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Artículos de revistas sobre el tema "Imine acids"

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Publicado: 18 de mayo de 2024

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1

Zarei, Maaroof. "One-step Synthesis of β-lactams Using Cyanuric Fluoride". Journal of Chemical Research 37, n.º 1 (enero de 2013): 25–27. http://dx.doi.org/10.3184/174751912x13545429290478.

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Cyanuric fluoride works as an efficient acid activator reagent for the direct [2+2] ketene–imine cycloaddition of substituted acetic acids and imines in a one-pot synthesis under mild conditions. The yields are good to excellent and the reaction conditions are mild, simple and efficient.
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2

Wulff, William, Xin Zhang y Yijing Dai. "The Acceleration of the Rearrangement of α-Hydroxy Aldimines by Lewis or Brønsted Acids". Synlett 29, n.º 15 (28 de agosto de 2018): 2015–18. http://dx.doi.org/10.1055/s-0037-1610262.

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An efficient method was developed for the synthesis of α-amino ketones from α-hydroxy imines. The reaction occurs through an α-iminol rearrangement involving the migration of a substituent of the carbinol carbon to the imine carbon. The optimal catalysts were found to be silica gel or montmorillonite K 10, which effected migration of a variety of aryl and alkyl substituents in high yields. The rearrangement can also be carried out on imines generated in situ from aldehydes and amines in essentially the same yields as those from the preformed imines.
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3

Sikervar, Vikas, Ravindra Sonawane, Raghuramaiah Mandadapu, Amol Satish Dehade, Shrikant Abhiman Shete y Mark Montgomery. "Lewis Acid Mediated [3+2] and [3+3] Annulations of an Azomethine Imine with Donor–Acceptor Cyclopropanes". Synthesis 53, n.º 16 (10 de mayo de 2021): 2865–73. http://dx.doi.org/10.1055/a-1503-8068.

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AbstractTwo different Lewis acids were used for developing [3+2] and [3+3] regioselective cycloaddition reactions of an azomethine imine with activated cyclopropanes. Scandium(III) triflate catalyzes a [3+2] cycloaddition reaction of the azomethine imine with cyclopropanes to form tetrahydropyrazolone derivatives and tricyclic tetrahydrofuran derivatives in moderate yields. Complementary to this, a novel [3+3] cycloaddition reaction of the azomethine imine with activated cyclopropanes was developed by using EtAlCl2 as a Lewis acid to form hexahydropyridazinone derivatives in high regioselectivity.
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4

Morales Salazar, Daniel, Arvind Kumar Gupta y Andreas Orthaber. "Reactivity studies of an imine-functionalised phosphaalkene; unusual electrostatic and supramolecular stabilisation of a σ2λ3-phosphorus motif via hydrogen bonding". Dalton Transactions 47, n.º 31 (2018): 10404–9. http://dx.doi.org/10.1039/c8dt01607k.

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5

Alex, S., P. Turcotte, R. Fournier y D. Vocelle. "Study of the protonation of simple Schiff bases in solvents of various polarity by means of Raman spectroscopy". Canadian Journal of Chemistry 69, n.º 2 (1 de febrero de 1991): 239–45. http://dx.doi.org/10.1139/v91-038.

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In this study, the protonation of simple Schiff bases by organic acids in various solvents is investigated by Raman spectroscopy and the spectral response of the C=N+ stretching mode is correlated with the macroscopic properties of the medium surrounding the imine. Upon protonation, the unperturbed C=N stretch increases in frequency due to the combination of the coupling with the C=N+H bend and a partial rehybridization of the C=N bond. Depending on the proton location relative to that of its counterion, one mechanism may prevail over the other. Intensity measurements show that protonation is mostly controlled by the hydrogen bonding properties of the solvent and by the polarity of the medium. However, whatever the solvent, full proton transfer cannot be achieved with organic acids with pKa similar to the COOH of amino acids found in visual or bacterial pigments, meaning that the protonation mechanism may depend upon particular properties of the protein. Key words: imines, protonation, Raman spectroscopy, rhodopsin, Schiff base.
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6

Wang, Hao-Ran, En-He Huang, Chen Luo, Wen-Feng Luo, Yin Xu, Peng-Cheng Qian, Jin-Mei Zhou y Long-Wu Ye. "Copper-catalyzed tandem cis-carbometallation/cyclization of imine-ynamides with arylboronic acids". Chemical Communications 56, n.º 35 (2020): 4832–35. http://dx.doi.org/10.1039/d0cc01424a.

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An efficient copper-catalyzed regioselective cis-carbometallation/cyclization of imine-ynamides with arylboronic acids enables the facile and practical synthesis of valuable 2,3-disubstituted indolines.
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7

Bissonnette, Martine, Hoa Le Thanh y Daniel Vocelle. "Interaction of strong acids with a conjugated imine". Canadian Journal of Chemistry 63, n.º 8 (1 de agosto de 1985): 2298–302. http://dx.doi.org/10.1139/v85-379.

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The state of protonation of a Schiff base, trans-trans-heptadienylidene tert-butylamine (HBA) was evaluated by uv and 1H nmr spectroscopies. Using three strong acids, HCl, HBr, HI and by taking spectra at low temperatures, it was found that in a non-polar solvent like chloroform (or CDCl3), no proton exchange occurred between the iminium ion and the halide anion. In contrast, CD3OH induced a leveling effect and some proton transfer occurred between the iminium ion and the solvent for the HBr and HI salts. No proton exchange was present for the HBA:HCl salt. The interaction of trichloroacetic acid with HBA was also studied: full proton exchange occurred between the iminium ion and CD3OH. In CDCl3, proton transfer was also present between the iminium ion and the carboxylate anion. These facts are discussed in relation with the controversy surrounding the true state of protonation of rhodopsin.
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8

Bakulina, Olga, Alexander Ivanov, Vitalii Suslonov, Dmitry Dar’in y Mikhail Krasavin. "A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline". Beilstein Journal of Organic Chemistry 13 (18 de julio de 2017): 1413–24. http://dx.doi.org/10.3762/bjoc.13.138.

