1485-07-0Relevant articles and documents
Conversion of thioureas to fluorescent isothiouronium-based photoinduced electron transfer sensors for oxoanion sensing
Nishizawa, Seiichi,Cui, Ying-Yu,Minagawa, Masakazu,Morita, Kotaro,Kato, Yuichi,Taniguchi, Shinichiro,Kato, Ryo,Teramae, Norio
, p. 866 - 870 (2002)
A convenient conversion is described of thiourea-based receptors to fluorescent isothiouronium-based photoinduced electron transfer (PET) sensors for oxoanion sensing. Naphthalene- or anthracene-functionalized mono-isothiouroniums are synthesized from the corresponding thioureas, in which the fluorophore is connected to the sulfur atom of the thiourea moiety by a methylene or an ethylene spacer. Even though all of the isothiouroniums with a methylene spacer readily decompose in MeOH upon excitation of the fluorophore moiety, the isothiouronium with an ethylene spacer shows good stability under identical conditions. The naphthyl isothiouronium with an ethylene spacer shows a significant fluorescence enhancement upon formation of a 1 : 1 complex with oxoanions in MeOH, and the selectivity follows the order of hydrogen phosphate > acetate ? dihydrogen phosphate ? chloride. The results in the present work indicate that various types of fluorescent PET sensors might be readily obtainable from non-fluorescent thiourea-based receptors by the introduction of appropriate fluorophores at the sulfur atom of thiourea-binding sites.
New method of fluorination using potassium fluoride in ionic liquid: Significantly enhanced reactivity of fluoride and improved selectivity
Kim, Dong Wook,Song, Choong Eui,Chi, Dae Yoon
, p. 10278 - 10279 (2002)
We have found the new nucleophilic fluorination reaction of some halo- and mesylalkanes to the corresponding fluoroalkanes with KF in the presence of [bmim][BF4] under various reaction conditions. 2-(3-Methanesulfonyloxypropoxy)naphthalene (1) was used as a model compound to optimize this fluorination reaction. Whereas the fluorination of the mesylate 1 with KF in an organic solvent such as CH3CN at 100 °C occurred hardly even after 24 h, the same reaction in ionic liquids, [bmim][BF4], as a reaction solvent was completed within 1.5 h, affording the wanted product 2-(3-fluoropropoxy)naphthalene 2a (85%) together with the alkene byproduct 2c (10%). Very interestingly, however, the addition of water (5 equiv) completely eliminated the formation of the undesired alkene 2c and thus gave higher yield of 2a (92%, entry 2). The use of acetonitrile as a cosolvent did not affect the reactivity of the fluorination. The presence of a proper amount of cosolvent was rather desirable (94% yield of 2a). We performed fluorination reactions with other ionic liquids ([bmim][PF6], [bmim][SbF6], [bmim][OTf], and [bmim][N(Tf)2], and two other cosolvents, to find the optimal ionic liquid and cosolvent. Nine different compounds were examined, including the 10 g-synthesis of 2-(fluoromethyl)naphthalene in 93% of isolated yield. Copyright
INTER- AND INTRA-MOLECULAR PHOTOCYCLOADDITION OF ENOL ETHERS TO NAPHTHALENE
Gilbert, Andrew,Heath, Peter,Kashoulis-Koupparis, Annoula,Ellis-Davies, Graham C. R.,Firth, Susan M.
, p. 31 - 36 (1988)
The isomeric non-conjugated naphthyl enol ether bichromophores (6) and (7) display markedly different photoreactivities.The former undergoes ? + 2?> cycloaddition from the S1 state whereas the latter is relatively photostable.The two cyano derivatives (4) and (5) both yield intramolecular cycloadducts but the orientation of the addition is the opposite of that predicted from the reported intermolecular cyanonaphthalene-enol ether photoreactions. 2,3-Dihydrofuran undergoes specific "head to head" endo photoaddition to naphthalene but in contrast the major adducts from 2,3-dihydrofuran and this arene have "head to head" exo and "head to tail" endo structures.The adduct (18) undergoes a facile 1,3-shift to yield the (4? + 2?) endo adduct (19).The reactivities of the bichromophores and the regiochemistries of the additions are considered in relation to the relative charge densities at the 1- and 2-positions of the S1 arene.
Mutagenicity of N-acyloxy-N-alkoxyamides as an indicator of DNA intercalation part 1: Evidence for naphthalene as a DNA intercalator
Banks, Tony M.,Clay, Samuel F.,Glover, Stephen A.,Schumacher, Rhiannon R.
