Supplementary Material for Photochemical & Photobiological Sciences

Supplementary Material for Photochemical & Photobiological Sciences

This journal is © The Royal Society of Chemistry and Owner Societies 2002

Supplementary Information

Experimental

Coumarin carboxylic acid (1) and 7-hydroxycoumarin (8) were purchased from Aldrich and Wako Pure Chemicals, respectively.

Synthesis.

3-Acetylcoumarin (2) [S1], 3-carbethoxycoumarin (3) [11a], 3-benzoylcoumarin (4) [11b], 3-carbethoxy-7-hydroxycoumarin (5) [2a,2b], 3-acetyl-7-hydroxycoumarin (6) [2b], 3-benzoyl-7-hydroxycoumarin(7) [2b], 3-carbethoxy-7-methoxycoumarin (9) [S2], 3-acetyl-7-methoxycoumarin (10) [21], 3-benzoyl-7-methoxycoumarin (11) [S3], 7-methoxycoumarin (12) [21], 7-acetoxy-3-carbethoxycoumarin (13) [S2], 7-acetoxy-3-acetylcoumarin (14) [S2], 7-acetoxy-3-benzoylcoumarin (15) [S2], 7-acetoxycoumarin (16) [12], 3-carbethoxy-7-diethylaminocoumarin (17) [S4], 3-acetyl-7-diethylaminocumarin (18) [S5], 3-benzoyl-7-diethylaminocumarin (19) [S3],7-methoxy-3-methylquinoxalinone (22) [13c], 3-methyl-7-nitroquinoxalinone (23) [13a], 3-methyl-6-nitroquinoxalinone (24) [13a], 3-ethoxycarbonylquinoxalinone (27) [13d], 3-ethoxycarbonyl-7-nitroquinoxalinone (32) [13d], 3-phenylquinoxalinone (34) [13b], 7-nitro-3-phenylquinoxalinone (37) [13f], 3-methyl-1,4-benzoxazinone (40) [14b, 14c], 3-phenyl-1,4-benzoxazinone (41) [14b], 7-methoxy-3-methyl-1,4-benzoxadinone (42) [14e], 7-methoxy-3-phenyl-1,4-benzoxadinone (43) [14c] and 7-hydroxay-3-methyl-1,4-benzoxadinone (44) [14d] were synthesized and purified as previously reported.

3-Cyano-7-diethylaminocoumarin (20). 4-Ethylaminosalicylaldehyde (325 mg) and cyanoethylacetate (495 mg) were dissolved in ethanol (15 ml). After the addition of pyperidine (0.5 ml), the mixture was refluxed for 90 min. The precipitates were collected and were chromatographed on silica gel with ethyl acetate-n-hexane-dichloromethane (1:2:1) to afford 20 (96 mg, 24%) as a yellow powder. mp: 228-229ºC. H (CDCl3) 7.94 (1H, s), 7.28 (1H, d, J 8.8), 6.61 (1H, dd, J8.8 2.4), 6.44 (1H, d, J 2.4), 3.44 (4H, q, J 7.2), 1.22 (6H, t, J 7.2). APCI-MS: m/z 243 [(M+H)+].

7-Aminoquinoxalinone (21).32 (62 mg) was dissolved in a mixture of benzene (10 ml), methanol (4 ml) and conc. hydrochloric acid (2 ml). After the addition of iron powder (128 mg), the mixture was vigorously stirred at 50ºC for 30 min and neutralized with NaHCO3 solution. The reaction mixture was poured into dichloromethane (100 ml) and 21 was extracted with dichloromethane (100 ml) three times. The organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-methanol (9:1) to afford 21 (6.8 mg, 17.9%) as a yellow powder. mp: >300ºC. H (CD3OD) 7.75 (1H, s), 7.47 (1H, d, J 8.8), 6.69 (1H, dd, J8.8 2.4), 6.41 (1H, d, J 2.4). APCI-MS: m/z 162 [(M+H)+].

7-Amino-3-methylquinoxalinone (25).23 (70 mg) was dissolved in a mixture of benzene (15 ml), methanol (20 ml) and conc. hydrochloric acid (2 ml). After the addition of iron powder (380 mg), the mixture was vigorously stirred at 50ºC for 45 min and neutralized with NaHCO3 solution. The reaction mixture was poured into dichloromethane (100 ml) and 25 was extracted with dichloromethane (100 ml) three times. The organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-methanol (9:1) to afford 21 (1.1 mg, 1.8%) as a yellow powder. mp: 298-300ºC (decomp.). H (CD3OD) 7.32 (1H, d, J 8.8), 6.58 (1H, dd, J8.8 2.4), 6.33 (1H, d, J 2.4), 2.30 (3H, s). APCI-MS: m/z 176 [(M+H)+].

