**4. Conclusions**

In summary, we have synthesized a series of OA-dithiocarbamate derivatives in a twostep protocol at room temperature, offering a readily accessible synthetic route to obtain novel OA derivatives in high yields. Moreover, some of the compounds were shown to be promising hit compounds, with remarkably improved broad-spectrum antiproliferative activities compared to the natural product OA. Mechanistic insights of their activities on certain tumor cell lines are currently underway in our laboratory.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/molecules28031414/s1. Figures S1–S42: 1H and 13C NMR spectrum of **2**, **3a**–**t**; Figures S43–S63: HRMS spectrum of **2**, **3a**–**t**.

**Author Contributions:** Y.C., Z.X. and Y.Z. (Yueshui Zhao). conceptualized and designed this article. L.T., Y.Z. (Yan Zhang) and J.X. conducted the experiments and wrote the manuscript. Q.Y., F.D., X.W., M.L., J.S. and S.D. provided critical comments and edited the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the National Natural Science Foundation of China (Grant No. 81972643), SCU-Luzhou Platform Construction of Scientific and Technological Innovation (Grant No. 2022CDLZ-20), and the Research Fund of Southwest Medical University (Grant No. 2021ZKQN106).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