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A series of 15 benzene-fused hexahydropyrrolo[1,2-b]isoquinolonic acids with substantial degree of steric encumbrance has been prepared via a novel variant of the Castagnoli–Cushman reaction of homophthalic anhydride (HPA) and various indolenines. The employment of a special kind of a cyclic imine component reaction allowed, for the first time, isolating a Mannich-type adduct between HPA and an imine component which has been postulated but never obtained in similar reactions.
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9

Zaccheria, Federica, Federica Santoro, Elvina Iftitah y Nicoletta Ravasio. "Brønsted and Lewis Solid Acid Catalysts in the Valorization of Citronellal". Catalysts 8, n.º 10 (22 de septiembre de 2018): 410. http://dx.doi.org/10.3390/catal8100410.

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Terpenes are valuable starting materials for the synthesis of molecules that are of interest to the flavor, fragrance, and pharmaceutical industries. However, most processes involve the use of mineral acids or homogeneous Lewis acid catalysts. Here, we report results obtained in the liquid-phase reaction of citronellal with anilines under heterogeneous catalysis conditions to give tricyclic compounds with interesting pharmacological activity. The terpenic aldehyde could be converted into octahydroacridines with a 92% yield through an intramolecular imino Diels–Alder reaction of the imine initially formed in the presence of an acidic clay such as Montmorillonite KSF. Selectivity to the desired product strongly depended on the acid sites distribution, with Brønsted acids favoring selectivity to octahydroacridine and formation of the cis isomer. Pure Lewis acids such as silica–alumina with a very low amount of alumina gave excellent results with electron-rich anilines like toluidine and p-anisidine. This protocol can be applied starting directly from essential oils such as kaffir lime oil, which has a high citronellal content.
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10

Ahmad, Rasool, Rizwan, Altaf, Rashid, Mahmood y Ayub. "Role of Pyridine Nitrogen in Palladium-Catalyzed Imine Hydrolysis: A Case Study of (E)-1-(3-bromothiophen-2-yl)-N-(4-methylpyridin-2-yl)methanimine". Molecules 24, n.º 14 (17 de julio de 2019): 2609. http://dx.doi.org/10.3390/molecules24142609.

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In the present study, 4-methylpyridin-2-amine was reacted with 3-bromothiophene-2-carbaldehyde and the Schiff base (E)-1-(3-bromothiophen-2-yl)-N-(4-methylpyridin-2-yl)methanimine was obtained in a 79% yield. Coupling of the Schiff base with aryl/het-aryl boronic acids under Suzuki coupling reaction conditions, using Pd(PPh3)4 as catalyst, yielded products with the hydrolysis of the imine linkages (5a–5k, 6a–6h) in good to moderate yields. To gain mechanistic insight into the transition metal-catalyzed hydrolysis of the compounds, density functional theory (DFT) calculations were performed. The theoretical calculations strongly supported the experiment and provided an insight into the transition metal-catalyzed hydrolysis of imines.
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11

Jung, Seunghee, Yuya Kawashima, Takuya Noguchi y Nobuyuki Imai. "Synthesis of Acetaminophen Analogues Containing α-Amino Acids and Fatty Acids for Inhibiting Hepatotoxicity". Synthesis 51, n.º 19 (15 de julio de 2019): 3683–96. http://dx.doi.org/10.1055/s-0037-1611893.

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Acetaminophen is a popular antipyretic analgesic medicine that has weaker anti-inflammatory properties and lower incidence of side effects than nonsteroidal anti-inflammatory drugs (NSAIDs). However, acetaminophen causes hepatotoxicity due to the reactive metabolite N-acetyl-p-benzoquinone imine (NAPQI). We have obtained acetaminophen analogues in 57–99% yields by using aniline derivatives with protected α-amino acids and fatty acids via the corresponding mixed carbonic carboxylic anhydrides in aqueous MeCN. We have also succeeded in synthesizing AM404 analogues in 76–97% yields, which are expected to be promising candidates for reducing hepatotoxicity.
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12

Sawada, Daichi, Ayana Hirono, Kouichi Asakura y Taisuke Banno. "pH-Tolerant giant vesicles composed of cationic lipids with imine linkages and oleic acids". RSC Advances 10, n.º 56 (2020): 34247–53. http://dx.doi.org/10.1039/d0ra06822e.

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13

Wang, Guohong, Min Li, Wenmin Pang, Min Chen y Chen Tan. "Lewis acids in situ modulate pyridazine-imine Ni catalysed ethylene (co)polymerisation". New Journal of Chemistry 43, n.º 34 (2019): 13630–34. http://dx.doi.org/10.1039/c9nj01243e.

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The Lewis acid-base interaction between B(iii) Lewis acids and the pyridazine moiety reduced the electron density from the Ni center and in situ modulated the pyridazine-imine nickel catalyzed ethylene (co)polymerisation.
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14

List, Benjamin, Vijay N. Wakchaure y Carla Obradors. "Chiral Brønsted Acids Catalyze Asymmetric Additions to Substrates that Are Already Protonated: Highly Enantioselective Disulfonimide-Catalyzed Hantzsch Ester Reductions of NH–Imine Hydrochloride Salts". Synlett 31, n.º 17 (14 de agosto de 2020): 1707–12. http://dx.doi.org/10.1055/s-0040-1706413.

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While imines are frequently used substrates in asymmetric Brønsted acid catalysis, their corresponding salts are generally considered unsuitable reaction partners. Such processes are challenging because they require the successful competition of a catalytic amount of a chiral anion with a stoichiometric amount of an achiral one. We now show that enantiopure disulfonimides enable the asymmetric reduction of N–H imine hydrochloride salts using Hantzsch esters as hydrogen source. Our scalable reaction delivers crystalline primary amine salts in great efficiency and enantioselectivity and the discovery suggests potential of this approach in other Brønsted acid catalyzed transformations of achiral iminium salts. Kinetic studies and acidity data suggest a bifunctional catalytic activation mode.
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15

Livingstone, Keith, Sophie Bertrand, Jenna Mowat y Craig Jamieson. "Metal-free C–C bond formation via coupling of nitrile imines and boronic acids". Chemical Science 10, n.º 44 (2019): 10412–16. http://dx.doi.org/10.1039/c9sc03032h.

