- Highly Efficient Supramolecular Catalysis by Endowing the Reaction Intermediate with Adaptive Reactivity
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A new strategy of highly efficient supramolecular catalysis is developed by endowing the reaction intermediate with adaptive reactivity. The supramolecular catalyst, prepared by host–guest complexation between 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and cucurbit[7]uril (CB[7]), was used for biphasic oxidation of alcohols. Cationic TEMPO+, the key intermediate, was stabilized by the electrostatic effect of CB[7] in aqueous phase, thus promoting the formation of TEMPO+ and inhibiting side reactions. Moreover, through the migration into the organic phase, TEMPO+ was separated from CB[7] and recovered the high reactivity to drive a fast oxidation of substrates. The adaptive reactivity of TEMPO+ induced an integral optimization of the catalytic cycle and greatly improved the conversion of the reaction. This work highlights the unique advantages of dynamic noncovalent interactions on modulating the activity of reaction intermediates, which may open new horizons for supramolecular catalysis.
- Jiao, Yang,Tang, Bohan,Zhang, Yucheng,Xu, Jiang-Fei,Wang, Zhiqiang,Zhang, Xi
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Read Online
- Upconverting-nanoparticle-assisted photochemistry induced by low-intensity near-infrared light: How low can we go?
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Upconverting nanoparticles (UCNPs) convert near-infrared (NIR) light into UV or visible light that can trigger photoreactions of photosensitive compounds. In this paper, we demonstrate how to reduce the intensity of NIR light for UCNP-assisted photochemistry. We synthesized two types of UCNPs with different emission bands and five photosensitive compounds with different absorption bands. A λ=974 nm laser was used to induce photoreactions in all of the investigated photosensitive compounds in the presence of the UCNPs. The excitation thresholds of the photoreactions induced by λ=974 nm light were measured. The lowest threshold was 0.5 W cm-2, which is lower than the maximum permissible exposure of skin (0.726 W cm-2). We demonstrate that low-intensity NIR light can induce photoreactions after passing through a piece of tissue without damaging the tissue. Our results indicate that the threshold for UCNP- assisted photochemistry can be reduced by using highly photosensitive compounds that absorb upconverted visible light. Low excitation intensity in UCNP-assisted photochemistry is important for biomedical applications because it minimizes the overheating problems of NIR light and causes less photodamage to biomaterials. Up, up, and away: Upconverting-nanoparticle (UCNP)-assisted photochemistry can be triggered by low-intensity (0.5 W cm-2) near-infrared (NIR) light when highly photosensitive compounds that absorb upconverted visible light are used (see figure). Low excitation intensity in UCNP-assisted photochemistry is important in biomedical applications because it minimizes the overheating problems of NIR light and causes less photodamage to biomaterials.
- Chen, Zhijun,Sun, Wen,Butt, Hans-Jürgen,Wu, Si
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- Polymer-supported IBX-amide reagents: Significant role of spacer and additive in alcohol oxidation
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We found that the spacer and additive play a significant role in the oxidation of alkyl alcohols using polymer-supported IBX-amide reagents. The introduction of the spacer between the polymer support and IBX-amide group improved the initial conversion rate (up to 60% conversion). Furthermore, various alcohol compounds, when reacted with IBX-amide resin in the presence of BF3·OEt2, were effectively converted into the corresponding aldehydes or ketones within 5-30 minutes in high purities (>94%) at room temperature. Georg Thieme Verlag Stuttgart.
- Chung, Woo-Jae,Kim, Duk-Ki,Lee, Yoon-Sik
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Read Online
- Synthesis of Azepino[1,2-a]indole-10-amines via [6+1] Annulation of Ynenitriles with Reformatsky Reagent
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Lewis acid-catalyzed [6+1] annulation reactions of 2-cyano-1-propargyl- and 2-alkynyl-1-cyanomethyl-indoles with Reformatsky reagent are described. 8-Aryl, 8-alkyl-, 8-hetaryl-, 9-aryl, and 9-alkyl-azepino[1,2-a]indole amines were obtained through a 7-endo-mode cyclization of the β-aminoacrylate intermediates. The antiproliferative activity of the azepino[1,2-a]indoles analogs against the HCT-116 cells were also examined.
