Molecules 2002, 7
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was removed in vacuo and water (20 mL) added to the resultant precipitate. The solution formed was
then extracted exhaustively with CH2Cl2, the extract concentrated in vacuo, and the crude product
recrystallised from hexane to yield 10a as light brown shiny crystals (0.102 g, 70%), mp 194-196°C;
1
IR cm-1: 1727, 1678, 1621; H-NMR δH: 3.45 (3H, s, -NH-CH3), 3.85 (3H, s, -O-CH3), 3.90 (3H, s, -
O-CH3), 6.05 (1H, s, H-7), 6.80-6.90 (2H, m, H-4, H-4'), 7.29-7.38 (1H, dd, J = 1, 8, H-5'), 7.50-7.70
(2H, m, H-3, H-6'), 8.09-8.18 (1H, dd, J = 1, 8, H-3'); 13C-NMR δC: 39.2, 55.7, 55.7, 94.5, 102.1,
111.6, 118.4, 128.0, 129.1, 129.4, 131.7, 132.8, 143.3, 146.5, 147.0, 149.2, 149.5, 159.1, 166.4; MS
m/e (relative intensity) 355 (M+, 46), 310 (12), 205 (100), 149 (40). HRMS calcd. for C19H17NO6:
355.1056. Found: 355.1071.
5,6-Dimethoxy-3-methylbenzofuran-2-carboxylic acid methyl phenyl amide (13).
To a mixture of N-methylaniline (0.462 g, 4.31 mmol) in CH2Cl2 (25 mL), 3-methyl-5,6-
dimethoxybenzofuran-2-carboxylic acid [21] (1.01 g, 4.27 mmol) was added with stirring. DMAP
(0.090 g, 0.44 mmol) was then added, followed by DCC (0.934 g, 4.53 mmol). The reaction mixture
was left to stir at room temperature for 23 h. After this time the mixture was filtered and the filtrate
was washed successively with water (2 x 10 mL), 5% acetic acid (2 x 10 mL) and again with water (2 x
10 mL). The organic solution was then dried (Na2SO4) and concentrated in vacuo. The crude product
was recrystallised from hexane to yield 13 as brown diamond shaped crystals (0.852 g, 62%), mp 102-
103°C; IR cm-1: 1653, 1620, 1597; 1H-NMR δH: 2.40 (3H, s, Ar-CH3), 3.50 (3H, s, -N-CH3), 3.80 (3H,
13
s, -O-CH3), 3.85 (3H, s, -O-CH3), 6.56 (1H, s, H-7), 6.85 (1H, s, H-4), 7.10-7.35 (5H, m, -N-Ar); C-
NMR δC: 9.2, 39.2, 56.2, 56.2, 94.7, 100.8, 120.7, 122.6, 126.0, 126.3, 128.9, 143.3, 144.5, 146.7,
148.4, 149.8, 161.6. Anal. Calcd. for C19H19NO4: C, 70.14; H, 5.89; N, 4.31. Found: C, 69.81; H,
6.04; N, 4.58%.
3-Bromomethyl-5,6-dimethoxybenzofuran-2-carboxylic acid methyl phenyl amide (14).
To a mixture of the amide 13 (1.66 g, 5.10 mmol) in CCl4 (100 mL), N-bromosuccinimide (NBS)
(1.11 g, 6.24 mmol) was added with stirring. The reaction was then enclosed in a dark box and
irradiated with a 100 W light bulb which allowed gentle reflux. After 24 h the mixture was filtered, the
filtrate was concentrated in vacuo, and the resulting crude product was triturated with hot hexane to
yield 14 as a tan powder (1.50 g, 73%), mp 113-115°C; IR cm-1: 1702, 1602, 1595; 1H-NMR δH: 3.50
(3H, s, -N-CH3), 3.80 (3H, s, -O-CH3), 3.90 (3H, s, -O-CH3), 5.00 (2H, s, -CH2-Br), 6.50 (1H, s, H-7),
13
7.05 (1H, s, H-4), 7.15-7.36 (5H, m, -N-Ar); C-NMR δC: 22.2, 39.3, 56.3, 56.3, 94.6, 100.8, 118.5,
123.24, 126.0, 126.1, 126.8, 128.9, 129.1, 143.9, 144.0, 147.1, 148.5, 150.3, 160.4. Anal. Calcd. for
C19H18BrNO4: C, 56.45; H, 4.49; N, 3.46. Found: C, 56.19; H, 4.57; N, 3.86. %.