- Strategies towards the synthesis of 6-N,N-diethylcarbamyloxy-1,4-dimethoxy- 7-naphthylboronic acid
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After acetylation, condensation between Danishefsky's diene and benzoquinone afforded a stable methoxytriacetoxydihydronaphthalene intermediate, which was subsequently transformed by the Snieckus DOM protocol into the regiospecific 7-naphthylboronic acid.
- Ameer,Green, Ivan R.,Krohn,Sitoza
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- Synthesis, biological evaluation, and correlation of cytotoxicity versus redox potential of 1,4-naphthoquinone derivatives
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A series of 1,4-naphthoquinone derivatives of lawsone (1), 6-hydroxy-1,4-naphthoquinone (2), and juglone (3) were synthesized by alkylation, acylation, and sulfonylation reactions. The yields of lawsone derivatives 1a-1k (type A), 6-hydroxy-1,4-naphthoqui
- Shen, Chien-Chang,Afraj, Shakil N.,Hung, Chia-Cheng,Barve, Balaji D.,Kuo, Li-Ming Yang,Lin, Zhi-Hu,Ho, Hisu-O.,Kuo, Yao-Haur
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- Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor
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A mild photocatalytic phenol oxygenation enabled by a continuous-flow photoreactor using visible light and pressurized air is described herein. Products for wide-ranging applications, including the synthesis of vitamins, were obtained in high yields by precisely controlling principal process parameters. The reactor design permits low organophotocatalyst loadings to generate singlet oxygen. It is anticipated that the efficient aerobic phenol oxygenation to benzoquinones and p-quinols contributes to sustainable synthesis.
- Wellauer, Jo?l,Miladinov, Dragan,Buchholz, Thomas,Schütz, Jan,Stemmler, René T.,Medlock, Jonathan A.,Bonrath, Werner,Sparr, Christof
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supporting information
p. 9748 - 9752
(2021/05/27)
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- Oxidative Dearomatization of Phenols and Polycyclic Aromatics with Hydrogen Peroxide Triggered by Heterogeneous Sulfonic Acids
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We report herein a method for the oxidative dearomatization of phenols and bare polycyclic arenes into the corresponding quinoid derivatives using hydrogen peroxide. The reaction is catalyzed by sulfonic acids and best results were achieved using heterogenized species. The best results using phenols were achieved using a hybrid material, namely a perfluorinated polymer functionalized with sulfonic acid groups supported on silica. The dearomatization of polycyclic aromatic hydrocarbons performed better using the polymeric acid catalyst. These methods operate under mild conditions, using mild and benign oxidants and thus minimizing the formation of waste.
- Pancrazzi, Francesco,Maestri, Giovanni,Maggi, Raimondo,Viscardi, Rosanna
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supporting information
p. 5407 - 5414
(2021/10/25)
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- PHOTOOXIDATION OF PHENOLIC COMPOUNDS
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The present invention relates to the photooxidation of phenolic compounds to the respective quinoid compounds using methylene blue as photosensitizer in a solvent mixture of water and alcohols using light of the high wavelength range of the visible spectrum.
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Page/Page column 18
(2021/11/26)
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- Synthesis, properties and singlet oxygen generation of thiazolidinone double bond linked porphyrin at meso and β-position
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Meso and β-substituted free base and zinc metallated thiazolidinone-porphyrin conjugates were synthesized by one pot four component Knoevenagel condensation by utilizing substituted amines, carbon disulfide, ethyl chloroacetate and porphyrin aldehydes. These newly synthesized conjugates were characterized by IR, 1H NMR, 13C NMR, UV-Vis, fluorescence and HRMS spectroscopy. The singlet oxygen generation behaviors of these porphyrin conjugates were studied and it was observed that these porphyrin conjugates followed type II singlet oxygen. Fluorescence and singlet oxygen quantum yields among meso-substituted (mono-, di, tetra) and β-substituted conjugates were examined. The photocatalytic photooxidation of naphthols and furan by using these new organic photocatalysts were further analysed and it was observed that meso-tetra substituted (Zn3a) and β-substituted (Zn6a) porphyrins are much efficient for generation of singlet oxygen and for photocatalytic photooxidation.
- Ahmad, Sohail,Yadav, Kumar Karitkey,Narang, Uma,Bhattacharya, Soumee,Singh, Sarangthem Joychandra,Chauhan
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p. 36090 - 36095
(2016/05/19)
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- Exploiting photooxygenations mediated by porphyrinoid photocatalysts under continuous flow conditions
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Photooxygenation reactions are a powerful synthetic tool to produce oxidized organic compounds; however, these reactions often exhibit experimental limitations including the production of complex mixtures that hinder desired product isolation and scale-up. Herein, we present a photocatalysed protocol under continuous flow conditions using a simple home built photoreactor and porphyrinoids as photocatalysts. Reaction conditions, long-term experiments, and scope demonstrate a protocol that is cost-effective, safe, reproducible and robust, thus allowing the production of relevant substituted naphthoquinones with interest in natural product synthesis and biological activity.
