4.4. General Procedure for Iridium-Catalyzed arene C–H borylation Using NNB-type Ligand

B₂pin₂, [IrCl(COD)]₂ (1.0 mol%), preligand 1 (2.0 mol%), and (hetero)arene (0.2 mmol, if solid) were placed in a dried Schlenk flask (15 mL in volume) equipped with a stirring bar. After evacuating and refilling the flask with dry nitrogen three times, (hetero)arene (0.2 mmol, if liquid) and methoxycyclopentane (CAPE, 0.5 mL) were added with syringes under a stream of nitrogen. The resulting mixture was stirred at the corresponding temperature for the assigned time. After cooling to room temperature, the reaction mixture was concentrated and then purified by column chromatography on silica gel to give the target product (The spectra data for the borylated compounds can be seen in the Supplementary Material).

2-(3,5-Dimethoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5). [56]. Yield: 47.5 mg (90%); white solid; m.p.: 87–88 °C; ¹H-NMR (400 MHz, CDCl₃) δ 6.95 (d, J = 2.4 Hz, 2H), 6.57 (t, J = 2.4 Hz, 1H), 3.82 (s, 6H), 1.34 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 160.5, 111.7, 104.6, 84.0, 55.5, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 31.3 (bs).

4,4,5,5-Tetramethyl-2-(3,4,5-trimethoxyphenyl)-1,3,2-dioxaborolane (5a). Yield: 58.2 mg (99%); white solid; m.p.: 104–106 °C; ¹H-NMR (400 MHz, CDCl₃) δ 7.04 (s, 2H), 3.91 (s, 6H), 3.87 (s, 3H), 1.35 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) 153.0, 140.9, 111.3, 84.0, 60.9, 56.3, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 32.0 (bs). The spectral data were in accordance with the literature [16].

2-(3-Chloro-5-methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5b) [31]. Yield: 51.5 mg (96%); colorless oil; ¹H NMR (400 MHz, CDCl₃) δ 7.37 (d, J = 1.6 Hz, 1H), 7.19 (d, J = 2.4 Hz, 1H), 6.99 (t, J = 2.4 Hz, 1H), 3.82 (s, 3H), 1.34 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 160.0, 134.7, 127.0, 117.9, 117.5, 84.3, 55.7, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.9 (bs).

2-(3-Bromo-5-methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5c) [27]. Yield: 61.8 mg (99%); colorless oil; ¹H-NMR (400 MHz, CDCl₃) δ 7.52 (d, J = 1.2 Hz, 1H), 7.24 (d, J = 2.4 Hz, 1H), 7.15 (t, J = 2.0 Hz, 1H), 3.81 (s, 3H), 1.34 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 160.0, 129.9, 122.8, 120.7, 118.0, 84.3, 55.7, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.5 (bs).

2-(3-Bromo-5-(trifluoromethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5d) [31]. Yield: 67.9 mg (97%); colorless oil; ¹H-NMR (400 MHz, CDCl₃) δ 8.1 (s, 1H), 7.97 (s, 1H), 7.83 (s, 1H), 1.36 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃), 141.0, 132.1 (q, J = 32.7 Hz), 131.0 (q, J = 3.7 Hz), 130.0 (q, J = 3.7 Hz), 123.4 (q, J = 273.0 Hz), 122.6, 84.8, 25.0; ¹⁹F-NMR (376.5 MHz, CDCl₃) δ -62.7; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.3 (bs).

Dimethyl 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isophthalate (5e) [57]. Yield: 63.4 mg (99%); white solid; ¹H-NMR (400 MHz, CDCl₃) δ 8.77 (t, J = 2.0 Hz, 1H), 8.64 (d, J = 2.0 Hz, 1H), 3.95 (s, 1H) 1.37 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 166.4, 140.0, 133.4, 130.2, 84.5, 52.4, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.6 (bs).

2-(3-Bromo-2-fluoro-5-(trifluoromethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5f) [6]. Yield: 72.1 mg (98%); white solid; ¹H-NMR (400 MHz, CDCl₃) δ 7.98–7.93 (m, 1H), 7.91 (dd, J = 6.0, 2.0 Hz, 1H), 1.37 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 164.9 (d, J = 258.5 Hz), 133.9 (m), 133.2 (m), 127.6 (dd, J = 33.8, 3.7 Hz), 123.1 (q, J = 272.5 Hz), 110.2 (d, J = 24.6 Hz), 84.9, 24.9; ¹⁹F-NMR (376.5 MHz, CDCl₃) δ –62.0, –91.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 29.5 (bs).

2-(3-Bromo-5-(trifluoromethoxy)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5g) [6]. Yield: 70.2 mg (96%); colorless oil; ¹H-NMR (400 MHz, CDCl₃) δ 7.86 (d, J = 1.2 Hz, 1H), 7.56 (s, 1H), 7.46 (s, 1H), 1.34 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 149.3, 136.1, 127.1, 125.5, 122.6, 120.5 (q, J = 257.9 Hz), 84.7, 25.0; ¹⁹F-NMR (376.5 MHz, CDCl₃) δ –57.8; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.2 (bs).