- Iioka, Ryoya,Yorozu, Kohei,Sakai, Yoko,Kawai, Rika,Hatae, Noriyuki,Takashima, Katsuki,Tanabe, Genzoh,Wasada, Hiroaki,Yoshimatsu, Mitsuhiro
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p. 1553 - 1558
(2021/02/26)
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- Non-alkylator anti-glioblastoma agents induced cell cycle G2/M arrest and apoptosis: Design, in silico physicochemical and SAR studies of 2-aminoquinoline-3-carboxamides
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Malignant gliomas are the most common brain tumors, with generally dismal prognosis, early clinical deterioration and high mortality. Recently, 2-aminoquinoline scaffold derivatives have shown pronounced activity in central nervous system disorders. We herein reported a series of 2-aminoquinoline-3-carboxamides as novel non-alkylator anti-glioblastoma agents. The synthesized compounds showed comparable activity to cisplatin against glioblastoma cell line U87 MG in vitro. Among them, we found that 6a displayed good inhibitory activity against A172 and U118 MG glioblastoma cell lines and induced cell cycle arrest in the G2/M phase and apoptosis in U87 MG by flow cytometry analysis. Additionally, 6a displayed low cytotoxicity to several normal human cell lines. In silico study showed 6a had promising physicochemical properties and was predicted to cross the blood–brain barrier. Moreover, preliminary structure–activity relationships are also investigated, shedding light on further modifications towards more potent agents on this series of compounds. Our results suggest this compound has a promising potential as an anti-glioblastoma agent with a differential effect between tumor and non-malignant cells.
- Gu, Xiangyu,Liu, Jianwen,Ni, Xintong,Qi, Yingxue,Qian, Xuhong,Shao, Xusheng,Xu, Xiaoyong,Yuan, Pengtao
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supporting information
(2021/09/22)
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- Buchwald-Hartwig versus Microwave-Assisted Amination of Chloroquinolines: En Route to the Pyoverdin Chromophore
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The reaction of 2-chloro-6,7-dimethoxy-3-nitroquinoline with a series of amines and aminoalkanoates under basic microwave-mediated conditions and under Buchwald-Hartwig amination conditions is reported. The microwave irradiation favored the reaction with amines, resulting in yields of up to 80percent, whereas amino acid functionalization gave yields comparable to those of Buchwald-Hartwig amination. tert-Butyl (2 R)-4-[(6,7-dimethoxy-3-nitroquinolin-2-yl)amino]-2-hydroxybutanoate was successfully cyclized to the pyoverdin chromophore, a subunit of siderophores.
- Altevogt, Luca,Baro, Angelika,Bilitewski, Ursula,Freund, Marcel,Laschat, Sabine,Lin, Yulin,Rudolf, Richard,Seubert, Philipp
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supporting information
p. 1177 - 1181
(2020/07/20)
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- Optical control of protein activity and gene expression by photoactivation of caged cyclofen
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The use of light to control the expression of genes and the activity of proteins is a rapidly expanding field. While many of these approaches use a fusion between a light activatable protein and the protein of interest to control the activity of the latter, it is also possible to control the activity of a protein by uncaging a specific ligand. In that context, controlling the activation of a protein fused to the modified estrogen receptor (ERT) by uncaging its ligand cyclofen-OH has emerged as a generic and versatile method to control the activation of proteins quantitatively, quickly and locally in a live organism. Here, we present the experimental details behind this approach.
