3. Materials and Methods
3.1. General Methods
The reactions under microwave irradiation were performed in a Biotage Initiator 2.5 using standard sealed microwave glass vials (2–5 mL) and a normal absorption level. Solvents were dried immediately prior to use by distillation from a drying agent: Tetrahydrofuran (THF) from Na/benzophenone and CH
3CN from CaH
2 [
39]. Commercial reagents were purchased from Sigma-Aldrich Chemical Co. and Alfa Aesar and were used without further purification. Analytical thin-layer chromatography was performed on Polygram SIL G/UV254 silica gel plates and chromatograms were visualized under UV light (254 and 360 nm). Purification on column chromatography was carried out on Merck silica gel 60 (0.063–0.2 mm) with the indicated solvent mixtures. Pre-coated TLC plates SIL G-100 UV254 (Macherey–Nagel) and SILICA GEL GF plates (1000 μm, Analtech) were used for preparative TLC purification.
1H and
13C-NMR spectra were acquired in CDCl
3 (0.03%
v/
v TMS), DMSO-
d6 or CD
3CN at room temperature using Bruker Avance instruments (500 or 600 MHz for
1H-NMR and 125 or 150 MHz for
13C-NMR). Chemical shifts were reported in parts per million (ppm) from tetramethylsilane and referenced to the residual solvent peak (CDCl
3: δ 7.26 for
1H-NMR, δ 77.00/77.16 for
13C-NMR; DMSO-
d6: δ 2.50 for
1H-NMR, δ 39.52 for
13C-NMR; CD
3CN: δ 1.93 for
1H-NMR, δ 1.32, 118.26 for
13C-NMR). For
1H-NMR, data were reported in the following manner: chemical shift (integration, multiplicity, coupling constant where applicable). The following abbreviations were used: s (singlet), br (broad), d (doublet), t (triplet), dd (double doublet), td (triplet of doublets), m (multiplet). Coupling constants (
J) were given in Hertz (Hz).
13C-NMR were obtained with complete proton decoupling. MS and HRMS data were recorded in a VG Micromass ZAB-2F spectrometer and an ESI instrument LCT Premier XE Micromass (ESI-TOF). IR spectra were recorded on a Bruker IFS 28/55 spectrophotometer. All compounds were named using the ACD40 Name-Pro program, which is based on IUPAC rules.
3.2. General Procedures for the Synthesis of 4-Substituted 1,2,3-Triazolyl-Naphthoquinonic Derivatives
Method A: A solution of 0.57 mmol of the corresponding azide and 121.9 mg (0.57 mmol) of the alkyne in 6 mL of CH2Cl2 (DCM) was added to a mixture of CuSO4.5H2O (5.7 mg, 0.023 mmol) and sodium ascorbate (13.7 mg, 0.069 mmol) in 6 mL of water. The reaction mixture was stirred vigorously at room temperature until the disappearance of the alkyne. Then it was extracted with DCM (3 × 15 mL) and purified through silica gel column chromatography with a growing gradient of polarity DCM:MeOH (100:0–0:100).
Method B: The alkyne and 1.0 equivalent of the corresponding azide were dissolved in 5 mL of dried CH3CN. Then, CuI (15–25 mol %) was added and the reaction mixture was stirred under argon atmosphere and at room temperature for 72 h. The solvent was removed under reduced pressure and purified through silica gel column chromatography with a growing gradient of polarity DCM:MeOH (100:0–0:100) when needed.
Method C: A solution of the corresponding boronic acid (0.24 mmol) and 78.5 mg (1.2 mmol) of sodium azide in 1.5 mL of H2O were added to a vigorously stirred mixture of Cu2O (3.4 mg, 0.024 mmol) in 0.06 mL of 20% of NH3 and 0.12 mL of H2O. The reaction mixture was stirred for 16 h at room temperature under an oxygen atmosphere. Then, 30 mg (0.14 mmol) of N-propargylated naphthoquinone (6), 8.11 mg (0.041 mmol) of sodium ascorbate, 1.5 mL of H2O, and 3 mL of acetone were added. After stirring for 48 h, the reaction mixture was extracted with ethyl acetate (EtOAc). Subsequently, the aqueous phase was acidified with 5% HCl until pH 2 and it was extracted with EtOAc (3 × 15 mL). The combined organic phases were dried over anhydrous MgSO4 and, after the elimination of the solvent, the corresponding residue was purified by silica gel column cromatography (CC) or TLC-preparative with DCM or 5% DCM/MeOH.
3.3. 2-[(1-Butyl-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3a)
A variation of method A was used for the synthesis of this compound. As 1-azidobutane is very volatile, we obtained better results when it was synthesized in situ by dissolving 101.4 µL (0.94 mmol) of 1-bromo-butane and 306.8 mg (4.7 mmol) of NaN3 in 8 mL of dimethyl formamide (DMF) under an argon atmosphere. Then, the reaction mixture was refluxed for 24 h. After it reached room temperature, 100.0 mg (0.47 mmol) of the alkyne, 4.7 mg (0.019 mmol) of CuSO4.5H2O, 11.2 mg (0.057 mmol) of sodium ascorbate, and 8 mL of water was added. After 48 h, the reaction mixture was extracted with EtOAc (3 × 15 mL) and the combined organic phases were dried over anhydrous MgSO4 and after elimination of the solvent, and purified through silica gel column chromatography with a growing gradient of polarity DCM:MeOH (100:0–0:100). Hence, 97.2 mg (54%) of compound 3a was obtained. 1H-NMR (CDCl3, 400 MHz) δ 8.04 (2H, m), 7.73 (1H, s), 7.71 (2H, m), 6.38 (1H, s), 5.22 (2H, s), 4.34 (2H, t, J = 7.2 Hz), 1.87 (2H, m), 1.33 (2H, m), 0.92 (3H, t, J = 7.3 Hz); 13C-NMR (CDCl3, 100 MHz) δ 184.8 (C), 180.0 (C), 159.0 (C), 141.5 (C), 134.4 (CH), 133.4 (CH), 132.0 (C), 131.1 (C), 126.7 (CH), 126.2 (CH), 123.4 (CH), 111.2 (CH), 63.0 (CH2), 50.3 (CH2), 32.2 (CH2), 19.8 (CH2), 13.5 (CH3); EIMS m/z (%) 311 ([M+], 55); 283 (67); 139 (31); 110 (100); 89 (62); 76 (30); 68 (57); 57 (78); 54 (42); HREIMS: 311.1267 (calcd for C17H17N3O3 311.1270); FT-IR (ATR) νmax: 2963, 2934, 2114, 1730, 1686, 1655, 1611, 1465, 1266, 1246, 1046, 1013, 858 cm−1.
3.4. 2-[(1-Undecyl-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3b)
Following the experimental procedure described in method A, from 113.5 mg (0.57 mmol) of 1-azidoundecane (2b) and 121.9 mg (0.57 mmol) of the alkyne, we synthesized compound 3b (208.4 mg, 89%). 1H-NMR (CDCl3, 400 MHz) δ 7.97 (2H, m), 7.73 (1H, s), 7.63 (2H, m), 6.35 (1H, s), 5.18 (2H, s), 4.29 (2H, t, J = 7.2 Hz), 1.84 (2H, t, J = 6.4 Hz), 1.25 (2H, brs), 1.17 (14H, brs), 0.80 (3H, m); 13C-NMR (CDCl3, 100 MHz) δ 184.6 (C), 179.8 (C), 158.8 (C), 141.2 (C), 134.2 (CH), 133.3 (CH), 131.8 (C), 130.9 (C), 126.5 (CH), 126.0 (CH), 123.5 (CH), 111.1 (CH), 62.9 (CH2), 50.5 (CH2), 31.8 (CH2), 30.1 (CH2), 29.5 (CH2), 29.4 (CH2), 29.3 (CH2), 28.9 (CH2), 27.9 (CH2), 26.4 (CH2), 22.6 (CH2), 14.0 (CH3); EIMS m/z (%) 409 ([M+], 41); 254 (12); 236 (34); 208 (100); 173 (30); 105 (19); 89 (13); 82 (10); 70 (18); 57 (33); 55 (25); HREIMS: 409.2356 (calcd for C24H31N3O3 409.2365); FT-IR (ATR) νmax: 2921, 2852, 1721, 1679, 1652, 1609, 1464, 1243, 1042, 1009, 832 cm−1.
3.5. 2-[(1-Bencyl-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3c)
Following the experimental procedure described in method A, from 76.5 mg (0.57 mmol) of 1-azidomethylbenzene 2c and 121.9 mg (0.57 mmol) of the alkyne, we synthesized compound 3c (169.4 mg, 85%). 1H-NMR (CDCl3, 400 MHz) δ 8.01 (2H, t, J = 7.3 Hz), 7.71 (2H, m), 7.43 (1H, s), 7.37 (3H, m), 7.29 (2H, m), 6.39 (1H, s), 5.54 (2H, s), 5.21 (2H, s); 13C-NMR (CDCl3, 100 MHz) δ 184.7 (C), 179.8 (C), 158.8 (C), 141.8 (C), 134.3 (CH), 134.3 (C), 133.3 (CH), 131.8 (C), 130.9 (C), 129.1 (2xCH), 128.9 (CH), 128.2 (2 CH), 126.6 (CH), 126.1 (CH), 123.8 (CH), 111.1 (CH), 62.9 (CH2), 54.4 (CH2); EISM m/z (%) 345 ([M+], 9); 317 (18); 198 (6); 172 (9); 144 (40); 104 (8); 91 (100), 89 (10); 68 (13); 65 (7); HREISM: 345.1120 (calcd for C20H15N3O3 345.1113); FT-IR (ATR) νmax: 3052, 1682, 1653, 1616, 1454, 1336, 1307, 1207, 1122, 1047, 890 cm−1.
