3.2. General Procedure A for the Synthesis of Boron-Containing α-Acyloxyl Amides A1–21
2-(Cyclohexylamino)-2-oxo-1-phenylethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A1). A 10 mL glass tube containing the 4-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), benzaldehyde (0.10 mL, 1.00 mmol), and D.I. H
2O (1 mL) was first microwave irradiated for 6 min (45 °C, 150 W) under medium speed magnetic stirring. Cyclohexyl isocyanide (
3, 0.124 mL, 1.00 mmol) was then added to the reaction mixture. The additional microwave irradiation was applied for 120 min (45 °C, 150 W) under medium speed magnetic stirring. After being diluted in dichloromethane, the resulted reaction mixture was washed twice with a saturated aqueous solution of NaHCO
3 and with brine. The resulted organic layer was collected and dried over MgSO
4 and concentrated
in vacuo. The crude product was then dissolved in ethyl acetate (3 mL) prior the slow addition of
n-hexane. The resulting precipitate was formed and collected by filtration affording the desired product in 88% yield. mp = 198 °C.
1H-NMR (CDCl
3) δ: 8.06 (d,
J = 7.8 Hz, 2H), 7.90 (d,
J = 8.3 Hz, 2H), 7.53 (d,
J = 7.2 Hz, 2H), 7.42–7.33 (m, 3H), 6.31 (s, 1H), 6.03 (br, 1H), 3.87–3.79 (m, 1H), 1.94 (d,
J = 8.8 Hz, 1H), 1.91–1.85 (m, 1H), 1.72–1.61 (m, 2H), 1.61–1.56 (m, 3H), 1.41–1.31 (m, 14H), 1.23–1.08 (m, 3H).
13C-NMR (CDCl
3) δ: 167.3, 164.9, 135.7, 134.9, 131.4, 128.9, 128.8, 128.7, 127.4, 84.3, 76.0, 48.1, 32.8, 25.4, 24.9, 24.6.
11B-NMR (CDCl
3) δ: 31.0. HRMS (ESI, positive ion):
m/z [M+H]
+, found 464.2607. C
27H
34BNO
5 requires 464.2606.
2-(Cyclohexylamino)-2-oxo-1-phenylethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A2). The desired compound (384 mg, 83% yield) was prepared by General Procedure A using 3-carboxyphenyl boronic acid ester (248 mg, 1.00 mmol), benzaldehyde (0.102 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 152 °C.
1H-NMR (CDCl
3) δ: 8.50 (s, 1H), 8.16 (d,
J = 7.8 Hz, 1H), 8.03 (d,
J = 7.4 Hz, 1H), 7.54 (d,
J = 7.2 Hz, 2H), 7.48 (t,
J = 7.5 Hz, 1H), 7.32–7.41 (m, 3H), 6.31 (s, 1H), 6.15 (br, 1H), 3.80–3.89 (m, 1H), 1.87–1.98 (m, 2H), 1.64–1.74 (m, 3H), 1.56–1.64 (m, 2H), 1.32–1.43 (m, 12H), 1.13–1.27 (m, 4H).
13C-NMR (CDCl
3) δ: 167.4, 164.9, 139.8, 136.0, 132.4, 128.9, 128.7, 128.1, 127.4, 84.2, 76.0, 48.1, 32.8, 25.5, 24.8, 24.6.
11B-NMR (CDCl
3) δ: 31.0. HRMS (ESI, positive ion):
m/z [M+H]
+, found 464.2583. C
27H
34BNO
5 requires 464.2606.
2-(Cyclohexylamino)-2-oxo-1-phenylethyl2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A3). The desired compound (311 mg, 80% yield) was prepared by General Procedure A using 4-carboxy-3-fluorophenylboronic acid ester (266 mg, 1.00 mmol), benzaldehyde (0.102 mL, 1.00 mmol) and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 181 °C.
1H-NMR (CDCl
3) δ: 7.93 (t,
J = 7.3 Hz, 1H), 7.67–7.59 (m, 2H), 7.51 (d,
J = 6.9 Hz, 2H), 7.38–7.28 (m, 3H), 6.82 (br, 1H), 6.31 (s, 1H), 3.87–3.79 (m, 1H), 1.96–1.88 (m, 2H), 1.70 (td,
J = 8.9, 4.3 Hz, 2H), 1.63–1.55 (m, 1H), 1.41–1.30 (m, 12H), 1.29–1.17 (m, 4H).
13C-NMR (CDCl
3) δ: 167.1, 162.5, 161.2(d), 135.7, 131.8, 130.3, 130.3, 128.8, 128.7, 128.6, 127.3, 122.7, 122.6, 119.7, 119.6, 84.5, 76.0, 47.9, 32.6, 25.3, 24.7, 24.4.
11B-NMR (CDCl
3) δ: 30.44. HRMS (ESI, positive ion):
m/z [M+H]
+, found 482.2515. C
27H
33BFNO
5 requires 482.2520.
2-(Cyclohexylamino)-2-oxo-1-(4-(trifluoromethyl)phenyl)ethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A4). The desired compound (405 mg, 76% yield) was prepared by General Procedure A using 4-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 4-(trifluoromethyl)benzaldehyde (0.13 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol). mp = 249 °C.
1H-NMR (CDCl
3) δ: 8.06 (d,
J = 8.3 Hz, 2H), 7.93 (d,
J = 8.3 Hz, 2H), 7.69–7.62 (m, 4H), 6.35 (s, 1H), 6.17 (br, 1H), 3.86–3.78 (m, 1H), 1.95–1.86 (m, 2H), 1.72–1.63 (m, 2H), 1.60 (td,
J = 12.9, 3.8 Hz, 1H), 1.41–1.31 (m, 14H), 1.23–1.11 (m, 3H).
13C-NMR (CDCl
3) δ: 166.6, 164.7, 139.5, 135.0, 130.9, 128.7, 127.6, 125.7, 125.7, 123.9(d), 84.3, 75.1, 48.3, 32.8, 25.4, 24.8, 24.6.