- Hamouri, Fatima,Zhang, Weiting,Aujard, Isabelle,Le Saux, Thomas,Ducos, Bertrand,Vriz, Sophie,Jullien, Ludovic,Bensimon
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- Synthesis and photochemical studies of 2-nitrobenzyl-caged N-hydroxysulfonamides
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Recently, N-hydroxysulfonamides (RSO2NHOH) caged by photolabile protecting groups have attracted significant interest as potential photoactive nitroxyl (HNO) donors. The selectivity of the desired HNO generation pathway from photocaged N-hydroxysulfonamides versus a competing pathway involving O-N bond cleavage is dependent on the specific photodeprotection mechanism of the phototrigger. We present a new class of photocaged N-hydroxysulfonamides incorporating the well-established o-nitrobenzyl photoprotecting group, including a derivative incorporating an additional carbonate linker. Photodecomposition of o-NO2Bn-ON(H)SO2CF3 and the corresponding 2-nitro-4,5-dimethoxybenzyl analog generated the desired HNO and CF3SO2- as a minor pathway, with competing photoinduced O-N bond cleavage to release CF3SO2NH2 as the major photodecomposition pathway. Photolysis of the corresponding -SO2CH3 analogs resulted in O-N bond cleavage only. The presence of the o-nitro substituent was shown to be essential for photoactivity. Photorelease of the parent HNO donor CH3SO2NHOH was observed as the major product upon irradiation of o-NO2Bn-OC(O)ON(H)SO2CH3, with the desired HNO release and O-N bond cleavage occurring as minor pathways. Photoproduct quantum yields for each species have been determined by actinometry. The effect of solvent, pH and air on the mechanism of photodecomposition was studied for o-NO2Bn-ON(H)SO2CH3. The ratio of the solvents in the solvent mixture (CH3CN and phosphate buffer, pH 7.0), the pH of the aqueous component of the buffer, and the presence of oxygen did not affect the amount of each photoproduct and the observed rate constant for O-N bond cleavage. Possible mechanisms for the various pathways are proposed.
- Zhou, Yang,Bharadwaj, Vinay,Rahman, Mohammad S.,Sampson, Paul,Brasch, Nicola E.,Seed, Alexander J.
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- A preparation method of gefitinib (by machine translation)
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The present invention relates to organic chemical and medical technology field, in particular relates to a preparation method of gefitinib. The present invention provides a preparation method of gefitinib, obtained by formula I compounds, the formula I compound preparation method comprises the following steps: nitration reaction, oxidation reaction, selective demethylation reaction, reduction reaction, a cyclization reaction, phenolic hydroxyl acetylation reaction. The present invention provides a preparation method can at the same time reducing the cost, it is easy for the refined purification, easy preparation and control of related impurities, the overall preparation process routes are greatly optimized, is suitable for industrial scale production. (by machine translation)
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Paragraph 0092-0094
(2019/05/16)
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- Iodine(III)-Catalyzed Electrophilic Nitration of Phenols via Non-Br?nsted Acidic NO2+ Generation
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The first catalytic procedure for the electrophilic nitration of phenols was developed using iodosylbenzene as an organocatalyst based on iodine(III) and aluminum nitrate as a nitro group source. This atom-economic protocol occurs under mild, non-Br?nsted acidic and open-flask reaction conditions with a broad functional-group tolerance including several heterocycles. Density functional theory (DFT) calculations at the (SMD:MeCN)Mo8-HX/(LANLo8+f,6-311+G) level indicated that the reaction proceeds through a cationic pathway that efficiently generates the NO2+ ion, which is the nitrating species under neutral conditions.
