New Spectral Data of Some Flavonoids from Deguelia hatschbachii A .

Entre os flavonóides isolados de Deguelia hatschbachii encontram-se escandenina (1), robustato de metila (2) e 4’,5-diidroxi-6-(3,3-dimetilalila)-7-metoxiflavanona (3) que foram identificados pela comparação dos dados espectroscópicos previamente publicados. A obtenção de novos dados espectroscópicos (RMN, RMN-2D e EM/EM) permitiu a atribuição dos deslocamentos químicos de todos os hidrogênios e carbonos nos espectros de RMN H e C destas substâncias, assim como a elucidação dos caminhos de fragmentação de 1-3 no espectrômetro de massas.


Introduction
Deguelia hatschbachii A. M. G. Azevedo (Leguminosae-Fabaceae) is a new species native to Brazil.It is a medium sized tree, 3-6 m in height, with pink flowers and can be found in the East-south of Minas Gerais State and in the region of Mata Atlântica along the states of Espírito Santo, Rio de Janeiro and São Paulo.
In a previous report 1 we described the structural determination of five new compounds, which were isolated together with eight known ones from the roots of D. hatschbachii.
Since the 1 H and 13 C NMR literature data for compounds 1-3 are incomplete (Figure 1), in this paper we report the complete assignment of 1 H and 13 C NMR spectral data of 1-3 by using 1D-and 2D-NMR techniques as well as the fragmentation pathways of 1 and 3 in the mass spectrometer, based on MS/MS experiments.
EIMS 70 eV, direct probe, MS/MS experiments were performed in a VG Auto Spec-Fisions Instrument by using electron ionization technique at 70 eV (linked scan at 8KeV collisions with Helium).

Results and Discussion
Scandenin 1 was previously isolated from Derris spruceana 2 and Derris scandens. 3We now report, for the first time, its 13 C NMR spectral data (Table 2).The carbon resonances were identified by extensive 2D-NMR correlation experiments [HETCOR and COLOC] (Table 3).
Methyl robustate 2 was previously isolated from Derris robusta 5 when only UV, IR and low resolution 1 H NMR (60 MHz) spectral data were reported.We now include 1 H (300 MHz), 13 C NMR data (Tables 1 and 2) and the fragmentation pathway for this compound (Figure 3).The 1 H NMR spectrum of compound 3 showed the same absorptions found for the flavanone previously isolated from Lonchocarpus minimiflorus, 6 when only MS and low resolution 1 H NMR (90 MHz) spectral data were reported.1D-and 2D-NMR experiments allowed the full assignment of all hydrogen and carbon shift values (Tables 1, 2, 4 and 5).4).

Conclusions
The combination of 1D-and 2D-NMR techniques has allowed the complete assignment of the 1 H and 13 C spectral  data of the known flavonoids 1-3, until now not found in the literature.
Our results will fill the gap in literature data for these compounds, which are rarely found in nature and can be used to facilitate further assignments of other analogous flavonoids.