All materials and solvents were purchased from Merck and Aldrich and were used without any additional purification. The melting points of the products were determined in open capillary tubes using BAMSTEAB Electrothermal apparatus model 9002. Mass spectra were taken by a Micro mass Platform II: EI mode (70 eV). Silica plates (Merck) were used for TLC analysis.
Preparation of 5-hydroxy-8-(perfluoropyridin-4-yloxy) naphthalene-1,4-dione 2a and 5,8-bis(perfluoropyridin-4-yloxy)naphthalene-1,4-dione 2b
Pentafluoropyridine 1 (0.16 g, 1 mmol), 5,8-dihydroxynaphthalene-1,4-dione 2 (0.19 g, 1 mmol) and potassium carbonate (0.11 g, 1.0 mmol) were stirred together in DMF (5 mL) at reflux temperature for 8 h. After completion of the reaction (indicated by TLC), reaction mixture was evaporated to dryness and water (10 mL) was added and extracted with dichloromethane (2 × 10 mL) and ethylacetate (2 × 10 mL). The mixture was filtered, volatiles evaporated and the residue purified by column chromatography on silica gel using ethyl acetate/n-hexane (1:10).
5-hydroxy-8-(perfluoropyridin-4-yloxy)naphthalene-1,4-dione
2a
(0.1 g, 29 %) as an orange solid; mp 240 °C dec; 1H NMR (CDCl3): δ (ppm) 4.1 (1H, s, OH), 7.2–8.3 (4H, m, Ar–H), 19F NMR (DMSO): δ (ppm) −87.6 (2F, s, F-2,6), −162.0 (2F, s, F-3,5), 13C NMR (CDCl3): δ (ppm) 115.3, 117.2, 119.7, 120.3, 125.4, 128.3, 131.0, 137.5, 150.3, 159.2, 169.2, 170.1, 171.8, MS (EI), m/z (%) = 341 (M+) (32 %) 318, 309, 301, 291, 272, 255, 246, 224, 198, 180, 152, 126, 106, 86, 58, 44.
5,8-bis(perfluoropyridin-4-yloxy)naphthalene-1,4-dione
2b
(0.08 g, 16 %) as an orange/yellow solid; mp 330 °C dec; 1H NMR (CDCl3): δ (ppm) 7.2 (5H, m, Ar–H), 19F NMR (CDCl3): δ (ppm) −83.5 (2F, s, F-2,6), −84.2 (2F, s, F-2′,6′), −135.4 (2F, s, F-3,5), −139.4 (2F, s, F-3′,5′). 13C NMR (CDCl3): δ (ppm) 91.8, 128.8, 130.9, 178.0, MS (EI), m/z (%) = 490 (M+ +2) (25 %), 461, 443, 409, 384, 369, 350, 331, 318, 302, 268, 255, 239, 212, 181, 167, 149, 136, 104, 90, 77, 57, 43.
Preparation of 1-hydroxy-4-(perfluoropyridin-4-yloxy) anthracene-9,10-dione 3c and 1,4-bis(perfluoropyridin-4-yloxy)anthracene-9,10-dione 3d
Pentafluoropyridine 1 (0.16 g, 1 mmol), 1,4-dihydroxyanthracene-9,10-dione 3 (0.24 g, 1 mmol) and potassium carbonate (0.11 g, 1.0 mmol) were heated in DMF (5 mL) at reflux for 12 h (monitored by TLC). After completion of the reaction, the solvent was evaporated to dryness; water (10 mL) was added and extracted with dichloromethane (2 × 10 mL) and ethylacetate (2 × 10 mL). The mixture was filtered, volatiles evaporated and the residue purified by column chromatography on silica gel using ethyl acetate/n-hexane (1:10).
1-hydroxy-4-(perfluoropyridin-4-yloxy)anthracene-9,10-dione
3c
(0.16 g, 41 %) as a yellow solid; mp 355 °C dec; 1H NMR (CDCl3): δ (ppm) 4.1 (1H, s, OH), 7.2-8.3 (6H, m, Ar–H), 19F NMR (CDCl3): δ (ppm) −88.2 (2F, s, F-2,6), −158.1 (2F, s, F-3,5),13C NMR (CDCl3): δ (ppm) 126.5, 127.0, 133.6, 133.9, 138.8, 145.4, 148.5, 160.9, 188.9, MS (EI), m/z (%) = 389 (M), 371, 354, 340, 321, 307, 290, 263, 237, 212, 195, 181, 157, 143, 125, 112, 91, 77, 57, 43.
1,4-bis(perfluoropyridin-4-yloxy)anthracene-9,10-dione
3d
(0.06 g, 11 %) as a red/black solid; mp 315 °C dec; 1H NMR (CDCl3): δ (ppm) 4.2 (1H, s, OH), 7.2–8.7 (6H, m, Ar–H), 19F NMR (CDCl3): δ (ppm) −87.5 (2F, s, F-2,6), −91.8 (2F, s, F-2′,6′), −156.5 (2F, s, F-3,5), −162.6 (2F, s, F-3′,5′),13C NMR (CDCl3): δ (ppm) 120.9, 122.2, 123.4, 123.6, 124.5, 127.1, 128.5, 129.1, 130.1, 132.4, 136.5, 139.2, 140.4, 146.4, 147.4, 166.1, 170.2, MS (EI), m/z (%) = 538 (M), 496, 480, 439, 411, 398, 384, 362, 347, 331, 316, 302, 283, 270, 255, 239, 225, 209, 196, 181, 167, 154, 129, 105, 86, 57, 43.
Preparation of 1-hydroxy-8-(perfluoropyridin-4-yloxy)anthracene-9,10-dione 4e
Pentafluoropyridine 1 (0.16 g, 1 mmol), 1,8-dihydroxyanthracene-9,10-dione 4 (0.24 g, 1 mmol) and potassium carbonate (0.11 g, 1.0 mmol) were heated in DMF (5 mL) at reflux for 12 h (monitored by TLC). After completion of the reaction, the solvent was evaporated to dryness; water (10 mL) was added and extracted with dichloromethane (2 × 10 mL) and ethylacetate (2 × 10 mL). The mixture was filtered, volatiles evaporated and the residue purified by column chromatography on silica gel using ethyl acetate/n-hexane (1:8).
1-hydroxy-8-(perfluoropyridin-4-yloxy)anthracene-9,10-dione
4e
(0.09 g, 23 %) as a red solid; mp 340 °C dec; 1H NMR (CDCl3): δ (ppm) 4.3 (1H, s, OH), 7.1–8.0 (6H, m, Ar–H), 19F NMR (CDCl3): δ (ppm) −91.6 (2F, s, F-2,6), −162.5 (2F, s, F-3,5),13C NMR (CDCl3): δ (ppm) 120.9, 122.2, 123.2, 123.6, 124.5, 127.1, 128.8, 130.2, 130.9, 131.2, 132.4, 136.5, 139.2, 140.4, 146.4, 147.9, 161.0, 164.0, 167.8. MS (EI), m/z (%) = 389 (M+), 387, 370, 364, 360, 342, 316, 299, 281, 255, 240, 223, 202, 184, 169, 155, 141, 127, 101, 79, 57, 43.