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Insights into diastereoisomeric characterization of tetrahydropyridazine amino acid derivatives: crystal structures and gas phase ion chemistry
No full textStructural, conformational properties, and gas phase reactivity of two representative diastereoisomeric members of a series of α,α- tetrahydropyridazine amino acid derivatives have been investigated by using X-ray crystallography, tandem mass spectrometry and theoretical calculations. Both diastereoisomers show an unusual screw-boat conformation of the tetrahydropyridazine ring. While protonated molecules mainly decompose in the gas phase by loss of acetamide, the main reactivity of the [M + Na]+ species consists of loss of PhNCO followed by acetamide and it is strictly dependent upon the stereochemistry of the parent compound. The most stable energy minimized structures obtained by theoretical calculations are in full agreement with the experimental data and allowed us to rationalize the gas phase reaction pathways. © 2013 The Royal Society of Chemistry
Base or copper promoted annulation reactions of α-aminohydrazones
No full textThe title compounds, obtained by 1,4-addition of sarcosine or glycine ethyl ester on conjugated azoalkenes, gave the 1-ureido-4-amino-3-methyl-1H-pyrazol-5(2H)-ones through a base promoted heterocyclization process, while in the presence of copper (I) species the 1-ureido-5-methyl-4-imidazolines and the 4-methoxycarbonyl-5-methyl-1-ureidoimidazole were obtained. The mechanism of these reactions is discussed
Unusual [4+2]-cycloaddition reaction between electron-poor 1,2-diaza-1,3-dienes and electron-poor alkenes: useful entry for novel tetrahydropyridazines
No full textRENEWABLE BIO-ORGANIC RESOURCES FOR THE SYNTHESIS OF NOVEL HETEROCYCLES: PHTHALOCYANINES, PORPHYRINS, FULLEROPYRROLIDINES, LACTONES
No full textThe Reaction of Meldrum's Acid and Its Derivatives with Conjugated Azoalkenes: A Convenient Route to 1-Amino-1H-pyrrol-2(3H)-ones
No full textThe reaction of Meldrum's acid and its 5-substituted derivatives with conjugated azoalkenes in the presence of triethylamine produces, via 1,4-conjugate addition, corresponding hydrazones which undergo decarboxylative alcoholysis and simultaneous cyclization to give 3-unsubstituted and 3-monosubstituted 1-amino-1H-pyrrol-2-(3H)-ones respectively
SINTESI CHEMO- E REGIOSELETTIVA DI PIRROLI E PIRAZOLI PER REAZIONE DI DIENI DI DANISHEFSKY CON 1,2-DIAZA-1,3-BUTADIENI
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NUOVA ED ELEGANTE SINTESI DI IMIDAZOLI DA ALFA-AZIRIDINOIDRAZONI VIA 1,5 ELETTROCICLIZZAZIONE DI AZAVINIL AZOMETIN ILIDI
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