6-Amino-3-methylquinoxalinone (26).24 (113 mg) was dissolved in a mixture of dichloromethane (20 ml), methanol (10 ml) and conc. hydrochloric acid (2 ml). After the addition of iron powder (260 mg), the mixture was vigorously stirred at room temperature for 2 h and neutralized with NaHCO3 solution. The reaction mixture was poured into dichloromethane (100 ml) and 26 was extracted with dichloromethane (100 ml) three times. The organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-methanol (9:1) to afford 26 (4.6 mg, 4.7%) as a yellow powder. mp: 293-295ºC (decomp.). H (CD3OD) 7.00 (1H, d, J 8.7), 6.95 (1H, d, J 2.3), 6.87 (1H, dd, J 8.72.3), 2.38 (3H, s). APCI-MS: m/z 176 [(M+H)+].

3-Ethoxycarbonyl-7-methoxyquinoxalinone (28). 4-Methoxy-1,2-phenylenediamine (390 mg) was dissolved in ethanol (80 ml). After the addition of diethyl ketomalonate (532 mg), the mixture was refluxed for 90 min and concentrated in vacuo. The residue was recrystalized from ethanol four times to afford 28 (19.4 mg, 2.8%) as a white powder. mp: 227-229ºC. H (CDCl3) 7.86 (1H, d, J 9.1), 7.02 (1H, d, J 9.1), 6.73 (1H, s), 4.51 (2H, q, J 7.1), 3.92 (3H, s), 1.45 (3H, t, J 7.1). APCI-MS: m/z 249 [(M+H)+].

3-Ethoxycarbonyl-6-methoxyquinoxalinone (29). 4-Methoxy-1,2-phenylenediamine (182 mg) was dissolved in ethanol (50 ml). After the addition of diethyl ketomalonate (600 mg), the mixture was refluxed for 150 min and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-n-hexane (2:1) to afford 29 (15.0 mg, 4.6%) as a yellow powder. mp: 172-174ºC. H (CDCl3) 7.41 (1H, d, J 9.0), 7.38 (1H, d, J 2.7), 7.30 (1H, dd, J 9.0 2.7), 4.55 (2H, q, J 7.0), 3.87 (3H, s), 1.47 (3H, t, J 7.0). APCI-MS: m/z 249 [(M+H)+].

3-Ethoxycarbonyl-7-hydroxyquinoxalinone (30) and 3-ethoxycarbonyl-6-hydroxyquinoxalinone (31). 4-Hydroxy-2-nitroaniline (135 mg) was dissolved in a mixture of benzene (20 ml), methanol (2 ml) and conc. hydrochloric acid (2 ml). After the addition of iron powder (770 mg), the mixture was refluxed for 3 h and neutralized with NaOH solution. The reaction mixture was poured into dichloromethane (100 ml) and 4-hydroxy-1,2-phenylenediamine was extracted with dichloromethane (100 ml) three times. The organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was added to conc. HCl (2ml) and recrystalized from ethanol to afford 4-hydroxy-1,2-phenylenediamine monohydrochloride (13.3 mg, 9.5%) as a pink powder. 4-Hydroxy-1,2-phenylenediamine monohydrochloride (394 mg) was dissolved in ethanol (50 ml). After the addition of diethyl ketomalonate (1.0 g), the mixture was stirred at 60ºC for 1 h and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-dichloromethane-methanol to afford 30 (30 mg, 5.2 %) as a yellow powder and 31 (13.0 mg, 2.3%) as a yellow powder. 30. mp: 281-284ºC (decomp.). H (CD3CN) 7.56 (1H, d, J 8.5), 6.76 (1H, dd, J8.5 2.7), 6.59 (1H, d, J 2.7), 4.28 (2H, q, J 7.2), 1.26 (3H, t, J 7.2). APCI-MS: m/z 235 [(M+H)+].31. mp: 258-260ºC (decomp.). H (CD3CN) 7.05-7.15 (3H, m), 4.31 (2H, q, J 7.2), 1.27 (3H, t, J 7.2). APCI-MS: m/z 235 [(M+H)+].

7-Amino-3-ethoxycarbonylquinoxalinone (33).32 (225 mg) was dissolved in a mixture of dichloromethane (20 ml), ethanol (15 ml) and conc. hydrochloric acid (3 ml). After the addition of iron powder (300 mg), the mixture was vigorously stirred at room temperature for 30 min and neutralized with NaHCO3 solution. The reaction mixture was poured into dichloromethane (100 ml) and 33 was extracted with dichloromethane (100 ml) three times. The organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-methanol (9:1) to afford 33 (83 mg, 41.6%) as a yellow powder. mp: 268-270ºC (decomp.). H (CD3OD) 7.54 (1H, d, J 8.8), 6.74 (1H, d, J 8.8 2.3), 6.36 (1H, dd, J 2.3), 4.38 (2H, q, J 7.2), 1.38 (3H, t, J 7.2). APCI-MS: m/z 234 [(M+H)+].