11B-NMR (CDCl
3) δ: 31.2. HRMS (ESI, positive ion):
m/z [M+H]
+, found 532.2483. C
28H
33BF
3NO
5 requires 532.2488.
2-(Cyclohexylamino)-2-oxo-1-(4-(trifluoromethyl)phenyl)ethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (A5). The desired compound (416 mg, 79% yield) was prepared by General Procedure A using 3-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 4-(trifluoromethyl)benzaldehyde (0.136 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 150 °C.
1H-NMR (CDCl
3) δ: 8.51 (s, 1H), 8.16 (td,
J = 7.8, 1.5 Hz, 1H), 8.08–8.03 (m, 1H), 7.68 (d,
J = 8.1 Hz, 2H), 7.63 (d,
J = 8.3 Hz, 2H), 7.50 (t,
J = 7.5 Hz, 1H), 6.38 (br, 1H), 6.33 (s, 1H), 3.87–3.78 (m, 1H), 1.92 (dt,
J = 12.4, 3.1 Hz, 2H), 1.73–1.65 (m, 2H), 1.63–1.56 (m, 1H), 1.41–1.32 (m, 13H), 1.26–1.14 (m, 3H).
13C-NMR (CDCl
3) δ: 166.7, 164.7, 140.0, 139.7, 135.9, 132.3, 130.8, 128.3, 128.1, 127.6, 125.6, 125.5, 123.9(d), 84.2, 75.2, 48.2, 32.7, 25.4, 24.8, 24.5.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 532.2487. C
28H
33BF
3NO
5 requires 532.2488.
2-(Cyclohexylamino)-2-oxo-1-(4-(trifluoromethyl)phenyl)ethyl2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A6). The desired compound (279 mg, 51% yield) was prepared by General Procedure A using 4-carboxy-3-fluorophenyl boronic acid ester (266 mg, 1.00 mmol), 4-(trifluoromethyl)benzaldehyde (0.136 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 220 °C.
1H-NMR (CDCl
3) δ: 7.93 (t,
J = 7.3 Hz, 1H), 7.68–7.60 (m, 6H), 6.83 (br, 1H), 6.34 (s, 1H), 3.85–3.78 (m, 1H), 1.96–1.88 (m, 2H), 1.71 (td,
J = 13.4, 4.0 Hz, 2H), 1.60 (td,
J = 12.6, 3.7 Hz, 1H), 1.43–1.31 (m, 14H), 1.28–1.20 (m, 3H).
13C-NMR (CDCl
3) δ: 166.4, 162.5, 161.3, 139.7, 132.0, 130.9, 130.5, 127.6, 125.6, 125.6, 124.8, 122.8, 119.3, 119.2, 84.7, 75.6, 48.1, 32.7, 32.6, 25.4, 24.8, 24.4.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 550.2376. C
28H
32BF
4NO
5 requires 550.2394.
2-(Cyclohexylamino)-1-(2-fluorophenyl)-2-oxoethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A7). The desired compound (418 mg, 87% yield) was prepared by General Procedure A using 4-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 2-fluorobenzaldehyde (0.105 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 167 °C.
1H-NMR (CDCl
3) δ: 8.05 (d,
J = 8.30 Hz, 2H), 7.89 (d,
J = 8.1 Hz, 2H), 7.58 (dt,
J = 7.4, 1.5 Hz, 1H), 7.33 (ddt,
J = 7.7, 5.5, 1.7 Hz, 1H), 7.19–7.14 (m, 1H), 7.08 (t,
J = 9.1 Hz, 1H), 6.48 (s, 1H), 6.17 (br, 1H), 3.87–3.79 (m, 1H), 2.00–1.93 (m, 1H), 1.88–1.81 (m, 1H), 1.73–1.61 (m, 2H), 1.61–1.55 (m, 1H), 1.40–1.29 (m, 13H), 1.27–1.10 (m, 3H)
13C-NMR (CDCl
3) δ: 166.5, 164.9, 160.7(d), 134.8, 131.2, 130.7, 130.0, 128.7, 124.4, 124.4, 123.2, 115.7, 84.2, 70.8, 48.2, 32.6, 25.4, 24.8, 24.5.
11B-NMR (CDCl
3) δ: 31.1. HRMS (ESI, positive ion):
m/z [M+H]
+, found 482.2512. C
27H
33BFNO
5 requires 482.2520.
2-(Cyclohexylamino)-1-(2-fluorophenyl)-2-oxoethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A8). The desired compound (415 mg, 86% yield) was prepared by General Procedure A using 3-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 2-fluorobenzaldehyde (0.105 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 173 °C.
1H-NMR (CDCl
3) δ: 8.50 (s, 1H), 8.13 (d,
J = 7.7 Hz, 1H), 8.01 (d,
J = 7.4 Hz, 1H), 7.60–7.55 (m, 1H), 7.45 (t,
J = 7.5 Hz, 1H), 7.34–7.28 (m, 1H), 7.15 (t,
J = 7.6 Hz, 1H), 7.06 (t,
J = 9.2 Hz, 1H), 6.32 (br, 1H), 3.87–3.80 (m, 1H), 1.96 (d,
J = 11.6 Hz, 1H), 1.85 (d,
J = 12.0 Hz, 1H), 1.72–1.61 (m, 2H), 1.59–1.53 (m, 1H), 1.40–1.29 (m, 14H), 1.29–1.12 (m, 3H).
13C-NMR (CDCl
3) δ: 166.5, 164.8, 160.6, 139.7, 135.9, 132.2, 130.6, 129.9, 128.5, 127.9, 124.3, 123.2, 115.5, 84.0, 70.7, 48.1, 32.5, 25.3, 24.7, 24.4.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 482.2514. C
27H
33BFNO
5 requires 482.2520.
