Search results for "Reagent"
showing 10 items of 699 documents
Reactions of Peroxides on Solid Surfaces
2014
This article describes the different roles that solid surfaces play in heterogeneous reactions involving peroxides, namely, (i) the solid surface interacts with the peroxide in the absence of any other substrate, (ii) the solid surface promotes the reaction activating either the peroxide or the substrate, (iii) the peroxide forms part of the solid active surface, and (iv) the substrate forms part of the active surface. The chapter covers reactions involving peroxides or discrete peroxydic transient species on solid surfaces or at solid–liquid and solid–gas interfaces, and provides general descriptions of different solid materials, details on reaction conditions, and synthetic procedures for…
ARYL-VINYLSULFONE—REAGENTIEN ZUM SCHUTZ UND NACHWEIS VON THIOLFUNKTIONEN
1983
Abstract Aryl vinyl sulfones selectively react with thiol groups to acid-stable compounds which easily are cleaved by mild bases to thiol compounds. Ester and amide groups are not attacked under these conditions. Therefore, these compounds are good protecting groups or labels in peptide chemistry. The following aryl vinyl sulfones were investigated: phenyl vinyl sulfone 1, p-carbethoxyphenyl vinyl sulfone 15 and the fluorescent 5-dimethylaminonaphthyl 1-vinyl sulfone 5 and 5-methoxynaphthyl-1 vinyl sulfone 10. The last two compounds are very useful reagents for the quantitative determination of SH-groups in polypeptides such as enzymes. Aryl-vinylsulfone reagieren selektiv mit Thiolgruppen …
Fluorous TBAF: A Convenient and Selective Reagent for Fluoride-Mediated Deprotections
2009
A fluorous analogue of TBAF has been developed for its use in the clean removal of silicon-derived protecting groups. Purification of the crude mixtures by fluorous solid-phase extractions allowed alcohols, amines, and carboxylic acids to be obtained in high purity, with no need of chromatographic separations. The moderate reactivity of fluorous TBAF was exploited in selective deprotections of several bifunctional molecules.
Studies on the Stereoselective Selenolactonization, Hydroxy and Methoxy Selenenylation of α- and β-Hydroxy Acids and Esters. Synthesis of δ- and γ-La…
2003
Abstract The diastereoselective synthesis of hydroxy substituted γ- and δ-lactones was accomplished following two approaches. A 5- or 6-endo cyclization promoted by electrophilic selenium reagents of α- or β-hydroxy acids and a 5- or 6-exo cyclization of hydroxy esters obtained through a diastereoselective hydroxy selenenylation reaction of α- or β-hydroxy esters. Moreover, the diastereoselective methoxy selenenylation of the above compounds was investigated showing a case in which the compound that was unreactive in the hydroxy selenenylation conditions gave, in the methoxy selenenylation conditions, the deprotected diol. The usefulness of the methoxy selenenylation procedure was proven by…
ChemInform Abstract: Addition of Organolithium Reagents to Cinnamic Acids.
2010
Abstract Reaction of tert -butyllithium with p - and m -substituted cinnamic acids at low temperature affords mixtures of 1,4- and 1,3-addition products, whose composition depend on the nature of the substituents. Electron-donating and electron-withdrawing groups favour 1,4- and 1,3-additions, respectively. Linear correlations are obtained with electronic effect and with radical substituent constants.
Photoinduced Molecular Rearrangements. The Photochemistry of Some 1,2,4-Oxadiazoles in the Presence of Nitrogen Nucleophiles. Formation of 1,2,4-Tria…
1996
The photochemistry of some 3,5-disubstituted 1,2,4-oxadiazoles in the presence of nitrogen nucleophiles [external, such as added amines or hydrazines, or internal, such as an o-aminophenyl moiety at C(3) of the oxadiazole ring] has been investigated. In the irradiation of 5-amino-(or 5-N-substituted amino) 3-phenyl-1,2,4-oxadiazoles in the presence of aliphatic primary amines (or ammonia), photolytic species arising from heterolytic cleavage of the ring O−N bond capture the nucleophilic reagent to give open-chain intermediates, which develop into 1,2,4-triazolin-5-ones. Similarly, irradiations of 3,5-diphenyl-, 3-methoxy-5-phenyl-, and 5-methyl-3-phenyl-1,2,4-oxadiazoles gave 1,2,4-triazole…
ChemInform Abstract: Light Induced C-C Coupling of 2-Chlorobenzazoles with Carbamates, Alcohols, and Ethers.
2016
A light induced, transition-metal-free C-C coupling reaction of 2-chlorobenzazoles with aliphatic carbamates, alcohols, and ethers is presented. Inexpensive reagents, namely sodium acetate, benzophenone, water, and acetonitrile, are employed in a simple reaction protocol using a cheap and widely available 25 W energy saving UV-A lamp at ambient temperature.
Synthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins
1998
New linear and angular thienocoumarins and thiopyranocoumarins were synthesized. The key intermediates were appropriate methyl derivatives of 7-mercaptocoumarin, which were condensed with chloro-ketones or propargyl chloride. Thioethers were cyclized under various conditions in order to determine which methods produced the best yields of the desired thienocoumarins 15, 16, 17, 18, 22, 23, 24, 27 and thiopyranocoumarins 28 and 29.
Synthetic and Biological Applications of Fluorous Reagents as Phase Tags
2011
The search for new and better techniques for the purification of organic compounds has made the recent emergence of fluorous chemistry in the field of organic synthesis possible. Using fluorous reagents as phase tags allows for the access of different synthetic routes, and this has been translated into a time reduction and higher simplicity compared to standard, nonfluorous procedures. The synthesis in fluorous phase of target molecules can be pursued in a parallel or combinatorial manner in order to access chemical libraries with structural and/or stereochemical diversity. The preparation of radiolabeled molecules also benefits from the advantages of fluorous synthesis. Finally, biochemica…
N,N-Dimethylformamide Diethyl Acetal
2001
(1; R1 = Et, R2 = Me) [1188-33-6] C7H17NO2 (MW 147.25) InChI = 1S/C7H17NO2/c1-5-9-7(8(3)4)10-6-2/h7H,5-6H2,1-4H3 InChIKey = BWKAYBPLDRWMCJ-UHFFFAOYSA-N (2; R1 = Me, R2 = Me) [4637-24-5] C5H13NO2 (MW 119.19) InChI = 1S/C5H13NO2/c1-6(2)5(7-3)8-4/h5H,1-4H3 InChIKey = ZSXGLVDWWRXATF-UHFFFAOYSA-N (3; R1 = PhCH2, R2 = Me) [2016-04-8] C17H21NO2 (MW 271.39) InChI = 1S/C17H21NO2/c1-18(2)17(19-13-15-9-5-3-6-10-15)20-14-16-11-7-4-8-12-16/h3-12,17H,13-14H2,1-2H3 InChIKey = JFIKHFNGAURIIB-UHFFFAOYSA-N (4; R1 = Et, R2 = Et) [22630-13-3] C9H21NO2 (MW 175.31) InChI = 1S/C9H21NO2/c1-5-10(6-2)9(11-7-3)12-8-4/h9H,5-8H2,1-4H3 InChIKey = AYZXEGOJMRKZCV-UHFFFAOYSA-N (mild and selective reagents for alkylation, f…