethylaminovinyl ketones [R-C(O)CH=CH-NMe2, where R = Ph, MeO-4-C6H4, F-4-C6H4, C
- Rosa, Fernanda A.,Machado, Pablo,Bonacorso, Helio G.,Zanatta, Nilo,Martins, Marcos A. P.
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p. 879 - 885
(2008/09/21)
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- DIAZEPINE DERIVATIVES AS 5-HT2A ANTAGONISTS
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Compounds of formula I: are selective 5HT2A antagonists and hence find use in treatment or prevention of a variety of CNS disorders.
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Page/Page column 8
(2008/06/13)
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- Pyrazolo[1,5-a]pyrimidin-7-yl phenyl amides as novel antiproliferative agents: Exploration of core and headpiece structure-activity relationships
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A novel series of antiproliferative agents containing pyrazolo[1,5-a]pyrimidin-7-yl phenyl amides, selective for p21-deficient cells, were identified by high-throughput screening. Exploration of the SAR relationships in the headpiece, core, and tailpiece
- Powell, Dennis,Gopalsamy, Ariamala,Wang, Yanong D.,Zhang, Nan,Miranda, Miriam,McGinnis, John P.,Rabindran, Sridhar K.
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p. 1641 - 1645
(2007/10/03)
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- Identification and optimisation of 5-amino-7-aryldihydro-1,4-diazepines as 5-HT2A ligands
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A several series of low molecular weight 5-HT2A leads were identified from an analysis of HTS data, the exploration of SAR and optimization of one series using parallel synthesis are described, affording compound 22 (5-HT2A IC50 1.1 nM).
- Swain, Christopher J.,Teran, Ana,Maroto, Marta,Cabello, Angeles
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p. 6058 - 6062
(2007/10/03)
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- Oxidation of alkylarenes by nitrate catalyzed by polyoxophosphomolybdates: Synthetic applications and mechanistic insights
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Alkylarenes were catalytically and selectively oxidized to the corresponding benzylic acetates and carbonyl products by nitrate salts in acetic acid in the presence of Keggin type molybdenum-based heteropolyacids, H3+xPVxMo12-xO40 (x = 0-2). H 5PV2Mo10O40 was especially effective. For methylarenes there was no over-oxidation to the carboxylic acid contrary to what was observed for nitric acid as oxidant. The conversion to the aldehyde/ketone could be increased by the addition of water to the reaction mixture. As evidenced by IR and 15N NMR spectroscopy, initially the nitrate salt reacted with H5PV2Mo10O 40 to yield a NVO2+[H 4PV2Mo10O40] intermediate. In an electron-transfer reaction, the proposed NVO2 +[H4PV2Mo10O40] complex reacts with the alkylarene substrate to yield a radical-cation-based donor-acceptor intermediate, NIVO2[H4PV 2Mo10O40]-ArCH2R+.. Concurrent proton transfer yields an alkylarene radical, ArCHR., and NO2. Alternatively, it is possible that the NVO 2+[H4PV2Mo10O 40] complex abstracts a hydrogen atom from alkylarene substrate to directly yield ArCHR. and NO2. The electron transfer-proton transfer and hydrogen abstraction scenarios are supported by the correlation of the reaction rate with the ionization potential and the bond dissociation energy at the benzylic positions of the alkylarene, respectively, the high kinetic isotope effect determined for substrates deuterated at the benzylic position, and the reaction order in the catalyst. Product selectivity in the oxidation of phenylcyclopropane tends to support the electron transfer-proton transfer pathway. The ArCHR. and NO2 radical species undergo heterocoupling to yield a benzylic nitrite, which undergoes hydrolysis or acetolysis and subsequent reactions to yield benzylic acetates and corresponding aldehydes or ketones as final products.
- Khenkin, Alexander M.,Neumann, Ronny
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p. 6356 - 6362
(2007/10/03)
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- Pyrazole and Isoxazole Derivatives as New, Potent, and Selective 20-Hydroxy-5,8,11,14-eicosatetraenoic Acid Synthase Inhibitors
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In a previous paper, we reported the N-hydroxyformamidine derivative HET0016 as a potent and selective 20-HETE synthase inhibitor. Despite its attraction as a potential therapeutic agent for cerebral diseases, the preparation of an injectable formulation
- Nakamura, Toshio,Sato, Masakazu,Kakinuma, Hiroyuki,Miyata, Noriyuki,Taniguchi, Kazuo,Bando, Kagumi,Koda, Ayumi,Kameo, Kazuya
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p. 5416 - 5427
(2007/10/03)
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- Reaction of β-keto ethyleneacetals with hydroxylamine: A correction
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A reaction of 2-(2-nitrobenzoylmethyl)-1,3-dioxolane (3) with hydroxylamine, followed by acid catalyzed cyclization, produced 5-(2- nitrophenyl)isoxazole (5) as the only isolable product, whereas 2- (benzoylmethyl)-1,3-dioxolane (9) under identical condit
- Paradkar,Latham,Krishnaswami
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p. 1497 - 1500
(2007/10/02)
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- SYNTHESES OF (+)- AND (-)-MELLEIN UTILIZING AN ANNELATION REACTION OF ISOXAZOLES WITH DIMETHYL 3-OXOGLUTARATE
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Naturally occurring dihydroisocoumarins, (+)- and (-)-mellein (2 and 3), metabolites of fungals, Cercospora sp. and Aspergillus sp., etc., were synthesized from the isoxazoles (32) and (33) by the annelation reactions with dimethyl 3-oxoglutarate.
