Xn:Harmful;
135-19-3Relevant articles and documents
2,4-dinitrophenyl ether-containing chemodosimeters for the selective and sensitive in vitro and in vivo detection of hydrogen sulfide
El Sayed, Sameh,De La Torre, Cristina,Santos-Figueroa, Luis E.,Martinez-Manez, Ramon,Sancenon, Felix,Orzaez, Mar,Costero, Ana M.,Parra, Margarita,Gil, Salvador
, p. 244 - 254 (2015)
Four probes (i.e. D1-D4) for the selective and sensitive fluorogenic detection of HS- have been prepared and characterised. HEPES (10 mM, pH 7.4)-DMSO 99:1 v/v solutions of D1-D4 are essentially non-fluorescent. Changes in the emission using D1-D4 in the presence of anions (F-, Cl-, Br-, I-,N-3, CN-, SCN-, AcO-,CO2-3 ,PO2-4,SO2-4, HS- and OH-), biothiols (GSH, Cys, Hcy, Me-Cys and lipoic acid), reducing agents (SO2-3 and S2O2-3) and oxidants (H2O2) demonstrated that only HS- is able to induce the appearance of intense emission bands in the 400-520 nm range in the four probes. The selectivity observed was ascribed to a unique hydrogen sulfide-induced hydrolysis of the 2,4-dinitrophenyl ether moiety that yielded the corresponding free highly fluorescent alcohols. The potential detection of intracellular HS- was also studied.
Effect of cyclodextrin complexation on photo-fries rearrangement of naphthyl esters
Banu, Habeeb Shayira,Pitchumani, Kasi,Srinivasan, Chockalingam
, p. 9601 - 9610 (1999)
Photolysis of β-cyclodextrin inclusion complexes of 1- and 2-naphthyl esters (acetates and benzoates) in aqueous medium, results in rearrangement to give one isomer of acylnaphthol in excess, whereas the solid state irradiation of the cyclodextrin complexes yields selectively one isomer. In addition, formation of cleavage product is totally suppressed. This remarkable selectivity is attributed to specific modes of the complexation of the esters into the β-CD cavity.
An efficient approach for the synthesis and antimicrobial evaluation of some new benzocoumarins and related compounds
Hekal, Mohamed H.,Abu El-Azm, Fatma S. M.,Samir, Sandy S.
, p. 2175 - 2186 (2021)
A convenient synthetic approach for pharmaceutically important benzocoumarin-based heterocyclic compounds has been studied. β-enaminonitrile has been used for the synthesis of a broad diversity of new benzocoumarins and related compounds over different reaction steps. Various synthetic approaches were used in this research for synthesis of heterocyclic systems such as acid-catalyzed hydrolysis, decarboxylation, deamination, ring opening and ring closure. The molecular structures of the newly synthesized derivatives were established by elemental analyses and spectral data (IR, 1H-NMR, and 13C-NMR). Some of the newly synthesized compounds were explored for their antimicrobial activities.
Regio- and stereochemistry of Na-mediated reductive cleavage of alkyl aryl ethers
Azzena, Ugo,Carraro, Massimo,Meloni, Claudia,Murgia, Irene,Pisano, Luisa,Pittalis, Mario,Luisi, Renzo,Musio, Biagia,Degennaro, Leonardo
, p. 1550 - 1554 (2014)
We have investigated the regio-and stereochemistry of the reductive dealkoxylation of alkyl aryl ethers. Chiral non-racemic secondary alcohols were converted into the corresponding m-terphenyl or 2-biphenyl ethers either via inversion of configuration under Mitsunobu reaction conditions or with retention of configuration under SNAr conditions. The successive cleavage of the aromatic C-O bond occurred in the presence of a stoichiometric amount of Na metal in dry tetrahydrofuran at rt with retention of configuration, thus highlighting that the overall inversion or retention of configuration for the whole two-step procedure is dictated by the stereochemistry of the first synthetic step.
MILD CLEAVAGE OF METHOXYMETHYL (MOM) ESTERS WITH TRIMETHYLSILYLBROMIDE
Hanessian, Stephen,Delorme, Daniel,Dufresne, Yves
, p. 2515 - 2518 (1984)
Trimethylsilyl bromide is an effective reagent for the deprotection of methoxymethyl ethers under mild conditions.
Synthesis, structures and inclusion properties of tetranaphthalides: New macrocyclic clathrate hosts
Tanaka, Koichi,Hori, Kyosuke,Masumoto, Asuka,Arakawa, Ryuichi,Caira, Mino R.
, p. 2911 - 2915 (2011)
Novel tetranaphthalide host compounds 3 and 4 bearing isomeric naphthalene moieties have been synthesized and their inclusion properties were investigated. These host compounds enclathrated several kinds of ketones, cyclic ethers, amides, sulfoxides and aromatic compounds. The structures of two representative inclusion compounds containing different host molecules and a common guest (dimethyl sulfoxide) were investigated by X-ray diffraction to determine the nature of guest inclusion and to rationalize their distinctly different thermal decomposition profiles.