- Juárez-Ornelas, Kevin A.,Jiménez-Halla, J. Oscar C.,Kato, Terumasa,Solorio-Alvarado, César R.,Maruoka, Keiji
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supporting information
p. 1315 - 1319
(2019/03/07)
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- A 3, 4 - dihydro -7 - methoxy -4 - [...] -6 - ethoxylate ester preparation method (by machine translation)
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The present invention relates to organic chemical and medical technology field, in particular to a 3, 4 - dihydro - 7 - methoxy - 4 - [...] - 6 - ethoxylate ester preparation method. The present invention provides a gefitinib 3, 4 - dihydro - 7 - methoxy - 4 - [...] - 6 - ethoxylate ester preparation method comprises the following steps: nitration reaction, oxidation reaction, selective demethylation reaction, reduction reaction, a cyclization reaction, phenolic hydroxyl acetylation reaction. Preparation method provided by the invention can at the same time reducing the cost, it is easy for the refined purification, easy preparation and control of related impurities, the overall preparation process routes are greatly optimized, is suitable for industrial scale production. (by machine translation)
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Paragraph 0067-0069
(2019/05/16)
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- Design and discovery of quinazoline- and thiourea-containing sorafenib analogs as EGFR and VEGFR-2 dual TK inhibitors
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Both EGFR and VEGFR-2 play a critical role in tumor growth, angiogenesis and metastasis, and targeting EGFR and VEGFR-2 simultaneously represents a promising approach to cancer treatment. In this work, a series of novel quinazoline- and thiourea-containing sorafenib analogs (10a–v) were designed and synthesized as EGFR and VEGFR-2 dual TK inhibitors. Their in vitro enzymatic inhibitory activities against EGFR and VEGFR-2, and antiproliferative activities against HCT-116, MCF-7 and B16 cell lines were evaluated and described. Most of the compounds showed potent activities against both cell lines and TK kinases. Compounds 10b and 10q which exhibited the most potent inhibitory activities against EGFR (IC50 = 0.02 μM and 0.01 μM, respectively), VEGFR-2 (IC50 = 0.05 μM and 0.08 μM, respectively), and good antiproliferative activities, also displayed competitive anti-tumor activities than sorafenib in vivo by B16 melanoma xenograft model test.
- Sun, Shaofeng,Zhang, Jingwen,Wang, Ningning,Kong, Xiangkai,Fu, Fenghua,Wang, Hongbo,Yao, Jianwen
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- A Vinylogous Photocleavage Strategy Allows Direct Photocaging of Backbone Amide Structure
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Side-chain modifications that respond to external stimuli provide a convenient approach to control macromolecular structure and function. Responsive modification of backbone amide structure represents a direct and powerful alternative to impact folding and function. Here, we describe a new photocaging method using histidine-directed backbone modification to selectively modify peptides and proteins at the amide N-H bond. A new vinylogous photocleavage method allows photorelease of the backbone modification and, with it, restoration of function.
- Mangubat-Medina, Alicia E.,Martin, Samuel C.,Hanaya, Kengo,Ball, Zachary T.
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p. 8401 - 8404
(2018/06/29)
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- Stabilization of High Oxidation State Upconversion Nanoparticles by N-Heterocyclic Carbenes
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The stabilization of high oxidation state nanoparticles by N-heterocyclic carbenes is reported. Such nanoparticles represent an important subset in the field of nanoparticles, with different and more challenging requirements for suitable ligands compared to elemental metal nanoparticles. N-Heterocyclic carbene coated NaYF4:Yb,Tm upconversion nanoparticles were synthesized by a ligand-exchange reaction from a well-defined precursor. This new photoactive material was characterized in detail and employed in the activation of photoresponsive molecules by low-intensity near-infrared light (λ=980 nm).
- M?ller, Nadja,Rühling, Andreas,Lamping, Sebastian,Hellwig, Tim,Fallnich, Carsten,Ravoo, Bart Jan,Glorius, Frank
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p. 4356 - 4360
(2017/04/03)
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- Cascade photocaging of diazeniumdiolate: A novel strategy for one and two photon triggered uncaging with real time reporting
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We report a new strategy, viz. cascade photocaging, for protecting diethylamine diazeniumdiolate (O2-position), a light sensitive molecule. Upon photolysis, the cascade photocage at first releases the light activatable linker (latent fluorophore) O2-caged diazeniumdiolate, which undergoes spontaneous 1,8-elimination, triggering the release of the diazeniumdiolate anion and the fluorophore.