3.6. 2-[4-[(1,4-Dioxo-2-naphthyl)oximethyl]triazol-1-yl]-naphthalene-1,4-dione (3d)
Following the experimental procedure described in method B, from 114.7 mg (0.57 mmol) of 2-azidonaphthoquinone, 121.9 mg (0.57 mmol) of the alkyne, and 16.4 mg (0.086 mmol) of CuI in 5 mL of dried CH3CN, we synthesized compound 3d (75.4 mg, 32%). 1H-NMR (CDCl3, 400 MHz) δ 8.88 (1H, s, H-5′), 8.21 (1H, dd, J = 8.1, 1.8 Hz), 8.16 (1H, d, J = 8.1, 1.8 Hz), 8.10 (2H, m), 7.86 (2H, m), 7.78 (1H, s), 7.74 (2H, m), 6.46 (1H, s), 5.36 (2H, s); 13C-NMR (CDCl3, 100 MHz) δ 184.8 (C), 183.7 (C), 179.9 (C), 179.3 (C), 158.9 (C), 142.7 (C), 139.2 (C), 135.3 (CH), 134.6 (CH), 134.5 (CH), 133.6 (CH), 132.1 (C), 131.6 (C), 131.2 (C), 131.1 (C), 127.5 (CH), 127.2 (CH), 126.9 (CH), 126.8 (CH), 126.4 (CH), 126.3 (CH), 111.4 (CH), 62.6 (CH2, OCH2); EIMS m/z (%) 411 ([M+], 29); 382 (11); 329 (52); 327 (63); 299 (26); 254 (46); 239 (30); 209 (100); 173 (58); 156 (50); 128 (32); 115 (14); 105 (45); 89 (40); 76 (45); 54 (7); HREIMS: 411.0851 (calcd for C23H13N3O5 411.0855); FT-IR (ATR) νmax: 3188, 3077, 2929, 1681, 1658, 1584, 1337, 1242, 1011, 940, 844 cm−1.
3.7. 3-Amino-2-[4-[(1,4-dioxo-2-naphtyl)oximethyl]triazol-1-yl]-naphthalene-1,4-dione (3e)
Following the experimental procedure described in method A, from 23.6 mg (0.11 mmol) of the azide and 24.0 mg (0.11 mmol) of the alkyne, we synthesized compound 3e (32.5 mg, 69%). 1H-NMR (CDCl3, 400 MHz) δ 8.92 (1H, s), 8.22 (12H, d, J = 7.8 Hz), 8.12 (3H, m), 7.83 (1H, t, J = 7.1 Hz), 7.75 (3H, m), 6.49 (1H, s, H-3), 5.37 (2H, s); 13C-NMR (CDCl3, 150 MHz) δ 185.0 (C), 180.6 (C), 180.0 (C), 175.9 (C), 159.1 (C), 141.3 (C), 140.3 (C), 135.8 (CH), 134.5 (CH), 133.6 (CH), 133.2 (CH), 132.2 (C), 132.1 (C), 131.2 (C), 129.7 (C), 127.3 (CH), 127.0 (CH), 126.9 (CH), 126.8 (CH), 126.4 (CH), 112.5 (C), 111.4 (CH), 62.8 (CH2); EIMS m/z (%) 426 ([M+], 1); 225 (100); 224 (30); 173 (21); 171 (11); 153 (4); 105 (22); 104 (9); 89 (13); 63 (2); HREIMS: 426.0949 (calcd for C23H14N4O5 426.0964); FT-IR (ATR) νmax: 3597, 3439, 3288, 3068, 1685, 1610, 1576, 1359, 1309, 1279, 1208, 1043, 1007, 855 cm−1.
3.8. 2-[[1-[2-Oxo-2-(4-phenylphenyl)ethyl]triazol-4-yl]-methoxy]naphthalene-1,4-dione (3f)
Following the experimental procedure described in method B, from 135.1 mg (0.57 mmol) of azide 2f, 121.9 mg (0.57 mmol) of the alkyne, and 16.4 mg (0.086 mmol) of CuI, we synthesized compound 3f (32.2 mg, 13%). 1H-NMR (CDCl3, 400 MHz) δ 8.12 (2H, dd, J = 7.3, 0.9 Hz), 8.08 (2H, d, J = 8.4 Hz), 7.95 (1H, s), 7.77 (2H, d, J = 8.4 Hz), 7.73 (2H, m), 7.64 (2H, d, J = 7.3 Hz), 7.50 (2H, m), 7.44 (1H, m), 6.47 (1H, s), 5.91 (2H, s), 5.33 (2H, s); 13C-NMR (CDCl3, 125 MHz) δ 185.0 (C), 184.9 (C), 179.8 (C), 159.1 (C), 147.7 (C), 145.9 (C), 139.5 (C), 134.4 (CH), 133.5 (CH), 132.6 (C), 132.1 (C), 131.3 (C), 129.2 (2 CH), 128.9 (2 CH), 128.9 (CH), 127.9 (2 CH), 127.5 (2 CH), 126.8 (CH), 126.3 (CH), 125.8 (CH), 111.5 (CH), 111.4 (CH), 62.9 (CH2), 56.2 (CH2); EIMS m/z (%) 449 ([M+], 2); 198 (6); 182 (14); 181 (100); 153 (14); 152 (19); 105 (6); 89 (2); 77 (3); 76 (3); HREIMS: 449.1391 (calcd for C27H19N3O4 449.1376); FT-IR (ATR) νmax: 2924, 2853, 1682, 1652, 1605, 1447, 1355, 1236, 1157, 1014, 936, 844 cm−1.
3.9. 2-[[1-(2-Oxochromen-4-yl)triazol-4-yl]methoxy]-naphthalene-1,4-dione (3g)
Following the experimental procedure described in method B, compound 3g was synthesized from 48.6 mg (0.26 mmol) of 4-azide-coumarin (2g), 48.7 mg (0.26 mmol) of the alkyne, and 16.4 mg (0.086 mmol) of CuI. After 72 h of reaction at room temperature, the obtained solid was filtered and washed with DCM, yielding 3g (61.7 mg, 59%) without further purification. 1H-NMR (DMSO-d6, 500 MHz) δ 9.02 (1H, s), 8.04 (1H, d, J = 7.6 Hz), 8.01 (1H, d, J = 7.5 Hz), 7.84 (4H, m), 7.61 (1H, d, J = 8.5 Hz), 7.47 (1H, t, J = 7.8 Hz), 7.02 (1H, s), 6.71 (1H, s), 5.43 (2H, s); 13C-NMR (DMSO-d6, 150 MHz) δ 185.2 (C), 180.0 (C), 160.1 (C), 159.3 (C), 154.0 (C), 146.4 (C), 142.2 (C), 135.2 (CH), 134.3 (CH), 134.2 (CH), 131.9 (C), 131.2 (C), 127.7 (CH), 126.7 (CH), 126.1 (CH), 125.8 (CH), 125.6 (CH), 117.7 (CH), 114.7 (C), 111.5 (CH), 111.3 (CH), 62.2 (CH2); EIMS m/z (%) 399 ([M+], 61); 198 (18); 145 (13); 127 (11); 118 (10); 115 (21); 104 (28); 101 (36); 90 (22); 89 (100); 77 (28); 76 (46); 63 (51); 51 (24); HREIMS: 399.0855 (calcd for C22H13N3O5 399.0855); FT-IR (ATR) νmax: 3250, 3057, 2992, 2127, 1715, 1605, 1490, 1385, 1249, 1182, 1016, 937, 852, 749 cm−1.
3.10. 2-(2-Dimethylaminoethyl)-6-{4-[(1,4-dioxo-2-naphthyl)-oximethyl]triazol-1-yl}benzo[de] isoquinoline-1,3-dione (3h)
Following the experimental procedure described in method B, compound 3h was synthesized from 36.3 mg (0.17 mmol) of azide 2h, 52.9 mg (0.17 mmol) of the alkyne, and 16.4 mg (0.086 mmol) of CuI in dried THF. The corresponding residue was purified by preparative with DCM/MeOH 10%, yielding 3h (54.7 mg, 61%), and 2-amino-3-methylnaphthalene-1,4-dione (9.3 mg, 19%). 1H-NMR (CDCl3, 500 MHz) δ 8.71 (2H, m), 8.25 (1H, s), 8.23 (1H, d, J = 8.6 Hz), 8.12 (2H, m), 7.85 (2H, m), 7.76 (1H, t, J = 7.4 Hz), 7.74 (1H, t, J = 7.4 Hz), 6.51 (1H, s), 5.43 (2H, s), 4.37 (2H, t, J = 6.8 Hz), 2.70 (2H, t, J = 6.8 Hz), 2.37 (6H, s); 13C-NMR (CDCl3, 125 MHz) δ 184.8 (C), 179.6 (C), 163.8 (C), 163.2 (C), 159.0 (C), 142.6 (C), 137.9 (C), 134.6 (CH), 133.6 (CH), 132.5 (CH), 132.1 (C), 131.2 (C), 130.8 (CH), 129.3 (CH), 129.3 (C), 128.9 (CH), 126.9 (CH), 126.6 (C), 126.4 (CH), 126.0 (CH), 124.4 (C), 123.8 (CH), 123.3 (C), 111.5 (CH), 62.9 (CH2), 57.1 (CH2), 45.8 (2 CH3), 38.5 (CH2); HRMS-ES (+): 544.1587 (calcd for C29H23N5O5Na [M + Na]+ 544.1597); FT-IR (ATR) νmax: 3350, 3200, 2924, 2823, 1657, 1604, 1345, 1239, 1039, 1012, 858 cm−1.
