نتایج جستجو برای: 3 diketones
تعداد نتایج: 1811794 فیلتر نتایج به سال:
1-Silyl-2,6-diketones, readily prepared by addition of (silylmethyl)metal reagents to 1,5-lactols followed by oxidation of the resultant diols, can be efficiently transformed into 3-hydroxycyclohexanones, cyclohex-2-enones, or 1-(silylmethyl)cyclopentane-1,2-diols under nucleophilic, basic, or single electron-transfer reduction conditions, respectively. The latter cyclitols can be further trans...
A regio- and stereoselective intramolecular direct aldol reaction of 2,7-diketones derived from carbohydrates has been developed to construct cycloalkanones , which were dehydrated to obtain heavily oxygenated cycloalkenones .
We investigated the chelating effect of FeCl3 on three beta-diketones, curcumin [1], (-)-3-(trifluoroacetyl)camphor [2] and 3-formylchromone [3], as judged by changes in their cytotoxicity and absorption spectra. Addition of an equimolar concentration of FeCl3 almost completely abrogated the cytotoxicity and changed the pattern of absorption spectra (decrease in the peak height at 430 nm) of [1...
The practical application of most the UV-based advanced oxidation/reduction technologies (AOTs) is still limited because poor selectivity reactive species in AOTs and inner filter effects caused by complicated components water. Recently, new photochemical techniques based on low molecular weight diketones have attracted much attention higher stronger anti-interference ability. Thi...
The ionic liquid 1-butyl-3-methyl-imidazolium hydrogen sulfate, [bmim]HSO4, was used as a catalyst and reaction medium for the pyrrole synthesis, and a wide range of aliphatic, aromatic, heteroaromatic and carboxylic 1,4-diketones easily underwent condensations with aniline and ethylenediamine to form polysubstituted pyrroles. Sequential decarboxylation/Paal-Knorr pyrrole condensation was obser...
Over the last decade, concerns have been raised about potential respiratory health effects associated with occupational exposure to the flavoring additives diacetyl and 2,3-pentanedione. Both of these diketones are also natural components of many foods and beverages, including roasted coffee. To date, there are no published studies characterizing workplace exposures to these diketones during co...
Benzylaminoalkenones and benzylaminoalkenoates 3 were synthesized from reaction of benzylamine with corresponding 1,3-diketones and 1,3-ketoesters in the presence of catalytic amount of chloroacetic acid under microwave radiation. This method offers several advantages including high yield of products, recyclable of the catalyst and easy experimental work-up procedure.
We report the experimental determination of the intramolecular enol-enol tautomerization rate of an unsymmetric β-diketone, benzoylacetone, with femtosecond transient absorption in the ultraviolet. Initially, there is an equilibrium of two possible enolic structures in solution, which is disturbed upon UV excitation by exciting a disproportionate fraction of one enolic form. Comparison to symme...
Aldolase antibodies that operate via an enamine mechanism were developed by in vitro selection. Antibody Fab phage display libraries were created where the catalytic active site residues of aldolase antibodies 38C2 and 33F12 were combined with a naive human antibody V gene repertoire. Selection from these libraries with 1,3-diketones covalently trapped the amino groups of reactive lysine residu...
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