2-(Cyclohexylamino)-1-(2-fluorophenyl)-2-oxoethyl2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A9). The desired compound (340 mg, 68% yield) was prepared by General Procedure A using 4-carboxy-3-fluorophenylboronic acid ester (266 mg, 1.00 mmol), 2-fluorobenzaldehyde (0.10 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 69 °C.
1H-NMR (CDCl
3) δ: 7.89 (t,
J = 7.3 Hz, 1H), 7.63–7.55 (m, 2H), 7.50 (dt,
J = 7.4, 1.6 Hz, 1H), 7.31–7.26 (m, 1H), 7.11 (dt,
J = 7.5, 0.8 Hz, 1H), 7.06–7.01 (m, 1H), 6.78 (br, 1H), 6.45 (s, 1H), 3.87–3.79 (m, 1H), 1.94 (dd,
J = 12.0, 3.0 Hz, 1H), 1.91–1.85 (m, 1H), 1.68 (tdd,
J = 17.1, 13.1, 4.0 Hz, 3H), 1.60–1.52 (m, 1H), 1.38–1.19 (m, 18H).
13C-NMR (CDCl
3) δ: 166.3, 162.5, 161.8, 160.1, 131.7, 130.7, 130.0, 124.2, 123.2, 122.5, 119.4, 115.6, 84.4, 71.2, 47.9, 32.4, 25.3, 24.7, 24.3.
11B-NMR (CDCl
3) δ: 30.8. HRMS (ESI, positive ion):
m/z [M+H]
+, found 500.2425. C
27H
32BF
2NO
5 requires 500.2425.
2-(Cyclohexylamino)-1-(3-methoxyphenyl)-2-oxoethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A10). The desired compound (347 mg, 70% yield) was prepared by General Procedure A using 4-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 3-methoxybenzaldehyde (0.12 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 176 °C.
1H-NMR (CDCl
3) δ: 8.06 (d,
J = 8.1 Hz, 2H), 7.90 (d,
J = 8.1 Hz, 2H), 7.29 (t,
J = 8.0 Hz, 1H), 7.11 (d,
J = 7.7 Hz, 1H), 7.08 (s, 1H), 6.89 (dd,
J = 8.2, 2.3Hz, 1H), 6.27 (s, 1H), 6.08 (br, 1H), 3.84–3.77 (m, 4H), 1.92 (d,
J = 9.5 Hz, 1H), 1.89–1.84 (m, 1H), 1.66 (dt,
J = 14.4, 4.0 Hz, 2H), 1.61–1.55 (m, 1H), 1.40–1.30 (m, 14H), 1.21–1.08 (m, 3H).
13C-NMR (CDCl
3) δ: 167.1, 164.9, 159.7, 137.1, 134.8, 131.4, 129.7, 128.7, 119.5, 114.4, 113.0, 84.2, 75.8, 55.2, 48.1, 32.7, 25.4, 24.8, 24.6.
11B-NMR (CDCl
3) δ: 30.8. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2717. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-1-(3-methoxyphenyl)-2-oxoethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A11). The desired compound (377 mg, 77% yield) was prepared by General Procedure A using 3-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 3-methoxybenzaldehyde (0.121 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 167 °C.
1H-NMR (CDCl
3) δ: 8.51 (s, 1H), 8.16 (td,
J = 7.8, 1.5 Hz, 1H), 8.03 (d,
J = 7.2 Hz, 1H), 7.48 (t,
J = 7.5 Hz, 1H), 7.29 (t,
J = 8.0 Hz, 1H), 7.13–7.08 (m, 2H), 6.89 (dd,
J = 8.2, 2.5 Hz, 1H), 6.27 (s, 1H), 6.15 (br, 1H), 3.87–3.80 (m, 4H), 1.97–1.87 (m, 2H), 1.74–1.64 (m, 3H), 1.59 (td,
J = 12.8, 3.6 Hz, 1H), 1.41–1.33 (m, 14H), 1.27–1.14 (m, 3H).
13C-NMR (CDCl
3) δ: 167.3, 164.8, 159.7, 139.8, 137.2, 136.0, 132.4, 129.7, 128.7, 128.0, 119.6, 114.5, 112.9, 84.2, 75.8, 55.3, 48.1, 32.7, 25.5, 24.8, 24.6.
11B-NMR (CDCl
3) δ: 30.5. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2704. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-1-(3-methoxyphenyl)-2-oxoethyl2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A12). The desired compound (320 mg, 63% yield) was prepared by General Procedure A using 4-carboxy-3-fluorophenylboronic acid ester (266 mg, 1.00 mmol), 3-methoxybenzaldehyde (0.12 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 163 °C.
1H-NMR (CDCl
3) δ: 7.95 (t,
J = 7.2 Hz, 1H), 7.68–7.59 (m, 2H), 7.30–7.26 (m, 1H), 7.13–7.06 (m, 2H), 6.89–6.85 (m, 1H), 6.75 (br, 1H), 6.29 (s, 1H), 3.86–3.81 (m, 1H), 3.80 (s, 3H), 1.93 (br, s, 2H), 1.71 (td,
J = 8.6, 4.2 Hz, 2H), 1.63–1.57 (m, 1H), 1.43–1.38 (m, 2H), 1.36 (s, 13H), 1.28–1.19 (m, 3H).
13C-NMR (CDCl
3) δ: 166.9, 162.5, 161.2, 159.6, 137.1, 131.9, 130.3, 129.6, 122.6, 119.6, 119.4, 114.4, 112.9, 84.5, 76.2, 55.1, 47.9, 32.6, 25.4, 24.7, 24.4.
11B-NMR (CDCl
3) δ: 30.2. HRMS (ESI, positive ion):
m/z [M+H]
+, found 512.2615. C
28H
35BFNO
6 requires 512.2625.
2-(Cyclohexylamino)-1-(2-methoxyphenyl)-2-oxoethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A13). The desired compound (428 mg, 87% yield) was prepared by General Procedure A using 4-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 2-methoxybenzaldehyde (0.121 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 182 °C.