3.11. 5-[4-[(1,4-Dioxo-2-naphthyl)oximethyl]triazol-1-yl]-benzo[de]isoquinoline-1,3-dione (3i)
Following the experimental procedure described in method B, compound 3i was synthesized from 74.6 mg (0.24 mmol) of azide 2i, 51.2 mg (0.24 mmol) of the alkyne, and 16.4 mg (0.086 mmol) of CuI in 8 mL of dried THF. After 72 h of reaction at room temperature, the obtained solid was filtered and washed with n-hexane, yielding compound 3i (61.7 mg, 57%) without further purification. 1H-NMR (DMSO-d6, 500 MHz) δ 9.34 (1H, s), 9.05 (1H, s), 8.92 (1H, s), 8.55 (2H, m), 7.99 (3H, m), 7.85 (2H, m), 6.69 (1H, s), 5.42 (2H, s), 4.22 (2H, brs); 13C-NMR (DMSO-d6, 125 MHz) δ 184.5 (C), 179.4 (C), 163.1 (C), 162.7 (C), 158.8 (C), 135.6 (CH), 134.5 (CH), 133.7 (CH), 131.7 (C), 131.5 (CH), 131.4 (C), 128.7 (CH), 126.1 (CH), 125.6 (CH), 124.1 (CH), 124.1 (C), 123.9 (CH), 122.3 (CH), 122.2 (C), 111.0 (CH), 62.2 (OCH2) (four quaternary carbons of compound 3i were not observed in the 13C-NMR spectrum due to the fluxional effect); EIMS m/z (%) 450 ([M+], 3); 368 (30); 264 (20); 256 (23); 236 (42); 137 (31); 121 (21); 97 (83); 83 (85); 57 (100); HREIMS: 450.0978 (calcd for C25H14N4O5 450.0954); FT-IR (ATR) νmax: 3117, 2980, 2824, 2772, 1705, 1663, 1615, 1525, 1338, 1247, 1214, 1058, 899, 790 cm−1.
3.12. 2-[(1-Phenyltriazol-4-yl)methoxy]-naphthalene-1,4-dione (3j)
Following the general procedure described in method B, 52.7 mg (0.25 mmol) of the alkyne and 25 mol % of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3j (24.8 mg, 30%) without further purification. 1H-NMR (CDCl3, 400 MHz) δ 8.10 (1H, s), 8.08 (2H, m), 7.73 (4H, m), 7.54 (2H, m), 7.47 (1H, t, J = 7.4 Hz), 6.47 (1H, s), 5.35 (2H, s); 13C-NMR (CDCl3, 100 MHz) δ 184.8 (C), 180.0 (C), 159.0 (C), 142.4 (C), 136.9 (C), 134.5 (CH), 133.5 (CH), 132.8 (C), 131.2 (C), 130.0 (2 CH), 129.3 (CH), 126.8 (CH), 126.4 (CH), 121.9 (CH), 120.8 (2 CH), 111.4 (CH), 63.0 (CH2); EIMS m/z (%) 331 ([M+], 12); 303 (12); 274 (10); 173 (8); 146 (7); 130 (100); 89 (11); 77 (37); 57 (9); HREIMS: 331.0954 (calcd for C19H13N3O3 331.0957); FT-IR (ATR) νmax: 3137, 2923, 1679, 1643, 1600, 1504, 1258, 1232, 1038, 1007, 865 cm−1.
3.13. 2-[(1-(2-Methoxyphenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3k)
Following the general procedure described in method B, 53.9 mg (0.25 mmol) of the alkyne, 37.8 mg (0.25 mmol) of 2-methoxybenzylazide, and 25 mol % of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3k (80.3 mg, 88%) without further purification. 1H-NMR (CDCl3, 400 MHz) δ 8.31 (1H, s), 8.16 (1H, dd, J = 7.6, 1.4 Hz), 8.10 (1H, dd, J = 7.6, 1.4 Hz), 7.73 (1H, dd, J = 7.8, 1.5 Hz), 7.73 (2H, m), 7.44 (1H, td, J = 7.8, 1.5 Hz), 7.11 (2H, m), 6.50 (1H, s), 5.35 (2H, s), 3.90 (3H, s); 13C-NMR (CDCl3, 100 MHz) δ 184.9 (C), 180.1 (C), 159.1 (C), 147.1 (C), 134.4 (CH), 133.5 (CH), 132.1 (C), 131.2 (C), 130.5 (CH), 126.8 (CH), 126.3 (CH), 126.0 (CH), 125.6 (CH), 122.3 (C), 121.4 (CH), 112.4 (CH), 111.4 (CH), 63.1 (CH2), 56.1 (CH3); EIMS m/z (%) 361 ([M+], 5); 303 (4); 174 (10); 160 (100); 145 (15); 92 (9); 89 (10); 77 (18); 64 (5); HREIMS: 361.1060 (calcd for C20H15N3O4 361.1063); FT-IR (ATR) νmax: 3173, 2933, 2837, 1682, 1646, 1599, 1508, 1333, 1242, 1005, 878, 722 cm−1.
3.14. 2-[(1-(3-Methoxyphenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3l)
Following the general procedure described in method B, 52.9 mg (0.25 mmol) of the alkyne, 37.3 mg (0.25 mmol) of 3-methoxybenzylazide, and 25% mol of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3l (84.6 mg, 94%) without further purification. 1H-NMR (CDCl3, 500 MHz) δ 8.17 (1H, s), 8.13 (1H, d, J = 7.5 Hz), 8.09 (1H, d, J = 7.5 Hz), 7.77 (1H, t, J = 7.4 Hz), 7.72 (1H, t, J = 7.4 Hz), 7.43 (1H, t, J = 8.3 Hz), 7.34 (1H, brs), 7.27 (1H, brs), 7.00 (1H, dd, J = 8.3, 2.0 Hz), 6.47 (1H, s), 5.34 (2H, s), 3.89 (3H, s); 13C-NMR (CDCl3, 100 MHz) δ 184.8 (C), 180.2 (C), 160.8 (C), 159.0 (C), 142.3 (C), 137.9 (C), 134.5 (CH), 133.5 (CH), 132.1 (C), 131.2 (C), 130.7 (CH), 126.8 (CH), 126.4 (CH), 122.0 (CH), 115.2 (CH), 112.7 (CH), 111.4 (CH), 106.6 (CH), 63.0 (CH2), 55.8 (CH3); EIMS m/z (%) 361 ([M+], 21); 304 (6); 160 (100); 159 (23); 145 (12); 117 (18); 107 (20); 92 (22); 89 (28); 77 (22); 64 (11); HREIMS: 361.1059 (calcd for C20H15N3O4 361.1063); FT-IR (ATR) νmax: 3153, 2930, 1680, 1651, 1605, 1497, 1461, 1304, 1236, 1155, 1041, 1007, 941, 841 cm−1.
3.15. 2-[(1-(3-Trifluoromethyl-phenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3m)
Following the general procedure described in method B, 52.8 mg (0.25 mmol) of the alkyne, 50.5 mg (0.27 mmol) of 3-trifluoromethylbenzylazide, and 25 mol % of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3m (45.8 mg, 46%) without further purification. 1H-NMR (CDCl3, 500 MHz) δ 8.24 (1H, s), 8.13 (1H, dd, J = 7.5, 0.8 Hz), 8.09 (1H, dd, J = 7.5, 0.8 Hz), 8.05 (1H, brs), 7.99 (1H, brd, J = 7.9 Hz), 7.74 (4H, m), 6.45 (1H, s), 5.36 (2H, s); 13C-NMR (CDCl3, 125 MHz) δ 184.8 (C), 180.0 (C), 158.8 (C), 142.9 (C), 137.2 (C), 134.6 (CH), 133.6 (CH), 132.7 (C, J = 36.7 Hz), 132.0 (C), 131.1 (C), 130.8 (CH), 126.8 (CH), 126.4 (CH), 125.8 (CH, J = 3.6 Hz), 123.8 (CH), 121.9 (CH), 117.7 (CH, J = 3.9 Hz), 111.4 (CH), 62.9 (CH2); EIMS m/z (%) 339 ([M+], 8); 371 (9); 342 (7); 198 (100); 197 (22); 178 (10); 174 (14); 145 (39); 105 (11); 89 (10); 76 (6); 63 (2); HREIMS: 339.0819 (calcd for C20H12N3O4F3 399.0831); FT-IR (ATR) νmax: 3155, 3081, 2937, 1676, 1658, 1609, 1463, 1319, 1246, 1177, 1007, 870, 782, 704 cm−1.
