- [1,3]-Claisen rearrangement via removable functional group mediated radical stabilization
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A thermal O-to-C [1,3]-rearrangement of α-hydroxy acid derived enol ethers was achieved under mild conditions. The 2-aminothiophenol protection of carboxylic acids facilitates formation of the [1,3] precursor and its thermal rearrangement via stabilization of a radical intermediate. Experimental and theoretical evidence for dissociative radical pair formation, its captodative stability via aminothiophenol, and a unique solvent effect are presented. The aminothiophenol was deprotected from rearrangement products as well as after derivatization to useful synthons.
- Alam, Md Nirshad,Dash, Soumya Ranjan,Mukherjee, Anirban,Pandole, Satish,Marelli, Udaya Kiran,Vanka, Kumar,Maity, Pradip
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supporting information
p. 890 - 895
(2021/02/01)
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- Discovery of Potent and Selective Leads against Toxoplasma gondii Dihydrofolate Reductase via Structure-Based Design
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Current treatment of toxoplasmosis targets the parasite’s folate metabolism through inhibition of dihydrofolate reductase (DHFR). The most widely used DHFR antagonist, pyrimethamine, was introduced over 60 years ago and is associated with toxicity that can be largely attributed to a similar affinity for parasite and human DHFR. Computational analysis of biochemical differences between Toxoplasma gondii and human DHFR enabled the design of inhibitors with both improved potency and selectivity. The approach described herein yielded TRC-19, a promising lead with an IC50 of 9 nM and 89-fold selectivity in favor of Toxoplasma gondii DHFR, as well as crystallographic data to substantiate in silico methodology. Overall, 50% of synthesized in silico designs met hit threshold criteria of IC50 2-fold selectivity favoring Toxoplasma gondii, further demonstrating the efficiency of our structure-based drug design approach.
- Welsch, Matthew E.,Zhou, Jian,Gao, Yueqiang,Yan, Yunqing,Porter, Gene,Agnihotri, Gautam,Li, Yingjie,Lu, Henry,Chen, Zhongguo,Thomas, Stephen B.
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supporting information
p. 1124 - 1129
(2016/12/16)
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- Visible-light-promoted Wohl-Ziegler functionalization of organic molecules with N-bromosuccinimide under solvent-free reaction conditions
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The visible-light-induced transformation of toluenes with N-bromosuccinimide (NBS) under solvent-free reaction conditions (SFRC) was studied. The reaction took place in spite of the very restricted molecular motion; toluenes could be regioselectively converted to benzyl bromides. Selective radical-chain reactions with NBS were carried out in liquid/liquid and in solid/solid systems; furthermore, reactions could be performed in the presence of air. The radical scavenger TEMPO (=2,2,6,6-tetramethylpiperidin-1- yloxy) completely suppressed the side-chain bromination of toluenes with NBS under SFRC. Electron-withdrawing groups decreased the reactivity of the toluenes, and the Hammett reaction constant ρ+ = -1.7 indicated involvement of polar radical intermediates with electrophilic character.
- Jereb, Marjan,Zupan, Marko,Stavber, Stojan
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scheme or table
p. 555 - 566
(2009/09/06)
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- An efficient synthesis of benzyl bromides from aromatic aldehydes using polymethylhydrosiloxane and (bromodimethyl)sulfonium bromide or N-bromosuccinimide
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Polymethylhydrosiloxane (PMHS) in combination with (bromodimethyl)sulfonium bromide or NBS has been utilized for the first time for reductive bromination of aromatic aldehydes at room temperature to afford the corresponding benzyl bromides in excellent yields.
- Das, Biswanath,Srinivas, Yallamalla,Holla, Harish,Laxminarayana, Keetha,Narender, Ravirala
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p. 6681 - 6683
(2008/03/12)
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- Aryl sulfonamide and sulfonyl compounds as modulators of PPAR and methods of treating metabolic disorders
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Aryl sulfonamide and sulfonyl compounds as modulators of peroxisome proliferator activated receptors, pharmaceutical compositions comprising the same, and methods of treating disease using the same are disclosed.
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Page/Page column 97
(2010/02/14)
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- N-acylamino benzyl ether derivatives
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This invention relates to N-acylamino aryl derivatives of the formula 1where R1, R21, R22, R23, R3, R4, R5 R6, R7, R8, R, and n are as defined herein and where X is —CHRO, —OCHR—, —CH2S—, —SCH2—, —CH2CH2—, —CH=CH— or —C≡C—. The compounds of the invention are selective monoamine oxidase B inhibitors, and they are therefore useful in the treatment of diseases mediated by monoamine oxidase B, for example, for the treatment of Alzheimer's disease or senile dementia.
