MODIFIED PYRIDINE-SUBSTITUTED COUMARINS
373
crude product, which was subjected to column chromatography using ethyl acetate–
petroleum ether (1:4) as eluent to obtain pure product 8a–f.
4-Methyl-3-phenyl-6-(1-phenyl-9,10-dihydro-4-azaphenanthren-3-yl)
coumarin (8a)
IR (KBr, nmax, cm−1): 700 and 752 (C-H bending of mono substituted benzene
=
=
=
ring), 1544 (C N aromatic stretching), 1608 (C C aromatic stretching), 1721 (C O
d-lactone stretching), 2919 (C-H aliphatic stretching), 3053 (C-H aromatic stretch-
1
0
ing); H NMR (400 MHz, CDCl3, d): 2.47 (3H, s, CH3), 2.89–3.00 (4H, m, C9
0
and C10 protons), 7.27–7.65 (15H, m, Ar-H), 8.37 (1H, dd, J ¼ 1.6 and 8.4 Hz,
C7-H), 8.53 (1H, d, J ¼ 1.6 Hz, C5-H), 8.58 (1H, concealed dd, C5 -H); 13C NMR
0
(100 MHz, CDCl3, d): 16.81 (CH3), 25.30 (CH2), 28.11 (CH2), 117.12 (CH),
119.66 (CH), 120.69 (C), 123.39 (CH), 125.61 (CH), 127.14 (CH), 127.52 (CH),
127.63 (C), 128.21 (CH), 128.25 (CH), 128.40 (C), 128.45 (CH), 128.58 (CH),
128.78 (CH), 129.32 (CH), 129.90 (CH), 130.10 (CH), 134.53 (C), 134.96 (C),
135.91 (C), 138.31 (C), 139.14 (C), 147.95 (C), 149.62 (C), 152.85 (C), 153.00 (C),
153.11 (C), 160.92 (d-lactone CO). Anal. calcd. for C35H25NO2: C, 85.52; H, 5.13;
N, 2.85%. Found: C, 85.38; H, 5.18; N, 2.81%.
General Procedure for the Synthesis of 4-Methyl-3-phenyl-6-(4-
phenylbenzofuro[3,2-b]pyridin-2-yl)coumarins 9a–f
A solution of 4-methyl-3-phenyl-6-coumarinoyl methyl pyridinium salt 6
(0.003 mol) in glacial acetic acid (50 mL) was taken in a round-bottom flask. To this
ammonium acetate (0.03 mol) and appropriate 2-arylidene aurone 5a–f (0.003 mol)
were added with stirring. The stirring was further continued for 45 min, and then
the reaction mixture was refluxed for 12 h. The reaction mixture was allowed to cool
to room temperature and was poured into ice-cold water. It was then extracted with
chloroform (3 × 30 mL). The chloroform extract was washed with water (2 × 20 mL)
and then dried over anhydrous Na2SO4. The removal of chloroform under reduced
pressure gave the crude product, which was subjected to column chromatography
using ethyl acetate–petroleum ether (1:4) as eluent to obtain pure product 9a–f.
4-Methyl-3-phenyl-6-(4-phenylbenzofuro[3,2-b]pyridin-2-yl)coumarin
(9a)
IR (KBr, nmax, cm−1): 700 and 752 (C-H bending of mono substituted benzene
=
=
=
ring), 1464 (C N aromatic stretching), 1609 (C C aromatic stretching), 1715 (C O
d-lactone stretching), 2921 (C-H aliphatic stretching), 3055 (C-H aromatic stretching);
1H NMR (400 MHz, CDCl3, d): 2.47 (3H, s, CH3), 7.29–7.71 (15H, m, Ar-H), 8.29
0
(1H, dd, J ¼ 1.6 and 8.4 Hz, C7-H), 8.35 (1H, concealed dd, C9 -H), 8.55 (1H, d,
J ¼ 1.6 Hz, C5-H); 13C NMR (100 MHz, CDCl3, d): 16.82 (CH3), 117.21 (CH),
117.96 (CH), 120.82 (C), 121.45 (CH), 123.93 (CH), 125.11 (CH), 127.37 (CH),
127.58 (C), 128.24 (CH), 128.29 (CH), 128.49 (CH), 128.86 (CH), 129.00 (CH),
129.08 (CH), 130.14 (CH), 130.21 (CH), 133.33 (C), 134.54 (C), 136.11 (C), 138.69
(C), 140.93 (C), 144.25 (C), 146.77 (C), 147.97 (C), 153.17 (C), 155.65 (C), 161.51