3.16. 2-[(1-(3-Nitrophenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3n)
Following the general procedure described in method B, 56.3 mg (0.27 mmol) of the alkyne, 43.6 mg (0.27 mmol) of 3-nitrobenzylazide, and 25 mol % of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3n (90.8 mg, 91%) without further purification. 1H-NMR (CDCl3, 500 MHz) δ 8.64 (1H, t, J = 2.1 Hz), 8.35 (1H, ddd, J = 8.1, 2.1, 0.9 Hz), 8.32 (1H, s), 8.20 (1H, ddd, J = 8.1, 2.1, 0.9 Hz), 8.14 (1H, dd, J = 7.6, 1.4 Hz), 8.11 (1H, dd, J = 7.6, 1.4 Hz), 7.79 (1H, t, J = 8.1 Hz), 7.75 (2H, m), 6.68 (1H, s), 5.40 (2H, s); 13C-NMR (CDCl3, 125 MHz) δ 184.8 (C), 180.0 (C), 158.9 (C), 149.2 (C), 143.3 (C), 137.6 (C), 134.6 (CH), 133.6 (CH), 132.1 (C), 131.6 (CH), 131.2 (C), 126.9 (CH), 126.4 (CH), 126.2 (CH, C), 123.7 (CH, C), 121.8 (CH), 115.6 (CH), 111.5 (CH), 62.9 (CH); EIMS m/z (%) 376 ([M+], 11); 348 (11); 175 (100); 174 (34); 173 (34); 145 (11); 129 (69); 128 (23); 105 (21); 101 (16); 92 (10); 89 (34); 76 (57); 63 (12); HREIMS: 376.0807 (calcd for C19H12N4O5 376.0808); FT-IR (ATR) νmax: 3080, 2959, 2879, 1672, 1609, 1539, 1346, 1243, 1191, 1041, 1013, 867, 778, 737, 670 cm−1.
3.17. 2-[(1-(4-Methoxyphenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3o)
Following the general procedure described in method B, 44.8 mg (0.21 mmol) of the alkyne, 31.4 mg (0.21 mmol) of 4-methoxybenzylazide, and 25% mol of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3o (74.7 mg, 98%) without further purification. 1H-NMR (CDCl3, 500 MHz) δ 8.13 (1H, dd, J = 7.5, 1.2 Hz), 8.10 (1H, dd, J = 7.5, 1.1 Hz), 8.08 (1H, s), 7.76 (1H, td, J = 7.4, 1.3 Hz), 7.72 (1H, td, J = 7.4, 1.3 Hz), 7.64 (1H, d, J = 9.0 Hz), 7.03 (2H, d, J = 9.0 Hz), 6.47 (1H, s), 5.34 (2H, s), 3.88 (3H, s); 13C-NMR (CDCl3, 125 MHz) δ 184.8 (C), 180.2 (C), 160.3 (C), 159.0 (C), 142.2 (C), 134.5 (CH), 133.5 (CH), 132.1 (C), 131.2 (C), 130.4 (C), 126.8 (CH), 126.4 (CH), 122.5 (2 CH), 122.1 (CH), 115.0 (2 CH), 111.4 (CH), 63.1 (CH2), 55.8 (CH3); EIMS m/z (%) 361 ([M+], 14); 161 (12); 160 (93); 159 (27); 146 (12); 145 (34); 144 (24); 117 (49); 105 (22); 101 (24); 92 (55); 89 (100); 77 (53); 76 (47); 64 (40); 63 (37); 51 (17); HREIMS: 361.1057 (calcd for C20H15N3O4 361.1063); FT-IR (ATR) νmax: 3151, 2937, 2838, 1679, 1655, 1609, 1515, 1308, 1242, 1018, 830, 720 cm−1.
3.18. 2-[(1-(4-Hydroxymethyl-phenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3p)
Following the general procedure described in method B, 59.8 mg (0.28 mmol) of the alkyne, 42.0 mg (0.28 mmol) of 1-azido-4-(hydroxymethyl)bencene, and 25% mol of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3p (84.8 mg, 85%) without further purification. 1H-NMR (DMSO-d6, 500 MHz) δ 9.00 (1H, s), 8.02 (1H, d, J = 7.5 Hz), 8.00 (1H, d, J = 7.5 Hz), 7.86 (4H, m), 7.55 (2H, d, J = 8.2 Hz), 6.68 (1H, s), 5.39 (1H, t, J = 5.6 Hz), 5.36 (2H, s), 4.59 (2H, d, J = 5.6 Hz); 13C-NMR (CDCl3, 125 MHz) δ 184.5 (C, C-4), 179.4 (C, C-1), 158.8 (C, C-2), 143.5 (C, C-4′), 135.0 (C, C-4′′), 134.5 (CH, C-6), 133.6 (CH, C-7), 131.4 (C, C-4a), 130.8 (C, C-8a), 127.6 (2 CH, C-3′′+C-5′′), 127.6 (C, C-1′′), 126.1 (CH, C-5), 125.5 (CH, C-8), 123.7 (CH, C-5′), 120.0 (2 CH, C-2′′ + C-6′′), 111.0 (CH, C-3), 62.2 (CH2, OCH2), 62.2 (CH2, CH2OH); EIMS m/z (%) 361 ([M+], 15); 160 (45); 158 (8); 142 (16); 130 (53); 105 (28); 101 (20); 89 (100); 77 (94); 76 (49); 75 (20); 63 (32); 51 (31); HREIMS: 361.1057 (calcd for C20H15N3O4 361.1063); FT-IR (ATR) νmax: 3475, 3106, 2932, 2878, 1684, 1659, 1610, 1522, 1246, 1207, 1049, 820, 725 cm−1.
3.19. 2-[(1-(4-Mercaptophenil)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3q)
Following the general procedure described in method B, 47.5 mg (0.22 mmol) of the alkyne, 33.8 mg (0.22 mmol) of 4-mercaptobenzylazide, and 25% mol of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3q (71.5 mg, 88%) without further purification. 1H-NMR (DMSO-d6, 500 MHz) δ 9.01 (1H, s), 8.01 (2H, m), 7.67 (2H, d, J = 8.4 Hz), 7.86 (2H, m), 7.80 (2H, d, J = 8.4 Hz), 6.66 (1H, s), 5.35 (2H, s); 13C-NMR (DMSO-d6, 125 MHz) δ 184.5 (C, C-4), 179.9 (C, C-1), 159.2 (C, C-2), 142.1 (C, C-4′), 136.4 (C, C-1′′), 134.5 (CH, C-6), 133.6 (CH, C-7), 131.5 (C, C-4a), 131.4 (C, C-4′′), 130.8 (C, C-8a), 128.7 (2 CH, C-3′′ + C-5′′), 126.1 (CH, C-5), 125.5 (CH, C-8), 123.7 (CH, C-5′), 121.4 (2 CH, C-2′′ + C-6′′), 111.0 (CH, C-3), 62.1 (CH2, OCH2); HRMS-ES (−): 362.0598 (calcd for C19H12N3O3S [M − H+]− 362.0599); FT-IR (ATR) νmax: 3294, 3068, 2931, 2128, 1651, 1607, 1496, 1330, 1240, 1012, 824, 720 cm−1.
3.20. 2-[(1-(4-Fluoromethyl-phenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3r)
Following the general procedure described in method B, 46.5 mg (0.22 mmol) of the alkyne, 34.3 mg (0.22 mmol) of 1-azido-4-fluorobenzene, and 25% mol of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3r (77.6 mg, 78%) without further purification. 1H-NMR (CDCl3, 500 MHz) δ 8.14 (1H, m), 8.13 (1H, s), 8.10 (1H, d, J = 7.6 Hz), 7.72 (4H, m), 7.23 (2H, t, J = 8.6 Hz), 6.46 (1H, s), 5.34 (2H, s); 13C-NMR (CDCl3, 125 MHz) δ 184.8 (C), 180.0 (C), 162.8 (C-F, J = 245.4 Hz), 159.0 (C), 142.6 (C), 134.5 (CH), 133.6 (CH), 132.1 (C), 131.2 (C), 126.9 (CH), 126.4 (CH), 122.9 (2 CH, J = 8.4 Hz), 122.1 (CH), 117.0 (2 CH, J = 23.0 Hz), 111.4 (CH), 63.0 (C); EIMS m/z (%) 349 ([M+], 8); 173 (8); 148 (100); 129 (9); 122 (14); 105 (13); 101 (33); 95 (71); 89 (66); 76 (31); 75 (45); 63 (14); 51 (19); HREIMS: 349.0848 (calcd for C19H12N3O3F, [M+] 349.0863); FT-IR (ATR) νmax: 3226, 3060, 2933, 2874, 2129, 1683, 1643, 1607, 1331, 1241, 1118, 1015, 940, 723 cm−1.