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16

Shatskiy, Andrey, Anton Axelsson, Elena V. Stepanova, Jian-Quan Liu, Azamat Z. Temerdashev, Bhushan P. Kore, Björn Blomkvist, James M. Gardner, Peter Dinér y Markus D. Kärkäs. "Stereoselective synthesis of unnatural α-amino acid derivatives through photoredox catalysis". Chemical Science 12, n.º 15 (2021): 5430–37. http://dx.doi.org/10.1039/d1sc00658d.

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A protocol for stereoselective C-radical addition to a chiral glyoxylate-derived N-sulfinyl imine was developed through visible light-promoted photoredox catalysis, providing a convenient method for the synthesis of unnatural α-amino acids.
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17

KOBAYASHI, Shû y Haruro ISHITANI. "Catalytic Activation of Imine Derivatives Using Novel Lewis Acids." Journal of Synthetic Organic Chemistry, Japan 56, n.º 5 (1998): 357–67. http://dx.doi.org/10.5059/yukigoseikyokaishi.56.357.

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18

Roche, Stéphane P. "In the Pursuit of (Ald)Imine Surrogates for the Direct Asymmetric Synthesis of Non-Proteinogenic α-Amino Acids". Synthesis 53, n.º 16 (24 de marzo de 2021): 2767–76. http://dx.doi.org/10.1055/a-1463-4266.

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AbstractNature remarkably employs posttranslational modifications of the 20 canonical α-amino acids to devise a far larger structural, conformational, and functional diversity found in non-proteinogenic amino acids (NPAAs), which ultimately translates into a plethora of complex biological functions. Synthetic chemists are continuously trying to reproduce and even extrapolate the repertoire of NPAA building blocks to build structural diversity into bioactive molecules and materials. The direct asymmetric functionalization of α-imino esters represents one of the most robust and attractive routes to NPAAs. This review summarizes the most prominent examples of bench-stable (ald)imine surrogates exploited for the synthesis of NPAAs, including our most recent results in the nucleophilic substitution of α-haloglycines and other α-halo­aminals. A synopsis of kinetic studies, reaction optimizations, and enantio­selective catalytic methods is also presented.1 Introduction2 Asymmetric Synthesis of Tertiary α-Substituted NPAAs2.1 From N,O-Acetals (α-Hydroxy/Alkyloxy/Acetoxyglycines)2.2 From α-Amido Sulfones2.3 From α-Haloglycine Esters2.4 From N,O-Bis(Boc) Hydroxyglycine3 Asymmetric Synthesis of Acyclic Quaternary α,α-Disubstituted NPAAs4 Concluding Remarks
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19

Meyer, Timo, Nadine Zumbrägel, Christina Geerds, Harald Gröger y Hartmut H. Niemann. "Structural Characterization of an S-enantioselective Imine Reductase from Mycobacterium Smegmatis". Biomolecules 10, n.º 8 (31 de julio de 2020): 1130. http://dx.doi.org/10.3390/biom10081130.

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NADPH-dependent imine reductases (IREDs) are enzymes capable of enantioselectively reducing imines to chiral secondary amines, which represent important building blocks in the chemical and pharmaceutical industry. Since their discovery in 2011, many previously unknown IREDs have been identified, biochemically and structurally characterized and categorized into families. However, the catalytic mechanism and guiding principles for substrate specificity and stereoselectivity remain disputed. Herein, we describe the crystal structure of S-IRED-Ms from Mycobacterium smegmatis together with its cofactor NADPH. S-IRED-Ms belongs to the S-enantioselective superfamily 3 (SFam3) and is the first IRED from SFam3 to be structurally described. The data presented provide further evidence for the overall high degree of structural conservation between different IREDs of various superfamilies. We discuss the role of Asp170 in catalysis and the importance of hydrophobic amino acids in the active site for stereospecificity. Moreover, a separate entrance to the active site, potentially functioning according to a gatekeeping mechanism regulating access and, therefore, substrate specificity is described.
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20

Hartshorn, RM y AM Sargeson. "Reactions of Chelated β-Functionalized Amino Acids With Thionyl Chloride". Australian Journal of Chemistry 45, n.º 1 (1992): 5. http://dx.doi.org/10.1071/ch9920005.

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A variety of bis (ethane-1,2-diamine)cobalt(III) complexes containing chelated β-functionalized amino acids have been treated with SOCl2 in dimethylformamide. These compounds undergo β-elimination reactions to give chelated enamines followed by either rearrangement to the related imine complexes or further reactions with SOCl2 to give chelated isothiazole-3-carboxylato complexes. Mechanisms are proposed for the reactions.
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21

Canta, Alessandra, Karin I. Öberg y Mahesh Rajappan. "The Formation of Imines and Nitriles during VUV Photoirradiation of NH3:C2H x Ice Mixtures". Astrophysical Journal 953, n.º 1 (1 de agosto de 2023): 81. http://dx.doi.org/10.3847/1538-4357/acda99.