- Behara, Krishna Kalyani,Rajesh,Venkatesh, Yarra,Pinninti, Bhaskar Rao,Mandal, Mahitosh,Singh, N. D. Pradeep
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p. 9470 - 9473
(2017/09/01)
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- Examples of xylochemistry: Colorants and polymers
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Against the backdrop of modern sustainable chemistry and valorization of biomass for chemical raw materials, the syntheses of indigo dyes and polyamides as representatives of two classes of everyday chemical products based on xylochemicals are described. Wood-derived starting materials were transformed into functional materials using the principles of green chemistry to expand the scope of products gained from renewable resources. The indigo dyes were synthesized in a short, straightforward sequence starting from vanillin. Two polyamides, representatives of an important class of polymers, were obtained from 4-propylcyclohexanol, which is one of the longest known (and most abundant) hydrogenative depolymerization products of lignin.
- Kühlborn, Jonas,Danner, Ann-Kathrin,Frey, Holger,Iyer, Rishab,Arduengo, Anthony J.,Opatz, Till
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supporting information
p. 3780 - 3786
(2017/08/23)
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- Dual inhibitors of epidermal growth factor receptor and topoisomerase IIα derived from a quinoline scaffold
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Based on the quinazoline bearing EGFR inhibitors, a series of thirty four compounds having a quinoline scaffold were synthesised and evaluated in vitro for EGFR kinase inhibitory activity. A structure-activity relationship study revealed that 2,4-bis(arylamino) substituted quinolines possessed better anti-EGFR kinase activity. Compounds 3f and 3m emerged as potent EGFR kinase inhibitors (200 and 210 nM, respectively) and showed excellent anticancer activity at the micromolar level against a panel of cancer cell lines comparable to erlotinib. Furthermore, representative compounds inhibited the human topoisomerase IIα selectively and catalytically, did not intercalate with DNA, increased intracellular ROS concentration (except 3m) and altered the mitochondrial membrane potential of the cancer cells. Cell cycle analysis and annexin-V staining in a lung cancer cell line showed that the compounds delayed cell cycle progression by inducing cell cycle arrest and subsequent apoptosis at the G1 phase. The facts were further corroborated through molecular modeling studies.
- Chauhan, Monika,Joshi, Gaurav,Kler, Harveen,Kashyap, Archana,Amrutkar, Suyog M.,Sharma, Praveen,Bhilare, Kiran D.,Chand Banerjee, Uttam,Singh, Sandeep,Kumar, Raj
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p. 77717 - 77734
(2018/06/22)
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- Synthesis and Evaluation of a New Series of 8-(2-Nitroaryl)Xanthines as Adenosine Receptor Ligands
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(Table presented.). A new series of 1,3-dimethylxanthine derivatives bearing 8-(2-nitroaryl) residue was synthesized and evaluated for affinity for recombinant human adenosine receptors subtypes. Nitrate esters of 7-substituted-1,3-dimethyl-8-phenylxanthines were also synthesized and tested. Introducing a nitro substituent at the 2-position of the 8-substituted phenyl ring resulted in generally low affinity for adenosine receptors (ARs), selectivity toward the A2A subtype was enhanced in some of the compounds. 8-(4-Cyclopentyloxy-5-methoxy-2-nitrophenyl)-1,3-dimethylxanthine (9e) proved to be a potent compound among the 2-nitrophenyl substituted xanthines exhibiting a Ki = 1 μM at human A2A ARs with at least 30 fold selectivity versus human A1 and A2B ARs. Replacement of 8-chloropropoxy phenyl with 8-nitrooxypropoxy phenyl resulted in a negligible change in binding affinity of the 8-substituted xanthines for various AR subtypes. Drug Dev Res 77 : 241–250, 2016.
- Bansal, Ranju,Kumar, Gulshan,Rohilla, Suman,Klotz, Karl-Norbert,Kachler, Sonja,Young, Louise C.,Harvey, Alan L.