3.21. 2-[(1-(3-Fluoro-4-methoxyphenyl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3s)
Following the general procedure described in method B, 42.8 mg (0.21 mmol) of the alkyne, 42.8 mg (0.21 mmol) of 3-fluoro-4-methoxybenzylazide, and 25% mol of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3s (89.3 mg, 89%) without further purification. 1H-NMR (CDCl3, 400 MHz) δ 8.13 (1H, dd, J = 7.3, 1.4 Hz), 8.10 (1H, dd, J = 7.3, 1.4 Hz), 8.09 (1H, s), 7.75 (1H, td, J = 7.3, 1.4 Hz), 7.73 (1H, td, J = 7.3, 1.4 Hz), 7.54 (1H, dd, J = 11.2, 2.5 Hz), 7.45 (1H, brd, J = 8.7 Hz), 7.09 (1H, t, J = 8.7 Hz), 6.45 (1H, s), 5.33 (2H, s), 3.96 (3H, s); 13C-NMR (CDCl3, 100 MHz) δ 184.8 (C), 180.0 (C), 159.0 (C), 152.5 (C-F, J = 248.0 Hz), 148.4 (C, J = 10.3 Hz), 142.4 (C), 134.5 (CH), 133.6 (CH), 132.1 (C), 131.2 (C), 130.0 (C, J = 34.9 Hz), 126.8 (CH), 126.4 (CH), 121.9 (CH), 126.7 (CH, J = 13.4 Hz), 113.9 (CH), 111.4 (CH), 110.0 (CH, J = 90.6 Hz), 63.0 (CH2), 56.7 (CH3); EIMS m/z (%) 379 ([M+], 3); 322 (4); 178 (100); 177 (19); 163 (13); 135 (5); 110 (6); 89 (9); 82 (9); 82 (7); 77 (6); 76 (6); 63 (3); HREIMS: 379.00970 (calcd for C20H14N3O4F 379.0968); FT-IR (ATR) νmax: 3078, 2322, 2289, 2046, 1681, 1652, 1608, 1521, 1451, 1242, 1202, 1047, 1013, 859, 719 cm−1.
3.22. 2-[(1-(1H-Indol-5-yl)-triazol-4-yl)methoxy]-naphthalene-1,4-dione (3t)
Following the general procedure described in method B, 24.8 mg (0.16 mmol) of the alkyne, 33.3 mg (0.16 mmol) of 5-azido-1H-indole, and 25 mol % of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3t (48.8 mg, 84%) without further purification. 1H-NMR (DMSO-d6, 500 MHz) δ 11.46 (1H, brs), 8.92 (1H, s), 8.04 (1H, s), 8.01 (2H, m), 7.86 (2H, m), 7.59 (2H, brs), 7.52 (1H, s), 6.69 (1H, s), 6.59 (1H, s), 5.35 (2H, s); 13C-NMR (DMSO-d6, 125 MHz) δ 184.5 (C), 179.5 (C), 158.9 (C), 141.5 (C), 135.6 (C), 134.5 (CH), 133.6 (CH), 131.5 (C), 130.8 (C), 129.3 (C), 127.7 (CH), 127.6 (C), 126.1 (CH), 125.5 (CH), 124.0 (CH), 114.4 (CH), 112.3 (2 CH), 111.0 (CH), 101.9 (CH), 62.4 (CH2); EIMS m/z (%) 370 ([M+], 6); 174 (32); 169 (100); 168 (62); 142 (21); 116 (80); 105 (47); 89 (61); 77 (21); 76 (26); 63 (16); 51 (11); HREIMS: 370.1055 (calcd for C21H14N4O3, 370.1066); FT-IR (ATR) νmax: 3342, 3163, 1683, 1647, 1606, 1349, 1239, 1208, 1057, 1014, 866, 727 cm−1.
3.23. 2-{[1-(E)-2-(4-Trifluorometyl-phenyl)vinyl)-triazol-4-yl]methoxy}-naphthalene-1,4-dione (3u)
Following the general procedure described in method B, 66.6 mg (0.31 mmol) of the alkyne, 66.9 mg (0.31 mmol) of azide 2u, and 25 mol % of CuI were stirred at room temperature for 72 h. Then, the solvent was removed at reduced pressure and the solid was washed with n-hexane, yielding triazole 3u (128.7 mg, 96%) without further purification. 1H-NMR (DMSO-d6, 500 MHz) δ 8.78 (1H, s), 8.39 (1H, d, J = 14.7 Hz), 8.02 (1H, d, J = 7.5 Hz), 7.99 (1H, d, J = 7.5 Hz), 7.83 (6H, m), 7.57 (1H, d, J = 14.7 Hz), 6.65 (1H, s), 5.36 (2H, s); 13C-NMR (DMSO-d6, 125 MHz) δ 184.5 (C), 179.4 (C), 158.8 (C), 141.7 (C), 138.1 (C), 134.5 (CH), 133.7 (CH), 131.5 (C), 130.8 (C), 128.4 (C), 127.5 (2 CH), 126.1 (CH), 125.7 (2 CH, J = 3.4 Hz), 125.5 (CH), 123.4 (CH), 120.0 (CH), 111.0 (CH), 62.1 (CH2); HRMS-ES (+): 448.0873 (calcd for C22H14F3N3O3Na [M + Na]+ 448.0874); FT-IR (ATR) νmax: 3566, 3066, 1685, 1650, 1608, 1418, 1323, 1244, 1205, 1113, 1016, 931, 814, 723 cm−1.
3.24. 2-[(4-Butyl)-triazol-1-yl]-naphthalene-1,4-dione (4a)
Following the general procedure described in method B, 77.71 µL (0.68 mmol) of 1-hexyne, 67.3 mg (0.34 mmol) of 2-azide-1,4-naphthoquinone, and 20 mol % of CuI were stirred at room temperature for 17 h. Then, the solvent was removed at reduced pressure and the residue was purified by TLC-preparative with n-hexane/EtOAc (40%), yielding triazole 4a (73.5 mg, 77%). 1H-NMR (CDCl3, 500 MHz) δ 8.38 (1H, s), 8.21 (1H, m), 8.16 (1H, m), 7.84 (2H, m), 7.75 (1H, s), 2.83 (2H, t, J = 7.7 Hz), 1.74 (2H, m), 1.44 (2H, m), 0.97 (3H, t, J = 7.4 Hz); 13C-NMR (CDCl3, 125 MHz) δ 184.0 (C), 179.7 (C), 149.7 (C), 139.6 (C), 135.0 (CH), 134.4 (CH), 131.6 (C), 131.3 (C), 127.3 (CH), 126.6 (CH), 126.2 (CH), 122.9 (CH), 31.3 (CH2), 25.4 (CH2), 22.4 (CH2), 13.9 (CH3); HRMS-ES (+) 304.1062 (calcd for C16H15N3O2Na [M + Na]+ 304.1062); FT-IR (ATR) νmax: 3164, 3072, 2957, 2928, 1652, 1593, 1291, 1251, 1043, 1016, 985, 829, 784, 715 cm−1.
3.25. 2-[(4-Phenyl)-triazol-1-yl]-naphthalene-1,4-dione (4j)
Following the general procedure described in method B, 47.9 mg (0.24 mmol) of 2-azide-1,4-naphthoquinone, 52.8 µL of phenylacetylene, and 20 mol % of CuI were stirred at room temperature for 48 h. Then, the solvent was removed at reduced pressure and the residue was purified by TLC-preparative with n-hexane/EtOAc (40%), yielding triazole 4j (51.7 mg, 71%). 1H-NMR (CDCl3, 400 MHz) δ 8.93 (1H, s), 8.36 (1H, d, J = 6.6 Hz), 8.19 (1H, d, J = 6.6 Hz), 7.95 (2H, d, J = 7.4 Hz), 7.87 (2H, m), 7.85 (1H, s), 7.49 (2H, t, J = 7.3 Hz), 7.40 (1H, t, J = 7.3 Hz); 13C-NMR (CDCl3, 100 MHz) δ 183.9 (C), 179.6 (C), 149.0 (C), 139.4 (C), 135.2 (CH), 134.5 (CH), 131.7 (C), 131.2 (C), 129.8 (C), 129.1 (2 CH), 128.9 (CH), 127.4 (CH), 126.7 (CH), 126.4 (CH), 126.1 (2 CH), 121.5 (CH); EIMS m/z (%) 301 ([M]+, 2); 274 (20); 273 (100); 217 (10); 157 (13); 129 (19); 101 (24); 89 (5); 76 (9); HREIMS: 301.0850 (calcd for C18H11N3O2 301.0851); FT-IR (ATR) νmax: 3152, 2924, 2853, 2194, 1672, 1592, 1415, 1260, 1005, 915, 762, 691 cm−1.
3.26. 2-[(1-Undecyl-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7b)
Following the experimental procedure described in method C, from 56.0 mg (0.28 mmol) of 1-azido-undecane and 28 mg (0.14 mmol) of N-propargylated quinone (6), we obtained 46.3 mg (80%) of compound 7b. 1H-NMR (CDCl3, 500 MHz) δ 8.09 (1H, d, J = 7.6 Hz), 8.05 (1H, d, J = 7.6 Hz), 7.73 (1H, t, J = 7.6 Hz), 7.63 (1H, t, J = 7.5 Hz), 7.52 (1H, s), 6.34 (1H, s), 5.82 (1H, s), 4.50 (2H, d, J = 5.6 Hz), 4.35 (2H, t, J = 7.3 Hz), 1.90 (2H, m), 1.62 (2H, s), 1.27 (14H, m), 0.87 (3H, t, J = 7.0 Hz); 13C-NMR (CDCl3, 125 MHz) δ 183.0 (C), 181.5 (C), 147.5 (C), 134.7 (CH), 133.5 (C), 132.2 (C), 132.1 (CH), 130.5 (C), 121.7 (CH), 126.3 (CH), 126.2 (CH), 101.7 (CH), 50.5 (CH2), 38.3 (CH2), 31.9 (CH2), 30.2 (CH2), 29.6 (CH2), 29.5 (CH2), 29.3 (CH2), 29.2 (CH2), 28.9 (CH2), 26.5 (CH2), 22.6 (CH2), 14.0 (CH3); HRMS-ES (+): 431.2423 (calcd for C24H32N4O2Na, [M + Na]+ 431.2417); FT-IR (ATR) νmax: 3346, 3135, 3079, 2958, 2922, 2853, 1683, 1596, 1570, 1501, 1471, 1442, 1360, 1348, 1316, 1257, 1223, 1153, 1129, 1102, 1079, 1058, 1032, 988, 935, 897, 829 cm−1.