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Abstract Nitriles are key reactants in prebiotic synthesis networks of RNA bases and amino acids. The detection of CH3CN and other complex nitriles in planet-forming disks suggests that such molecules are regularly delivered to nascent planets, increasing the likelihood of origins of life outside of Earth. In this paper, we investigate the formation of CH3CN and the closely related imines from the vacuum ultraviolet irradiation of NH3:C2H6, NH3:C2H4, and NH3:C2H2 ice mixtures at 10–50 K. CH3CN is formed in a subset of these experiments, with the highest yield of ∼5% with respect to the initial NH3 abundance achieved at the lowest ice temperatures for the least saturated hydrocarbon ice mixture. We find that the imine CH3CH=NH serves as an intermediate for the production of CH3CN in all ices and its yield generally appears higher than that of CH3CN. If the investigated ice chemistry is an important formation pathway of nitriles, we should observe CH3CH=NH > CH3CN. The opposite is true toward the Galactic Center, while no published constraints on CH3CH=NH exist in disks. Such constraints are needed to distinguish between the formation pathway presented in this work and other possible gas and ice nitrile formation pathways in different astrophysical environments. In the meantime, we conclude that NH3:hydrocarbon ice photochemistry is an excellent candidate for efficient low-temperature interstellar imine production.
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22

Lu, S. P. y Anita H. Lewin. "Enamine/imine tautomerism in α,β-unsaturated-α-amino acids". Tetrahedron 54, n.º 50 (diciembre de 1998): 15097–104. http://dx.doi.org/10.1016/s0040-4020(98)00908-9.

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23

Zagraniarsky, Yulian, Bojidarka Ivanova, Karamfil Nikolov, Sabi Varbanov y Tsvetanka Cholakova. "Synthesis of Dimethylphosphinyl-substituted α-Amino(aryl)methylphosphonic Acids and Their Esters". Zeitschrift für Naturforschung B 63, n.º 10 (1 de octubre de 2008): 1192–98. http://dx.doi.org/10.1515/znb-2008-1009.

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AbstractDimethylphosphinylmethylamine (1) and its aldimines 2 were used for the preparation of dimethyl and diethyl α-amino(aryl)methylphosphonates 3a - l via imine hydrophosphonylation and Kabachnik-Fields reaction. Their acid hydrolysis gave rise to the corresponding α-aminophosphonic acids 4a - e. Compounds 3 and 4 have two different phosphorus-containing groups - phosphonyl and dimethylphosphinyl - and might have interesting biological activity.
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24

Wang, Ziyang, Xiao Lin, Xuling Chen, Pengfei Li y Wenjun Li. "Organocatalytic stereoselective 1,6-addition of thiolacetic acids to alkynyl indole imine methides: access to axially chiral sulfur-containing tetrasubstituted allenes". Organic Chemistry Frontiers 8, n.º 13 (2021): 3469–74. http://dx.doi.org/10.1039/d1qo00394a.

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A chiral phosphoric acid-catalyzed enantioselective 1,6-conjugate addition of thiolacetic acid to alkynyl indole imine methide in situ formed from α-(3-indolyl) propargylic alcohol has been established.
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25

Monnier, Karin, Gérard Schmitt, Bernard Laude, Marie-France Mercier, Marek M. Kubicki y Michel Jannin. "Étude de la stéréochimie de la réaction de cycloaddition dipolaire-1,3 de quelques 5-phényl-3,6-dihydro-2H-1,4-oxazin-2-ones avec les N-méthyl et N-phénylmaléimides". Canadian Journal of Chemistry 73, n.º 2 (1 de febrero de 1995): 181–90. http://dx.doi.org/10.1139/v95-027.

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Six derivatives of 5-phenyl-3,4-dihydro-2H-1,4-oxazin-2-ones 1 were synthetized from α-amino acids. These compounds are precursors of six-membered cyclic azomethine ylids involving one stereocenter. The 1,3-dipolar species react with N-methyl and N-phenylmaleimides, leading diastereospecifically to cycloadducts where the approach of the dipolarophile occurs from the less hindered side of the 1,3-dipole and with the maleimido moiety in an exo position. Unfortunately, racemization was observed during the cycloaddition reaction, presumably owing to reversible imine–enamine transformation. Keywords: α-amino acids, cyclic azomethine ylids, diastereospecificity.
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26

Hussein, Buthaina, Laurance M. S. Bourghli, Muhammed Alzweiri, Yusuf Al-Hiari, Mohammad Abu Sini, Soraya Alnabulsi y Batool Al-Ghwairi. "Synthesis and Biological Evaluation of Carbonic Anhydrase III and IX Inhibitors using Gas Chromatography with Modified pH Sensitive Pellets". Jordan Journal of Pharmaceutical Sciences 16, n.º 2 (24 de julio de 2023): 426–39. http://dx.doi.org/10.35516/jjps.v16i2.1470.

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Fifteen compounds were synthesized and tested as potential carbonic anhydrase III (CAIII) and carbonic anhydrase IX (CAIX) inhibitors, six of which are novel. Amides (a1-4), hydroxamic acids (b1-2), and imines (c1-9) derivatives were evaluated for their inhibitory activity against CAII and CAIX using gas chromatography with modified pH-sensitive pellets. The derivatives showed inhibition percentages between 12-56% for CAIII and 44-59% for CAIX, compared to 49% and 63% for captopril (the positive control), respectively. Imines showed the best inhibition of CAIII, while all derivatives showed comparable activity against CAIX. It is hypothesized that the nitrogen atom in imine, amide, or hydroxamic acid moieties in the vicinity of an ionizable group is in coordination with the zinc ion in the active site. Furthermore, the candidates were tested for their antimicrobial and antifungal activity. Generally, they showed low to zero activity against some gram-positive and negative bacteria. This supports the theory of their ability to bind to human carbonic anhydrase but not to bacterial one. These compounds could serve as useful scaffolds to develop more potent and selective carbonic anhydrase inhibitors as anti-obesity and anticancer candidates.
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27

Hammershoei, Anders, Richard M. Hartshorn y Alan M. Sargeson. "Oxidation of chelated amino acids to imine derivatives with thionyl chloride". Inorganic Chemistry 29, n.º 22 (octubre de 1990): 4525–30. http://dx.doi.org/10.1021/ic00347a039.

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28

KOBAYASHI, S. y H. ISHITANI. "ChemInform Abstract: Catalytic Activation of Imine Derivatives Using Novel Lewis Acids". ChemInform 29, n.º 42 (19 de junio de 2010): no. http://dx.doi.org/10.1002/chin.199842298.

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29

Trifonov, Latchezar S. y Alexander S. Orahovats. "Cycloaddition of Carbodiimides and Triphenylketen-imine to Allenic Acids. Preliminary Communication". Helvetica Chimica Acta 69, n.º 7 (29 de octubre de 1986): 1585–87. http://dx.doi.org/10.1002/hlca.19860690711.