2-(4-Bromo-2,6-difluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5h) [6]. Yield: 63.0 mg (99%); colorless oil; ¹H-NMR (400 MHz, CDCl₃) δ 7.05 (m, 2H), 1.37 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 166.6 (dd, J = 254.0, 14.0 Hz), 125.7 (t, J = 12.8 Hz), 115.3 (m), 84.5, 24.8; ¹⁹F-NMR (376.5 MHz, CDCl₃) δ –99.8(s); ¹¹B-NMR (128.4 MHz, CDCl₃) δ 29.7 (bs).

2,6-Dichloro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (5i) [6]. Yield: 52.4 mg (96%); white solid; ¹H-NMR (400 MHz, CDCl₃) δ 7.59 (s, 2H), 1.35 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 150.5, 127.9, 85.4, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 29.8 (bs).

4,4,5,5-Tetramethyl-2-(perfluorophenyl)-1,3,2-dioxaborolane (5j) [24]. Yield: 58.2 mg (99%); colorless oil; ¹H NMR (400 MHz, CDCl₃) δ 1.38 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 85.1, 24.8; ¹⁹F-NMR (376.5 MHz, CDCl₃) δ –129.5 (m, 2F), –149.7 (m, 1F), –161.9 (m, 2F); ¹¹B-NMR (128.4 MHz, CDCl₃) δ 29.2 (bs).

2-(3,4-Dibromophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5k) [58]. Yield: 70.0 mg (97%); colorless oil; ¹H-NMR (400 MHz, CDCl₃) δ 8.03 (s, 1H), 7.62 (d, J = 8.0 Hz, 1H), 7.55 (dd, J = 8.0, 1.2 Hz, 1H) 1.34 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 139.8, 134.6,133.4, 128.3, 124.8, 84.5, 25.0; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.6 (bs).

4,4,5,5-Tetramethyl-2-(2,4,6-trimethoxyphenyl)-1,3,2-dioxaborolane (5l) [6]. Yield: 30.1 mg (20%); white solid; ¹H-NMR (400 MHz, CDCl₃) δ 6.04 (s, 2H), 3.79 (s, 3H), 3.75 (s, 6H), 1.36 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 164.7, 163.3, 90.4, 83.6, 55.8, 55.4, 24.8; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 32.5 (bs).

(4r,8r)-4-Methyl-2,6-dioxo-8-(5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)thiophen-3-yl)hexahydro-[1,3,2]oxazaborolo[2,3-b][1,3,2]oxazaborol-4-ium-8-uide (5m) [53]. Yield: 71.6 mg (98%); white solid; ¹H-NMR (400 MHz, DMSO-d₆) δ 7.89 (d, J = 0.8, 1H), 7.61 (d, J = 0.8 1H), 4.32 (d, J = 17.2Hz, 2H), 4.13 (d, J = 17.2Hz, 2H), 2.57 (s, 3H), 1.29(s, 12H). ¹³C-NMR (100 MHz, DMSO-d₆) δ 169.6, 142.5, 139.0, 84.3, 62.2, 47.9, 25.1.

(4r,8r)-8-(2,4-difluoro-3,5-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-4-methyl-2,6-dioxohexahydro-[1,3,2]oxazaborolo[2,3-b][1,3,2]oxazaborol-4-ium-8-uide (5n) [53]. Yield: 103.6 mg (99%); white solid; ¹H-NMR (400 MHz, DMSO-d₆) δ 7.90 (t, J = 8, 1H), 4.40 (d, J = 17.2Hz, 2H), 4.13 (d, J = 17.2Hz, 2H), 2.64 (s, 3H), 1.30 (s, 12H). ¹³C-NMR (100 MHz, DMSO-d₆) δ 169.5, 84.5, 84.2, 66.8, 63.2, 48.3, 25.1, 24.9.

2-(6-chlorobenzo[d][1,3]dioxol-4-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5o) [6]. Yield: 37.8 mg (67%); white solid; ¹H-NMR (400 MHz, CDCl₃) δ 7.17 (d, J = 2.0 Hz, 1H), 6.86 (d, J = 2.4 Hz, 1H), 6.04 (s, 2H), 1.36 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 151.6, 148.1, 127.0, 126.0, 112.0, 102.0, 84.4, 24.9; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 30.0 (bs).

2,2′-(5-chlorobenzo[d][1,3]dioxole-4,7-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (5p) [6]. Yield: 65.3 mg (80%); white solid; ¹H-NMR (400 MHz, CDCl₃) δ 7.16 (s, 1H), 6.06 (s, 2H), 1.39 (s, 12H), 1.35 (s, 12H); ¹³C-NMR (100 MHz, CDCl₃) δ 152.2, 150.6, 129.6, 127.4, 101.9, 84.7, 84.3, 24.95, 24.86; ¹¹B-NMR (128.4 MHz, CDCl₃) δ 31.5 (bs).