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.
Apocynaceae; Aspidosperma nitidum; indole alkaloid; 1,2,9-triazabicyclo[7.2.1] system