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30

Zahardis, J., S. Geddes y G. A. Petrucci. "The ozonolysis of primary aliphatic amines in single and multicomponent fine particles". Atmospheric Chemistry and Physics Discussions 7, n.º 5 (15 de octubre de 2007): 14603–38. http://dx.doi.org/10.5194/acpd-7-14603-2007.

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Abstract. The oxidative processing by ozone of the particulate amines octadecylamine (ODA) and hexadecylamine (HDA) is reported. Ozonolysis of these amines resulted in strong NO2− and NO3− ion signals that increased with ozone exposure as monitored by photoelectron resonance capture ionization aerosol mass spectrometry. These products suggest a mechanism of progressive oxidation of the particulate amines to nitro alkanes. Additionally, a strong ion signal at 125 m/z is assigned to the ion NO3−(HNO3). For ozonized mixed particles containing ODA or HDA + oleic acid (OL), with pO3≥3×10−7 atm, imine, secondary amide, and tertiary amide products were measured. These products most likely arise from reactions of amines with aldehydes (for imines) and stabilized Criegee intermediates (SCI) or secondary ozonides (for amides) from the fatty acid. The routes to amides via SCI and/or secondary ozonides was shown to be more important than comparable amide forming reactions between amines and organic acids, using azelaic acid as a test compound. Finally, direct evidence is provided for the formation of a surface barrier in the ODA + OL reaction system that resulted in the retention of OL at high ozone exposures (up to 10−3 atm for 17 s). This effect was not observed in HDA + OL or single component OL particles, suggesting that it may be a species-specific surfactant effect from an in situ generated amide or imine. Implications to tropospheric chemistry, including particle bound amines as sources of oxidized gas phase nitrogen species (e.g. NO2, NO3), formation of nitrogen enriched HULIS via ozonolysis of amines and source apportionment are discussed.
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31

Zahardis, J., S. Geddes y G. A. Petrucci. "The ozonolysis of primary aliphatic amines in fine particles". Atmospheric Chemistry and Physics 8, n.º 5 (29 de febrero de 2008): 1181–94. http://dx.doi.org/10.5194/acp-8-1181-2008.

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Abstract. The oxidative processing by ozone of the particulate amines octadecylamine (ODA) and hexadecylamine (HDA) is reported. Ozonolysis of these amines resulted in strong NO2– and NO3– ion signals that increased with ozone exposure as monitored by photoelectron resonance capture ionization aerosol mass spectrometry. These products suggest a mechanism of progressive oxidation of the particulate amines to nitroalkanes. Additionally, a strong ion signal at 125 m/z is assigned to the ion NO3– (HNO3). For ozonized mixed particles containing ODA or HDA + oleic acid (OL), with pO3≥3×10–7 atm, imine, secondary amide, and tertiary amide products were measured. These products most likely arise from reactions of amines with aldehydes (for imines) and stabilized Criegee intermediates (SCI) or secondary ozonides (for amides) from the fatty acid. The routes to amides via SCI and/or secondary ozonides were shown to be more important than comparable amide forming reactions between amines and organic acids, using azelaic acid as a test compound. Finally, direct evidence is provided for the formation of a surface barrier in the ODA + OL reaction system that resulted in the retention of OL at high ozone exposures (up to 10−3 atm for 17 s). This effect was not observed in HDA + OL or single component OL particles, suggesting that it may be a species-specific surfactant effect from an in situ generated amide or imine. Implications to tropospheric chemistry, including particle bound amines as sources of oxidized gas phase nitrogen species (e.g.~NO2, NO3), formation of nitrogen enriched HULIS via ozonolysis of amines and source apportionment are discussed.
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32

Bacha, Katia, Julien Estager, Sylvie Brassart-Pasco, Catherine Chemotti, Antony E. Fernandes, Jean-Pierre Mbakidi, Magali Deleu y Sandrine Bouquillon. "Synthesis and Activity of Ionic Antioxidant-Functionalized PAMAMs and PPIs Dendrimers". Polymers 14, n.º 17 (27 de agosto de 2022): 3513. http://dx.doi.org/10.3390/polym14173513.

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For this study, new dendrimers were prepared from poly(propylene imine) (PPI) and polyamidoamine (PAMAM) dendrimers using an efficient acid-base reaction with various phenolic acids. The syntheses were also optimized in both microwave and microfluidic reactors. These ionic and hydrophilic dendrimers were fully characterized and showed excellent antioxidant properties. Their cytotoxic properties have been also determined in the case of fibroblast dermal cells.
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33

Wu, Anxin, Jungang Wang, Yan Cheng y Jiachen Xiang. "Synthesis of 2,5-Disubstituted Oxazoles from Arylacetylenes and α-Amino Acids through an I2/Cu(NO3)2•3H2O-Assisted Domino Sequence". Synlett 30, n.º 06 (7 de febrero de 2019): 743–47. http://dx.doi.org/10.1055/s-0037-1612087.

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A new strategy has been developed for the synthesis of 2,5-disubstituted oxazoles from easily available arylacetylenes and α-amino acids in the presence of Cu(NO3)2•3H2O and iodine. This reaction ­process involves the I2/Cu(NO3)2•3H2O-assisted transformation of ­arylacetylene to α-iodo acetophenone, Kornblum oxidation to phenylglyoxal, condensation to imine, decarboxylation/annulation/oxidation reaction sequence to approach 2,5-disubstituted oxazoles.
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34

Carvalho, M. Fernanda N. N., M. João Ferreira, Ana S. O. Knittel, Maria da Conceição Oliveira, João Costa Pessoa, Rudolf Herrmann y Gabriele Wagner. "Strecker degradation of amino acids promoted by a camphor-derived sulfonamide". Beilstein Journal of Organic Chemistry 12 (18 de abril de 2016): 732–44. http://dx.doi.org/10.3762/bjoc.12.73.