1H-NMR (CDCl
3) δ: 8.08 (d,
J = 8.1 Hz, 2H), 7.88 (d,
J = 8.1 Hz, 2H), 7.58 (dd,
J = 7.5, 1.4 Hz, 1H), 7.34–7.29 (m, 1H), 7.00 (t,
J = 7.5 Hz, 1H), 6.92 (d,
J = 8.3 Hz, 1H), 6.57 (s, 1H), 6.17 (br, 1H), 3.89–3.84 (m, 3H), 3.82–3.74 (m, 1H), 1.98–1.92 (m, 1H), 1.79–1.72 (m, 1H), 1.69–1.63 (m, 1H), 1.60–1.51 (m, 2H), 1.38–1.26 (m, 14H), 1.25–1.12 (m, 2H), 1.10–1.03 (m, 1H).
13C-NMR (CDCl
3) δ: 167.3, 165.3, 156.5, 134.6, 131.8, 129.9, 128.7, 128.5, 124.2, 121.0, 110.9, 84.1, 77.2, 76.8, 70.8, 55.5, 47.8, 32.5, 25.4, 24.7, 24.3.
11B-NMR (CDCl
3) δ: 31.0. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2713. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-1-(2-methoxyphenyl)-2-oxoethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A14). The desired compound (392 mg, 79% yield) was prepared by General Procedure A using 3-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), 2-methoxybenzaldehyde (0.121 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 164 °C.
1H-NMR (CDCl
3) δ: 8.54 (s, 1H), 8.18 (d,
J = 7.8 Hz, 1H), 7.99 (d,
J = 7.2 Hz, 1H), 7.58 (d,
J = 7.4 Hz, 1H), 7.44 (t,
J = 7.5 Hz, 1H), 7.30 (t,
J = 7.7 Hz, 1H), 6.99 (t,
J = 7.5 Hz, 1H), 6.91 (d,
J = 8.1 Hz, 1H), 6.57 (s, 1H), 6.24 (br, 1H), 3.87 (s, 3H), 3.82–3.76 (m, 1H), 1.95 (d,
J = 9.4 Hz, 1H), 1.77 (d,
J = 11.6 Hz, 1H), 1.70–1.63 (m, 1H), 1.61–1.51 (m, 2H), 1.38–1.27 (m, 13H), 1.26–1.06 (m, 4H).
13C-NMR (CDCl
3) δ: 167.4, 165.3, 156.6, 139.3, 136.0, 132.3, 129.9, 129.0, 128.6, 127.7, 124.2, 120.9, 110.9, 83.9, 70.9, 55.5, 47.7, 32.5, 25.3, 24.7, 24.3.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2715. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-1-(2-methoxyphenyl)-2-oxoethyl2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A15). The desired compound (324 mg, 63% yield) was prepared by General Procedure A using 4-carboxy-3-fluorophenylboronic acid ester (266 mg, 1.00 mmol), 2-methoxybenzaldehyde (0.121 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 75 °C.
1H-NMR (CDCl
3) δ: 7.93 (t,
J = 7.2 Hz, 1H), 7.60 (d,
J = 7.6 Hz, 1H), 7.56 (d,
J = 11.1 Hz, 1H), 7.51 (dd,
J = 7.6, 1.5 Hz, 1H), 7.30–7.26 (m, 2H), 6.95 (t,
J = 7.4 Hz, 1H), 6.88 (d,
J = 8.3 Hz, 1H), 6.60 (br, 1H), 6.56 (s, 1H), 3.86–3.76 (m, 4H), 1.95 (dd,
J = 12.0, 3.0 Hz, 1H), 1.84–1.78 (m, 1H), 1.72–1.65 (m, 1H), 1.65–1.58 (m, 1H), 1.58–1.52 (m, 1H), 1.39–1.28 (m, 14H), 1.27–1.11 (m, 3H).
13C-NMR (CDCl
3) δ: 167.2, 162.8, 162.0, 160.3, 156.8, 131.6, 130.0, 129.1, 124.1, 122.5, 122.4, 120.8, 120.1, 111.0, 84.3, 71.7, 55.5, 47.6, 32.4, 25.3, 24.6, 24.3.
11B-NMR (CDCl
3) δ: 30.1. HRMS (ESI, positive ion):
m/z [M+H]
+, found 512.2608. C
28H
35BFNO
6 requires 512.2625.
2-(Cyclohexylamino)-2-oxo-1-(pyridin-3-yl)ethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A16). The desired compound (260 mg, 56% yield) was prepared by General Procedure A using 4-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), pyridine-3-aldehyde (0.09 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 230 °C.
1H-NMR (CDCl
3) δ: 8.77 (s, 1H), 8.60 (d,
J = 4.5 Hz, 1H), 8.04 (d,
J = 8.3 Hz, 2H), 7.93-7.86 (m, 3H), 7.32 (dd,
J = 7.9, 4.8 Hz, 1H), 6.32 (s, 1H), 6.25 (br, 1H), 3.84–3.78 (m, 1H), 1.95–1.85 (m, 2H), 1.71–1.62 (m, 2H), 1.61–1.56 (m, 1H), 1.39–1.30 (m, 13H), 1.25–1.10 (m, 4H).
13C-NMR (CDCl
3) δ: 166.5, 164.8, 150.1, 148.5, 135.3, 135.0, 131.7, 130.9, 128.7, 123.5, 84.3, 73.8, 48.3, 32.7, 25.3, 24.8, 24.6.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 465.2553. C
26H
33BN
2O
5 requires 465.2566.
2-(Cyclohexylamino)-2-oxo-1-(pyridin-3-yl)ethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A17). The desired compound (240 mg, 52% yield) was prepared by General Procedure A using 3-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), pyridine-3-aldehyde (0.094 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 127 °C.