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p. 241 - 250
(2016/08/28)
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- Bimolecular photoactvarion of NBD fluorescence
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The concatenation of a photochemical transformation with a chemical reaction allows the activation of nitrobenzoxadiazole (NBD) fluorescence under optical control. Specifically, the coupling of photoinduced deprotection with nucleophilic substitution converts a nonemissive NBD chromophore into a fluorescent product. These operating principles can evolve into a general mechanism to implement fluorescent switches based on the attractive photophysical properties of NBDs.
- Shaban Ragab, Sherif,Swaminathan, Subramani,Garcia-Amorós, Jaume,Captaina, Burjor,Raymo, Fran?isco M.
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p. 1570 - 1573
(2015/03/18)
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- Eumelanin-inspired core derived from vanillin: A new building block for organic semiconductors
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An eumelanin-inspired core derived from the natural product, vanillin (vanilla bean extract) was utilized for the synthesis of eumelanin-inspired small molecules and polymer via Sonogashira cross coupling. The materials demonstrate that the methyl 4,7-dibromo-5,6-dimethoxy-N-methyl-1H-indole-2-carboxylate core can serve as a new building block for organic semiconductors.
- Selvaraju, Subhashini,Sachinthani, K. A. Niradha,Hopson, RaiAnna A.,McFarland, Frederick M.,Guo, Song,Rheingold, Arnold L.,Nelson, Toby L.
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p. 2957 - 2959
(2015/02/19)
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- SYSTEMS AND METHODS FOR PRODUCTION OF ARTIFICIAL EUMELANIN
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"Black" photoactive materials that comprise synthetic eumelanin polymers are provided, as are methods of making and using the polymers. The synthetic eumelanin polymers are made from the plant oil vanillin, and exhibit defined structural and chemical characteristics (e.g. homogeneity, solubility, etc.) that make them suitable for use in devices that require photoactive materials, such as solar cells.
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- Diastereoselective construction of highly functionalized tetrahydroquinolinoisoxazole scaffolds via intramolecular nitrone cycloaddition
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A novel strategy towards the construction of highly diversified tetrahydroquinolinoisoxazole frameworks with high diastereoselectivity via intramolecular 1,3-dipolar nitrone cycloaddition reaction is described for the first time. All the synthesized tetrahydroquinolinoisoxazoles are new and obtained in excellent yields under catalyst free condition.
- Bakthadoss, Manickam,Devaraj, Anthonisamy
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p. 3954 - 3960
(2015/06/08)
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- Facile and efficient oxidation of quinazolines into quinazolin-4(3 H)-ones by peracetic acid
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A new approach to synthesize quinazoline-4(3H)-ones was achieved by oxidation of quinazolines using peracetic acid, which possesses some advantages of economic reagents, simplified operation, high efficiency, and environmental friendliness. Application of this method allowed us to synthesize a series of quinazolin-4(3H)-ones with different substituents at 6 and 7 positions in good to excellent yields, including the key intermediates of tyrosine kinase inhibitors such as PD153035, Erlotinib, and Gefitinib. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Jin, Jian-Wen,Zhang, Lin,Meng, Guang-Rong,Zhu, Jian-Hua,Zhang, Qian
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p. 346 - 351
(2014/01/06)
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- Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedl?nder reaction
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In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedl?nder condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.
- Gavara, Laurent,Boisse, Thomas,Hénichart, Jean-Pierre,Da?ch, Adam,Rigo, Beno?t,Gautret, Philippe
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p. 7544 - 7561
(2010/12/25)
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- A nanophase segregated mesophase morphology in self-organized novel disc-rod oligomesogens
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A nanophase segregated layered phase (SmA) with alternating calamitic and discotic layers was observed for the first time in novel linked disc-rod oligomesogens, containing six cyanobiphenyl moieties radially-attached to a central tricycloquinazoline discotic heteroaromatic core via flexible alkyl spacers. The Royal Society of Chemistry 2009.