3.27. 2-[(1-Benzyl-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7c)
Following the experimental procedure described in method C, from 40.8 mg (0.28 mmol) of benzylazide and 28 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 27.3 mg (86%) of compound 7c. 1H-NMR (CDCl3, 500 MHz) δ 8.06 (1H, d, J = 7.6 Hz), 8.01 (1H, d, J = 7.6 Hz), 7.71 (1H, t, J = 7.6 Hz), 7.60 (1H, t, J = 7.5 Hz), 7.48 (1H, s), 7.36 (3H, m), 7.27 (2H, m), 6.39 (1H, s), 5.78 (1H, s), 5.53 (2H, s), 4.47 (2H, d, J = 5.7 Hz); 13C-NMR (CDCl3, 125 MHz) δ 182.9 (C), 181.5 (C), 147.5 (C), 143.1 (C), 134.6 (CH), 134.3 (C), 133.4 (C), 132.0 (CH), 130.4 (C), 129.1 (2 CH), 128.8 (CH), 128.1 (2 CH), 126.2 (CH), 126.1 (CH), 121.8 (CH), 101.6 (CH), 54.3 (CH2), 38.2 (CH2); EIMS m/z (%) 344 ([M+], 43); 225 (78); 173 (37); 146 (16); 105 (24); 104 (16); 91 (100); HREIMS: 344.1261 (calcd for C20H16N4O2 344.1273); FT-IR (ATR) νmax: 3330, 3117, 3064, 2921, 2853, 1681, 1592, 1561, 1496, 1455, 1438, 1352, 1311, 1252, 1217, 1152, 1124, 1096, 1075, 1051, 1027, 981, 932, 862, 845, 822 cm−1.
3.28. 2-[[1-(1,4-Dioxo-2-naphthyl)-triazol-4-yl]methylamino]-naphthalene-1,4-dione (7d)
Following the experimental procedure described in method B, from 63.7 mg (0.32 mmol) of 2-azidonaphthoquinone and 66.8 mg (0.32 mmol) of N-propargylated naphthoquinone (6), we obtained 42.0 mg (32%) of compound 7d. 1H-NMR (CDCl3, 400 MHz) δ 8.67 (1H, s), 8.21 (1H, dd, J = 8.8, 2.2 Hz), 8.17 (1H, dd, J = 8.8, 2.2 Hz), 8.09 (2H, m), 7.84 (2H, m), 7.78 (1H, s), 7.74 (1H, td, J = 7.5, 1.1 Hz), 7.64 (1H, t, J = 7.5, 1.1 Hz), 6.38 (1H, brs, NH), 5.88 (1H, s), 4.63 (2H, d, J = 5.8 Hz); 13C-NMR (DMSO-d6, 150 MHz) δ 184.5 (C), 182.1 (C), 182.0 (C), 179.2 (C), 148.7 (C), 144.6 (C), 140.7 (C), 135.3 (CH), 135.2 (C), 135.0 (C), 133.4 (C), 132.8 (CH), 131.8 (C), 131.7 (C), 130.9 (CH), 127.2 (CH), 126.7 (CH), 126.4 (C), 126.3 (CH), 126.0 (CH), 125.8 (CH), 101.1 (CH), 37.4 (CH2); EIMS m/z (%): 410 ([M+], 1); 255 (19); 254 (100); 226 (11); 197 (8); 186 (15); 173 (22); 158 (21); 146 (16); 102 (16); 83 (14); 76 (17); HREIMS: 410.1218 (calcd for C23H14N4O4 410.1015); FT-IR (ATR) νmax: 3338, 3152, 3072, 2932, 2857, 1661, 1604, 1513, 1352, 1294, 1186, 1038, 968, 920, 846 cm−1.
3.29. 2-(2-Dimethylaminoethyl)-6-{4-[(1,4-dioxo-2-naphthyl)-aminomethyl]triazol-1-yl}benzo[de] isoquinoline-1,3-dione (7h)
Following the experimental procedure described in method B, from 31.7 mg (0.1 mmol) of azide 2h and 18.0 mg (0.09 mmol) of N-propargylated naphthoquinone (6), we obtained 29.4 mg (66%) of compound 7h. 1H-NMR (CDCl3, 500 MHz) δ 8.63 (2H, d, J = 7.2 Hz), 8.13 (1H, d, J = 8.5 Hz), 8.05 (3H, m), 7.77 (2H, d, J = 7.5 Hz), 7.71 (1H, t, J = 7.3 Hz), 7.61 (1H, t, J = 7.3 Hz), 6.62 (1H, s), 4.69 (2H, d, J = 5.7 Hz), 4.34 (2H, t, J = 6.7 Hz), 2.71 (2H, t, J = 6.5 Hz), 2.37 (6H, s); 13C-NMR (CDCl3, 125 MHz) δ 183.0 (C), 181.5 (C), 163.5 (C), 163.0 (C), 147.5 (C), 143.6 (C), 137.8 (C), 134.8 (CH), 133.3 (C), 132.2 (CH), 130.5 (CH), 130.4 (C), 129.1 (CH), 129.0 (C), 128.7 (2 CH), 126.4 (C), 126.3 (CH), 126.2 (CH), 124.4 (CH), 124.1 (C), 123.6 (CH), 123.0 (C), 102.0 (CH), 56.9 (CH2), 45.6 (2 CH3), 38.3 (CH2), 38.1 (CH2); EIMS m/z (%): 446 (46); 441 (27); 173 (74); 158 (34); 149 (56); 146 (27); 113 (22); 111 (22); 105 (32); 99 (25); 97 (22); 85 (45); 71 (82); 58 (39); 57 (100); 55 (35); HREIMS: 521.1937 (calcd for C29H24N6O4), [M+] 521.1937); FT-IR (ATR) νmax: 3338, 2967, 2864, 2824, 2259, 1699, 1656, 1599, 1569, 1508, 1477, 1434, 1347, 1305, 1240, 1158, 1121, 1024, 1000, 860, 832 cm−1.
3.30. 2-[(1-Phenyl-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7j)
Following the experimental procedure described in method C, from 31.2 mg (0.24 mmol) of phenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 10.9 mg (24%) of compound 7j. 1H-NMR (CDCl3, 500 MHz) δ 8.10 (1H, dd, J = 7.8, 1.1 Hz), 8.06 (1H, dd, J = 7.6, 1.1 Hz), 7.98 (1H, s), 7.73 (3H, m), 7.63 (1H, td, J = 7.5, 1.2 Hz), 7.53 (2H, t, J = 7.8 Hz), 7.46 (1H, t, J = 7.4 Hz), 6.42 (1H, s), 5.88 (1H, s), 4.60 (2H, d, J = 5.8 Hz) ppm; 13C-NMR (CDCl3, 125 MHz) δ 183.1 (C), 181.6 (C), 147.5 (C), 143.5 (C), 136.87 (C), 134.8 (CH), 133.5 (C), 132.2 (CH), 130.5 (C), 129.9 (2 CH), 129.1 (CH), 126.4 (CH), 126.3 (CH), 120.7 (2 CH), 120.2 (CH), 101.9 (CH), 38.2 (CH2) ppm; EIMS m/z (%): 330 ([M+], 21), 302 (27), 301 (16), 245 (11), 173 (14), 130 (100), 129 (13), 105 (13), 104 (17), 77 (70), 76 (14), 51 (19); HREIMS: 330.1117 (calcd for C19H14N4O2 330.1117); FT-IR (ATR) νmax: 3346, 3132, 3058, 2931, 1671, 1596, 1562, 1501, 1442, 1348, 1306, 1281, 1253, 1222, 1175, 1156, 1122, 1091, 1050, 1024, 983, 927, 856 cm−1.