1H-NMR (CDCl
3) δ: 8.76 (s, 1H), 8.56 (s, 1H), 8.46 (s, 1H), 8.10 (d,
J = 7.8 Hz, 1H), 8.00 (d,
J = 7.4 Hz, 1H), 7.88 (d,
J = 8.1 Hz, 1H), 7.43 (t,
J = 7.5 Hz, 1H), 7.32–7.27 (m, 1H), 6.60 (br, 1H), 6.28 (s, 1H), 3.82–3.74 (m, 1H), 1.93–1.81 (m, 2H), 1.67–1.59 (m, 2H), 1.57–1.50 (m, 1H), 1.35–1.27 (m, 13H), 1.22–1.09 (m, 4H).
13C-NMR (CDCl
3) δ: 166.5, 164.7, 149.8, 148.5, 140.0, 135.9, 135.3, 132.3, 128.1, 123.5, 84.1, 73.7, 48.2, 32.6, 25.3, 24.7, 24.5.
11B-NMR (CDCl
3) δ: 30.9. HRMS (ESI, positive ion):
m/z [M+H]
+, found 465.2548. C
26H
33BN
2O
5 requires 465.2566.
2-(Cyclohexylamino)-2-oxo-1-(pyridin-3-yl)ethyl2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A18). The desired compound (270 mg, 52% yield) was prepared by General Procedure A using 4-carboxy-3-fluorophenylboronic acid ester (266 mg, 1.00 mmol), pyridine-3-aldehyde (0.094 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 203 °C.
1H-NMR (CDCl
3) δ: 8.75 (s, 1H), 8.57 (dd,
J = 4.7, 1.1 Hz, 1H), 7.91 (t,
J = 7.2 Hz, 1H), 7.83 (td,
J = 7.9, 1.7 Hz, 1H), 7.66–7.58 (m, 2H), 6.83 (br, 1H), 6.32 (s, 1H), 3.86–3.78 (m, 1H), 1.95–1.89 (m, 2H), 1.70 (td,
J = 8.9, 4.1 Hz, 2H), 1.62–1.55 (m, 1H), 1.41–1.31 (m, 14H), 1.26–1.19 (m, 3H).
13C-NMR (CDCl
3) δ: 166.2, 162.6, 161.3, 150.0, 148.6, 135.2, 131.9, 131.8, 130.5, 123.4, 122.7, 119.2, 84.6, 74.1, 48.1, 32.6, 25.4, 24.8, 24.4.
11B-NMR (CDCl
3) δ: 30.0. HRMS (ESI, positive ion):
m/z [M+H]
+, found 483.2455. C
26H
32BFN
2O
5 requires 483.3012.
2-(Cyclohexylamino)-1-(furan-2-yl)-2-oxoethyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A19). The desired compound (260 mg, 57% yield) was prepared by General Procedure A using 4-carboxyphenyl boronic acid ester (248 mg, 1.00 mmol), furan-2-carbaldehyde (0.08 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 182.5 °C.
1H-NMR (CDCl
3) δ: 8.02 (d,
J = 8.3 Hz, 2H), 7.87 (d,
J = 8.3 Hz, 2H), 7.41 (s, 1H), 6.55 (d,
J = 3.2 Hz, 1H), 6.39 (s, 1H), 6.36 (dd,
J = 3.1, 1.8 Hz, 1H), 6.20 (br, 1H), 3.87–3.80 (m, 1H), 1.99–1.93 (m, 1H), 1.90–1.83 (m, 1H), 1.71–1.61 (m, 2H), 1.57 (td,
J = 12.9, 3.7 Hz, 1H), 1.38–1.29 (m, 14H), 1.25–1.09 (m, 3H).
13C-NMR (CDCl
3) δ: 164.9, 164.8, 148.1, 143.5, 134.7, 131.1, 128.7, 111.2, 110.6, 84.2, 69.2, 48.2, 32.6, 25.3, 24.7, 24.5.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 454.2399. C
25H
32BNO
6 requires 454.2406.
2-(Cyclohexylamino)-1-(furan-2-yl)-2-oxoethyl3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (
A20). The desired compound (280 mg, 63% yield) was prepared by General Procedure A using 3-carboxyphenylboronic acid ester (248 mg, 1.00 mmol), furan-2-carbaldehyde (0.082 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 161.5 °C.
1H-NMR (CDCl
3) δ: 8.46 (s, 1H), 8.12 (d,
J = 7.8 Hz, 1H), 8.00 (d,
J = 7.3 Hz, 1H), 7.44 (t,
J = 7.4 Hz, 1H), 7.40 (s, 1H), 6.55 (d,
J = 3.3 Hz, 1H), 6.38 (s, 1H), 6.35 (dd,
J = 3.0, 1.9 Hz, 1H), 6.30 (br, 1H), 3.89–3.81 (m, 1H), 1.97 (d,
J = 9.2 Hz, 1H), 1.91–1.85 (m, 1H), 1.73–1.62 (m, 2H), 1.54–1.60 (m, 1H), 1.29–1.40 (m, 14H), 1.12–1.28 (m, 3H).
13C-NMR (CDCl
3) δ: 165.0, 164.7, 148.2, 143.4, 139.7, 135.9, 132.4, 128.4, 127.9, 111.2, 110.5, 84.0, 69.2, 48.2, 32.5, 25.3, 24.7, 24.4.
11B-NMR (CDCl
3) δ: 30.7. HRMS (ESI, positive ion):
m/z [M+H]
+, found 454.2394. C
25H
32BNO
6 requires 454.2406.
2-(Cyclohexylamino)-2-oxo-1-(4-(trifluoromethyl)phenyl)ethyl benzoate (
A21). The desired compound (360 mg, 89% yield) was prepared by General Procedure A using benzoic acid (122.12 mg, 1.00 mmol), 4-(trifluoromethyl)benzaldehyde (0.13 mL, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 201 °C.
