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1,546 results on '"Zanatta, Nilo"'

28. Regioselective synthesis of (Z)-5-methylene-containing morpholin-2-ones.

Author

Camargo, Adriano F., Pereira, Genilson S., Mittersteiner, Mateus, Marangoni, Mario A., Moraes, Paulo A., Bonacorso, Helio G., Martins, Marcos A. P., and Zanatta, Nilo

Subjects
ENANTIOMERIC purity, AMINO group, CHEMICAL synthesis, COMPLEX organizations, CARBONYL compounds
Abstract

An efficient, one-pot, protecting-group-free, and regioselective protocol to obtain enantiomerically pure (Z)-5-methylene-containing morpholin-2-ones, using α-amino acids and 5-bromo-4-methoxy enones as selective starting materials, is reported. The reaction was fully selective in providing the (Z)- regioisomer in all cases, regardless of the α-amino acid used; however, when a secondary amino group was used, only the (E)-isomer was observed. The synthesized compounds were obtained at yields of up to 92%, and their structure was unambiguously assigned by x-ray and 2D-NMR experiments. [ABSTRACT FROM AUTHOR]

Published
2024
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34. In vitro and in silico analysis of the efficiency of tetrahydropyridines as drug efflux inhibitors in Escherichia coli

Author

Silva, Lande, Jr, Carrion, Lillian Lucas, von Groll, Andrea, Costa, Sofia Santos, Junqueira, Elisabete, Ramos, Daniela Fernandes, Cantos, Jéssica, Seus, Vinicius Rosa, Couto, Isabel, Fernandes, Liana da Silva, Bonacorso, Hélio Gauze, Martins, Marcos Antônio Pinto, Zanatta, Nilo, Viveiros, Miguel, Machado, Karina S., and Almeida da Silva, Pedro Eduardo

Published
2017
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35. Ammonium carboxylate salts: the additivity of intermolecular interaction energies in charged organic compounds.

Author

Rosa, Jessica M. L., Lima, Priscila S. V., Bonacorso, Helio G., Zanatta, Nilo, and Martins, Marcos A. P.

Subjects
INTERMOLECULAR interactions, ORGANIC compounds, AMMONIUM salts, CRYSTAL structure, CRYSTAL lattices, CARBOXYLATES
Abstract

The supramolecular organization of organic salts has been widely researched, revealing recurring patterns in crystalline lattices that describe their supramolecular properties. In recent years, our research group has underscored the importance of considering the crystalline structures as a whole, incorporating all the necessary energetic and topological information for a comprehensive understanding of the crystalline system. Given this context, we investigated a series of ammonium mono- and dicarboxylate salts (1–12) to determine whether subtle structural modifications in the anionic organic component lead to relevant energy and topology changes in the crystalline lattice. To achieve this, we selected structures whose carboxylate anion only possesses an alkyl chain and is devoid of other functional groups. The ammonium cation (NH4+) was fixed to determine the effect of variations in the alkyl chains of the selected mono- and dicarboxylates, such as length and degree of unsaturation. Additionally, probable crystallization mechanisms were proposed to elucidate some of the topological and energetic aspects involved in the crystallization of these compounds. Destabilizing interactions were observed in 10 crystalline structures, and the MEP data showed that the most destabilizing interactions occur by the proximity of portions with the same type of charge. Some dimers have unexpectedly low intermolecular interaction energies despite having large contact areas. Based on these data we demonstrate the additivity of intermolecular interactions, that is, the low intermolecular interaction energy in these dimers is the result of the sum of destabilizing energies and stabilizing energies. The cluster energy efficiency data revealed that most crystal lattices display typical characteristics of uncharged organic compounds. The proposed crystallization mechanisms showed a gradual increase in nucleus complexity in the initial stages and the total number of nucleation stages, resulting in five main patterns: monomer → 1D → 3D (1–2), monomer → dimer → 2D → 3D (3), monomer → 1D → 2D → 3D (4–5), monomer → dimer → 3D (6), and monomer → 2D → 3D (7–12). [ABSTRACT FROM AUTHOR]

Published
2024
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43. Polymorphism in N-(5-methylisoxazol-3-yl)malonamide: understanding the supramolecular structure and the crystallization mechanism.

Author

Pagliari, Anderson B., Rosa, Jéssica M. L., de Lima, Priscila S. V., Zimmer, Geórgia C., da Silva, Maria E. C., de Oliveira, Érica G., Bonacorso, Helio G., Zanatta, Nilo, and Martins, Marcos A. P.

Subjects
CRYSTALLIZATION, DIMETHYL sulfoxide, SOLVENTS, MOLECULES, CRYSTALS, CARBON
Abstract

The supramolecular architectures of amide-containing compounds are highly dependent on the side-chain substituents, although the potential impact of isoxazole substituents on polymorph formation has not been thoroughly explored. Hence, three distinct forms of N1,N3-bis(5-methylisoxazol-3-yl)malonamide (1) were obtained and characterized: two polymorphic forms and one solvate. An in-depth analysis of the interactions and energy content of the crystals based on supramolecular clusters allowed us to propose crystallization mechanisms (crystal retrosynthesis). Specifically, the energy similarities between the interaction of the first sites NHamide⋯O＝Camide (form 1I) and the symmetric sites NHamide⋯Nisox (form 1II) were found to contribute to their formation. Nonetheless, the presence of DMSO resulted in the formation of form 1III, where the solvent molecule disrupted amide-amide interactions. The first nuclei are more stable than forms 1I and 1II. The compound of N1,N2-bis(5-methylisoxazol-3-yl)oxalamide (2) was used as a comparison, and through the absence of polymorphs, revealed that the central carbon in molecule 1 allows a flexible adaptation that leads to the three forms. These findings suggest that variations in solvents, flexibility, and the presence/absence of amide–amide interactions can modulate the competition between amide-containing isoxazole compounds. [ABSTRACT FROM AUTHOR]

Published
2023
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