- Bisoyi, Hari Krishna,Raghunathan,Kumar, Sandeep
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scheme or table
p. 7003 - 7005
(2010/04/25)
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- Efficient synthesis of novel six-member ring-fused quinoline derivatives via the Friedlaender reaction
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Novel quinolines fused with a six-member ring 5a-j were prepared in high yields (75-95%) via the Friedlaender reaction of dimethoxy-substituted o-aminobenzaldehydes of 3a or 3b with cyclic ketones 4, respectively. The structures of 5aj were determined by IR, 1H NMR, MS, and elemental analysis.
- Yang, Dingqiao,Guo, Wei,Cai, Yuepeng,Jiang, Lasheng,Jiang, Kailing,Wu, Xiaobing
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p. 229 - 233
(2008/09/19)
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- A facile synthesis of 2-methylquinolines via Pd-catalyzed aza-Wacker oxidative cyclization
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(Chemical Equation Presented) A novel Pd-catalyzed Wacker-type oxidative cyclization under air is described. By using this cyclization, a series of 2-methylquinolines are readily prepared with good yields under mild conditions.
- Zhang, Zuhui,Tan, Jiajing,Wang, Zhiyong
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p. 173 - 175
(2008/09/18)
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- Cascade synthesis of 3-quinolinecarboxylic ester via benzylation/ propargylation-cyclization
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(Chemical Equation Presented) Reactions of 2-amino-aryl alcohols with β-ketoesters catalyzed by a catalytic amout of FeCl3 via tandem benzylation-cyclization produce the corresponding 3-quinolinecarboxylic esters in good to high yields. Extending this methodology to propargylation- cyclization, 2-nitrophenyl propargyl alcohols with β-ketoesters catalyzed by FeCl3 and SnCl2 also produce the 4-alkyne-3- quinolinecarboxylic esters. The mechanistic details of this benzylation/ propargylation and cyclization cascade process are also discussed.
- Fan, Jinmin,Wan, Changfeng,Sun, Gaojun,Wang, Zhiyong
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supporting information; scheme or table
p. 8608 - 8611
(2009/04/04)
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- The rotation of the nitro and formyl groups relative to the aromatic ring in some ortho-nitroarylaldehydes
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X-Ray crystallographic studies have shown that in ortho-nitroarylaldehydes the plane of an aryl nitro group is rotated relative to the aromatic ring to a greater extent than that of the adjacent formyl group.
- Hanson, James R.,Hitchcock, Peter B.,Toche, Francois
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body text
p. 476 - 478
(2009/08/07)
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- Macroporous polystyrene-supported IBX amide: the improved oxidative properties in various solvents
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In this study, macroporous polystyrene-supported IBX (MPS-IBX) amides were prepared in two simple steps, and the polymeric reagent was then evaluated for its efficiency in converting a range of alcohols to the corresponding carbonyl compounds in various solvents. The results indicated that the MPS-IBX amides were compatible with a variety of solvents, and had a more efficient oxidation activity toward alkyl alcohols than the gel type polystyrene-supported IBX amides. Finally, the resin that was consumed in the oxidation reaction was regenerated to give a restored loading level of 0.44-0.54 mmol/g.
- Jang, Hyung-Seok,Chung, Woo-Jae,Lee, Yoon-Sik
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p. 3731 - 3734
(2008/02/09)
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- Hexaalkoxytricycloquinazolines: New Discotic Liquid Crystals
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Tricycloquinazoline (TCQ), a molecule of both biological and physical interest, has been found to function as the core fragment for a new family of discotic mesogens, which have C3 symmetry and six aliphatic side chains.Six representative homologous 2,3,7,8,12,13-hexaalkoxy-TCQ derivatives 5 were synthesized, with alkyl side chain lengths varying from 3 to 16 carbon atoms.These highly fluorescent, heteroaromatic compounds are conveniently obtained by alkylation of hexahydroxy-TCQ, 10.The latter is prepared by trimerization of 5,6-dimethoxyanthranil, 8, followed by demethylation of the resultant hexamethoxy-TCQ, 9.All compounds, 5, are mesogenic within a very broad temperature range.The nature of these new mesophases was studied by DSC and by optical microscopy with polarized light and X-ray diffraction.DSC measurements show highly reversible behavior at both melting and clearing points, indicating high chemical stability.Photomicroscopic pictures show mosaic textures, characteristic of an ordered hexagonal, columnar phase (Dho), that are very similar to those we reported earlier for hexakis(thioalkoxy)-TCQ derivatives 4.The diffraction spacings of two representative compounds (having 5 and 11 carbon atoms in the side chain) in the mesophase are consistent with a two-dimensional hexagonal lattice having unit cell sides of a = 21.2 and 28.7 Angstroem, respectively, and containing one molecule per unit cell.
