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

• DOI: 10.1021/acs.jafc.1c07790
• Publication Date: 2022-02-07T22:11:35Z
• Authors: Lorena L. Mendes; Jodieh O. S. Varejão; José Antônio de S...; José Walkimar de ...; Ana K. S. M. Valdo; Felipe T. Martins; Bruno W. Ferreira; Robert W. Barreto; Toshik I. da Silva; Markus Kohlhoff; Eduardo J. Pilau; Eduardo V. V. Var...
• Keywords: Diketopiperazines

To investigate the herbicidal potential of 2,5-diketopiperazines (2,5-DKPs), we applied a known protocol to produce series 2,5-DKPs through intramolecular N-alkylation Ugi adducts. However, method was not successful for cyclization adducts presenting aromatic rings with some substituents at ortho position. Results from DFT calculations showed that presence voluminous groups position benzene ring results in destabilization transition structure. Lower activation enthalpies SN2-type were obtained when bromine, instead chlorine anion, is leaving group, indicating enthalpy step controls formation 2,5-DKP. Some and formed crystals suitable qualities single-crystal X-ray diffraction data collection. Phytotoxic damage on leaves weed Euphorbia heterophylla did differ those caused by commercial herbicide diquat.