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- Synthesis and electronic spectra of substituted oligo(phenylenevinylene)s
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A series of substituted oligo(p-phenylenevinylene)s (OPVs) with five benzene rings was prepared via PO-activated olefinations and Knoevenagel condensations. The central ring is substituted with two octyloxy groups to ensure good solubility of the OPVs and the lateral styrene units carry further substituents, with either electron-accepting or donating character and also combinations thereof. The spectral features of these OPVs are dominated by the basic chromophore; further auxochrome groups on the lateral rings (meta and para positions) shift the absorption and emission spectra only slightly to longer wavelengths. Significant bathochromic shifts (absorption ca 20 nm, emission ca 40 nm) are observed for OPVs with cyano groups on the terminal vinylene segments. The absorption spectra are independent from the concentration and solvatochromism is very small. The OPVs are photochemically stable to near-UV irradiation (366 nm) in neutral solution, whereas mid-UV irradiation (254 nm) causes decomposition of the chromophore. The presence of traces of acids or amines leads to different photochemical pathways. Copyright
- Detert, Heiner,Sugiono, Erli
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p. 587 - 590
(2007/10/03)
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- Benzylphosphonic acid inhibitors of human prostatic acid phosphatase
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A series of α-substituted benzylphosphonic acids is described as inhibitors of human prostatic acid phosphatase, an enzyme has been used as a model to study aryl phosphatases. The most potent inhibitors in this series are 2-trifluoromethylbenzhydrylphosphonic acid (9 μM), and α-(2-phenylethyl)benzylphosphonic acid (14 μM). The structure-activity studies suggest that bulk tolerance beyond the phosphate binding area limits the steric or hydrophobic contribution to inhibitor potency achieved through α-carbon substitution.
- Schwender,Beers,Malloy,Cinicola,Wustrow,Demarest,Jordan
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p. 311 - 314
(2007/10/03)
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- ORGANIC PHOSPHORUS COMPOUNDS 91. SYNTHESIS AND PROPERTIES OF 1-AMINO-2-ARYLETHYLPHOSPHONIC AND -PHOSPHINIC ACIDS AS WELL AS -PHOSPHINE OXIDES
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The preparation, physical and spectroscopic properties of 1-amino-2-arylethylphosphonic, and -phosphinic acids as well as -phosphine oxides, the phosphorus analogues of phenylalanine are described, and the reactions of 1-amino-2-(4-fluorophenyl)ethylphosphonates with acetals, isocyanides, esters, acid anhydrides, activated aromatic nitro- and halogen compounds, and with N-protected alanine are reported.It is shown that several of the 1-amino-2-arylethylphosphonic acids are strong inhibitors of PAL and anthocyanin synthesis and also are quite active botryticides.Among the active compounds were 1-amino-2-(4-fluorophenyl)ethylphosphonic acid, 3f, and the methyl-substituted compounds 3k, 3l, and 3m.The fluoroderivative 3f was also effective as a seed-dressing agent in barley showing a 100percent protection against the fungus Fusarium nivale at 600 ppm.
- Maier, Ludwig
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- MECHANISMS OF FREE-RADICAL REACTIONS. XX. REACTIVITY IN THE FREE-RADICAL HALOGENATION REACTIONS OF ARYLFLUOROALKANES
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The free-radical chlorination and bromination of meta- and para-substituted benzyl fluorides and 1,1-difluoro-2-phenylethane and also the chlorination of 1-fluoro-2-arylethanes by phenylchloroiodonium chloride and the bromination of meta- and para-substituted benzyl bromides were studied by the method of competing reactions.In all cases a good correlation is observed between log krel and the Brown ?+ constants.In cases where change in the reactivity in the transition from one reaction series to another is due mainly to the polar effect of the substituent whilethe selectivity is measured in relation to the polar effect direct relationships are observed between the reactivity and the selectivity.
- Dneprovskii, A. S.,Eliseenkov, E. V.
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p. 711 - 719
(2007/10/02)
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- Substituent Effects on Benzyl Radical ESR Hyperfine Coupling Constants. The ?α*Scale Based upon Spin Delocalization
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The electron spin resonance spectra of 21 para- and meta-substituted benzyl radicals have been analyzed.A substituent constant, ?α*, has been defined from the benzylic α-hydrogen hyperfine coupling constant.The ?α* constant reflects the component of energy that may be attributed to spin delocalization in a substituted benzyl radical in comparison to the unsubstituted radical.For the derivatives studied, para substitution is stabilizing, except when fluorine is the substituent; meta substitution destabilizes the benzyl radical.A series of radical reactions is reexamined with an extended Hammett relation.The relative importance of spin delocalization vs. polar effects is assessed by the ratio of ρ* to ρ.The importance of choosing substituents for which ?a* and ? differ widely for such an assessment is emphasized.
- Dust, Julian M.,Arnold, Donald R.
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p. 1221 - 1227
(2007/10/02)
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