7-Methoxy-3-phenylquinoxalinone (35) and 6-methoxy-3-phenylquinoxalinone (36). 4-Methoxy-1,2-phenylenediamine monohydrochloride (119 mg) was dissolved in 10% H2SO4 (25 ml). After the addition of benzoylformic acid (250 mg), the mixture was stirred at 70ºC for 2 h.The precipitates were corrected and were chromatographed on silica gel with ethyl acetate-n-hexane (1:2) to afford 35 (31.4 mg, 14.5%) as a pale yellow powder and 36 (12.4 mg, 5.7%) as a yellow powder. 35. mp: 240-241ºC. H (CDCl3) 10.05(1H, br), 8.33 (2H, m), 7.81 (1H, d, J 8.8), 7.46 (3H, m), 6.93 (1H, d, J 8.8), 6.61 (1H, s), 3.89 (3H, s). APCI-MS: m/z 254 [(M+H)+]. 36. mp: 248-250ºC. H (CDCl3) 8.35 (2H, m), 7.48 (3H, m), 7.39 (1H, d, J 2.7), 7.13 (2H, m), 3.88 (3H, s). APCI-MS: m/z 254 [(M+H)+].

7-Amino-3-phenylquinoxalinone (38).37 (93 mg) was dissolved in a mixture of dichloromethane (20 ml), ethanol (15 ml) and conc. hydrochloric acid (3 ml). After the addition of iron powder (235 mg), the mixture was vigorously stirred at room temperature for 30 min and neutralized with NaHCO3 solution. The reaction mixture was poured into dichloromethane (100 ml) and 38 was extracted with dichloromethane (100 ml) three times. The organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-n-hexane (3:1) to afford 38 (39 mg, 47.2%) as a yellow powder. mp: 300-301ºC (decomp.). H (CD3OD) 8.04 (2H, m), 7.46 (1H, d, J 8.6), 7.33 (3H, m), 6.63 (1H, dd, J 8.6 2.4), 6.35 (1H, dd, J 2.4). APCI-MS: m/z 236 [(M–H)-].

7-Acetylamino-3-phenylquinoxalinone (39). 38 (30.2 mg) was dissolved in pyridine (5 ml). After the addition of acetic anhydride (2 ml), the mixture was stirred at 70ºC for 2 h. The solution was poured into 2N HCl (60 ml) and extracted using AcOEt (300 ml). The organic layer was dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-n-hexane (3:1) to afford 39 (26.9 mg, 75.6%) as a yellow powder. mp: >300ºC. H (CD3OD) 8.14 (2H, m), 7.92 (1H, d, J 2.3), 7.69 (1H, d, J 8.8), 7.37 (3H, m), 7.20 (1H, dd, J 8.8 2.3), 2.09 (3H, s). APCI-MS: m/z 278 [(M–H)-].

7-Hydroxy-3-phenyl-1,4-benzoxadinone (45). 2-Aminoresorcin monohydrochloride (100 mg) was dissolved in ethanol (2.5 ml). After the addition of triethylamine (62.5 mg), benzoylformic acid (93 mg), and acetic acid (0.2 ml), the mixture was stirred at room temperature for 2 h and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate-n-hexane (2:1) to afford 45 (60 mg, 41%) as a yellow powder. mp: 228ºC. H (CD3CN) 8.11 (2H, m), 7.58 (1H, d, J 8.8), 7.43 (3H, m), 6.82 (1H, dd, J 8.8, 2.6), 6.70 (1H, d, J 2.6). APCI-MS: m/z 240 [(M+H)+].

3-Ethoxycarbonyl-7-hydroxy-1,4-benzoxadinone (46). A yellow powder. mp: 197ºC. H (CD3CN) 7.58 (1H, d, J 8.8), 6.83 (1H,dd, J 8.8 2.4), 6.68 (1H, d, J 2.4), 4.31 (2H, q, J 7.1), 1.28 (3H, t, J 7.1). APCI-MS: m/z 208 [(M+H)+].

References

S1. O. Widman, Ueber Desmotropie zwischen Acetyl- und Oxyvinyl-Gruppen, Ber., 1902, 35, 1153-1159.

S2. (a) S. Rangaswami and T. R. Seshadri, A note on certain constitutional factors controlling visible fluorescence in compounds of the benzo-pyrone group , Proc. Indian. Acad. Sci., 1940, 12A, 375-380. (b) S. Rangaswami, T. R. Seshadri and V. Venkateswarlu, The remarkable fluorescence of certain coumarin derivatives, Proc. Indian. Acad. Sci., 1940, 13A, 316-321.

S3. D. P. Specht, P. A. Martic and S. Farid, Ketocoumarins – a new class of triplet sensitizers, Tetrahedron, 1982, 38, 1203-1211.

S4. E. R. Bissell, An improved synthesis of certain 3-ethoxycarbonylcoumarins, Synthesis, 1982, 10, 846-848.

S5. F. Gao, H. R. Li and Y. Yang, Influence of the molecular structure and medium on the absorption and emission character of ketocoumarin derivatives and probability of as fluorescence probes, Dyes Pigments, 2000, 47, 231-238.

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