- Takeuchi, Naoki,Goto, Kaori,Sasaki, Yuki,Fujita, Takashi,Okazaki, Kohsuke,et al.
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p. 357 - 374
(2007/10/02)
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- SYNTHESIS AND STRUCTURE OF 5-HYDRAZINO- AND 5-HYDROXYAMINO-3-ARYL-2-PYRAZOLINES AND -2-ISOXAZOLES
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It was established by the methods of 1H and 13C NMR spectroscopy that the oximohydrazones and bis(hydrazones) of aroylacetic aldehydes exist in the form of the corresponding 5-hydrazino- and 5-hydroxyamino-3-aryl-pyrazolines and -2-isoxazolines.The features of the aromatization of these compounds to the corresponding pyrazoles and isoxazoles were studied.Data on the mass-spectral study of the 5-hydroxyamino-2-pyrazoline-5-hydrazino-2-isoxazoline tautomerism in the gas phase are presented.
- Zelenin, K. N.,Malov, M. Yu.,Ershov, A. Yu.,Terent'ev, P. B.,Kalandarishvili, A. G.,et al.
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p. 772 - 779
(2007/10/02)
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- CHIRAL ACETYLENES AS SYNTHETIC INTERMEDIATES. V. A REINVESTIGATION ON THE SYNTHESIS OF OPTICALLY ACTIVE ISOXAZOLES
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The synthesis of 3- or 5-alkyl isoxazoles and pyrazoles has been achieved starting from alkyl-substituted acetylenic ketones: the influence of the structure of the carbonyl compound on the isomeric composition of the heterocyclic compound has been studied.Some optically active monoalkyl-substituted isoxazoles have also been prepared: in this context, an investigation on the stereochemistry of the cyclization process has been carried out.
- Falorni, Massimo,Lardicci, Luciano,Giacomelli, Giampaolo
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- THE REACTIONS OF ISOTHIAZOLIUM SALTS WITH NITROGEN NUCLEOPHILIC REAGENTS
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Isothiazolium salts were allowed to react with a number of nitrogen nucleophiles including ammonia, hydrazine, phenylhydrazine, hydroxylamine, and benzylamine.The products obtained suggest that the position of initial nucleophilic attack is at the sulphur
- Hassan, Mohamed E.,Magraby, M. A.,Aziz, Magda A.
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p. 1885 - 1892
(2007/10/02)
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- THE CHEMISTRY OF FULMINIC ACID REVISED
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The availability of a new synthesis of fulminic acid by hydrolysis of trimethylsilanecarbonitrile oxide allowed a reinvestigation of the chemistry of the title compound.Thus, cycloadditions to olefinic and acetylenic dipolarophiles are improved with respect to previous results and the oligomerisation is proved to occur via the reactive species hydroxyiminoacetonitrile oxide 7 and hydroxyiminomethyl-hydroxyimino-acetonitrile oxide 8.The Z-configuration, found for the oxime groups in these intermediates, is maintained in their derivatives, under kinetic control.
- Sarlo, Francesco De,Guarna, Antonio,Brandi, Alberto,Goti, Andrea
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p. 5181 - 5186
(2007/10/02)
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- New Synthesis of Pyrazole and Isoxazole Derivatives
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A convenient synthesis of 5-aryl-1-phenylpyrazoles and 5-arylisoxazoles, from readily available ketimine 1 dimethylformamide dimethylacetal and phenylhydrazine or hydroxylamine, is described.
- Molina, P.,Fresneda, P. M.
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p. 461 - 464
(2007/10/02)
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- SYNTHESIS AND REARRANGEMENT OF CYCLOADDUCTS FROM TRIMETHYLSILANECARBONITRILE OXIDE
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The cycloadducts from trimethylsilanecarbonitrile oxide and ethylenic or acetylenic compounds easily rearrange to open-chain intermediates, which, in turn, are hydrolysed respectively to β-hydroxynitriles and β-oxonitriles.The cycloadducts of the same nitrile oxide with sulfur dioxide and sulfinylamines are unstable, too, leading respectively to trimethylsilylisocyanate and trimethylsilylcarbodiimides.All these reactions are of preparative interest, in comparison with previous methods.
- Sarlo, Francesco De,Brandi, Alberto,Goti, Andrea,Guarna, Antonio,Rovero, Paolo
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p. 511 - 518
(2007/10/02)
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- SIMPLE IN SITU PREPARATION OF FULMINIC ACID
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Fulminic acid, generated in situ by hydrolysis of trimethylsilanecarbonitrile oxide, is employed in cycloaddition reactions.
- Sarlo, Francesco De,Brandi, Alberto,Guarna, Antonio,Goti, Andrea,Corezzi, Silvia
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p. 1815 - 1816
(2007/10/02)
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- Halogenation of Vinyl Ketoximes. Synthesis of Isoxazoles and Preparation and Silver Ion-Promoted Reactions of 4-Halo-2-isoxazolines
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Reaction of several α,β-unsaturated ketoximes with N-bromosuccinimide (NBS) gave isoxazoles, but yields were lower and the reaction less general than a similar transformation using iodine under basic conditions.With β,β-disubstituted oximes, 4-halo-5,5-disubstituted-2-isoxazolines were obtained using NBS, iodine, or N-chlorosuccinimide.Treatment of the 4-bromoisoxazolines with silver acetate or silver nitrate caused either elimination with rearrangement to give isoxazoles or substitution at C-4, depending upon the nature of the substituents at C-5.
- Hansen, John F.,Kim, Yong In,McCrotty, Stephen E.,Strong, Scott A.,Zimmer, Douglas E.
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p. 475 - 479
(2007/10/02)
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