25 documents found, page 1 of 3
Reactivity of ethyl nitrosoacrylate toward pyrrole, indole and pyrrolo[3,2-c]ca...
Benzi, Alice; Lopes, Susana M. M.; Nunes, Sandra; Giorgi, Gianluca; Bianchi, Lara; Tavani, Cinzia; Pais, Alberto; Petrillo, GiovanniNitrosoalkenes react with 8-methyl-1,6-dihydropyrrolo[3,2-c]carbazole to give both 2- and 3-alkylated products via hetero-Diels-Alder reaction followed by the cycloadduct ring-opening. Quantum chemical calculations, at DFT level of theory, were carried out to investigate the regioselectivity of the cycloaddition of ethyl nitrosoacrylate with 1,6-dihydropyrrolo[3,2-c]carbazoles as well as with pyrrole and indole...
Ethyl 7-Acetyl-8a-methyl-3-(1-phenyl-1H-tetrazol-5-yl)-1,4,4a,5,6,8a-hexahydro-...
Lopes, Susana M. M.; Lemos, Américo; Paixão, José A.; Melo, Teresa M. V. D. Pinho eThe Diels–Alder reaction of ethyl 3-(1-phenyl-1H-tetrazol-5-yl-1,2-diaza-1,3-butadiene- 1-carboxylate with 2-acetyl-6-methyl-2,3-dihydro-4H-pyran (methyl vinyl ketone dimer) regios- electively afforded the corresponding 3-(tetrazol-5-yl)-hexahydro-7H-pyrano[2,3-c]pyridazine in quantitative yield. An X-ray crystal structure of this cycloadduct is reported.
Color Polymorphs of ROY-ol
Nogueira, Bernardo A.; Lopes, Susana M. M.; Milani, Alberto; André, Vânia; Paixão, José A.; Eusébio, M. Ermelinda S.; Melo, Teresa M. V. D. Pinho eColor polymorphism is a fascinating property exhibited by compounds that have polymorphs of different colors. The most famous family of substances forming molecular organic color polymorphs is the ROY family of compounds. ROY, which states for the red, orange, and yellow colors of the polymorphs of 5-methyl-2-((2-nitrophenyl)amino)thiophene-3-carbonitrile, is currently the compound exhibiting the largest number...
Ethyl 7-Acetyl-8a-methyl-3-(1-phenyl-1H-tetrazol-5-yl)-1,4,4a,5,6,8a-hexahydro-...
Lopes, Susana M. M.; Lemos, Americo; Paixão, José A.; Pinho e Melo, Teresa M. V. D.The Diels–Alder reaction of ethyl 3-(1-phenyl-1<i>H</i>-tetrazol-5-yl-1,2-diaza-1,3-butadiene-1-carboxylate with 2-acetyl-6-methyl-2,3-dihydro-4<i>H</i>-pyran (methyl vinyl ketone dimer) regioselectively afforded the corresponding 3-(tetrazol-5-yl)-hexahydro-7<i>H</i>-pyrano[2,3-<i>c</i>]pyridazine in quantitative yield. An X-ray crystal structure of this cycloadduct is reported.
2,4,6-Trinitro-N-(m-tolyl)aniline: A New Polymorphic Material Exhibiting Differ...
Nogueira, Bernardo A.; Lopes, Susana M. M.; Lopes, Susy; Nikitin, Timur; Rodrigues, Ana Clara B.; Eusébio, Maria Ermelinda S.; Paixão, J. A.2,4,6-Trinitro-N-(m-tolyl)aniline or N-picryl-m-toluidine (abbreviated as TMA), exhibiting color polymorphism, was synthesized and characterized structurally, spectroscopically, and thermodynamically. The studies consider both the isolated molecule of the compound (studied theoretically at the DFT- (B3LYP)/6-311++G(d,p) level and experimentally by matrixisolation infrared spectroscopy) and its polymorphic cryst...
Reduction of Oximes and Hydrazones: Asymmetric and Diastereoselective Approaches
Ribeiro, João L. P.; Alves, Cláudia; Cardoso, Ana L.; Lopes, Susana M. M.; Pinho e Melo, Teresa M. V. D.The asymmetric reduction of oximes and hydrazones is an attractive and versatile strategy for the synthesis of chiral amines, which are valuable building blocks in organic synthesis. This review summarizes the relevant developments, made in the last decade, on the enantioselective and diastereoselective reduction of oximes and hydrazones involving metal-catalyzed hydrogenation/hydrogenolysis reactions, hydride ...
Synthesis and structure-activity relationships of new chiral spiro-β-lactams hi...
Alves, Nuno Guerreiro; Bártolo, Inês; Alves, Américo J. S.; Fontinha, Diana; Francisco, Denise; Lopes, Susana M. M.; Soares, Maria I. L.The synthesis and antimicrobial activity of new spiro-β-lactams is reported. The design of the new molecules was based on the structural modulation of two previously identified lead spiro-penicillanates with dual activity against HIV and Plasmodium. The spiro-β-lactams synthesized were assayed for their in vitro activity against HIV-1, providing relevant structure-activity relationship information. Among the te...
Reactivity of steroidal 1-azadienes toward enamines: an approach to novel chira...
Lopes, Susana M. M.; Santos, Joana R. C.; Pinho e Melo, Teresa M. V. D.The chemical behavior of steroidal N-sulfonyl-1-azadienes toward carbonyl compounds, in the presence of pyrrolidine, is described. With aldehydes, these azadienes participate in hetero-Diels-Alder reactions with the in situ generated enamines. The stereoselectivity results from the approach of the dienophiles from the less hindered α-face of the steroid, with the pyrrolidine moiety endo and retention of the ena...
One-Pot Synthetic Approach to Dipyrromethanes and Bis(indolyl)methanes via Nitr...
Cardoso, Ana L.; Lopes, Susana M. M.; Grosso, Carla; Pineiro, Marta; Lemos, Américo; Pinho e Melo, Teresa M. V. D.A one-pot regio- and stereoselective synthesis of a dipyrromethane and a bis(indolyl)methane based on two consecutive reactions of nitrosoalkenes with pyrrole or indole, respectively, is described as an experiment to be carried out by upper-division undergraduate students in a laboratory classroom. Importantly, the ability of electrophilic conjugated nitrosoalkenes to react via Michael addition or hetero-Diels−...
Synthesis and structure-activity relationships of new chiral spiro-ß-lactams hi...
G. Alves, Nuno; Bártolo, Inês; Alves, Américo; Fontinha, Diana; Francisco, Denise; Lopes, Susana M. M.; Soares, Maria I. L.; Simões, Carlos J. V.The synthesis and antimicrobial activity of new spiro-β-lactams is reported. The design of the new molecules was based on the structural modulation of two previously identified lead spiro-penicillanates with dual activity against HIV and Plasmodium. The spiro-β-lactams synthesized were assayed for their in vitro activity against HIV-1, providing relevant structure-activity relationship information. Among the te...