1H-NMR (CDCl
3) δ: 8.10 (d,
J = 8.4 Hz, 2H), 7.67–7.63 (m, 5H), 7.52 (t,
J = 7.5 Hz, 2H), 6.34 (s, 1H), 6.14 (br, 1H), 3.84–3.79 (m, 1H), 1.94–1.90 (m, 2H), 1.72–1.63 (m, 2H), 1.90–1.60 (m, 4H), 1.39–1.33 (m, 2H), 1.23–1.16 (m, 3H).
13C-NMR (CDCl
3) δ: 166.6, 164.6, 139.6, 133.9, 131.1, 130.9, 129.7, 128.9, 128.7, 127.58, 125.7, 124.7, 122.9, 75.1, 48.3, 32.9, 32.8, 25.3, 24.6.
3.3. General Procedure B for the Synthesis of Boron-Containing α-Acyloxyl Amide B1–10
2-(Cyclohexylamino)-2-oxo-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl benzoate (
B1). A 10 mL glass tube containing the benzoic acid (122 mg, 1.00 mmol),
p-formylphenylboronic acid ester (232 mg, 1.00 mmol), and D.I. H
2O (1 mL) was first microwave irradiated for 6 min (45 °C, 150 W) under medium speed magnetic stirring. The cyclohexyl isocyanide (
3, 0.124 mL, 1.00 mmol) was then added to the reaction mixture. The additional microwave irradiation was applied for 150 min (45 °C, 150 W) under medium speed magnetic stirring. After being diluted in dichloromethane, the resulted reaction mixture was washed twice with a saturated aqueous solution of NaHCO
3 and with brine. The resulted organic layer was collected and dried over MgSO
4 and concentrated
in vacuo. The crude product was then dissolved in ethyl acetate (3.0 mL) prior the slow addition of
n-hexane. The resulting precipitate was formed and collected by filtration affording the desired product in 75% yield, mp = 166 °C.
1H-NMR (CDCl
3) δ: 8.08 (d,
J = 7.7 Hz, 2H), 7.83 (d,
J = 7.9 Hz, 2H), 7.61–7.56 (m, 1H), 7.54 (d,
J = 7.9 Hz, 2H), 7.45 (t,
J = 7.7 Hz, 2H), 6.29 (s, 1H), 6.11 (br, 1H), 3.83–3.75 (m, 1H), 1.93–1.82 (m, 2H), 1.69–1.60 (m, 2H), 1.59–1.53 (m, 1H), 1.36–1.27 (m, 15H), 1.19–1.04 (m, 3H).
13C-NMR (CDCl
3) δ: 167.0, 164.9, 138.5, 135.1, 133.5, 129.7, 129.2, 128.5, 126.5, 83.8, 75.9, 48.2, 32.7, 25.3, 24.7, 24.6.
11B-NMR (CDCl
3) δ: 31.5. HRMS (ESI, positive ion):
m/z [M+H]
+, found 464.2616. C
27H
34BNO
5 requires 464.2614.
2-(Cyclohexylamino)-2-oxo-1-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl benzoate (
B2). The desired compound (320 mg, 69% yield) was prepared by General Procedure B using benzoic acid (122.12 mg, 1.00 mmol),
m-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 165 °C.
1H-NMR (CDCl
3) δ: 8.08 (d,
J = 7.4 Hz, 2H), 7.96 (s, 1H), 7.80 (d,
J = 7.0 Hz, 1H), 7.65 (d,
J = 7.8 Hz, 1H), 7.57 (t,
J = 7.4 Hz, 1H), 7.45 (t,
J = 7.6 Hz, 2H), 7.39 (t,
J = 7.6 Hz, 1H), 6.29 (s, 1H), 6.11 (br, 1H), 3.85–3.78 (m, 1H), 1.93 (d,
J = 9.6 Hz, 1H), 1.86 (d,
J = 9.6 Hz, 1H), 1.70–1.60 (m, 2H), 1.60–1.54 (m, 1H), 1.40–1.25 (m, 14H), 1.22–1.06 (m, 3H).
13C-NMR (CDCl
3) δ: 167.2, 164.9, 135.3, 135.0, 134.0, 133.4, 130.2, 129.7, 129.3, 128.4, 128.0, 83.8, 76.0, 48.1, 32.7, 25.3, 24.7, 24.6.
11B-NMR (CDCl
3) δ: 30.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 464.2607. C
27H
34BNO
5 requires 464.2614.
2-(Cyclohexylamino)-2-oxo-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-4-nitro-benzoate (
B3). The desired compound (290 mg, 57% yield) was prepared by General Procedure B using 4-nitrobenzoic acid (167.19 mg, 1.00 mmol),
p-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 108 °C.
1H-NMR (CDCl
3) δ: 8.30–8.20 (m, 4H), 7.84 (d,
J = 8.1 Hz, 2H), 7.53 (d,
J = 7.6 Hz, 2H), 6.23 (s, 1H), 5.93 (br, 1H), 3.80–3.73 (m, 1H), 1.92–1.86 (m, 1H), 1.80 (d,
J = 11.4 Hz, 1H), 1.69–1.53 (m, 3H), 1.37–1.26 (m, 14H), 1.17–1.00 (m, 3H).
13C-NMR (CDCl
3) δ: 166.4, 163.5, 150.7, 137.6, 135.3, 134.7, 130.9, 126.8, 123.6, 83.9, 76.7, 48.5, 32.6, 25.3, 24.7, 24.6.
11B-NMR (CDCl
3) δ: 31.0. HRMS (ESI, positive ion):
m/z [M+H]
+, found 509.2448. C
27H
33BN
2O
7 requires 509.2465.
2-(Cyclohexylamino)-2-oxo-1-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-4-nitro-benzoate (
B4). The desired compound (299 mg, 59% yield) was prepared by General Procedure B using 4-nitrobenzoic acid (167 mg, 1.00 mmol),
m-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 94 °C.