3.31. 2-[(1-(2-Methoxyphenyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7k)
Following the experimental procedure described in method C, from 38.5 mg (0.24 mmol) of 2-methoxyphenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 6.8 mg (14%) of compound 7k. 1H-NMR (CDCl3, 500 MHz) δ 8.11 (1H, s), 8.10 (1H, dd, J = 7.8, 1.0 Hz), 8.06 (1H, dd, J = 7.8, 0.9 Hz), 7.77 (1H, dd, J = 7.9, 1.6 Hz), 7.73 (1H, td, J = 7.7, 1.1 Hz), 7.63 (1H, t, J = 7.54 Hz), 7.43 (1H, td, J = 7.8, 1.5 Hz), 7.11 (2H, m), 6.40 (1H, s), 5.89 (1H, s), 4.59 (2H, d, J = 5.7 Hz), 3.90 (3H, s) ppm; 13C-NMR (CDCl3, 125 MHz) δ 183.1(C), 181.6 (C), 151.1 (C), 147.6 (C), 141.9 (C), 134.7 (CH), 133.5 (C), 132.1 (CH), 130.6 (C), 130.3 (CH), 126.3 (CH), 126.2 (CH), 126.1 (C), 125.5 (CH), 124.2 (CH), 121.3 (CH), 112.3 (CH), 101.8 (CH), 56.0 (CH3), 38.3 (CH2) ppm; EIMS m/z (%): 360 ([M+], 30), 332 (18), 161 (17), 160 (100), 145 (17), 130 (15), 120 (15), 92 (16), 77 (31); HREIMS: 360.1236 (calcd for C20H16N4O3 360.1222); FT-IR (ATR) νmax: 3403, 3358, 3139, 3085, 3064, 3011, 2955, 2916, 2848, 1671, 1599, 1565, 1502, 1460, 1355, 1336, 1304, 1283, 1247, 1172, 1156, 1117, 1092, 1074, 1053, 993, 928, 860, 847, 829 cm−1.
3.32. 2-[(1-(3-Methoxyphenyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7l)
Following the experimental procedure described in method C, from 37.2 mg (0.24 mmol) of 3-methoxyphenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 27.3 mg (53%) of compound 7l. 1H-NMR (CDCl3, 500 MHz) δ 8.08 (1H, d, J = 7.3 Hz), 8.04 (1H, d, J = 7.2 Hz), 7.97 (1H, s), 7.72 (1H, td, J = 7.6, 1.2 Hz), 7.62 (1H, td, J = 7.5, 1.2 Hz), 7.40 (1H, t, J = 8.17 Hz), 7.32 (1H, t, J = 2.1 Hz), 7.23 (1H, dd, J = 7.9, 1.2 Hz), 6.97 (1H, dd, J = 8.3, 1.9 Hz), 6.43 (1H, s), 5.87 (1H, s), 4.59 (2H, d, J = 5.8 Hz), 3.87 (3H, s) ppm; 13C-NMR (CDCl3, 125 MHz) δ 183.0 (C), 181.5 (C), 160.6 (C), 147.5 (C), 143.4 (C), 137.8 (C), 134.8 (CH), 133.4 (C), 132.2 (CH), 130.6 (CH), 130.5 (C), 126.3 (CH), 126.2 (CH), 120.2 (CH), 114.9 (CH), 112.4 (CH), 106.4 (CH), 101.8 (CH), 55.6 (CH3), 38.1 (CH2) ppm; EIMS m/z (%): 360 ([M+], 13), 202 (67), 173 (55), 160 (100), 158 (39), 146 (29), 130 (21), 123 (28), 107 (31), 105 (37), 104 (59), 102 (27), 92 (40), 77 (58), 76 (54), 64 (22), 51 (20); HREIMS: 360.1210 (calcd for C20H16N4O3 360.1222); FT-IR (ATR) νmax: 3198, 3142, 3091, 3018, 2959, 2922, 2853, 2186, 1695, 1599, 1564, 1489, 1440, 1357, 1335, 1313, 1257, 1168, 1123, 1103, 1046, 1026, 1010, 984, 934, 856, 830 cm−1.
3.33. 2-[(1-(3-Trifluoromethyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7m)
Following the experimental procedure described in method C, from 45.7 mg (0.24 mmol) of 3-(trifluoromethyl)phenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 23.7 mg (44%) of compound 7m. 1H-NMR (CDCl3, 500 MHz) δ 8.07 (3H, m), 8.01 (1H, s), 7.96 (1H, d, J = 7.7 Hz), 7.71 (3H, m), 7.63 (1H, t, J = 7.4 Hz), 6.43 (1H, s), 5.87 (1H, s), 4.63 (2H, d, J = 5.7 Hz) ppm; 13C-NMR (CDCl3, 125 MHz) δ 183.1 (C), 181.5 (C), 147.5 (C), 144.1 (C), 137.2 (C), 134.8 (CH), 133.4 (C), 132.6 (C, J2C-F = 33.7 Hz), 132.2 (CH), 130.6 (CH), 130.5 (C), 126.37 (CH), 126.3 (CH), 125.6 (CH, J3C-F = 2.13 Hz), 123.7 (CH), 123.2 (C, J1C-F = 274 Hz), 120.0 (CH), 117.6 (CH, J3C-F = 3.7 Hz), 102.0 (CH), 38.2 (CH2) ppm; EIMS m/z (%): 398 ([M+] 9); 370 (30); 313 (19); 240 (37); 199 (31); 198 (100); 158 (58); 130 (21); 105 (29); 104 (25); 102 (24); 77 (19); 76 (34); HREIMS: 398.1025 (calcd for C20H13F3N4O2 398.0991); FT-IR (ATR) νmax: 3352, 3130, 3083, 1679, 1601, 1568, 1504, 1458, 1347, 1310, 1286, 1243, 1171, 1117, 1094, 107, 1051, 1001, 976, 901, 878, 811 cm−1.
3.34. 2-[(1-(3-Nitrophenyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7n)
Following the experimental procedure described in method C, from 40.2 mg (0.24 mmol) of 3-nitrophenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 14.2 mg (44%) of compound 7n. 1H-NMR (DMSO-d6, 500 MHz) δ 8.99 (1H, s), 8.70 (1H, s), 8.39 (1H, d, J = 8.2 Hz), 8.31 (1H, d, J = 8.2 Hz), 8.07 (1H, t, J = 6.1 Hz), 8.01 (1H, d, J = 7.6 Hz), 7.93 (1H, d, J = 7.6 Hz), 7.87 (1H, t, J = 8.2 Hz), 7.82 (1H, t, J = 7.5 Hz), 7.74 (1H, t, J = 7.5 Hz), 5.77 (1H, s), 4.61 (2H, d, J = 6.17 Hz) ppm; 13C-NMR (DMSO-d6, 125 MHz) δ 181.6 (C), 181.4 (C), 148.5 (C), 148.3 (C), 144.9 (C), 137.2 (C), 134.8 (CH), 133.0 (C), 132.3 (CH), 131.5 (CH), 130.4 (C), 126.0 (CH), 125.7 (CH), 125.3 (CH), 123.0 (CH), 121.8 (CH), 114.7 (CH), 100.7 (CH), 37.4 (CH2) ppm; EIMS m/z (%): 375 ([M+], 39); 348 (23); 347 (61); 346 (34); 300 (28); 198 (23); 182 (28); 175 (72); 174 (23); 173 (64); 146 (35); 145 (34); 130 (26); 129 (100); 128 (25); 105 (58); 104 (33); 102 (41); 101 (32); 92 (21); 89 (31); 77 (37); 76 (79); 75 (26); HREIMS: 375.0983 (calcd for C19H13N5O4 375.0968); FT-IR (ATR) νmax: 3360, 3248, 3122, 3083, 3059, 2918, 2850, 1677, 1605, 1567, 1524, 1346, 1304, 1255, 1180, 1159, 1122, 1093, 1075, 1049, 982, 931, 897, 869, 834, 814 cm−1.
3.35. 2-[(1-(4-Methoxyphenyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7o)
Following the experimental procedure described in method C, from 38.5 mg (0.24 mmol) of 3-methoxyphenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 29.4 mg (57%) of compound 7o. 1H-NMR (CDCl3, 500 MHz) δ 8.08 (1H, dd, J = 7.7, 0.9 Hz), 8.04 (1H, dd, J = 7.7, 1.1 Hz), 7.90 (1H, s), 7.72 (1H, td, J = 7.6, 1.3 Hz), 7.62 (3H, m), 7.00 (2H, m), 6.43 (1H, s), 5.87 (1H, s), 4.58 (2H, d, J = 5.8 Hz), 3.86 (3H, s) ppm; 13C-NMR (CDCl3, 125 MHz) δ 183.0 (C), 181.5 (C), 160.0 (C), 147.5 (C), 143.2 (C), 134.7 (CH), 133.4 (C), 132.1 (CH), 130.6 (C), 130.3 (C), 126.3 (CH), 126.2 (CH), 122.3 (2 CH), 120.3 (CH), 114.9 (2xCH), 101.8 (CH), 55.6 (CH3), 38.2 (CH2) ppm; EIMS m/z (%): 360 ([M+], 28); 360 (28); 332 (19); 202 (50); 187 (31); 173 (33); 160 (100); 158 (20); 123 (20); 108 (24); 105 (18); 104 (23); 77 (19); HREIMS: 360.1237 (calcd for C20H16N4O3 360.1222); FT-IR (ATR) νmax: 3309, 3138, 3073, 2923, 2843, 2051, 1979, 1861, 1683, 1593, 1560, 1518, 1495, 1441, 1350, 1305, 1243, 1189, 1120, 1095, 1042, 979, 931, 829 cm−1.
