Browsing by Autor "Jairo Quiroga"

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ChemInform Abstract: The Formation of Pyrazolo(1,5‐a)pyrimidines by the Reaction of 3‐(4‐ Chlorophenyl)pyrazol‐5‐amine with Chalcones.
(Wiley, 1995) Jairo Quiroga; Braulio Insuasty; Ricardo Rincon; Marina Larrahondo; Norbert Hanold; Herbert Meier
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Chromatographic and spectroscopic properties of regioisomers of some 1H‐1,5‐benzodiazepines
(Wiley, 1994) S. Vianna‐Rodrigues; L. Martins‐Viana; Jairo Quiroga; Braulio Insuasty; Rodrigo Abonı́a; W. Baumann
Abstract The separation of the two regioisomeric derivatives of 1 H ‐1,5‐benzodiazepine yielded from the reaction of 1,2‐diamino‐4‐methylbenzene with 4‐substituted acetophenones was performed by reversed phase high performance liquid chromatography, and the absorption spectra of the separated isomers have been determined for three isomer pairs which have been obtained starting from acetophenones with substituents of different electronegativity. The isomer ratio then could be estimated as well from the ratio of the peak areas as from the absorption spectra. They agree well with the known ratio determined from nmr intensities.
Cyclocondensation reaction of 1,2‐diamino‐4‐methylbenzene and p‐substituted acetophenones
(Wiley, 1993) Braulio Insuasty; Rodrigo Abonı́a; Jairo Quiroga; Herbert Meier
Abstract 1,2‐Diamino‐4‐methylbenzene 1 reacts in the presence of sulphuric acid with 4‐substituted acetophenones 2a‐e yielding 2,4‐diaryl‐2,3‐dihydro‐2,8‐dimethyl‐1 H ‐1,5‐benzodiazepines 3a‐e and as minor component 2,4‐diaryl‐2,3‐dihydro‐2,7‐dimethyl‐1 H ‐1,5‐benzodiazepines 4a‐e . The ratio 3:4 is in the range of 7:3. The structure determination of the regioisomers was performed by NOE measurements.
Novel (E)-1-(pyrrole-2-yl)-3-(aryl)-2-(propen-1-one) derivatives as efficient singlet oxygen quenchers: kinetics and quantum chemical calculations
(Royal Society of Chemistry, 2015) Carlos Díaz‐Uribe; William Vallejo; Wilmar Castellar; Jorge Trilleras; Stephanie Ortiz-Collazos; Ángela Rodríguez-Serrano; Ximena Zárate; Jairo Quiroga
Kinetics of singlet oxygen (1O2) quenching by newly synthesized chalcone derivatives with potential antioxidant applications, and DFT/MRCI calculations.
The formation of pyrazolo[1,5‐a]pyrimidines by the reaction of 3‐(4‐chlorophenyl)pyrazol‐5‐amine with chalcones
(Wiley, 1994) Jairo Quiroga; Braulio Insuasty; Ricardo Rincon; Marina Larrahondo; Norbert Hanold; Herbert Meier
Abstract Cyclocondensation reactions of the pyrazol‐5‐amine 1 and the 1‐aryl‐3‐phenyl‐2‐propen‐1‐ones 2a‐d yield the 6,7‐dihydropyrazolo[1,5‐ a ]pyrimidines 7a‐d . Whereas 7a‐c can be isolated in pure state, 7d is subjected to a spontaneous oxidation.
The reaction of aromatic α,β‐unsaturated ketones with 4,5‐diamino‐1,6‐dihydropyrimidin‐6‐ones
(Wiley, 1994) Braulio Insuasty; MÓNica Ramos; Jairo Quiroga; Adolfo Sánchez; Manuel Nogueras; Norbert Hanold; Herbert Meier
Abstract The reaction of 4,5‐diamino‐1,6‐dihydropyrimidin‐6‐ones 1 with one equivalent of the chalcones 2 leads in an acidic medium to the formation of the 2,4‐diaryl‐2,3,6,7‐tetrahydro‐1 H ‐pyrimido[4,5‐ b ][1,4]diazepin‐6‐ones 3a‐m . The structure elucidation of the products is based on detailed nmr investigations including selective 13 C[ 1 H] decoupling experiments.