## 2 Experimental
### Synthesis of 4-(1H-Indazole-3-yl)benzoic Acid (Compound 9)  
As shown in Scheme 1, compound **9** was obtained by saponification and subsequent deprotection of compound **8**, according to a previous report, with some modifications [36]. In practice, compound **8** (400 mg, 1.136 mmol) was dissolved into a mixed solution of THF (5 mL) with methanol (1 mL) under magnetic stirring at 25 \({}^{\circ}\)C. Then, the LiOH solution (LiOH-H\({}_{2}\)O of 476 mg dissolved in distilled H\({}_{2}\)O of 3 mL) was introduced. The resulting reaction mixture was further stirred at 25 \({}^{\circ}\)C for 18 h. When the time was up, the reaction mixture was acidified by dropping HCl solution (3 mol L\({}^{-1}\)), until the pH value was adjusted to 2. The mixture thus obtained was stirred for 2 h, to remove the bcc-group. Figure 3: Recycling experiments on Suzuki–Miyaura cross-coupling of compounds **3** with **7** catalyzed by Pd catalyst immobilized over imidazolium ionic liquid: (**a**) Pd(OAc)\({}_{2}\) over ILs; (**b**) PdCl\({}_{2}\) over ILs; (**c**) PdCl\({}_{2}\)(dppf) over ILs; (**d**) PdCl\({}_{2}\)(dttbpf) over ILs. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Entry a** & **Catalyst b** & **Solvent** & **Conversion (\%) c** & **Yield (\%) d** \\ \hline
1 & Pd(PPh\({}_{3}\))\({}_{4}\) & THE a & 10 & 10 \\
2 & & BMImBF\({}_{4}\)/THE & 4 & 4 \\
3 & & BMImPF\({}_{6}\)/THE & 17 & 17 \\
4 & Pd(OAc)\({}_{2}\) & THE & 30 & 30 \\
5 & & BMImBF\({}_{4}\)/THE & 59 & 59 \\
6 & & BMImPF\({}_{6}\)/THE & 57 & 57 \\
7 & PdCl\({}_{2}\) & THE & 14 & 14 \\
8 & & BMImBF\({}_{4}\)/THE & 62 & 62 \\
9 & & BMImPF\({}_{6}\)/THE & 47 & 47 \\
10 & PdCl\({}_{2}\)(dppf) & THE & 86 & 86 \\
11 & & BMImBF\({}_{4}\)/THE & 91 & 91 \\
12 & & BMImPF\({}_{6}\)/THE & 89 & 89 \\
13 & PdCl\({}_{2}\)(dtopf) & THE & 90 & 90 \\
14 & & BMImBF\({}_{4}\)/THE & 93 & 93 \\
15 & & BMImPF\({}_{6}\)/THE & 89 & 89 \\ \hline \hline \end{tabular} \({}^{\mathrm{a}}\) Reaction conditions (details as in Section 2.11): electrophorphic **3** (1.0 mmol), nucleophile **7** (1.2 mmol), Pd catalyst (4 mol%, based on organic halide), THE solvent system (Toluene, 4 mL; H\({}_{2}\)O, 2 mL; EtOH, 1 mL), Na\({}_{2}\)CO\({}_{3}\) (2.0 mmol), ILs (BMImPF\({}_{6}\) or BMImBF\({}_{4}\), 5 mL); 80 \({}^{\mathrm{c}}\), C\({}_{8}\) h. b Pd(PPh\({}_{3}\))\({}_{4}\), tetrakis(triphenylphosphine) palladium(0); Pd(OAc)\({}_{2}\), palladium(II) acetate; PdCl\({}_{2}\), palladium(II) chloride; PdCl\({}_{2}\)(dtopf), 1.1’-bis(diphenylphosphino)feronce-palaldium(ll)chloride dicholomethane; PdCl\({}_{2}\)(dtopf), 1.1’-bis(d-i-tert-butyl-phosphino)ferroceheldichloromplandium(II). c Conversion of electrophophile 3 (%), d isolated yield (%) of compound **8** (_tert_-butyl-3-(4-(methoxycarbonyl)phenyl)-1H-indazole-1-carboxylate), based on compound **3**. No by-products were found by flash chromatography for all entries in this table.  
\end{table} 
Table 2: Catalytic Suzuki–Miyaura cross-coupling of compounds **3** with **7**. Next, the reaction mixture was extracted with CH\({}_{2}\)Cl\({}_{2}\) (3 \(\times\) 50 mL), and the combined organic layers were dried over anhydrous MgSO\({}_{4}\) and then concentrated under reduced pressure. The residue was purified by flash chromatography (SiO\({}_{2}\), 100-200 mesh; dichloromethane/methanol = 10/1, \(v\)/\(v\), adding a few drops of triethylamine, 10 drops of triethylamine vs. 200 mL eluent) to afford compound **9** (247 mg, yield of 90%) as a white solid. Mp \(>\)280 \({}^{\circ}\)C \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta_{\rm H}\), ppm: 13.49 (1H, s, COOH), 8.11 (5H, dd, \(J\) = 8.3, 16.0 Hz, ArH), 7.63 (1H, d, \(J\) = 8.4 Hz, ArH), 7.43 (1H, m, ArH), 7.24 (1H, m, ArH) (Figure S17, Section S17, Supplementary Materials). \({}^{13}\)C NMR (101 MHz, DMSO-\(d_{6}\)) \(\delta_{\rm C}\), ppm: 167.78, 142.65, 142.23, 138.48, 130.55, 130.18, 127.08, 126.84, 122.04, 121.14, 120.68, 111.37 (Figure S18, Section S18, Supplementary Materials). ESI-HRMS (TOF-SIMS, positive, m/z): 239.0815 (Calcd.