*3.8. (E)-3-((E)-1-(Biphenyl-4-yl)-3-phenylallylidene)-1-methylindolin-2-one* (**9**)

To a solution of **3ea** (16.4 mg, 0.0354 mmol) in dioxane (1.0 mL) were added phenylboronic acid (5.2 mg, 0.043 mmol, 1.2 equiv.), K2CO3 (14.7 mg, 0.106 mmol, 3 equiv.) and

Pd(PPh3)4 (2.0 mg, 1.7 μmol, 5 mol%). The reaction mixture was stirred at 90 ◦C for 8 h, then cooled to rt and diluted with EtOAc (50 mL) and water (20 mL). The organic layer was separated, dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude residue was purified by column chromatography (silica gel, hexane:EtOAc = 8:1) to afford **9** (12.2 mg, 81% yield) as orange gum. *R*<sup>f</sup> = 0.43 (silica gel, hexane:EtOAc = 5:1); 1H NMR (500 MHz, CDCl3): *δ* 9.41 (d, *J* = 16.0 Hz, 1H), 7.85–7.79 (m, 2H), 7.77 (dd, *J* = 8.2, 1.1 Hz, 2H), 7.56 (d, *J* = 7.3 Hz, 2H), 7.53 (t, *J* = 7.7 Hz, 2H), 7.45–7.40 (m, 1H), 7.39–7.35 (m, 2H), 7.33 (t, *J* = 7.3 Hz, 2H), 7.31–7.27 (m, 1H), 7.13 (td, *J* = 7.7, 1.0 Hz, 1H), 6.77 (d, *J* = 7.7 Hz, 1H), 6.63 (td, *J* = 7.7, 0.9 Hz, 1H), 6.56 (d, *J* = 16.0 Hz, 1H), 5.92 (d, *J* = 7.7 Hz, 1H), 3.32 (s, 3H) ppm; 13C NMR (125 MHz, CDCl3) *δ* 168.1, 151.0, 142.9, 141.6, 141.2, 140.4, 137.0, 136.7, 129.3, 129.2, 129.1, 128.8, 128.4, 128.0, 127.9, 127.7, 127.2, 123.7, 123.4, 122.7, 121.7, 107.7, 25.9 ppm; HRMS (EI): calcd for C30H23NO [M+]: 413.1780, found 413.1776.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/molecules27165304/s1, copies of NMR spectra of **4**–**9**, and **3** (**3ac**, **3bc**, **3cc**, **3dc**, **3ea**).

**Author Contributions:** Conceptualization, J.H.S.; methodology, J.K. and M.K.; software, J.K. and M.K.; validation, J.K. and M.K.; formal analysis, J.K. and M.K.; investigation, J.K. and M.K.; resources, J.H.S. and K.J.S.; data curation, J.K. and M.K.; writing—original draft preparation, J.H.S. and J.K.; writing—review and editing, J.H.S. and K.J.S.; visualization, J.H.S. and J.K.; supervision, J.H.S. and K.J.S.; project administration, J.H.S.; funding acquisition, J.H.S. and K.J.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1A6A1A03025108) and Research Fund of 2019 of The Catholic University of Korea.

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available in the Supplementary Materials.

**Acknowledgments:** We thank Dain Lee and Boyoung Kim for their assistance in data collection.

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

**Sample Availability:** Samples of the compounds **3**–**9** are available from the authors.
