Fragmentation pattern of amides by EI and HRESI: study of protonation sites using DFT-3LYP data

Autor(es)

Fokoue, H. H. ^[1] ; Marques, J. V. ^[2] ; Correia, M. V. ^[3] ; Yamaguchi, L. F. ^[4] ; Qu, X. ^{[5, 6]} ; Aires-de-Sousa, J. ^{[5, 6]} ; Scotti, M. T. ^[7] ; Lopes, N. P. ^[8] ; Kato, M. J. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Fed Rio de Janeiro, Ctr Ciencias Saude, Inst Ciencias Biomed, Lab Avaliacao & Sintese Substancias Bioat LASSBio, CP 68024, BR-21944971 Rio De Janeiro - Brazil

^[2] Ginkgo Bioworks, Boston, MA 02210 - USA

^[3] Univ Brasilia, Inst Quim, CP 04478, BR-70704970 Brasilia, DF - Brazil

^[4] Univ Sao Paulo, Inst Quim, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[5] Univ Nova Lisboa, LAQV, Dept Quim, Fac Ciencias & Tecnol, P-2829516 Caparica - Portugal

^[6] Univ Nova Lisboa, REQUIMTE, Dept Quim, Fac Ciencias & Tecnol, P-2829516 Caparica - Portugal

^[7] Univ Fed Paraiba, Posgrad Prod Nat & Sintet Bioat, BR-58051900 Joao Pessoa, Paraiba - Brazil

^[8] Univ Sao Paulo, Dept Fis & Quim, Fac Ciencias Farmaceut Ribeirao Preto, BR-14040903 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: RSC ADVANCES; v. 8, n. 38, p. 21407-21413, 2018.
• Citações Web of Science: 1

Resumo

Amides are important natural products which occur in a few plant families. Piplartine and piperine, major amides in Piper tuberculatum and P. nigrum, respectively, have shown a typical N-CO cleavage when analyzed by EI-MS or HRESI-MS. In this study several synthetic analogs of piplartine and piperine were subjected to both types of mass spectrometric analysis in order to identify structural features influencing fragmentation. Most of the amides showed an intense signal of the protonated molecule {[}M + H](+) when subjected to both HRESI-MS and EI-MS conditions, with a common outcome being the cleavage of the amide bond (N-CO). This results in the loss of the neutral amine or lactam and the formation of aryl acylium cations. The mechanism of N-CO bond cleavage persists in ,-unsaturated amides because of the stability caused by extended conjugation. Computational methods determined that the protonation of the piperamides and their derivatives takes place preferentially at the amide nitrogen supporting the dominant the N-CO bond cleavage. (AU)

• Processo FAPESP: 14/50316-7 - Dimensões US-BIOTA São Paulo: diversidade de interações multi-tróficas quimicamente mediadas em gradientes nos trópicos
• Beneficiário: Massuo Jorge Kato
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático