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Item Síntese de compostos heteroazóicos substituídos no solvente alternativo PEG 400(Universidade Federal de Goiás, 2018-04-27) Ferreira, Achiles Silva; Chagas, Rafael Pavão das; http://lattes.cnpq.br/9712618482518275; Barros, Olga Soares do Rêgo; http://lattes.cnpq.br/8311808341863723; Barros, Olga Soares do Rêgo; http://lattes.cnpq.br/8311808341863723; Chagas, Rafael Pavão das; Milani, Jorge Luiz Sônego; Costa, Maisa BorgesThe present work describes the development of a simple and efficient methodology for the synthesis of 2-aminoheteroazoic compounds using the solvent PEG 400 as an alternative to toxic and flammable organic solvents. Several media and reactional conditions were compared. A series of substituted 2-aminothiazoic compounds was obtained in good yields (60 to 96%) by a 3 hour reaction procedure using PEG 400 at room temperature and without the need for additives or catalysts. A selenium analogue and a 2-imino-1,3-thiazoline were also obtained by this method. The products were characterized by 1H and 13C NMR and infrared spectroscopies and mass spectrometry. The method covers some points of Green Chemistry, such as: safe synthesis, prevention in the formation of residues or derivatives, development of products that do not harm the environment, energy efficiency and accident prevention.Item Síntese de derivados do bisabolol através de reações de heterociclização intramolecular promovidas por calcogenetos de organoíla(Universidade Federal de Goiás, 2017-03-07) Melo, Diêgo de; Barros, Olga Soares do Rêgo; http://lattes.cnpq.br/8311808341863723; Marques, Monique Ferreira; Queiroz Júnior, Luiz Henrique KengThis work describes a practical method for intramolecular heterocyclization of the (-)-α-bisabolol to obtain cyclic arylselenoethers and arylthioethers. The electrophilic cyclization addition is promoted by arylselenenyl bromide (ArSeBr) and arylsulfenyl chloride (ArSCl) through electrophilic addition across the terminally disubstituted double bond of the alfa-bisabolol. The cyclization reaction preceeded cleanly and smoothly under mild reaction conditions and provided the cyclic arylselenoethers and arylthioethers with 71% and 47% of yield respectively, employing pyridine as addictive under inert atmosphere. The methodology showed to be highly regioselective since the tetrahydrofuranes were obtained as unique products, presumably because of electronic and conformational factors. It is well known that cyclic ethers are present in the skeletons of several groups of natural compounds exhibiting important biological activities.Item Contribuição ao estudo de reações mediadas por calcogenetos Zn e Cu: hidrocalcogenação de ácidos e ésteres e síntese de sulfetos arílicos(Universidade Federal de Goiás, 2012-05-04) Nunes, Vanessa Loren; Barros, Olga Soares do Rêgo; http://lattes.cnpq.br/8311808341863723; Barros, Olga Soares do Rêgo; Souza, Aparecido Ribeiro de; Vasconcellos, Mário Luiz Araújo de AlmeidaThis work describes some studies on the preparation of unsymmetrical diaryl thioethers catalyzed by Copper(I)-Senelenophene-2-carboxylate. The results concern to the catalyzed cross-coupling reaction between aryl halides and aryl or alkylthiols using Copper(I)-Senelenophene-2-carboxylate (CuSC) a new Cu-catalyzed one-pot protocol. The products were obtained in good to excellent yields under relatively mild reaction conditions presenting chemoselectivity and functional group tolerance. Additionally, we have developed a chemio-, regio and stereoselective synthesis of vinyl chalcogenides compounds promoted by zinc chalcogenolates. In this protocol the reductive cleavage of chalcogen bond by the Zn/NH4OH system led to zinc chalcogenolates. The reaction was carried out with acids and esters propiolics afford β-chalcogenacrillic acids and esters under mild and basic conditions. The stereochemistry corresponding to anti-Markovnikov addition of the chalcogenolate constituents across the triple bond were obtained in good yields.Item Reações de abertura de oxiranas promovidas por organocalcogenolatos de zinco(Universidade Federal de Goiás, 2017-03-20) Silva, Francielle Rodrigues da; Barros, Olga Soares do Rêgo; http://lattes.cnpq.br/8311808341863723; Barros, Olga Soares do Rêgo; Kato, Lucilia; Beatriz, AdilsonSeveral methodologies has been reported to generate zinc organocalcogenolate reagents (NOGUEIRA; ZENI; ROCHA, 2004; NOGUEIRA et al., 2003; MUGESH; DU MONT; SIES, 2001). In this work, these reagents are generated by reductive cleavage of the calcogen-calcogen binding of the respective diorganoyl dicalcogenets using the Zn / NH4OH system. This work describes the opening reactions of oxiraneses promoted by organocalcogenolatos of zinc leading to a production of -hydroxyselenetos. The scope of the hydroselenation reaction was exploited with a variety of epoxides. Alkyloxiranes with low degree of substitution, produced hydroxyselenetos in good yields. The reactions, forming, were regioselective, with the nucleophile phenylselenolate attacking the least impeded medium of the oxirane, suggesting an opening mechanism type SN2. For aryl epoxides, the hydroxyselenic products are the phenylcalcogenolate group, and have also been subjected to a faster replacement, but regioselectivity is not complete, with signs of product mixing. Epoxides with two aryl groups bound to the same carbon, in turn, led to the major formation of the corresponding aldehyde, a result of the mechanism with migration of hydride. Finally, for alkyl epoxides, but with a greater degree of substitution, the regiochemical control, led to the formation of -hydroxyselene by the most substituted side. The methodology was efficient and the generation of the phenylcalcogenolate anion occurred easily within the system compared to other methods. Because the results are possible, finally, the reaction of opening epoxides using organocalcogenolate reagents is useful in this work because of the good regiochemical control, easy reproducibility and mild conditions employed.