- De Oliveira, Kleber T.,Miller, L. Zane,McQuade, D. Tyler
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p. 12717 - 12725
(2016/02/12)
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- Sequential, One-Pot Access to Arylated Benzoquinones/Naphthoquinones from Phenols/Naphthols
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A sequential one-pot approach towards arylated benzoquinones and naphthoquinones is reported. The reaction proceeds through oxidation of phenols/naphthols followed by CH-arylation with a catalytic amount of triflic acid. Preliminary cytotoxic studies were carried out with five different cell lines and some of the compounds show promising activity. This one-pot approach towards arylated benzoquinones and naphthoquinones proceeds through oxidation of phenols/naphthols followed by CH-arylation. Preliminary cytotoxic studies for some of the compounds showed promising activity.
- Jiang, Jia-Heng,Boominathan, Siva Senthil Kumar,Hu, Wan-Ping,Chen, Chung-Yu,Vandavasi, Jaya Kishore,Lin, Ying-Ting,Wang, Jeh-Jeng
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p. 2284 - 2289
(2016/05/19)
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- Synthesis of o-Carboxyarylacrylic Acids by Room Temperature Oxidative Cleavage of Hydroxynaphthalenes and Higher Aromatics with Oxone
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A simple procedure for the synthesis of a variety of o-carboxyarylacrylic acids has been developed with Oxone (2KHSO5·KHSO4·K2SO4); the oxidation reaction involves the stirring of methoxy/hydroxy-substituted naphthalenes, phenanthrenes, anthracenes, etc. with Oxone in an acetonitrile-water mixture (1:1, v/v) at rt. Mechanistically, the reaction proceeds via initial oxidation of naphthalene to o-quinone, which undergoes cleavage to the corresponding o-carboxyarylacrylic acid. The higher aromatics are found to yield carboxymethyl lactones derived from the initially formed o-carboxyarylacrylic acids.
- Parida, Keshaba Nanda,Moorthy, Jarugu Narasimha
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p. 8354 - 8360
(2015/09/01)
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- Bodipy derivatives as organic triplet photosensitizers for aerobic photoorganocatalytic oxidative coupling of amines and photooxidation of dihydroxylnaphthalenes
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We used iodo-Bodipy derivatives that show strong absorption of visible light and long-lived triplet excited states as organic catalysts for photoredox catalytic organic reactions. Conventionally most of the photocatalysts are based on the off-the-shelf compounds, usually showing weak absorption in the visible region and short triplet excited state lifetimes. Herein, the organic catalysts are used for two photocatalyzed reactions mediated by singlet oxygen ( 1O2), that is, the aerobic oxidative coupling of amines and the photooxidation of dihydroxylnaphthalenes, which is coupled to the subsequent addition of amines to the naphthoquinones, via C-H functionalization of 1,4-naphthoquinone, to produce N-aryl-2-amino-1,4-naphthoquinones (one-pot reaction), which are anticancer and antibiotic reagents. The photoreactions were substantially accelerated with these new iodo-Bodipy organic photocatalysts compared to that catalyzed with the conventional Ru(II)/Ir(III) complexes, which show weak absorption in the visible region and short-lived triplet excited states. Our results will inspire the design and application of new organic triplet photosensitizers that show strong absorption of visible light and long-lived triplet excited state and the application of these catalysts in photoredox catalytic organic reactions.
- Huang, Ling,Zhao, Jianzhang,Guo, Song,Zhang, Caishun,Ma, Jie
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p. 5627 - 5637
(2013/07/25)
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- Solar photochemistry: Optimisation of the photo Friedel-Crafts acylation of naphthoquinones
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A practical and robust photo Friedel-Crafts acylation of naphthoquinones is described. Although the reaction proceeds slowly in sunlight, the optimised conditions offer a substantial improvement to those already reported, by the utilisation of a more reliable and practical 'sun-mimicking' light source, a less hazardous solvent system (trifluorotoluene) and faster reaction times. Using these conditions, the reaction scope has been expanded to include functionalised aldehyde and naphthoquinone substrates, affording the desired photo-products in acceptable to excellent yields (17-81%). Factors influencing the regiochemistry of the photo Friedel-Crafts reaction on unsymmetrical naphthoquinones have also been investigated.
- Mitchell, Lorna J.,Lewis, William,Moody, Christopher J.
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supporting information
p. 2830 - 2842
(2013/10/08)
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- Enantioselective and Structure-Selective Diels-Alder Reactions of Unsymmetrical Quinones Catalyzed by a Chiral Oxazaborolidinium Cation. Predictive Selection Rules
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The chiral oxazaborolidinium cation 1 promotes Diels-Alder reactions between 2-triisopropylsilyloxy-1,3-butadiene and a number of unsymmetrical 1,4-benzoquinones in a highly enantioselective and structurally selective manner. The basis for the enantioselectivity is explained rationally in terms of a preferred type of transition-state assembly. Selection rules have been developed that allow the prediction of the principal reaction product of Diels-Alder reaction between unsymmetrical diene and quinone components. Copyright
- Ryu, Do Hyun,Zhou, Gang,Corey
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p. 4800 - 4802
(2007/10/03)
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- Novel compounds
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The present invention is directed to compounds of formula I, formula Ia, and formula Ib. wherein each of R1, R2, R3, R4, Ra, and Rb has been defined herein. The invention is also directed to a process for the preparation, the use and pharmaceutical compositions comprising the compounds described above. These novel compounds are useful in therapy, particularly for the treatment of type 2 diabetes.
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