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A camphor-derived sulfonimine with a conjugated carbonyl group, oxoimine 1 (O2SNC10H13O), reacts with amino acids (glycine, L-alanine, L-phenylalanine, L-leucine) to form a compound O2SNC10H13NC10H14NSO2 (2) which was characterized by spectroscopic means (MS and NMR) and supported by DFT calculations. The product, a single diastereoisomer, contains two oxoimine units connected by a –N= bridge, and thus has a structural analogy to the colored product Ruhemann´s purple obtained by the ninhydrin reaction with amino acids. A plausible reaction mechanism that involves zwitterions, a Strecker degradation of an intermediate imine and water-catalyzed tautomerizations was developed by means of DFT calculations on potential transition states.
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35

Senthil Kumar Raju, Archana Settu, Archana Thiyagarajan, Divya Rama, Praveen Sekar y Shridharshini Kumar. "Synthetic approaches of medicinally important Schiff bases: An updated Review". World Journal of Advanced Research and Reviews 16, n.º 3 (30 de diciembre de 2022): 838–52. http://dx.doi.org/10.30574/wjarr.2022.16.3.1394.

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The Schiff base defined by an imine or azomethine (-CH= N-) group, is mostly synthesized by the condensation reaction of carbonyl compounds (Aldehyde or Ketone) with compounds consisting of amine moiety. Schiff bases are among the most chiefly used organic compounds, revealing a wide range of applications, such as electroluminescent effects, fluorescence properties, nonlinear optical and chemosensory properties. The typical Schiff bases are crystalline solids that are basic, although at least some of them combine with strong acids to generate insoluble salt. Schiff bases are widely used in the pharmaceutical, electronic, cosmetic and polymer industries. Schiff bases use various alpha-amino acids and aldehydes in acidic or basic conditions. Schiff bases form a new class of drugs that can strengthen the immune system and also be used in the treatment of various ailments. The C=N imine bond's electrophilic carbon and nucleophilic nitrogen offer great binding chances with many nucleophiles and electrophiles, which can be used to suppress specific diseases, enzymes or DNA replication. These Schiff bases are synthesized from various aldehydes or ketones and amines under stirring conditions, catalyst-free, reflux conditions, conventional methods, microwave irradiation and ultrasonic conditions. Thus, Schiff bases and their derivatives can be synthesized using various techniques and may be further used for enormous biological applications with potent effects.
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36

Shavrina, Oksana, Lyudmyla Bezgubenko, Andrii Bezdudny, Petro Onys’ko y Yuliya Rassukana. "α-(Imino)pyridyldifluoroethyl Phosphonates: Novel Promising Building Blocks in Synthesis of Biorelevant Aminophosphonic Acids Derivatives". Organics 2, n.º 2 (23 de abril de 2021): 72–83. http://dx.doi.org/10.3390/org2020007.

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A convenient synthetic approach to previously unknown NH-iminophosphonates bearing 2-, 3-, and 4-pyridyldifluoromethyl groups at the imine carbon atom was developed. The synthetic potential of these novel building blocks was demonstrated by their conversion into highly functionalized acyclic and heterocyclic aminophosphonates and phosphonic acids combining in their structure biorelevant aminophosphonic fragment, difluoromethyl group, and pyridyl, piperidyl, thiazolidin-4-one, or thiazidinan-4-one heterocyclic moieties in a single molecular platform.
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37

Rössner, J., J. Velíšek, F. Pudil y J. Davídek. "Strecker degradation products of aspartic and glutamic acids and their amides". Czech Journal of Food Sciences 19, No. 2 (7 de febrero de 2013): 41–45. http://dx.doi.org/10.17221/6573-cjfs.

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Aspartic and glutamic acids, asparagine and glutamine were oxidised with either potassium peroxodisulphate or glyoxal. Nonvolatile products were derivatised and analysed by GC/FID and GC/MS. Volatile reaction products were isolated and analysed by the same methods. It was found that the degradation reactions of amino acids are complex. Amino acids are principally degraded via the corresponding a-keto acids to Strecker aldehydes (aspartic acid to oxalacetic and 3-oxopropionic acids and glutamic acid to a-ketoglutaric and 4-oxobutyric acids), which are unstable and decomposed by decarboxylation to the corresponding aldehydes. Aspartic acid also eliminates ammonia and yields fumaric acid whereas glutamic acid gives rise to an imine, pyroglutamic acid. A recombination of free radicals leads to dicarboxylic acids (succinic acid from aspartic acid, succinic, glutaric and adipic acids from glutamic acid). The major volatile products (besides the aldehydes) are lower carboxylic acids (acetic acid from aspartic acid and propionic acid acid from glutamic acid) that can at least partly arise by radical reactions. In both quality and quantity terms, a higher amount of degradation products arises by oxidation of amino acids by peroxodisulphate.
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38

Truong, Vouy Linh y Jennifer Y. Pfeiffer. "Rhodium-catalyzed diastereoselective 1,2-addition of arylboronic acids to chiral trifluoroethyl imine". Tetrahedron Letters 50, n.º 14 (abril de 2009): 1633–35. http://dx.doi.org/10.1016/j.tetlet.2009.01.112.

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39

Roy, Susmita, Tanmay Chatterjee, Biplab Banerjee, Noor Salam, Asim Bhaumik y Sk Manirul Islam. "Cu(ii) anchored nitrogen-rich covalent imine network (CuII-CIN-1): an efficient and recyclable heterogeneous catalyst for the synthesis of organoselenides from aryl boronic acids in a green solvent". RSC Adv. 4, n.º 86 (2014): 46075–83. http://dx.doi.org/10.1039/c4ra08909j.

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40

McGregor, Nicholas, Christophe Pardin y W. G. Skene. "Using Quenching Kinetics and Thermodynamics of Amino-Fluorophores as Empirical Tools for Predicting Boronic Acid Sensors Suitable for Use in Physiological Conditions". Australian Journal of Chemistry 64, n.º 11 (2011): 1438. http://dx.doi.org/10.1071/ch11297.