, p. 3699 - 3714 (2016)
N-Acyloxy-N-alkoxyamides are direct-acting mutagens in S. typhimurium TA100 with a linear dependence upon log P that maximises at log P0 = 6.4. Eight N-acyloxy-N-alkoxyamides (2-9) bearing a naphthalene group on any of the three side-chains and with log P0 6.4 have been demonstrated to be significantly and uniformly more mutagenic towards S. typhimurium TA100 than 50 mutagens without naphthalene. The activity enhancement of 2-9 is likely due to intercalative binding of naphthalene to bacterial DNA as a number are also active in TA98, a frame-shift strain of S. typhimurium, which is modified by intercalators. DNA damage profiles for naphthalene-bearing mutagens confirm enhanced reactivity with DNA when naphthalene is incorporated and a different binding mode when compared to mutagens without naphthalene. The effect is independent of whether the naphthalene is attached to an electron-donating alkyl or electron-withdrawing acyl group, alkyl tether length or, in the case of 6 and 7, the point of attachment to naphthalene. A new quantitative structure activity relationship has been constructed for all 58 congeners incorporating log P and an indicator variable, I, for the presence (I = 1) or absence (I = 0) of naphthalene and from which the activity enhancing effect of a naphthalene has been quantified at between three and four log P units. Contrary to conventional views, simple naphthalene groups could target molecules to DNA through intercalation.
Bidentate Lewis acids for the activation of 1,2-diazines - A new mode of catalysis
Kessler, Simon N.,Neuburger, Markus,Wegner, Hermann A.
, p. 3238 - 3245 (2011)
Bidentate Lewis acids were applied as catalysts for the inverse-electron-demand Diels-Alder (IEDDA) reaction of 1,2-diazines. The concept of catalysis is based on the coordination of the bidentate Lewis acid to both nitrogen atoms of the 1,2-diazine moiety, thereby reducing the electron density and lowering the energy of the LUMO. This should, according to frontier molecular orbital (FMO) theory, facilitate the cycloaddition step. This new concept was successfully applied to a variety of dienophiles and substituted phthalazine substrates. Careful investigations of the mechanism led to the isolation and characterization of key intermediates; all of which support the presented catalytic cycle. Copyright
An air-stable bisboron complex: A practical bidentate Lewis acid catalyst
Hong, Longcheng,Ahles, Sebastian,Heindl, Andreas H.,Tiétcha, Gastelle,Petrov, Andrey,Lu, Zhenpin,Logemann, Christian,Wegner, Hermann A.
, p. 618 - 625 (2018)
We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels-Alder (IEDDA) reaction of 1, 2-diazine as well as 1, 2, 4, 5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1, 2-bis(trimethylsilyl) benzene greatly enhancing its practicality. Comparative reactions were carried out to evaluate its catalytic activity in IEDDA reactions of diazine including phthalazine as well as 1, 2, 4, 5-tetrazine.
Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols
Mayr, Stefanie,Marin-Luna, Marta,Zipse, Hendrik
, p. 3456 - 3489 (2021/03/01)
Relative rates for the Lewis base-mediated acylation of secondary and primary alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydride derivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate size leads to an actual acceleration of the acylation process, the effect being larger for secondary as compared to primary alcohols. Computational results indicate that acylation rates are guided by noncovalent interactions (NCIs) between the catalyst ring system and the DED substituents in the alcohol and anhydride reactants. Thereby stronger NCIs are formed for secondary alcohols than for primary alcohols.
Chromium-Catalyzed Borylative Coupling of Aliphatic Bromides with Pinacolborane by Hydrogen Evolution
Fu, Aiping,Li, Chao,Luo, Meiming,Zeng, Xiaoming,Zhao, Lixing
supporting information, p. 2204 - 2208 (2021/06/28)
The chromium-catalyzed borylative coupling between aliphatic bromides and pinacolborane (HBpin) is described. This reaction was promoted by low-cost and bench-stable CrCl3as a precatalyst combined with 4,4′-di-tert-butyl-2,2′-dipyridyl and aluminum, presenting a rare example of using HBpin as a borane reagent by coupling with alkyl bromides in forming borylated alkanes. Mechanistic studies indicate that aluminum plays important roles in the formation of reactive Cr species and aliphatic radicals, which lead to (alkyl)Cr by reaction with HBpin to give the products.
AMINOPEPTIDASE A INHIBITORS AND PHARMACEUTICAL COMPOSITIONS COMPRISING THE SAME
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Page/Page column 69, (2020/06/10)
The present invention relates to a novel compound, to a composition comprising the same, to methods for preparing the compound, and the use of this compound in therapy. In particular, the present invention relates to compound that is useful in the treatment and prevention of primary and secondary arterial hypertension, ictus, myocardial ischaemia, cardiac and renal insufficiency, myocardial infarction, peripheral vascular disease, diabetic proteinuria, Syndrome X and glaucoma.
Allyl 4-Chlorophenyl Sulfone as a Versatile 1,1-Synthon for Sequential α-Alkylation/Cobalt-Catalyzed Allylic Substitution
Kojima, Masahiro,Matsunaga, Shigeki
, p. 1934 - 1946 (2020/07/03)
Despite their unique potential as rare 1,1-dipole synthons, allyl sulfones are rarely used in target-oriented syntheses, likely due to the lack of a general catalytic method for their branch-selective allylic substitution. Herein, we identified allyl 4-chlorophenyl sulfone as a versatile linchpin for both base-mediated α-derivatization and subsequent cobalt-catalyzed allylic substitution. The sequential transformations allow for highly regioselective access to branched allylic substitution products with a variety of aliphatic side chains. The photoredox-enabled cobalt catalysis is indispensable for achieving high yields and regioselectivity for the desulfonylative substitution in contrast to traditional metal-catalyzed protocols, which lead to inferior outcomes in the corresponding transformations.
