- Domino lignin depolymerization and reconnection to complex molecules mediated by boryl radicals
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Chemical degradation of lignin has attracted increasing interest due to its potential for producing chemicals from renewable resources. Herein, we present a new transition metal free degradation procedure utilizing DDQ-oxidation and boryl radical mediated degradation, followed by reconnection of a monomer intermediate to a new dimer in a domino process. Our results include the selective degradation of oxidized β-O-4 model compounds by a boryl radical initiated with a catalytic amount of 4-(4-pyridinyl)benzonitrile and bispinacolborane B2(pin)2 as well as its application to organosolv lignin. This sequential procedure expands the toolbox for lignin degradation from simple depolymerization to high-value products by incorporating bond forming transformations within the process, and also provides a new transition-metal free method for the construction of 1,6-diketone fragments.
- Hong, Longcheng,Pfeiffer, Janin,Spielmeyer, Astrid,Wegner, Hermann A.
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p. 3008 - 3014
(2020/06/17)
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- Rhodium-Catalyzed Room Temperature C-C Activation of Cyclopropanol for One-Step Access to Diverse 1,6-Diketones
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A rhodium-catalyzed room temperature C-C activation of cyclopropanol has been demonstrated for the single-step synthesis of a range of electronically and sterically distinct 1,6-diketones. This reaction proceeds efficiently in shorter reaction time following a highly atom-economical pathway. To illustrate the synthetic potential of 1,6-diketones, aldol and macrocyclization reactions have been successfully demonstrated. Preliminary mechanistic studies revealed the involvement of nonradical pathways.
- Ghosh, Asit,Pati, Bedadyuti Vedvyas,Ravikumar, P. C.
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supporting information
(2020/04/02)
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- Structural optimization of natural product nordihydroguaretic acid to discover novel analogues as AcrB inhibitors
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Drug efflux pumps confer multidrug resistance to dangerous bacterial pathogens which makes these proteins promising drug targets. Herein, we present initial chemical optimization and structure-activity relationship (SAR) data around a previously described efflux pump inhibitor, nordihydroguaretic acid (NDGA). Four series of novel NDGA analogues that target Escherichia coli AcrB were designed, synthesized and evaluated for their ability to potentiate the activity of antibiotics, to inhibit AcrB-mediated substrate efflux and reduce off-target activity. Nine novel structures were identified that increased the efficacy of a panel of antibiotics, inhibited drug efflux and reduced permeabilization of the bacterial outer and inner membranes. Among them, WA7, WB11 and WD6 possessing broad-spectrum antimicrobial sensitization activity were identified as NDGA analogues with favorable properties as potential AcrB inhibitors, demonstrating moderate improvement in potency as compared to NDGA. In particular, WD6 was the most broadly active analogue improving the activity of all four classes of antibacterials tested.
- Alenzy, Rawaf,Liu, Xingbang,Ma, Shutao,Ma, Yingang,Mowla, Rumana,Polyak, Steven W.,Song, Di,Teng, Yuetai,Venter, Henrietta,Wang, Yinhu
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- Dihedral-Angle-Controlled Crossover from Static Hole Delocalization to Dynamic Hopping in Biaryl Cation Radicals
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In cases of coherent charge-transfer mechanism in biaryl compounds the rates follow a squared cosine trend with varying dihedral angle. Herein we demonstrate using a series of biaryl cation radicals with varying dihedral angles that the hole stabilization
- Talipov, Marat R.,Navale, Tushar S.,Hossain, Mohammad M.,Shukla, Ruchi,Ivanov, Maxim V.,Rathore, Rajendra
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supporting information
p. 266 - 269
(2016/12/30)
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- Synthesis of 4-[2-(3,4-dimethoxybenzyl)cyclopentyl]-1,2-dimethoxybenzene Derivatives and Evaluations of Their Carbonic Anhydrase Isoenzymes Inhibitory Effects
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Rearrangement of 1,6-bis(3,4-dimethoxyphenyl)hexane-1,6-dione (8) gave two isomeric products having cyclopentene moiety. Starting from the major product (3,4-dimethoxyphenyl)[2-(3,4-dimethoxyphenyl)cyclopent-1-en-1-yl]methanone (11), eight new compounds (16-23) were obtained by the reactions such as reduction (by catalytic hydrogenation and NaBH4), nitration, 1,4-addition, bromination, and esterification reactions. Carbonic anhydrases (CA, E.C.4.2.1.1) are ubiquitous metalloenzymes present in almost all living organism that catalyze a simple reaction, the conversion of carbon dioxide (CO2) and water (H2O) to bicarbonate ion (HCO3-) and a proton (H+). CA isoenzymes I and II (hCA I and II) inhibition effects of synthesized eleven new and four known compounds (8-13 and 15-23) were investigated. Inhibition studies of the hCA I and II with 4-[2-(3,4-dimethoxybenzyl)cyclopentyl]-1,2-dimethoxybenzene derivatives revealed that they possess effective inhibitory potency. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized 4-[2-(3,4-dimethoxybenzyl)cyclopentyl]-1,2-dimethoxybenzene derivatives with Kis in the range of 313.16-1537.00 nm against hCA I and in the range of 228.31-1927.31 nm against hCA II, respectively.
- Artun?, Tekin,?etinkaya, Yasin,G??er, Hülya,Gül?in, Ilhami,Menzek, Abdullah,?ahin, Ertan,Supuran, Claudiu T.
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p. 594 - 607
(2016/03/19)
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- Synthesis and photochemical properties of photo-cleavable crosslinkers
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We report herein the synthesis and the development of homo-bifunctional photo-cleavable sulfhydryl group cross-linkers that are able to react and then to photorelease two cysteines leading to the photoregulation of cross-linkers cleavage.
- Omran, Ziad,Specht, Alexandre
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supporting information; experimental part
p. 2434 - 2436
(2009/08/07)
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- Synthesis and structure activity relationships of fibrinolytic 1,ω diphenyl 1,ω alkanediamines
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The promising results obtained in animal clot lysis experiments with the fibrinolytic bis(tetrahydroiso quinolines) VI prompted the preparation of a related series of 1,ω diphenyl 1,ω alkanediamines V. As measured in the standard rat screen (ip) the compo
- Fliedner Jr,Myers,Schor,Pachter
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p. 749 - 754
(2007/10/06)
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