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A series of water-soluble 1-amino-naphthalenes and 2-amino-fluorenes are prepared. These serve as model fluorophores for measuring the thermodynamics and kinetics of fluorescence quenching with phenylboronic acids and aliphatic amines. Steady-state and time-resolved fluorescence quenching kinetics are investigated using the Stern–Volmer method. Diffusion limited quenching constants and exergonic thermodynamics of electron transfer are derived for the 5-amino-1-napthol and 2-aminofluorene derivatives with phenylboronic acid and/or an aliphatic imine. No quenching and endergonic thermodynamics or electron transfer are observed for 5-sulfonamide, 5-sulfonic acid, or 5-hydroxy-7-sulfonic acid aminonaphthalene derivatives. Boronic acid sensors synthesized from these aminofluorophores by reductive amination with 2-formylphenylboronic acid undergo fluorescence revival in the presence of saccharides only when the fluorophore demonstrates diffusion limited quenching kinetics and exergonic thermodynamics of electron transfer with the boronic acid or imine quenchers. Thus, these two properties are suitable empirical tools for predicting saccharide-induced fluorescence revival of boronic acid sensors.
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41

Durai, Chandramathi R. Sherman y Margaret M. Harding. "Targeting Nucleic Acids using Dynamic Combinatorial Chemistry". Australian Journal of Chemistry 64, n.º 6 (2011): 671. http://dx.doi.org/10.1071/ch11023.

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Dynamic combinatorial chemistry (DCC) is a powerful method for the identification of novel ligands for the molecular recognition of receptor molecules. The method relies on self-assembly processes to generate libraries of compounds under reversible conditions, allowing a receptor molecule to select the optimal binding ligand from the mixture. However, while DCC is now an established field of chemistry, there are limited examples of the application of DCC to nucleic acids. The requirement to conduct experiments under physiologically relevant conditions, and avoid reaction with, or denaturation of, the target nucleic acid secondary structure, limits the choice of the reversible chemistry, and presents restrictions on the building block design. This review will summarize recent examples of applications of DCC to the recognition of nucleic acids. Studies with duplex DNA, quadruplex DNA, and RNA have utilized mainly thiol disulfide libraries, although applications of imine libraries, in combination with metal coordination, have been reported. The use of thiol disulfide libraries produces lead compounds with limited biostability, and hence design of stable analogues or mimics is required for many applications.
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42

Filatov, Vadim E., Dmitrii A. Iuzabchuk, Viktor A. Tafeenko, Yuri K. Grishin, Vitaly A. Roznyatovsky, Dmitrii A. Lukianov, Yulia A. Fedotova et al. "Dispirooxindole-β-Lactams: Synthesis via Staudinger Ketene-Imine Cycloaddition and Biological Evaluation". International Journal of Molecular Sciences 23, n.º 12 (15 de junio de 2022): 6666. http://dx.doi.org/10.3390/ijms23126666.

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In this work, we present the first synthesis of dispirooxindole-β-lactams employing optimized methodology of one-pot Staudinger ketene-imine cycloaddition with N-aryl-2-oxo-pyrrolidine-3-carboxylic acids as the ketene source. Spiroconjugation of indoline-2-one with β-lactams ring is considered to be able to provide stabilization and wide scope of functionalization to resulting scaffolds. The dispipooxindoles obtained demonstrated medium cytotoxicity in the MTT test on A549, MCF7, HEK293, and VA13 cell lines, and one of the compounds demonstrated antibacterial activity against E. coli strain LPTD.
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43

Fulton, Ronnie L. y Diana M. Downs. "DadY (PA5303) is required for fitness of Pseudomonas aeruginosa when growth is dependent on alanine catabolism". microbial Cell 9, n.º 12 (5 de diciembre de 2022): 190–201. http://dx.doi.org/10.15698/mic2022.12.788.

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Pseudomonas aeruginosa inhabits diverse environmental niches that can have varying nutrient composition. The ubiquity of this organism is facilitated by a metabolic strategy that preferentially utilizes low-energy, non-fermentable organic acids, such as amino acids, rather than the high-energy sugars preferred by many other microbes. The amino acid alanine is among the preferred substrates of P. aeruginosa. The dad locus encodes the constituents of the alanine catabolic pathway of P. aeruginosa. Physiological roles for DadR (AsnC-type transcriptional activator), DadX (alanine racemase), and DadA (D-amino acid dehydrogenase) have been defined in this pathway. An additional protein, PA5303, is encoded in the dad locus in P. aeruginosa. PA5303 is a member of the ubiquitous Rid protein superfamily and is desig-nated DadY based on the data presented herein. Despite its conservation in numerous Pseudomonas species and membership in the Rid superfamily, no physiological function has been assigned to DadY. In the present study, we demonstrate that DadA releases imino-alanine that can be deaminated by DadY in vitro. While DadY was not required for alanine catabolism in monoculture, dadY mutants had a dramatic fitness defect in competition with wildtype P. aeruginosa when alanine served as the sole carbon or nitrogen source. The data presented herein support a model in which DadY facilitates flux through the alanine catabolic pathway by removing the imine intermediate generated by DadA. Functional characterization of DadY contributes to our understanding of the role of the broadly conserved Rid family members.
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44

Yao, Suyang, Yanxi Pu, Lulu Ren, Manli Cao y Baohui Ye. "Photooxidative Dehydrogenation of Chiral Ir (III) Amino Acid Complexes Based on [Λ-Ir(ppy)2(MeCN)2](PF6)". Inorganics 11, n.º 10 (25 de septiembre de 2023): 380. http://dx.doi.org/10.3390/inorganics11100380.

