- The mckenna reaction – avoiding side reactions in phosphonate deprotection
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The McKenna reaction is a well-known and popular method for the efficient and mild synthesis of organophosphorus acids. Bromotrimethylsilane (BTMS) is the main reagent in this reaction, which transforms dialkyl phosphonate esters into bis(trimethylsilyl)esters, which are then easily converted into the target acids. However, the versatile character of the McKenna reaction is not always used to its full extent, due to formation of side products. Herein, demonstrated by using model examples we have not only analyzed the typical side processes accompanying the McKenna reaction, but also uncovered new ones. Further, we discovered that some commonly recommended precautions did not always circumvent the side reactions. The proposed results and recommendations may facilitate the synthesis of phosphonic acids.
- Justyna, Katarzyna,Ma?olepsza, Joanna,Kusy, Damian,Maniukiewicz, Waldemar,B?a?ewska, Katarzyna M.
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p. 1436 - 1446
(2020/07/08)
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- Synthesis and structure-activity relationship of tyrosinase inhibiting novel bi-heterocyclic acetamides: Mechanistic insights through enzyme inhibition, kinetics and computational studies
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The present research was designed for the selective synthesis of novel bi-heterocyclic acetamides, 9a-n, and their tyrosinase inhibition to overwhelm the problem of melanogenesis. The structures of newly synthesized compounds were confirmed by spectral techniques such as 1H NMR, 13C NMR, and EI-MS along with elemental analysis. The inhibitory effects of these bi-heterocyclic acetamides (9a-n) were evaluated against tyrosinase and all these molecules were recognized as potent inhibitors relative to the standard used. The Kinetics mechanism was analyzed by Lineweaver-Burk plots which explored that compound, 9h, inhibited tyrosinase competitively by forming an enzyme-inhibitor complex. The inhibition constants Ki calculated from Dixon plots for this compound was 0.0027 μM. The computational study was coherent with the experimental records and these ligands exhibited good binding energy values (kcal/mol). The hemolytic analysis revealed their mild cytotoxicity towards red blood cell membranes and hence, these molecules can be pondered as nontoxic medicinal scaffolds for skin pigmentation and related disorders.
- Butt, Abdul Rehman Sadiq,Abbasi, Muhammad Athar,Aziz-ur-Rehman,Siddiqui, Sabahat Zahra,Raza, Hussain,Hassan, Mubashir,Shah, Syed Adnan Ali,Shahid, Muhammad,Seo, Sung-Yum
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p. 459 - 472
(2019/02/19)
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- New indole based hybrid oxadiazole scaffolds with N-substituted acetamides: As potent anti-diabetic agents
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Current study is based on the sequential conversion of indolyl butanoic acid (1) into ethyl indolyl butanoate (2), indolyl butanohydrazide (3), and 1,3,4-oxadiazole-2-thiol analogs (4) by adopting chemical transformations. In a parallel series of reaction
- Nazir, Majid,Abbasi, Muhammad Athar,Aziz-ur-Rehman,Siddiqui, Sabahat Zahra,Khan, Khalid Mohammed,Kanwal,Salar, Uzma,Shahid, Muhammad,Ashraf, Muhammad,Arif Lodhi, Muhammad,Ali Khan, Farman
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p. 253 - 263
(2018/09/05)
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- 2-Oxo-1,2-dihydropyridinyl-3-yl amide-based GPa inhibitors: Design, synthesis and structure-activity relationship study
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Glycogen phosphorylase (GP), which plays a crucial role in the conversion of glycogen to glucose-1-phosphate, is a target for therapeutic intervention in diabetes. In this study, we report the design and synthesis of 29 new derivatives of 2-oxo-1,2-dihydro pyridin-3-yl amides, as potential inhibitors of GP. The hit rate (45%) was high with 13 compounds inhibiting GPa (between 33% at 4.40 mM and an IC50 of 1.92 μM). Two lead compounds were identified as compounds exhibiting good GPa inhibition (IC50 = 2.1 and 1.92 μM). SAR analysis of these compounds revealed sensitivity of GPa to the length of the 2-oxo-1,2-dihydro pyridin-3-yl amide derivative and a preference for inclusion of a 3,4-dichlorobenzyl moiety.
- Loughlin, Wendy A.,Jenkins, Ian D.,Karis, N. David,Schweiker, Stephanie S.,Healy, Peter C.