Hydrolytic enzymes conjugated to quantum dots mostly retain whole catalytic activity
Iyer, Aditya,Chandra, Anil,Swaminathan, Rajaram
, p. 2935 - 2943 (2014)
Background Tagging a luminescent quantum dot (QD) with a biological like enzyme (Enz) creates value-added entities like quantum dot-enzyme bioconjugates (QDEnzBio) that find utility as sensors to detect glucose or beacons to track enzymes in vivo. For such applications, it is imperative that the enzyme remains catalytically active while the quantum dot is luminescent in the bioconjugate. A critical feature that dictates this is the quantum dot-enzyme linkage chemistry. Previously such linkages have put constraints on polypeptide chain dynamics or hindered substrate diffusion to active site, seriously undermining enzyme catalytic activity. In this work we address this issue using avidin-biotin linkage chemistry together with a flexible spacer to conjugate enzyme to quantum dot. Methods The catalytic activity of three biotinylated hydrolytic enzymes, namely, hen egg white lysozyme (HEWL), alkaline phosphatase (ALP) and acetylcholinesterase (AChE) was investigated post-conjugation to streptavidin linked quantum dot for multiple substrate concentrations and varying degrees of biotinylation. Results We demonstrate that all enzymes retain full catalytic activity in the quantum dot-enzyme bioconjugates in comparison to biotinylated enzyme alone. However, unlike alkaline phosphatase and acetylcholinesterase, the catalytic activity of hen egg white lysozyme was observed to be increasingly susceptible to ionic strength of medium with rising level of biotinylation. This susceptibility was attributed to arise from depletion of positive charge from lysine amino groups after biotinylation. Conclusions We reasoned that avidin-biotin linkage in the presence of a flexible seven atom spacer between biotin and enzyme poses no constraints to enzyme structure/dynamics enabling retention of full enzyme activity. General significance Overall our results demonstrate for the first time that streptavidin-biotin chemistry can yield quantum dot enzyme bioconjugates that retain full catalytic activity as native enzyme.
Decarbethoxylative Arylation Employing Arynes: A Metal-Free Pathway to Arylfluoroamides
Gupta, Ekta,Kant, Ruchir,Mohanan, Kishor
, p. 6016 - 6019 (2017)
An efficient, metal-free decarbethoxylative arylation protocol for the synthesis of α-aryl-α-fluoroamides from fluoromalonamates, under ambient reaction conditions using aryne as an electrophilic arylating agent, is reported. This decarbethoxylative arylation proceeds under mild conditions and provides a practical and effective entry to a wide range of α-aryl-α-fluoroacetamides. Interestingly, the use of the tert-butyl ester of fluoromalonamate prevented the otherwise rapid decarboxylation step, affording the arylated fluoromalonamate in moderate yield.
Nucleophilic Hydroxylation in Water Media Promoted by a Hexa-Ethylene Glycol-Bridged Dicationic Ionic Liquid
Jadhav, Vinod H.,Kim, Jin Gwan,Jeong, Hyeon Jin,Kim, Dong Wook
, p. 7275 - 7280 (2015)
Hexaethylene glycol bis(3-hexaethylene glycol imidazolium) dimesylate ionic liquid (hexaEG-DHIM) was designed and prepared as a highly efficient promoter for the nucleophilic hydroxylation of alkyl halides to the corresponding alcohol products in neat water media. It was observed that hexaEG-DHIM promoter enhanced the nucleophilicity of water significantly in the reaction. In addition, the hexaEG-DHIM could be reused several times without loss of activity. Moreover, the hydroxylation reactions of base-sensitive and/or polar alkyl halide substrates proceeded highly chemoselectively in excellent yields.
Cationic reverse micelles create water with super hydrogen-bond-donor capacity for enzymatic catalysis: Hydrolysis of 2-naphthyl acetate by α-Chymotrypsin
Moyano, Fernando,Falcone, R. Falcone,Mejuto,Silber, Juana J.,Correa, N. Mariano
, p. 8887 - 8893 (2010)
Reverse micelles (RMs) are very good nanoreactors because they can create a unique microenvironment for carrying out a variety of chemical and biochemical reactions. The aim of the present work is to determine the influence of different RM interfaces on the hydrolysis of 2-naphthyl acetate (2NA) by α-chymotrypsin (α-CT). The reaction was studied in water/benzyl-nhexadecyldimethylammonium chloride (BHDC)/benzene RMs and, its efficiency compared with that observed in pure water and in sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) RMs. Thus, the hydrolysis rates of 2-NA catalyzed by α-CT were determined by spectroscopic measurements. In addition, the method used allows the joint evaluation of the substrate partition constant Kp between the organic and the micellar pseudophase and the kinetic parameters: catalytic rate constant kcat, and the Michaelis constant KM of the enzymatic reaction. The effect of the surfactant concentration on the kinetics parameters was determined at constant W 0= [H2O]/[surfactant], and the variation of W0 with surfactant constant concentration was investigated. The results show that the classical Michaelis-Menten mechanism is valid for α-CT in all of the RMs systerns studied and that the reaction takes place at both RM interfaces. Moreover, the catalytic efficiency values kcat/KM obtained in the RMs systems are higher than that reported in water. Furthermore, there is a remarkable increase in α-CT efficiency in the cationic RMs in comparison with the anionic system, presumably due to the unique water properties found in these confined media. The results show that in cationic RMs the hydrogen-bond donor capacity of water is enhanced due to its interaction with the cationic interface. Hence, entrapped water can be converted into "super-water" for the enzymatic reaction studied in this work.