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Octahedral chiral-at-metal Ir(III) complexes exhibit excellent structural stability and stereoselectivity in asymmetric synthesis. Selectively oxidative dehydrogenation of amino acids could be achieved by exploiting such complexes as chiral templates. The obtaining stable imine complexes can then be utilized in nucleophilic additions to generate corresponding chiral amine compounds. In this study, a conveniently synthesized [Λ-Ir(ppy)2(MeCN)2](PF6) chiral complex (ppy is 2-phenylpyridine) was utilized as a chiral template. A series of chiral amino acid complexes Λ-[Ir(ppy)2(D/L-AA)] (AA is amino acid) were prepared in high yield and optical purity. The above amino acid complexes were then oxidized to their corresponding imino acid complexes Λ-[Ir(ppy)2(AA-2H)] under visible light. All these complexes exhibited high selectivity during the dehydrogenation process without the formation of C-N bond coupling byproducts. The photooxidative dehydrogenation rates of these complexes were studied, which show that D-configured amino acids exhibited faster dehydrogenation rates when using the Λ-configured complex as a chiral template and the substitution of electron-donating or bulky groups in the N-α position of the amino acid decreased their dehydrogenation rates. The crystal structures of Λ-Ir(ppy)2(D-Thr) (Thr is threonine) and its dehydrogenated complex Λ-Ir(ppy)2(Thr-2H) indicate the process of photooxidative dehydrogenation and the configuration stability of metal center throughout the process.
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45

HAMMERSHOEI, A., R. M. HARTSHORN y A. M. SARGESON. "ChemInform Abstract: Oxidation of Chelated Amino Acids to Imine Derivatives with Thionyl Chloride." ChemInform 22, n.º 8 (23 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199108117.

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46

Cossette, Daniel y Daniel Vocelle. "A 13C and 15N nuclear magnetic resonance study of the protonation of a retinal Schiff base by acids of different pKas and in solvents of different polarities". Canadian Journal of Chemistry 65, n.º 7 (1 de julio de 1987): 1576–83. http://dx.doi.org/10.1139/v87-265.

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13C and 15N nuclear magnetic resonance spectra of mixtures of all-trans-retinylidene tert-butylamine (RtBA) and substituted acetic acids in equimolar concentrations in both CDCl3 and CD3OD were studied in relation to two questions: the nature of the state of protonation of a retinal Schiff base in the presence of carboxylic and mineral acids in solvents of different polarities, and secondly, to determine the nature of the interactions (if any) between the polar groups located on the acids and the polyenic chain of the retinal derivative. Using carboxylic acids of different pKas and three mineral acids, we present results that indicate that, in solvents of low polarity, weak acids can only partially protonate RtBA while, in a more polar milieu, the protonation percentages are higher. With polar groups such asNO2, Cl, Br, I, and CN, no specific interaction could be found between the polyenic chain of the imine and these groups. Variations in the intensity of certain peaks of RtBA were noted and these could possibly be related to the presence of the polar groups on the acids. Comparisons of our results with those obtained on rhodopsin and bacteriorhodopsin indicate that the milieu surrounding the chromophore must be polar if protonation is complete, while in a less polar environment partial protonation can be expected.
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47

Mondal, Sanjoy, Partha Bairi, Sujoy Das y Arun K. Nandi. "Phase selective organogel from an imine based gelator for use in oil spill recovery". Journal of Materials Chemistry A 7, n.º 1 (2019): 381–92. http://dx.doi.org/10.1039/c8ta09732a.

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The superior gelling property of anthracene anchored Schiff base is used as a phase-selective gelator promoting it for oil spill recovery from oil–water mixtures, even in the presence of salts, acids and bases.
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48

Bissonnette, Martine, Hoa Le Thanh y Daniel Vocelle. "Étude d'un modèle simplifié de la rhodopsine: la toute trans-rétinylidène tert-butylamine en présence de divers acides carboxyliques". Canadian Journal of Chemistry 63, n.º 7 (1 de julio de 1985): 1480–86. http://dx.doi.org/10.1139/v85-254.

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A model system of the chromophore of rhodopsin consisting of a Schiff base (all-trans-retinylidene tert-butylamine) and several carboxylic acids has been studied by uv–vis and 1H nmr spectroscopy. In methanol, a polar solvent, results indicate that weak acids are able to protonate fully the imine function, that all the double bonds are perturbed by protonation, that a leveling effect is present, and, finally, that a proton exchange between the protonated Schiff base and the solvent is also present. In chloroform, results indicate that weak acids cannot fully protonate the Schiff base and that an equilibrium exists between an ion pair [Formula: see text] and a neutral species [Formula: see text]. Furthermore, an interaction similar to Nakanishi's external point charge seems to exist between the polyenic chain of the Schiff base and a polar function on the acid. Finally, two comparisons are established: one with a similar ScHiff base – the trans,trans-2,4-heptadienylidene tert-butylamine – the other with rhodopsine.
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49

Fisyuk, Alexander, Ivan Kulakov, Anton Shatsauskas, Mariya Matsukevich, Irina Palamarchuk, Tulegen Seilkhanov y Yuriy Gatilov. "A New Approach to the Synthesis of Benzo[c][1,7]naphthyridin-4(3H)-ones". Synthesis 49, n.º 16 (7 de junio de 2017): 3700–3709. http://dx.doi.org/10.1055/s-0036-1590470.

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A simple and efficient approach has been developed for the synthesis of previously inaccessible 6-arylbenzo[c][1,7]naphthyridin-4(3H)-ones, which is based on the interaction of 3-amino-6-methyl-4-arylpyridin-2(1H)-ones and aromatic aldehydes in a strong acidic media (trifluoroacetic, phosphorous or polyphosphorous acids) under heating. The initial imine derivatives undergo Pictet–Spengler condensation to form intermediate 6-aryl-5,6-dihydrobenzo[c]-1,7-naphthyridin-4(3H)-ones, which are oxidized by atmospheric oxygen to give 3-amino-6-methyl-4-arylpyridin-2(1H)-ones as the final products.
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50

Mikami, Koichi, Masami Kaneko y Tomoko Yajima. "Asymmetric imine-ene reactions with chiral glyoxylate-derived α-imino esters: An efficient route to asymmetric synthesis of α-amino acids". Tetrahedron Letters 34, n.º 30 (julio de 1993): 4841–42. http://dx.doi.org/10.1016/s0040-4039(00)74104-9.

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