1H-NMR (CDCl
3) δ: 8.21 (s, 4H), 7.94 (s, 1H), 7.79 (d,
J = 7.1 Hz, 1H), 7.63 (d,
J = 8.0 Hz, 1H), 7.38 (t,
J = 7.6 Hz, 1H), 6.22 (s, 1H), 6.16 (br, 1H), 3.78–3.70 (m, 1H), 1.87 (d,
J = 10.4 Hz, 1H), 1.80–1.75 (m, 1H), 1.66–1.55 (m, 2H), 1.55–1.50 (m, 1H), 1.34–1.23 (m, 14H), 1.17–0.99 (m, 3H).
13C-NMR (CDCl
3) δ: 166.6, 163.4, 150.5, 135.6, 134.7, 134.1, 134.0, 130.8, 130.3, 128.2, 123.4, 83.8, 76.7, 48.4, 32.5, 25.2, 24.6, 24.5.
11B-NMR (CDCl
3) δ: 30.8. HRMS (ESI, positive ion):
m/z [M+H]
+, found 509.2442. C
27H
33BN
2O
7 requires 509.2465.
2-(Cyclohexylamino)-2-oxo-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-4-methyl-benzoate (
B5). The desired compound (344 mg, 72% yield) was prepared
by General Procedure B using 4-methylbenzoic acid (163.38 mg, 1.00 mmol),
p-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 90 °C.
1H-NMR (CDCl
3) δ: 7.97 (d, J = 7.8 Hz, 2H), 7.83 (d, J = 7.9 Hz, 2H), 7.53 (d, J = 7.9 Hz, 2H), 7.26 (d, J = 7.8 Hz, 2H), 6.28 (s, 1H), 6.07 (br, 1H), 3.83–3.75 (m, 1H), 2.41 (s, 3H), 1.92–1.84 (m, 3H), 1.69–1.61 (m, 2H), 1.60–1.55 (m, 1H), 1.37–1.30 (m, 14H), 1.18–1.07 (m, 3H).
13C-NMR (CDCl
3) δ: 167.2, 164.9, 144.4, 138.6, 135.1, 129.7, 129.3, 126.5, 83.8, 75.7, 48.1, 32.7, 25.3, 24.8, 24.6, 21.6.
11B-NMR (CDCl
3) δ: 30.9. HRMS (ESI, positive ion): m/z [M+H]
+, found 478.2752. C
28H
36BNO
5 requires 478.2771.
2-(Cyclohexylamino)-2-oxo-1-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-4-methyl-benzoate (
B6). The desired compound (302 mg, 63% yield) was prepared by General Procedure B using 4-methylbenzoic acid (163.38 mg, 1.00 mmol),
m-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 81 °C.
1H-NMR (CDCl
3) δ: 8.00–7.93 (m, 3H), 7.79 (d,
J = 7.4 Hz, 1H), 7.64 (d,
J = 7.8 Hz, 1H), 7.38 (t,
J = 7.6 Hz, 1H), 7.24 (d,
J = 7.8 Hz, 2H), 6.28 (s, 1H), 6.14 (br, 1H), 3.85–3.77 (m, 1H), 2.39 (s, 3H), 1.92 (d,
J = 9.6 Hz, 1H), 1.86 (d,
J = 11.4 Hz, 1H), 1.70–1.61 (m, 2H), 1.59–1.53 (m, 1H), 1.37–1.28 (m, 14H), 1.23–1.07 (m, 3H).
13C-NMR (CDCl
3) δ: 167.4, 164.9, 144.2, 135.2, 135.1, 133.9, 130.2, 129.7, 129.1, 128.0, 126.5, 83.8, 75.8, 48.1, 32.6, 25.3, 24.7, 24.5, 21.6.
11B-NMR (CDCl
3) δ: 30.7. HRMS (ESI, positive ion):
m/z [M+H]
+, found 478.2752. C
28H
36BNO
5 requires 478.2771.
2-(Cyclohexylamino)-2-oxo-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-4-methoxybenzoate (
B7). The desired compound (393 mg, 80% yield) was prepared by General Procedure B using 4-methoxybenzoic acid (182.58 mg, 1.00 mmol),
p-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 94 °C.
1H-NMR (CDCl
3) δ: 8.02 (d,
J = 8.7 Hz, 2H), 7.81 (d,
J = 8.1 Hz, 2H), 7.53 (d,
J = 8.1 Hz, 2H), 6.90 (d,
J = 8.7 Hz, 2H), 6.28–6.23 (m, 2H), 3.82–3.72 (m, 4H), 1.89–1.78 (m, 2H), 1.66–1.57 (m, 2H), 1.56–1.50 (m, 1H), 1.33–1.24 (m, 14H), 1.14–1.02 (m, 3H).
13C-NMR (CDCl
3) δ: 167.2, 164.5, 163.7, 138.7, 134.9, 131.7, 126.3, 121.4, 113.7, 83.6, 75.5, 55.2, 48.0, 32.5, 25.2, 24.6, 24.5.
11B-NMR (CDCl
3) δ: 30.8. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2717. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-2-oxo-1-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-4-methoxybenzoate (
B8). The desired compound (404 mg, 82% yield) was prepared by General Procedure B using 4-methoxybenzoic acid (182.58 mg, 1.00 mmol),
m-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 80 °C.
1H-NMR (CDCl
3) δ: 8.01 (d,
J = 8.56 Hz, 2H), 7.95 (s, 1H), 7.77 (d,
J = 7.6 Hz, 1H), 7.62 (d,
J = 7.6 Hz, 1H), 7.35 (t,
J = 7.6 Hz, 1H), 6.87 (d,
J = 9.0 Hz, 2H), 6.29 (br, 1H), 6.25 (s, 1H), 3.81–3.72 (m, 4H), 1.87 (d,
J = 10.4 Hz, 1H), 1.80 (d,
J = 10.4 Hz, 1H), 1.66–1.56 (m, 2H), 1.55–1.48 (m, 1H), 1.34–1.22 (m, 14H), 1.18–1.02 (m, 3H).
