## 2 Results and Discussion
### The Structural Elucidation of New Compounds
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Position**} & \multicolumn{2}{c}{**Compound 1**} & \multicolumn{2}{c}{**Compound 2**} \\ \cline{2-5}  & \(\delta_{\mathbf{H}}\) **(J[Hz])** & \(\delta_{\mathbf{C}}\) & \(\delta_{\mathbf{H}}\) **(J[Hz])** & \(\delta_{\mathbf{C}}\) \\ \hline
1 & 1.10, m & 38.1, t & 1.04, m & 38.2, t \\
2 & 1.84, m & 32.1, t & 1.48, m & 32.3, t \\
3 & 3.45, m & 72.2, d & 3.41, m & 72.1, d \\
4 & 2.29, m & 43.1, t & 2.24, m & 42.5, t \\
5 & - & 148.0, s & - & 144.1, s \\
6 & 5.77, d (4.1) & 121.5, d & 5.27, br s & 127.4, d \\
7 & 3.34, br s & 75.2, d & 3.72, br d (8.2) & 73.7, d \\
8 & 1.50, m & 38.0, d & 1.45, m & 40.7, d \\
9 & 1.28, m & 44.1, d & 1.02, m & 50.0, d \\
10 & - & 38.6, s & - & 37.6, s \\
11 & 1.53, m & 21.9, t & 1.54, m & 22.2, t \\
12 & 1.17, m & 41.1, t & 1.20, m & 41.5, t \\
13 & - & 43.5, s & - & 44.3, s \\
14 & 1.49, m & 50.6, d & 1.13, m & 58.0, d \\
15 & 1.15, m & 24.8, t & 1.24, m & 27.0, t \\
16 & 1.16, m & 25.5, t & 1.13, m & 25.4, t \\
17 & 1.48, m & 59.1, d & 1.44, m & 58.7, d \\
18 & 0.85, s & 13.7, q & 0.87, s & 14.1, q \\
19 & 0.99, s & 18.8, q & 1.06, s & 19.4, q \\
20 & - & 76.2, s & - & 76.2, s \\
21 & 1.24, s & 26.2, q & 1.24, s & 26.2, q \\
22 & 1.52, m & 43.4, t & 1.51, m & 43.4, t \\  & & & 1.65, m & 23.8, t \\
23 & 1.67, m & 23.4, t & 1.79, m & 23.8, t \\
24 & 0.94, m & 47.7, d & 0.93, m & 47.7, d \\
25 & 1.69, m & 30.4, d & 1.69, m & 30.4, d \\
26 & 0.87, d (6.5) & 20.1, q & 0.87, d (6.6) & 20.0, q \\
27 & 0.86, d (6.5) & 19.6, q & 0.86, d (6.6) & 19.6, q \\
28 & 1.66, m & 24.1, t & 1.33, m & 24.1, t \\
29 & 0.89, t (7.3) & 12.4, q & 0.88, t (7.3) & 12.4, q \\
7-OMe & 3.35, s & 56.9, q & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The \({}^{1}\)H (600 MHz) and \({}^{13}\)C (150 MHz) NMR data of compounds **1** and **2** in methanol-\(d_{4}\) (\(\delta\), ppm). Figure 3: Comparison of experimental circular dichroism (CD) and calculated electronic circular dichroism (ECD) spectra of compounds **1**–**3. **(A)** experimental CD and calculated ECD spectra of compound **1**; **(B)** experimental CD and calculated ECD spectra of compound **2**; **(C)** experimental CD and calculated ECD spectra of compound **3**. Compound **2** is also a white solid, and it will not be transformed into compound **1** in methanol solvent (Figure S30). In HR-ESI-MS, a molecular ion peak was observed (\(m/z_{\text{obsd}}\) 469.3644 [M + Na]\({}^{+}\); \(m/z_{\text{calcd}}\) 469.3658) that suggested a molecular formula of C\({}_{29}\)H\({}_{50}\)O\({}_{3}\) with 5 degrees of unsaturation. Based on 1D and 2D NMR spectra, we inferred that **2** was a steroid with a stigmasterol skeleton, which is similar to the structure of compound **1**. Analysis of \({}^{13}\)C NMR and DEPT spectra revealed that **2** lacked only one methoxy carbon compared to **1**, suggesting that the 7-OMe group was absent in **2**. Further analysis of HMBC and \({}^{1}\)H-\({}^{1}\)H COSY spectra revealed that C-7 is replaced by a hydroxyl group in **2** (Figure 2). The ROESY spectra revealed that H-7 (\(\delta_{\text{H}}\) 3.72) was correlated with H-9 (\(\delta_{\text{H}}\) 1.02) and H-14 (\(\delta_{\text{H}}\) 1.13), which means that the H-7 of compound **2** also showed an \(\alpha\) configuration. Although a hydroxyl group with a \(\beta\) configuration of 7-OH has been reported from stigmast-5-ene-3\(\beta\),7a,20\(\xi\)-triol [16], the chemical shift value at the C-7 in compound **2** was \(\delta_{\text{C}}\) 73.7, while the values at the C-7 in the two reported compounds were \(\delta_{\text{C}}\) 65.3 [32] and 65.2 [16]. And the calculated ECD curve of the 7R, 175 was close to the experimental CD curve of compound **2** (Figure 3); in this way, the structure of **2** was eventually determined, and the compound was named ailanstigol B. Compound **3** is a white powder.