RESUMO
Silica gel was found to be an excellent medium for some useful organic transformations under organic solvent-free conditions, such as (1) the Friedel-Crafts-type nitration of arenes using commercial aqueous 69% nitric acid alone at room temperature, (2) one-pot Wittig-type olefination of aldehydes with activated organic halides in the presence of tributyl- or triphenylphosphine and Hunig's base, and (3) the Morita-Baylis-Hillman reaction of aldehydes with methyl acrylate. After the reactions, the desired products were easily obtained in good to excellent yields through simple manipulation.
Assuntos
Compostos Orgânicos/química , Sílica Gel/química , Solventes/química , Aldeídos/química , Catálise , Ácido Nítrico/químicaRESUMO
4-Thialysine (S-(2-aminoethyl)-L: -cysteine) is an analog of lysine. It has been used as an alternative substrate for lysine in enzymatic reactions. Site-directed isotopomers are often needed for elucidation of mechanism of reactions. 4-Thialysine can be synthesized by reacting cysteine with 2-bromoethylamine, an important reagent in chemical-modification rescue (CMR) of proteins. Here, we present the synthesis of 4-thia-[6-(13)C]lysine, one of the isotopomers of 4-thialysine, from commercially available starting material [2-(13)C]glycine via formation of five intermediates including 2-amino[2-(13)C]ethanol and 2-bromo[1-(13)C]ethylamine. The compounds were characterized using various spectroscopic techniques. Moreover, we discuss that our strategy would provide access to site-directed isotopomers of 2-aminoethanol, 2-bromoethylamine and 4-thialysine. Biological activity of 4-thia-[6-(13)C]lysine was tested in the enzymatic reaction of lysine 5,6-aminomutase.
Assuntos
Cisteína/análogos & derivados , Etanolamina/química , Etilaminas/química , Glicina/química , Isótopos de Carbono , Cisteína/síntese química , Cisteína/química , Estrutura MolecularRESUMO
The easy and efficient aromatization of various 1,4-dihydropyridines was investigated using various metal nitrates, trinitratocerium(IV) bromate (TNCB), and tetrabutyl ammonium periodate (TBAP) as oxidant in acetic acid at 100 degrees C, as well as hexamethylenetetramine-iodine (HMTAI) reflux in methanol. The efficient conversion of nifedipine-d(3) to dehydronifedipine-d(3) as an internal standard can be used in the measurement of nifedipine concentration in a body.