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Conformational and structural analysis of 2-allyl-1,2-benzisothiazol-3(2H)-one ...
Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Coelho, Daniela; Cristiano, M. Lurdes S.; Fausto, Ruihttp://www.sciencedirect.com/science/article/B6TGS-4THC1JN-1/2/1228ea86baa026383b4037e881569263
Molecular structure and infrared spectra of the monomeric 3-(methoxy)-1,2-benzi...
Kaczor, Agnieszka; Almeida, Rui; Gómez-Zavaglia, Andrea; Cristiano, Maria de Lurdes S.; Fausto, RuiThe computational description of saccharin (1,2-benzisothiazol-3(2H)-one-1,1-dioxide) and its derivatives is difficult due to the presence of hypervalent SO bonds in their structures. Therefore, in this investigation, the HF, DFT/B3LYP and MP2 methods were used to predict the geometry and the infrared spectrum of the saccharyl derivative 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID). Their relative predict...
Conformational Space of the Pseudosaccharin Allyl Ether 3-(Allyloxy)-1,2-benzis...
Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Almeida, Rui; Cristiano, Maria de Lurdes S.; Fausto, RuiIn this work, the conformational space of the pseudosaccharyl ether 3-(allyloxy)-1,2-benzisothiazole 1,1-dioxide (ABID) has been studied by means of infrared spectroscopy and density functional theory (DFT) calculations. Five different low energy conformers (TSk, TC, GSk, GSk‘ and GC, with relative energies of 0.00, 1.97, 2.00, 3.82 and 6.02 kJ mol-1, respectively) were found on the DFT(B3LYP)/6-311++G(3df,3pd)...
Molecular structure and infrared spectra of the monomeric 3-(methoxy)-1,2-benzi...
Kaczor, Agnieszka; Almeida, Rui; Gómez-Zavaglia, Andrea; Cristiano, Maria de Lurdes S.; Fausto, RuiThe computational description of saccharin (1,2-benzisothiazol-3(2H)-one-1,1-dioxide) and its derivatives is difficult due to the presence of hypervalent SO bonds in their structures. Therefore, in this investigation, the HF, DFT/B3LYP and MP2 methods were used to predict the geometry and the infrared spectrum of the saccharyl derivative 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID). Their relative predict...
Substituent effects on the photolysis of methyl 2-carboxylate substituted aliph...
Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Cardoso, Ana L.; Melo, Teresa M. V. D. Pinho e; Fausto, RuiIn this study, the UV induced photochemical reactions of two 2H-azirines - methyl 2-chloro-3-methyl-2H-azirine-2-carboxylate (MCMAC) and methyl 3-methyl-2H-azirine-2-carboxylate (MMAC) - isolated in argon matrices are compared. For both compounds, irradiation with [lambda] > 235 nm led to observation of two primary photoprocesses: (a) CC bond cleavage, with production of nitrile ylides (P1-type products), and (...
Unusual Photochemical C−N Bond Cleavage in the Novel Methyl 2-Chloro-3-methyl-2...
Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Cardoso, Ana L.; Melo, Teresa M. V. D. Pinho e; Fausto, RuiThe structure, preferred conformers, vibrational spectrum, and photochemical behavior of the novel azirine, methyl 2-chloro-3-methyl-2H-azirine-2-carboxylate (MCMAC) were investigated in low-temperature matrixes and in the neat solid amorphous state by infrared spectroscopy and quantum-chemical calculations. Two conformers of the compound were observed in argon, krypton, and xenon matrixes, in agreement with th...
Intermolecular cycloaddition of nonstabilized azomethine ylides generated from ...
Cardoso, Ana L.; Kaczor, Agnieszka; Silva, Artur M. S.; Fausto, Rui; Melo, Teresa M. V. D. Pinho e; Gonsalves, António M. d'A. RochaThe 1,3-dipolar cycloaddition of dimethyl acetylenedicarboxylate with nonstabilized azomethine ylides, generated via the decarboxylative condensation of 1,3-thiazolidine-4-carboxylic acids with aldehydes, afforded 5,7a-dihydro-1H,3H-pyrrolo[1,2-c]thiazole derivatives. 2-Substituted-1,3-thiazolidine-4-carboxylic acids led to the stereoselective formation of 5,7a-dihydro-1H,3H-pyrrolo[1,2-c]thiazoles. Quantum-che...
Methyl 3-Methyl-2H-azirine-2-carboxylate Photochemistry Studied by Matrix-isola...
Kaczor, Agnieszka; Gómez-Zavaglia, Andrea; Cardoso, Ana L.; Melo, Teresa M. V. D. Pinho e; Fausto, RuiThe aliphatic 2H-azirine, methyl 3-methyl-2H-azirine-2-carboxylate (MMAC), has been synthesized and its monomeric form investigated by IR spectroscopy in an argon matrix, at 10 K, as well as theoretically (DFT/B3LYP/6-311++G(d,p)). Two low-energy conformers of MMAC (Ct and Cc) were found in the matrix, both exhibiting the cis conformation around the C−O bond but differing in the arrangement around the C−Cα bond...
Intermolecular cycloaddition of nonstabilized azomethine ylides generated from ...
Cardoso, Ana L.; Kaczor, Agnieszka; Silva, Artur M.S.; Fausto, Rui; Melo, Teresa M.V.D. Pinho e; Gonsalves, António M. d'A. RochaThe 1,3-dipolar cycloaddition of dimethyl acetylenedicarboxylate with nonstabilized azomethine ylides, generated via the decarboxylative condensation of 1,3-thiazolidine-4-carboxylic acids with aldehydes, afforded 5,7a-dihydro-1H,3H-pyrrolo[1,2-c]thiazole derivatives. 2-Substituted-1,3-thiazolidine-4-carboxylic acids led to the stereoselective formation of 5,7a-dihydro-1H,3H-pyrrolo[1,2-c]thiazoles. Quantum-che...
Hexahydro-Pyrrolo[1',2',5':3,4,5]Thiazolo[3,4-c]Oxazol-1-ones: New Chiral Tricy...
Melo, Teresa M.V.D Pinho e; Lopes, Susana M.M.; Gonsalves, Antonio M. d'A Rocha; Kaczor, Agnieszka; Fausto, Rui; Paixao, Paixao, Jose A; Beja, Ana MatosA simple and efficient approach to the synthesis of the new chiral hexahydropyrrolo [1',2',5':3,4,5]thiazolo[3,4-c]oxazol-1-one ring system is reported. Infrared spectroscopy, quantum-chemical calculations and X-ray analysis allowed the stereochemistry assignment of (2aS,4aR,6aR)-2a,3,4,4a,6,6ahexahydropyrrolo-[ 1',2',5':3,4,5]thiazolo[3,4-c]oxazol-1-one. [ABSTRACT FROM AUTHOR]. Copyright of Letters in Organic...
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