PROPERTIES OF INDAZOLE DERIVATIVES
Found: C, 67.92; H, 3.56; N, 13.12. HRMS calculated for C18H11N3O3
(Mþ) 317.08004, observed 317.07913.
DMSO-d6) d (ppm): 161.1; 159.8 (dd, J ¼ 6.6, 253.9 Hz, 2C); 148.8;
140.6; 138.4; 133.3; 133.2 (t, J ¼ 10.0 Hz); 121.9; 120.5; 112.5; 111.9
(d, J ¼ 24.5 Hz, 2C), 111.8. Elemental analysis for C14H7F2N3O3
(303.22 g/mol) calcd.: C, 55.45; H, 2.33; N, 13.86. Found: C, 54.98; H,
2.60; N, 13.80. HRMS calculated for C14H7F2N3O3 (Mþ) 303.04555,
observed 303.04556.
1-(2,6-Difluorobenzoyl)-5-nitro-1H-indazole (1b)
Yield: 52% mp: 218–219 8C; IR (KBr) cmꢀ1: 1704 (C O), 1524
—
—
(NO2), 1382 (NO2), 1013 (C-F); 1H-NMR (400 MHz, CDCl3) d (ppm):
8.73 (d, J ¼ 2.1 Hz, 1H, H-4), 8.71 (d, J ¼ 9.1 Hz, 1H, H-7), 8.54 (dd,
J ¼ 9.1, 2.1 Hz, 1H, H-6), 8.33 (s, 1H, H-3), 7.62–7.50 (m, 1H, H-40),
7.07 (t, J ¼ 8.1 Hz, 2H, H-50, H-30). 13C-NMR (400 MHz, CDCl3) d
(ppm): 161.3, 159.8 (d, J ¼ 260.4 Hz, 2C), 145.4, 141.7, 141.5, 133.3,
126.6, 124.8, 117.9, 116.1, 112.5, 111.9 (d, J ¼ 24.6 Hz, 2C).
Elemental analysis for C14H7F2N3O3 (303.22 g/mol) calcd.: C, 55.45;
H, 2.33; N, 13.86. Found: C, 55.78; H, 2.54; N, 13.67. HRMS
calculated for C14H7F2N3O3 (Mþ) 303.04555, observed 303.04549.
6-Nitro-1-(4-nitrobenzoyl)-1H-indazole (2c)
Yield: 58% mp: 238–239 8C; IR (KBr) cmꢀ1: 1698 (C O); 1526
—
—
(NO2), 1346 (NO2). 1H-NMR (400 MHz, DMSO-d6) d (ppm): 9.15 (s,
1H, H-7), 8.77 (s, 1H, H-3), 8.41 (d, J ¼ 8.5 Hz, 2H, H-30, H-50), 8.33
(dd, J ¼ 8.7, 1.3 Hz, 1H, H-5), 8.24 (d, J ¼ 8.5 Hz, 1H, H-4), 8.22 (d,
J ¼ 8.6 Hz, 2H, H-20, H-60). 13C-NMR (400 MHz, DMSO-d6) d (ppm):
166.8; 150.0; 148.6; 141.8; 138.9; 138.5; 132.5; 130.2; 123.9; 123.5;
120.5; 111.2. Elemental analysis for C14H8N4O5 (312.24 g/mol)
calcd.: C, 53.85; H, 2.58; N, 17.94. Found: C, 53.74; H, 2.83; N, 17.73.
HRMS calculated for C14H8N4O5 (Mþ) 312.04947, observed
312.04934.
5-Nitro-1-(4-nitrobenzoyl)-1H-indazole (1c)
Yield: 65% mp: 232–234 8C; IR (KBr) cmꢀ1: 1703 (C O), 1521
—
—
(NO2), 1386 (NO2). 1H-NMR (400 MHz, DMSO-d6) d (ppm): 8.94 (d,
J ¼ 1.7 Hz, 1H, H-4), 8.75 (s, 1H, H-3), 8.60 (d, J ¼ 9.1 Hz, 1H, H-7),
8.54 (dd, J ¼ 9.1, 1.7 Hz, 1H, H-6), 8.40 (d, J ¼ 8.6 Hz, 2H, H-30, H-50),
8.22 (d, J ¼ 8.6 Hz, 2H, H-20, H-60). 13C-NMR (400 MHz, DMSO-d6) d
(ppm): 166.9, 149.9, 145.2, 142.8, 142.2, 138.7, 132.4 (2C), 126.7,
125.1, 123.5 (2C), 119.4, 116.4. Elemental analysis for C14H8N4O5
(312.24 g/mol) calcd.: C, 53.85; H, 2.58; N, 17.94. Found: C, 53.70; H,
2.89; N, 17.75. HRMS calculated for C14H8N4O5 (Mþ) 312.04947,
observed 312.04950.
1-(3,4,5-Trimethoxybenzoyl)-6-nitro-1H-indazole (2d)
Yield: 35% mp: 190–191 8C; IR (KBr) cmꢀ1: 1677 (C O), 1530
—
—
1
(NO2), 1348 (NO2), 1132 (C—O). H-NMR (400 MHz, DMSO-d6) d
(ppm): 9.41 (s, 1H, H-7), 8.35 (s, 1H, H-3), 8.27 (dd, J ¼ 8.7, 1.9 Hz,
1H, H-5), 7.94 (d, J ¼ 8.7 Hz, 1H, H-4), 7.45 (s, 2H, H-20), 3.96 (s, 3H,
p-OCH3), 3.93 (s, 6H, 2 ꢁ m-OCH3). 13C-NMR (400 MHz, DMSO-d6) d
(ppm): 166.9; 152.7 (2C); 148.6; 142.6; 139.7; 139.4; 129.2; 126.5;
121.7; 119.7; 112.3; 109.3 (2C); 61.1; 56.4 (2C). Elemental analysis
for C17H15N3O6 (357.32 g/mol) calcd.: C, 57.14; H, 4.23; N, 11.76.
