2,5-diketopiperazines via intramolecular N-alkylation of Ugi adducts: a contribution to the synthesis, density functional theory study, X-ray characterization, and potential herbicide application
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Data
2022
Autores
Mendes, Lorena Lessa
Varejão, Jodieh Oliveira Santana
Sousa, José Antonio de
Carneiro, José Walkimar de Mesquita
Valdo, Ana Karoline Silva Mendanha
Martins, Felipe Terra
Ferreira, Bruno Wesley
Barreto, Robert Weingart
Silva, Toshik Iarley da
Kohlhoff, Markus
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Resumo
To investigate the herbicidal potential of 2,5-diketopiperazines (2,5-DKPs), we applied a known protocol to produce a series of 2,5-DKPs through intramolecular N-alkylation of Ugi adducts. However, the method was not successful for the cyclization of adducts presenting aromatic rings with some substituents at the ortho position. Results from DFT calculations showed that the presence of voluminous groups at the ortho position of a benzene ring results in destabilization of the transition structure. Lower activation enthalpies for the SN2-type cyclization of Ugi adducts were obtained when bromine, instead of a chlorine anion, is the leaving group, indicating that the activation enthalpy for the cyclization step controls the formation of the 2,5-DKP. Some Ugi adducts and 2,5-DKPs formed crystals with suitable qualities for single-crystal X-ray diffraction data collection. Phytotoxic damage of some 2,5-DKPs on leaves of the weed Euphorbia heterophylla did not differ from those caused by the commercial herbicide diquat.
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Ugi 4-CR, Multicomponent reaction, Isocyanides, Wild poinsettia, Herbicides
Citação
MENDES, Lorena L. et al. 2,5-diketopiperazines via intramolecular N-alkylation of Ugi adducts: a contribution to the synthesis, density functional theory study, X-ray characterization, and potential herbicide application. Journal of Agricultural and Food Chemistry, Washington, v. 70, n. 6, p. 1799-1809, 2022. DOI: 10.1021/acs.jafc.1c07790. Disponível em: https://pubs.acs.org/doi/10.1021/acs.jafc.1c07790. Acesso em: 7 nov. 2023.