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supporting information
p. 1 - 14
(2016/02/18)
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- SAR and identification of 2-(quinolin-4-yloxy)acetamides as Mycobacterium tuberculosis cytochrome bc 1 inhibitors
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A previous phenotypic screen by GSK identified 2-(quinolin-4-yloxy)acetamides as potent growth inhibitors of Mycobacterium tuberculosis (Mtb). We report the results of a preliminary structure-activity relationship (SAR) study of the compound class which has yielded more potent inhibitors. An Mtb cytochrome bd oxidase deletion mutant (cydKO) was found to be hypersensitive to most members of the compound library, while strains carrying single-nucleotide polymorphisms of the qcrB gene, which encodes a subunit of the menaquinol cytochrome c oxidoreductase (bc1) complex, were resistant to the library. These results identify that the 2-(quinolin-4-yloxy)acetamide class of Mtb growth inhibitors can be added to the growing number of scaffolds that target the M. tuberculosis bc1 complex.
- Phummarin, Narisa,Boshoff, Helena I.,Tsang, Patricia S.,Dalton, James,Wiles, Siouxsie,Barry, Clifton E.,Copp, Brent R.
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p. 2122 - 2127
(2016/11/18)
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- Design, synthesis and biological evaluation of hydroxamic acid derivatives as potential high density lipoprotein (HDL) receptor CLA-1 up-regulating agents
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Trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA) were reported in our recent publication as novel human high density lipoprotein (HDL) receptor CD36 and Lysosomal integral membrane protein-II Analogous-1 (CLA-1) up-regulators. As part of a
- Chen, Xiaofang,Wang, Li,Du, Yu,Wu, Yanbin,Jia, Xiaojian,Yang, Yuan,Hong, Bin
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experimental part
p. 9178 - 9193
(2012/01/12)
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- Structure-activity relationships in the binding of chemically derivatized CD4 to gp120 from human immunodeficiency virus
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The first step in HIV infection is the binding of the envelope glycoprotein gp120 to the host cell receptor CD4. An interfacial "Phe43 cavity" in gp120, adjacent to residue Phe43 of gp120-bound CD4, has been suggested as a potential target for therapeutic intervention. We designed a CD4 mutant (D1D2F43C) for site-specific coupling of compounds for screening against the cavity. Altogether, 81 cysteine-reactive compounds were designed, synthesized, and tested. Eight derivatives exceeded the affinity of native D1D2 for gp120. Structure-activity relationships (SAR) for derivatized CD4 binding to gp120 revealed significant plasticity of the Phe43 cavity and a narrow entrance. The primary contacts for compound recognition inside the cavity were found to be van der Waals interactions, whereas hydrophilic interactions were detected in the entrance. This first SAR on ligand binding to an interior cavity of gp120 may provide a starting point for structure-based assembly of small molecules targeting gp120-CD4 interaction.
- Xie, Hui,Ng, Danny,Savinov, Sergey N.,Dey, Barna,Kwong, Peter D.,Wyatt, Richard,Smith III, Amos B.,Hendrickson, Wayne A.
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p. 4898 - 4908
(2008/03/11)
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- Brain-specific drug delivery
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The subject compounds, which are adapted for the site-specific/sustained delivery of centrally acting drug species to the brain, are: (a) compounds of the formula wherein [D] is a centrally acting drug species, and [DHC] is the reduced, biooxidizable, blood-brain barrier penetrating lipoidal form of a dihydropyridine pyridinium salt redox carrier, with the proviso that when [DHC] is STR1 wherein R is lower alkyl or benzyl and [D] is a drug species containing a single NH2 or OH functional group, the single OH group when present being a primary or secondary OH group, said drug species being linked directly through said NH2 or OH function group to the carbonyl function of [DHC], then [D] must be other than a sympathetic stimulant, steroid sex hormone or long chain alkanol; and (b) non-toxic pharmaceutically acceptable salts of compounds of formula (I) wherein [D] is a centrally acting drug species and [DHC] is the reduced, biooxidizable, blood-brain barrier penetrating lipoidal form of a dihydropyridine pyridinium salt redox carrier. The corresponding ionic pyridinium salt type drug/carrier entitles [D--QC]+ X- are also disclosed.
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- Improved delivery through biological membranes XIX: Novel redox carriers for brain-specific chemical delivery systems
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New dihydropyridine ? pyridinium salt-type redox carrier systems were developed in which the drug is linked via the ring nitrogen atom of nicotinamide. The rate of oxidation of the dihydropyridine forms, and thus the overall and brain-specific distribution of the corresponding 3-carbamoyl-1-carbamoylalkyl-drug quaternary salts, depends on the number of methylene groups separating the ring nitrogen and the carbamoyl function linked to the drug.
- Bodor,AbdelAlim
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p. 241 - 245
(2007/10/02)
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