13C-NMR (CDCl
3) δ: 167.4, 164.5, 163.5, 135.1, 135.0, 133.8, 131.6, 130.0, 127.8, 121.4, 113.6, 83.6, 75.5, 55.2, 48.0, 32.4, 25.1, 24.6, 24.4.
11B-NMR (CDCl
3) δ: 31.6. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2707. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-2-oxo-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-3-methoxybenzoate (
B9). The desired compound (419 mg, 85% yield) was prepared by General Procedure B using 3-methoxybenzoic acid (182.58 mg, 1.00 mmol),
p-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 74 °C.
1H-NMR (CDCl
3) δ: 7.81 (d,
J = 7.4 Hz, 2H), 7.65 (d,
J = 7.8 Hz, 1H), 7.58–7.50 (m, 3H), 7.32 (dt,
J = 7.8, 3.5 Hz, 1H), 7.10–7.05 (m, 1H), 6.33 (br, 1H), 6.24 (s, 1H), 3.803.71 (m, 4H), 1.86 (d,
J = 11.8 Hz, 1H), 1.83–1.77 (m, 1H), 1.61 (t,
J = 13.8 Hz, 2H), 1.52 (d,
J = 9.6 Hz, 1H), 1.33–1.23 (m, 14H), 1.16–1.01 (m, 3H).
13C-NMR (CDCl
3) δ: 167.0, 164.7, 159.4, 138.4, 134.9, 130.4, 129.4, 126.3, 121.8, 119.5, 114.3, 83.6, 75.9, 55.2, 48.1, 32.5, 25.2, 24.6, 24.5.
11B-NMR (CDCl
3) δ: 31.5. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2702. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-2-oxo-1-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl-3-methoxybenzoate (
B10). The desired compound (437 mg, 89% yield) was prepared by General Procedure B using 3-methoxybenzoic acid (182.58 mg, 1.00 mmol),
m-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 67 °C.
1H-NMR (CDCl
3) δ: 7.96 (s, 1H), 7.78 (d,
J = 7.4 Hz, 1H), 7.63 (d,
J = 7.4 Hz, 1H), 7.66 (d,
J = 7.8 Hz, 1H), 7.57 (s, 1H), 7.36 (t,
J = 7.4 Hz, 1H), 7.32 (t,
J = 7.8 Hz, 1H), 7.08 (dd,
J = 8.3, 2.6 Hz, 1H), 6.29–6.22 (m, 2H), 3.82–3.76 (m, 4H), 1.89 (d,
J = 9.6 Hz, 1H), 1.82 (d,
J = 11.8 Hz, 1H), 1.67–1.58 (m, 2H), 1.56–1.51 (m, 1H), 1.34–1.26 (m, 14H), 1.19–1.13 (m, 1H), 1.13–1.05 (m, 2H).
13C-NMR (CDCl
3) δ: 167.2, 164.8, 159.4, 135.2, 134.9, 133.8, 130.4, 130.0, 129.4, 127.9, 121.9, 119.6, 114.3, 83.7, 75.9, 55.2, 48.1, 32.5, 25.2, 24.6, 24.5.
11B-NMR (CDCl
3) δ: 31.5. HRMS (ESI, positive ion):
m/z [M+H]
+, found 494.2713. C
28H
36BNO
6 requires 494.2720.
2-(Cyclohexylamino)-2-oxo-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl pyrazine-2-carboxylate (
B11). The desired compound (237 mg, 51% yield) was prepared by General Procedure B using pyrazine-2-carboxylic acid (124 mg, 1.00 mmol),
p-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 184 °C.
1H-NMR (CDCl
3) δ 9.30 (s, 1H), 8.78 (s, 1H), 8.72 (s, 1H), 7.82(d,
J= 7.8 Hz, 2H), 7.53 (d,
J = 7.8 Hz, 2H), 6.46 (br.), 6.32 (s, 1H), 3.80–3.79 (m, 1H), 1.91–1.84 (m, 2H), 1.69–1.64 (m, 2H), 1.58–1.56 (m, 1H), 1.34–1.32 (m, 14H), 1.25–1.20 (m, 3H).
13C-NMR (CDCl
3) δ 166.5, 162.4, 148.0, 146.4, 144.4, 142.8, 137.8, 135.2, 126.7, 83.87, 83.8, 48.2, 32.7, 32.6, 25.3, 24.7, 24.5.
11B-NMR (CDCl
3) δ 30.9. HRMS (ESI, positive ion):
m/z [M+H]
+, found 466.2503. C
25H
32BN
3O
5 requires 466.2519.
2-(Cyclohexylamino)-2-oxo-1-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl pyrazine-2-carboxylate (
B12). The desired compound (195 mg, 42% yield) was prepared by General Procedure B using pyrazine-2-carboxylic acid (124 mg, 1.00 mmol),
m-formylphenylboronic acid ester (232 mg, 1.00 mmol), and cyclohexyl isocyanide (0.124 mL, 1.00 mmol); mp = 140 °C.
1H-NMR (CDCl
3) δ 9.32 (s, 1H), 8.78 (s, 1H), 8.73 (s, 1H), 7.95 (s, 1H), 7.80 (d,
J = 7.2 Hz, 1H), 7.65 (d,
J = 7.8 Hz, 1H), 7.40 (t,
J = 7.2, 15 Hz, 1H), 6.42 (br.), 6.34 (s, 1H), 3.84–3.77 (m, 1H), 1.88–1.87 (m, 2H), 1.73–1.66 (m, 4H), 1.61–1.58 (m, 1H), 1.38–1.33 (m, 14H), 1.26–1.16 (m, 3H).
13C-NMR (CDCl
3) δ 166.7, 162.5, 148.0, 146.5, 144.4, 143.0, 135.7, 134.4, 134.2, 130.5, 128.3, 83.9, 48.3, 32.8, 32.7, 25.4, 24.9, 24.8, 24.61.
11B-NMR (CDCl
3) δ 30.4. HRMS (ESI, positive ion):
m/z [M+H]
+, found 466.2512. C
25H
32BN
3O
5 requires 466.2519.