Found: C, 56.88; H, 4.38; N, 11.90. HRMS calculated for C17H15N3O6
(Mþ) 357.09609, observed 357.09619.
1-(3,4,5-Trimethoxybenzoyl)-5-nitro-1H-indazole (1d)
Yield: 40% mp: 209–210 8C; IR (KBr) cmꢀ1: 1697 (C O), 1525
—
—
(NO2), 1343 (NO2) 1131 (C—O). 1H-NMR (400 MHz, CDCl3) d (ppm):
8.79 (d, J ¼ 1.8 Hz, 1H, H-4), 8.70 (d, J ¼ 9.1 Hz, 1H, H-7), 8.54 (dd,
J ¼ 9.1, 1.8 Hz, 1H, H-6), 8.44 (s, 1H, H-3), 7.48 (s, 2H, H-20, H-60), 4.01
(s, 3H, p-OCH3), 3.98 (s, 6H, 2 ꢁ m-OCH3). 13C-NMR (400 MHz,
CDCl3) d (ppm): 167.2, 152.8, 145.0, 142.8, 142.7, 140.5, 126.5,
125.7, 124.3 (2C), 117.8, 116.5, 109.3 (2C), 61.1, 56.4 (2C).
Elemental analysis for C17H15N3O6 (357.32 g/mol) calcd.: C, 57.14;
H, 4.23; N, 11.76. Found: C, 57.23; H, 4.52; N, 11.71. HRMS
calculated for C17H15N3O6 (Mþ) 357.09609, observed 357.09586.
Electrochemical Studies
Products reduction potential was determined in aprotic medium.
The working solution contained 2 ꢁ 10ꢀ4 mol Lꢀ1 indazol
derivative and 1 ꢁ 10ꢀ2 mol Lꢀ1 tetrabuthyl ammonium hexa-
fluorophosphate (99% Aldrich), TBAPF6, in dimethyl sulfoxide,
DMSO (p.a. Aldrich) as supporting electrolyte. Prior to each
experiment the solution was purged with high purity argon and
an argon atmosphere was maintained over the solution during
the whole experiment. A polycrystalline non-annealed platinum
disc, Pt, (geometrical surface area 0.07 cm2) was used as working
electrode. A platinum gauze of large geometrical area, separated
from the cell main compartment by a fine glass sinter, was used
as counter electrode. All potentials quoted in this paper are
referred to an Ag/AgCl electrode in tetramethylammonium
chloride to match the potential of a saturated calomel electrode,
SCE, at room temperature.[35]
1-(1-Naphthoyl)-6-nitro-1H-indazole (2a)
Yield: 49% mp: 190–191 8C; IR (KBr) cmꢀ1: 1704 (C O), 1535
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—
(NO2), 1344 (NO2). 1H-NMR (400 MHz, DMSO-d6) d (ppm): 9.60 (d,
J ¼ 0.8 Hz, 1H, H-7), 8.34 (dd, J ¼ 8.5, 1.9 Hz, 1H, H-5), 8.25 (s, 1H,
H-3), 8.09 (d, J ¼ 8.5 Hz, 1H, H-4), 8.00–7.94 (m, 3H, H20, H-30, H-80),
7.83 (d, J ¼ 7.1 Hz, 1H, H-40), 7.64–7.59 (m, 1H, H-70), 7.58–7.52 (m,
2H, H-50, H-60). 13C-NMR (400 MHz, DMSO-d6) d (ppm): 169.0;
148.7; 139.8; 139.1; 133.5; 132.1; 130.7; 130.5; 129.7; 128.7; 128.5;
127.6; 126.7; 124.9; 124.4; 121.8; 120.1; 112.2. Elemental analysis
for C18H11N3O3 (317.30 g/mol) calcd.: C, 68.14; H, 3.49; N, 13.24.
Found: C, 67.96; H, 3.65; N, 12.99. HRMS calculated for C18H11N3O3
(Mþ) 317.08004, observed 317.07947.
Half wave and peak potentials were obtained from cyclic
voltammograms. All electrochemical experiments were per-
formed at room temperature on an AUTOLAB PGSTAT20
galvanostat/potentiostat interfaced to a PC running the GPES
4.7 software which allowed experimental control and data
acquisition.
1-(2,6-Difluorobenzoyl)-6-nitro-1H-indazole (2b)
Theoretical Studies
Yield: 55% mp: 199–202 8C; IR (KBr) cmꢀ1: 1710 (C O), 1541
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—
1
(NO2), 1347 (NO2), 1010 (C-F). H-NMR (400 MHz, CDCl3) d (ppm)
Neutral, radical, and anionic form for all the series compounds
were optimized by the AM1 semi-empiric method in order to
obtain the lowest energy conformation of each derivative.
The obtained structures were further optimized using DFT
9.48–9.44 (m, 1H, H-7), 8.33 (dd, J ¼ 8.7, 2.0 Hz, 1H, H-5), 8.29 (d,
J ¼ 0.7 Hz, 1H, H-3), 7.94 (dd, J ¼ 8.7, 0.4 Hz, 1H, H-4), 7.60–7.51 (m,
1H, H-40), 7.07 (t, J ¼ 8.0 Hz, 2H, H-30, H-50). 13C-NMR (400 MHz,
J. Phys. Org. Chem. 2011, 24 1179–1187
Copyright ß 2011 John Wiley & Sons, Ltd.
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