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Helvetica Chimica Acta Vol. 86 (2003)
841, 755, 658. 1H-NMR: 12.09 (s, OH); 9.96 (s, CHO); 8.21 (br. d, J 7.2, HÀC(9)); 7.63 (d, J 8.4, HÀC(3));
7.60 (br. d, J 7.2, HÀC(6)); 7.50 (dt, J 8.1, 1.5, HÀC(7)); 7.43 (dt, J 7.5, 1.2, HÀC(8)); 7.23 (d, J 8.4,
HÀC(4)). 13C-NMR: 195.75 (s, CHO); 161.66 (s); 159.10 (s); 155.82 (s); 132.84( d); 127.07 (d); 123.81 (d);
123.09 (d); 122.56 (s); 116.08 (s); 113.16 (s); 111.32 (d); 104.59 (d). EI-MS: 213 (14, [M 1] ), 212 (100, M ),
211 (76), 183 (10), 155 (13), 149 (11), 127 (9), 97 (8), 83 (8), 71 (9), 69 (10). HR-MS: 212.0467 (M , C13H8O3
;
calc. 212.0473).
10. Coumarins 6 by Knoevenagel Condensation of the ortho-Hydroxyaldehydes 5: General Method. To a
soln. of ortho-hydroxyaldehyde 5 (0.0375 g, 0.177 mmol) in hot EtOH (10 ml) was added a soln. of diethyl
malonate (0.032 g, 0.20 mmol) in EtOH (1 ml), piperidine (1 drop), and AcOH (1 drop). The mixture was
refluxed for 5 h and then left at 08 overnight. The precipitate obtained was filtered and recrystallized from
EtOH.
Ethyl 3-Oxo-3H-benzofuro[3,2-f]-1-benzopyran-2-carboxylate (6a): From 5a. Yield 68%. Yellow crystals.
M.p. 167 1698 (EtOH). UV: 349 (4.25). IR (KBr): 3088, 2997, 2941, 1771s (br., CO), 1615, 1567, 1478, 1448,
1432, 1372, 1280, 1236, 1126, 1096, 1034, 979, 950, 818, 794, 750. 1H-NMR: 9.30 (s, HÀC(1)); 8.22 (br. d, J 8.4,
HÀC(11)); 7.86 (d, J 9.0, HÀC(5) or HÀC(6)); 7.70 (br. d, J 8.4, HÀC(8)); 7.61 (dt, J 7.5, 1.5, HÀC(9));
7.50 (dt, J 7.5, 1.5, HÀC(10)); 7.47 (d, J 9.0, HÀC(6) or HÀC(5)); 4.50 (q, J 7.2, MeCH2); 1.50 (t, J 7.2,
MeCH2). EI-MS: 309 (20, [M 1] ), 308 (100, M ), 263 (52), 236 (61), 208 (29), 179 (30), 150 (12). Anal. calc.
for C18H12O5: C 70.13, H 3.92; found: C 69.86, H 4.05.
Ethyl 2-Oxo-2H-benzofuro[2,3-g]-1-benzopyran-3-carboxylate (6b): From 5b. Yield 87%. Yellow crystals.
M.p. 186 1878(EtOH). UV: 348 (4.47). IR (KBr): 3063, 2983, 2905, 1760s (br., CO), 1638, 1613, 1568, 1455,
1433, 1396, 1366, 1257, 1206, 1040, 859, 798, 749. 1H-NMR ((D6)acetone): 8.85 (s, HÀC(4)); 8.30 (br. d, J 7.5,
HÀC(10)); 8.17 (s, HÀC(11) or HÀC(5)); 8.16 (s, HÀC(5) or HÀC(11)); 7.74(br. d, J 8.9, HÀC(7)); 7.70
(dt, J 7.8, 1.2, HÀC(8)); 7.51 (dt, J 7.2, 1.5, HÀC(9)); 4.37 (q, J 7.2, MeCH2); 1.38 (t, J 7.2, MeCH2). EI-
MS: 309 (20, [M 1] ), 308 (100, M ), 263 (68), 236 (65), 208 (30), 179 (34), 150 (11). Anal. calc. for C18H12O5:
C 70.13, H 3.92; found: C 70.28, H 4.10.
Ethyl 2-Oxo-2H-benzofuro[3,2-h]-1-benzopyran-3-carboxylate (6c): From 5c. Yield 44%. Light yellow
crystals. M.p. 215 2178 (EtOH) UV: 341 (4.27). IR (KBr): 3057, 2967, 1755 (CO), 1693 (CO), 1638, 1609,
1
1552, 1474, 1432, 1364, 1312, 1259, 1215, 1026, 976. H-NMR: 8.70 (s, HÀC(4)); 8.03 (br. d, J 7.5, HÀC(7));
7.89 (d, J 8.4, HÀC(5)); 7.73 (br. d, J 8.1, HÀC(10)); 7.62 (dt, J 7.2, 1.5, HÀC(9)); 7.56 (d, J 8.1,
HÀC(6)); 7.46 (dt, J 7.5, 0.9, HÀC(8)); 4.45 (q, J 7.2, MeCH2); 1.45 (t, J 7.2, MeCH2). MS: 309 (20, [M
1] ), 308 (100, M ), 263 (80), 236 (60), 208 (40), 179 (47), 150 (18). HR-MS: 308.0690 (M , C18H12O5 ; calc.
308.0685).
Ethyl 2-Oxo-2H-benzofuro[2,3-h]-1-benzopyran-3-carboxylate (6d): From 5d. Yield 20%. Light yellow
crystals. M.p. 172 1758 (EtOH). UV: 333 (4.22). IR (KBr): 3053, 2985, 2923, 1742 (CO), 1700 (CO), 1611,
1567, 1436, 1287, 1245, 1209, 1059, 812, 753. 1H-NMR: 8.72 (s, HÀC(4)); 8.45 (br. d, J 8.7, HÀC(11)); 7.69
(d, J 8.4, HÀC(5)); 7.66 (br. d, J 8.4, HÀC(8)); 7.58 (dt, J 7.5, 1.5, HÀC(9)); 7.56 (d, J 8.4, HÀC(6)); 7.50
(dt, J 7.2, 1.2, HÀC(10)); 4.45 (q, J 7.2, MeCH2); 1.45 (t, J 7.2, MeCH2). EI-MS: 309 (20, [M 1] ), 308
(100, M ), 263 (69), 236 (48), 208 (29), 179 (32). HR-MS: 308.0689 (M , C18H12O5 ; calc. 308.0685).
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