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HETEROCYCLES, Vol. 75, No. 12, 2008
residue obtained after the usual work-up was purified by silica gel column chromatography using AcOEt
/MeOH (9:1) as an eluent to give compound 3a as a bright yellow crystals (1.16 g, 97% yield), mp 236 °C.
IR (KBr): 3438, 3180, 1717, 1636-1424, 1315, 1268, 1246, 1072, 1069 cm-1. 1H NMR (DMSO-d6) δ 9.16
(s, 1H, H1); 8.06 (s, 1H, H6); 8.04 (s, 1H, H9); 4.06 (s, 3H, OMe); 4.02 (s, 3H, OMe); 3.99 (s, 3H,
CO2Me). 13C NMR (DMSO-d6) δ 163.5; 159.9; 159.2; 155.4; 155.3; 147.5; 145.7; 143.5; 130.0; 126.8;
117.3; 55.2; 54.1; 53.5. LC-MS: tr = 2.88 min. 305 [M+]. Anal. Calcd for C14H12N2O3S: C, 55.26; H,
3.97; N, 9.21. Found: C, 54.99; H, 3.72; N, 9.44.
Methyl 8-benzyloxy-7-methoxythieno[3,4-c]cinnoline-3-carboxylate (3b)
This compound was obtained following the same procedure described for 3a using methyl 3-amino-4-(3-
benzyloxy-4-methoxyphenyl)thiophene-2-carboxylate 1b. Bright orange powder (0.93 g, 90% yield), mp
1
236 °C. IR (KBr): 3090, 2925, 2237, 1704, 1607-1415, 1274, 1259, 1247, 1199, 1190, 1118 cm-1. H
NMR (DMSO-d6) δ 9.11 (s, 1H, H1); 8.20 (s, 1H, H6); 8.05 (s, 1H, H9); 7.57 (d, 3JHoHm = 5.9 Hz, 2H, Ho);
7.44 (dd, 3JHmHo = 3JHmHp = 5.9 Hz, 2H, Hm); 7.37 (t, 3JHpHm = 5.9 Hz, 1H, Hp); 5.37 (s, 2H, OCH2); 4.02 (s,
3H, OMe); 3.99 (s, 3H, CO2Me). 13C NMR (DMSO-d6) δ 160.8 (s, 1C, CO); 159.7 (s, 1C, CIV); 158.7 (s,
1C, CIV); 155.4 (s, 1C, CIV); 154.3 (s, 1C, CIV); 147.4 (s, 1C, CIV); 145.7 (s, 1C, CH); 144.9 (s, 1C, CH);
129.9 (s, 1C, C1H); 116.6 (s, 1C, CIV); 114.6 (s, 1C, CIV); 110.3 (s, 2C, CHo); 110.1 (s, 2C, CHm); 109.7
(s, 1C, CHp); 55.6 (s, 1C, CH2); 55.1 (s, 1C, Meester); 54.4 (s, 1C, OMe). LC-MS: tr = 10.02 min.; 381
[M+]. Anal. Calcd for C20H16N2O4S: C, 63.15; H, 4.24; N, 7.36. Found: C, 62.85; H, 4.48; N, 7.25.
Methyl 3-bromo-4-(4-methoxyphenyl)thiophene-2-carboxylate (4c)
This compound was obtained following the same procedure described for 3a using methyl 3-amino-4-(4-
methoxyphenyl)thiophene-2-carboxylate 1c
Crystallization from EtOH gave colorless crystals (8.14 g, 95% yield), mp 124 °C. IR (KBr): 3054, 1720,
1
3
1602-1418, 1275, 1117 cm-1. H NMR (DMSO-d6) δ 8.06 (s, 1H, H5); 7.37 (d, JHH = 7.8 Hz, 2H, HAr);
7.01 (d, 3JHH = 7.8 Hz, 2H, HAr); 3.84 (s, 3H, OMe); 3.79 (s, 3H, CO2Me). 13C NMR (DMSO-d6) δ 160.6
(s, 1C, CO); 159.2 (s, 1C, C2); 143.5 (s, 1C, CAr); 130.5 (s, 2C, CHAr); 130.0 (s, 1C, C5H); 127.3 (s, 1C,
C4); 126.7 (s, 1C, C3); 117.3 (s, 1C, CAr); 113.8 (s, 2C, CHAr); 55.2 (s, 1C, Meester); 52.5 (s, 1C, OMe).
MS m/z (%): 327-329 (19) [M+.]; 296-298 (100) [M+-(OMe)]; 268-270 (29) [M+-(CO2Me)]; 188 (35)
[M+-(Br, CO2Me)]; 173 (10). Anal. Calcd for C13H11BrO3S: C, 47.72; H, 3.39. Found: C, 47.89; H, 3.51.
Synthesis of diazonium tetrafluoroborate salts