3.36. 2-[(1-(4-Fluorophenyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7r)
Following the experimental procedure described in method C, from 34.8 mg (0.24 mmol) of 4-fluorophenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 21.7 mg (44%) of compound 7r. 1H-NMR (CDCl3, 500 MHz) δ 8.10 (1H, m), 8.07 (1H, dd, J = 7.6, 1.1 Hz), 7.92 (1H, s), 7.74 (1H, td, J = 7.6, 1.3 Hz), 7.70 (2H, m), 7.64 (1H, td, J = 7.6, 1.3 Hz), 7.23 (2H, m), 6.40 (1H, s), 5.87 (1H, s), 4.60 (2H, d, J = 5.8 Hz) ppm; 13C-NMR (CDCl3, 125 MHz) δ 183.1 (C), 181.5 (C), 162.6 (C, J1C-F = 250.3 Hz) 147.5 (C), 143.6 (C), 134.8 (CH), 133.4 (C), 133.1 (C, J4C-F = 2.6 Hz), 132.2 (CH), 130.5 (C), 126.4 (CH), 126.3 (CH), 122.7 (2 CH, J3C-F = 8.6 Hz), 120.3 (CH), 116.8 (2 CH, J2C-F = 23.07 Hz), 101.9 (CH), 38.2 (CH2) ppm; EIMS m/z (%) 348 ([M+], 14); 320 (32); 319 (19); 190 (37); 189 (19); 158 (31); 148 (100); 122 (20); 104 (20); 95 (55); 76 (18); 75 (19); HREIMS: 348.1027 (calcd for C19H13N4O2F) 348.1023); FT-IR (ATR) νmax: 3386, 2364, 2134, 1931, 1683, 1596, 1564, 1500, 1355, 1067, 969, 836 cm−1.
3.37. 2-[(1-(3-Fluoro-4-methoxyphenyl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7s)
Following the experimental procedure described in method C, from 41.3 mg (0.24 mmol) of 3-fluoro-4-methoxyphenylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated naphthoquinone (6), we obtained 24.8 mg (48%) of compound 7s. 1H-NMR (DMSO-d6, 500 MHz) δ 8.68 (1H, s), 8.02 (2H, m), 7.93 (1H, d, J = 7.5 Hz), 7.83 (2H, m), 7.74 (1H, t, J = 7.5 Hz), 7.69 (1H, d, J = 8.8 Hz), 7.35 (1H, t, J = 9.1 Hz), 5.77 (1H, s), 4.57 (2H, d, J = 6.1 Hz), 3.89 (3H, s) ppm; 13C-NMR (DMSO-d6, 125 MHz) δ 181.5 (C), 181.3 (C), 151.3 (C, J1C-F = 246.3 Hz), 148.2 (C), 147.5 (C, J2C-F = 10.4 Hz), 144.2 (C), 134.7 (CH), 132.9 (C), 132.2 (CH), 130.3 (C), 129.6 (C, J3C-F = 9.1 Hz), 125.7 (CH), 125.2 (CH), 121.3 (CH), 116.3 (CH, J3C-F = 3.7 Hz), 114.5 (CH, J4C-F = 2.7 Hz), 108.7 (CH, J2C-F = 23.4 Hz), 100.5 (CH), 56.3 (CH3), 37.3 (CH2) ppm; EIMS m/z (%): 378 ([M+], 23); 350 (19); 349 (12); 179 (11); 178 (100); 84 (11); HREIMS: 378.1132 (calcd for C20H15N4O3F) 378.1128); FT-IR (ATR) νmax: 3386, 3143, 2235, 2289, 2168, 1683, 1608, 1573, 1533, 1507, 1463, 1354, 1278, 1059, 801 cm−1.
3.38. 2-[(1-(1-H-Indo-5-yl)-triazol-4-yl)methylamino]-naphthalene-1,4-dione (7t)
Following the experimental procedure described in method C, from 39.1 mg (0.24 mmol) of 5-indolylboronic acid and 30.0 mg (0.14 mmol) of N-propargylated quinone (6), we obtained 22.4 mg (39%) of compound 7t. 1H-NMR (DMSO-d6, 500 MHz) δ 11.40 (1H, s), 8.65 (1H, s), 8.03 (2H, m), 7.97 (1H, s), 7.93 (1H, d, J = 7.6 Hz), 7.82 (1H, t, J = 7.5 Hz), 7.74 (1H, t, J = 7.5 Hz), 7.58 (2H, s), 7.51 (1H, s), 6.54 (1H, s), 5.81 (1H, s), 4.58 (2H, d, J = 6.1 Hz); 13C-NMR (DMSO-d6, 125 MHz) δ 181.5 (C), 181.4 (C), 148.2 (C), 143.7 (C), 135.3 (C), 134.6 (CH), 132.9 (C), 132.1 (CH), 130.4 (C), 129.3 (C), 127.6 (CH), 127.5 (C) 125.7 (CH), 125.2 (CH), 121.5 (CH), 114.1 (CH), 112.1 (CH), 111.8 (CH), 101.8 (CH), 100.4 (CH), 37.40 (CH2); EIMS m/z (%): 369 ([M+], 9); 173 (100); 160 (25); 158 (19); 146 (39); 132 (27); 116 (22); 105 (48); 104 (35); 89 (15); 76 (25); 66 (16); HREIMS: 369.1214 (calcd for C21H15N5O2 369.1226); FT-IR (ATR) νmax: 3344, 3274, 2928, 2323, 2254, 2113, 1673, 1604, 1560, 1513, 1458, 1426, 1350, 1309, 1261, 1225, 1123, 1047, 1024, 889, 824 cm−1.
3.39. Antiplasmodial Assay
F-32 Tanzania (chloroquine-sensitive) strains of
P. falciparum were cultured according to Trager and Jensen [
40] on glucose-enriched RPMI 1640 medium, supplemented with 10% human serum at 37 °C. After 24 h of incubation at 37 °C, the medium was replaced by fresh medium supplemented with the compound to be evaluated at three different concentrations (0.1, 1, and 10 µg/mL) and incubation was continued for a further 48 h. On the third day of the test, a blood smear was taken from each well and parasitemia was calculated for each concentration of sample compared to the control. IC
50 values were determined graphically by plotting concentrations versus percent inhibition. Chloroquine (0.04 µM) was used as a positive control. All tests were performed in triplicate.
3.40. Antiproliferative Activity
The human cancer cell lines HL60 (promyelocytic leukemia), HEL (human erythroleukemia), and SK-Br3 (breast adeno carcinoma) were purchased from ATCC and cultured in RPMI medium 10% FBS. The MTT assay, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide], was used to test the cytotoxicity of 1,2,3-triazolquinones and cell viability [
41]. Briefly, cells were plated in 96-well plates at 10,000 cells/well. Sixteen hours after plating, vehicle (0.1% DMSO, final concentration) or compound was added to cells at indicated concentrations. Forty-eight hours following compound addition, MTT (Sigma-Aldrich, St. Louis, MO, USA) was added to each well (0.3 mg/mL, final concentration) and plates were incubated for an additional 2 h at 37 °C. Medium was then aspirated and the formazan product was solubilized in SDS-HCl (20% SDS; HCl 0.02 M). The absorbance of each well was measured at 595 nm using an iMark Microplate Reader (BioRad, Hercules, CA, USA). Nonlinear regression analysis was performed to calculate IC
50 according to the GraphPad Prism 5 program (GraphPad Software, San Diego, CA, USA). The data were expressed by mean ± SEM (
n = 3).
3.41. Protein Preparation and Docking
The X-ray coordinates of
Plasmodium falciparum enzyme dihydroorotate dehydrogenase (P
fDHODH) was extracted from the Protein Data Bank (PDB code 1TV5). The PDB structures were prepared for docking using the Protein Preparation Workflow (Schrodinger, LLC, New York, NY, USA, 2018) accessible from within the Maestro program (Maestro, version 11.5; Schrodinger, LLC: New York, NY, USA, 2018). The substrate and water molecules were removed beyond 5 Å, bond corrections were applied to the cocrystallized ligands, and an exhaustive sampling of the orientations of groups was performed. Finally, the receptors were optimized in Maestro 11.5 by using OPLS3 force field before docking study. In the final stage, the optimization and minimization on the ligand–protein complexes were carried out with the OPLS3 force field and the default value for RMSD of 0.30 Å for non-hydrogen atoms was used. The receptor grids were generated using the prepared proteins, with the docking grids centered on the center of the bound ligand for each receptor. A receptor grid was generated using a 1.00 van der Waals (vdW) radius scaling factor and 0.25 partial charge cutoff. The binding sites were enclosed in a grid box of 20 Å
3 with default parameters and without constrains. The three-dimensional structures of the ligands to be docked were generated and prepared using LigPrep as implemented in Maestro 11.5 (LigPrep, Schrodinger, LLC: New York, NY, USA, 2018) to generate the most probable ionization states at pH 7 ± 1 (retain original ionization state). These conformations were used as the initial input structures for the docking. In this stage, a series of treatments are applied to the structures. Finally, the geometries are optimized using OPLS3 force field. These conformations were used as the initial input structures for the docking. The ligands were docked using the extra precision mode (XP) [
42] without using any constraints and a 0.80 van der Waals (vdW) radius scaling factor and 0.15 partial charge cutoff. The dockings were carried out with flexibility of the residues of the pocket near to the ligand. The generated ligand poses were evaluated with empirical scoring function, GlideScore a modified version of ChemScore [
43]; GlideScore implemented in Glide was used to estimate binding affinity and rank ligands [
44]. The XP Pose Rank was used to select the best-docked pose for each ligand.