NMR structural analysis of braznitidumine: a new indole alkaloid with 1,2,9-triazabicyclo[7.2.1] system, isolated from Aspidosperma nitidum (Apocynaceae)

• Autor(a) principal: Pereira,Maria M.
• Data de Publicação: 2006
• Outros Autores: Alcântara,Antônio Flávio de C., Piló-Veloso,Dorila, Raslan,Délio S.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000700012
• topic: Apocynaceae; Aspidosperma nitidum; indole alkaloid; 1,2,9-triazabicyclo[7.2.1] system

The phytochemical study of the stem bark of Aspidosperma nitidum led to the isolation of a new type of indole alkaloid with a 1,2,9-triazabicyclo[7.2.1] system, which has been called braznitidumine 1. The characterization of its chemical structure was carried out by IR, UV, ESIMS, and ¹H, 13C, and 15N NMR by using 1D and 2D (¹H ¹H COSY, ¹H ¹H NOESY, ¹H 13C HSQC and ¹H 13C HMBC) experiments. ¹H ¹H NOESY results showed that 1 presents a folded conformation with the approximation of the indole and the imidazolidine di-hydropyran groups. This configuration was investigated by theoretical calculations involving geometry optimization (DFT/BLYP/6-31G*) for the conformational analysis of this alkaloid. It confirmed the distance between the two groups in agreement with the NOESY experimental data.