- Kumar, Sandeep,Wachtel, Ellen J.,Keinan, Ehud
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p. 3821 - 3827
(2007/10/02)
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- Biologically Useful Chelators That Take Up Ca(2+) upon Illumination
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Two approaches were explored toward the goal of synthesizing physiologically useful Ca(2+)-selective chelators whose Ca(2+) affinities increase markedly upon photolysis.In the first approach, the known Ca(2+)-selective chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) was masked with a variety of photoremovable protecting groups on one of its four carboxyl groups, reducing its affinity for Ca(2+) to ca. 1E5 M-1.Upon irradiation around 356 nm, free chelator with an affinity constant ca. 1E7 M-1 was regenerated but with very low quantumefficiencies (-1.Photochemical rearrangement of the diazoacetyl group converted it into an electron-donating carboxymethyl group, causing the Ca(2+) affinity to increase 30-fold to 1.4E7 M-1.The photolysis of Ca(2+)-free diazo-2 had a quantum efficiency with 365-nm light (λmax 370 nm, ε ca. 22000 M-1cm-1) of ca. 0.03 and generated the high-affinity chelator with rate constants of 2300 s-1 after a flash.Ca(2+) was then bound with association and dissociation rate constants of 8.0E8 M-1s-1 and 58 s-1, respectively.Diazo-2 was incorporated into rat fibroblasts either by microinjection or by incubation as the membrane-permeable, enzymatically labile tetrakis(acetoxymethyl) ester and, when flash-photolyzed, caused a drop in intracellular free to or below resting values of ca. 1E-7 M.An even larger increase in affinity(1600-fold) was obtained by substituting both phenyl rings of BAPTA with diazoacetyl substituents.Therefore, these chelators can be used to generate controlled fast decrements in intracellular free to mimic or ablate a host of important cellular responses, especially in nerve and muscle.
- Adams, S. R.,Kao, J. P. Y.,Tsien, R. Y.
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p. 7957 - 7968
(2007/10/02)
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- Nucleophilic photosubstitutions of o-methoxynitrobenzenes
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We report a new synthesis of 3-nitroveratrole, based on the directed lithiation of veratrole, and photochemical substitutions of both 3-nitroveratrole and o-nitroanisole with several nucleophiles.Both aromatic substrates undergo photocyanation meta to the nitro group.With hydroxide ion, 3-nitroveratrole reacts meta to the nitro group, but 2-nitroanisole undergoes replacement of either substituent, the proportion of reaction at each site depending upon the OH(-) concentration. 3-Nitroveratrole undergoes an inefficient reaction with butylamine at each methoxy group; this reaction is apparently second order in amine.The reaction between o-nitroanisole and diethylamine results only in photohydrolysis.Keywords: photosubstitution, nucleophilic, 3-nitroveratrole, o-nitroanisole
- Bunce, Nigel J.,Stephenson, Karen Labonte
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p. 220 - 226
(2007/10/02)
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- Quinazoline compounds and antihypertensives
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Disclosed herein is an antihypertensive preparation containing, as an active component, a novel quinazoline derivative represented by the following general formula or a salt thereof: STR1 wherein R100 means a hydrogen atom or methoxy group, R200 and R300 denote individually a hydrogen atom or lower alkoxy group, R400 is a hydrogen atom or amino group, l stands for 2 or 3, and Het is a specific hetero ring group.
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