## 2 Results and Discussion  
### NMR Data  
In the \({}^{1}\)H NMR spectrum (Table 1), a signal observed in \(\delta_{\rm H}\) 3.90, 3.97, and 3.98 ppm, referring to hydrogen from the methoxy groups. In \(\delta_{\rm H}\) 7.75 (\(J\) = 15.60) and 7.94 (\(J\) = 15.60) are assigned to two doubles referring to unsaturated hydrogen \(\alpha\), \(\beta\), whose coupling constant (\(J\)) confirms the stereochemical _trans_ of the double bond. The singlet observed in 6.04 ppm refers to hydrogen-bonded to a carbon 5\({}^{\prime}\) of ring A. The singlet in 8.45 ppm refers to H-2, the signal in 7.59 ppm corresponds to H-5, whereas the signals in 8.22 (d, \(J\) =8.13 Hz) and 7.86 (d, \(J\) = 7.60 Hz) refer to H-4 and H-6, respectively. In the \({}^{1}\)H NMR spectrum, the signals in 3.90, 4.02, and 4.10 ppm referring to methoxyl hydrogen can be observed. In 8.33 (\(J\) = 16.1) and 8.36 (\(J\) = 15.4) are attributed to two doubles referring to unsaturated hydrogen \(\alpha\), \(\beta\), whose coupling constant (\(J\)) confirms the stereochemical \(E\) of the double bond. The singlet observed in 6.04 refers to hydrogen attached to the carbon 5\({}^{\prime}\) of ring A. The signals at 8.09 (d, \(J\) = 8.09 Hz) and 7.69 (d, \(J\) = 8.1 Hz) refer to H-3/5 and H-2/6, respectively.  
In the \({}^{13}\)C NMR spectrum (Table 1), the \(\delta_{\rm C}\) 192.7 ppm signal is assigned to the carbonyl group in the \(\alpha\), \(\beta\) unsaturated (enone) system. Ketone free carbonyl absorbs in 203.8. However, the presence of \(\alpha\), \(\beta\) unsaturation causes displacement in the signal position due to the decreased double character of the bond (C=O) [7 ]. Olefin carbons \(\alpha\) and \(\beta\) are observed at 130.6 and 139.6 ppm, respectively. The signals at 60.9 56.3 and 56.2 ppm refer to methoxyl carbons. At 159.6 (C-4\({}^{\prime}\)), 159.2 (C-6\({}^{\prime}\)), 158.9 (C-2\({}^{\prime}\)), 131.1 (C-5\({}^{\prime}\)), 106.9 (C-1\({}^{\prime}\)), 87.2 (C-3\({}^{\prime}\)) ppm, the signals for carbons are present in ring A, while carbons 1 to 6 present in ring B can be observed at 148.9 (C-3), 137.5 (C-1), 134.5 (C-6), 130.1 (C-5), 124.2 (C-4) and 122.3 (C-2) ppm (Figures S1-S4, see supplementary material).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & **1** & & **2** \\ \hline C & \(\delta_{\rm C}\) & \(\delta_{\rm H}\) & \(\delta_{\rm C}\) & \(\delta_{\rm H}\) \\ \hline
1\({}^{\prime}\) & 106.9 & & 106.9 & \\
2\({}^{\prime}\) & 158.9 & & 158.8 & \\
3\({}^{\prime}\) & 131.1 & & 131.2 & \\
4\({}^{\prime}\) & 159.6 & & 159.6 & \\
5\({}^{\prime}\) & 87.2 & 6.02 (s) & 87.4 & 6.04 (s) \\
6\({}^{\prime}\) & 159.2 & & 159.1 & \\ MeO-3\({}^{\prime}\) & 60.9 & 3.84 (s) & 60.9 & 3.90 (s) \\ MeO-4\({}^{\prime}\) & 56.3 & 3.97 (s) & 56.4 & 4.02 (s) \\ MeO-6\({}^{\prime}\) & 56.2 & 3.98 (s) & 56.3 & 4.10 (s) \\ C=O & 192.7 & & 192.7 & \\
1 & 137.5 & & 137.6 & \\
2 & 122.3 & 8.45 (s) & 122.3 & 8.09 (d, \(J\) = 8.09 Hz) \\
3 & 148.9 & & 124.4 & 7.69 (d, \(J\) = 8.1 Hz) \\
4 & 124.4 & 8.22 (d, \(J\) = 8.13 Hz) & 149.0 & \\
5 & 130.1 & 7.59 (t) & 130.1 & 7.69 (d, \(J\) = 8.1 Hz) \\
6 & 134.5 & 7.86 (d, \(J\) = 7.60 Hz) & 134.4 & 8.09 (d, \(J\) = 8.09 Hz) \\ C\(\alpha\) & 130.6 & 7.75 (d, \(J\) = 15.60 Hz) & 130.7 & 8.33 (d, \(J\) = 16.1 Hz) \\ C\(\beta\) & 139.6 & 7.94 (d, \(J\) = 15.60 Hz) & 139.3 & 8.36 (d, \(J\) = 15.4 Hz) \\ \hline \hline \end{tabular}
\end{table}
Table 1: \({}^{1}\)H and \({}^{13}\)C NMR data from chalcones 1 and 2 in CDCl\({}_{3}\). The chemical displacements in \({}^{13}\)C and \({}^{1}\)H are in ppm.