Molecules 2013, 18
1891
(hexane-ethyl acetate 1:3 v/v). mp 238.6–239.8 °C. IR (ATR, cm−1)
: 3470 (broad band), 3296
max
(broad band), 1712, 1614, 1469, 1011, 945, 715, 587. 1H-NMR (400 MHz, CDCl3 + DMSO-d6): 6.29
(d, 2H, J = 8.0 Hz, H-3'/H-5'), 6.92 (t, 1H, J = 8.0 Hz, H-4), 7.02 (s, 1H, H-3), 7.31 (d, 1H, J = 7.2 Hz,
H-4), 7.47 (t, 1H, J = 7.6 Hz, H-6), 7.59 (t, 1H, J = 7.2 Hz, H-5), 7.81 (d, 1H, J = 7.6 Hz, H-7). 13C-NMR
(100 MHz, CDCl3 + DMSO-d6): 75.6 (C-3), 106.9 (C-3'/C-5'), 108.6 (C-1'), 121.8 (C-4), 124.2 (C-7),
127.2 (C-8), 127.9 (C-6), 130.2 (C-4'), 133.3 (C-5), 151.1 (C-9), 157.5 (C-2'/C-6'), 171.5 (C-1). HREIMS
m/z (M+H+): Calculated for C14H11O4, 243.0657; found: 243.0658.
Compounds 15 and 16 were prepared using a procedure similar to that described for compound 14.
3-(2,6-Dihydroxy-4-methylphenyl)-isobenzofuran-1(3H)-one (15): The compound was obtained as a
pale yellow solid via aromatization of compound 12 in 71% yield (purified by silica gel column
chromatography, using hexane-ethyl acetate 1:3 v/v as the eluting solvent). The structure of the compound
is supported by the following data: TLC Rf = 0.82 (hexane-ethyl acetate 1:3 v/v). mp 228–231 °C. IR
(ATR, cm−1)
: 3579, 3201 (broad band), 2924, 2853, 1721, 1618, 1595, 1305, 1046, 952, 821,
max
734, 684, 535. 1H RMN (200 MHz, CDCl3 + MeOH-d4): 1.94 (s, 3H, -CH3), 5.94 (s, 2H, H-3'/H-5'),
6.82 (s, 1H, H-3), 7.11 (d, 1H, J = 7.2 Hz, H-4); 7.16–7.44 (m, 2H, H-5 e H-6), 7.62 (d, 1H, J = 7.2 Hz,
H-7). 13C-NMR (50 MHz, CDCl3 + MeOH-d4): 22.5 (-CH3), 72.2 (C-3), 106.9 (C-1'), 109.1 (C-3'/C-5'),
123.2 (C-4), 125.4 (C-6), 128.5 (C-8), 128.9 (C-7), 134.4 (C-5), 141.9 (C-4'), 152.6 (C-9), 158.3
(C-2'/C-6'), 173.2 (C-1). HREIMS m/z (M+H+): Calculated for C15H13O4, 257.0814; found: 257.0880.
3-(2,6-Dihydroxy-4-isopropylphenyl)-isobenzofuran-1(3H)-one (16): The compound was obtained as a
viscous orange oil via aromatization of compound 13 in 94% yield (purified by silica gel column
chromatography, using hexane-ethyl acetate 1:1 v/v as the eluting solvent). The structure of the
compound is supported by the following data: TLC Rf = 0.44 (hexane-ethyl acetate 1:1 v/v). IR (ATR,
cm−1)
: 3305 (broad band), 2959, 2924, 2870, 2159, 1726, 1621, 1596, 1433, 1034, 732. 1H-NMR
max
(300 MHz, MeOH-d4): 1,17 (d, 6H, J = 6.9 Hz, -CH(CH3)2), 2.68 (hept, 1H, J = 6.9 Hz;
-CH(CH3)2), 6.17 (s, 2H; H-3'/H-5'), 7.02 (s, 1H, H-3); 7.30 (dd, 1H, J = 7.5, J = 0.9 Hz, H-4),
7.49 (t, 1H, J = 7.2 Hz, H-5), 7.63 (td, 1H, J = 7.5, 1.2 Hz, H-6), 7.82 (d, 1H, J = 7.5 Hz, H-7). 13C-NMR
(75 MHz, MeOH-d4) : 22.9 (-CH(CH3)2), 34.2 (-CH(CH3)2), 76.8 (C-3), 104.6 (C-3/C-5'), 105.8 (C-1'), 121.8
(C-4), 124.1 (C-6), 127.0 (C-8), 128.0 (C-7), 133.7 (C-5), 151.8 (C-9), 152.3 (C-4'), 157.6 (C-2'/C-6'),
173.4 (C-1). HREIMS m/z (M+H+): Calculated for C17H17O4, 285.1127; found: 285.1116.
3.4. Synthesis of Compounds 17–19, Exemplified by the Synthesis of
2-(3-Oxo-1,3-dihydroisobenzofuran-1-yl)-1,3-phenylene diacetate (17)
A round-bottomed flask (25 mL) was charged with compound 14 (0.109 g, 0.45 mmol), chloroform
(5 mL), acetic anhydride (0.16 mL, 1.62 mmol), and a catalytic amount of DMAP (0.005 g, 0.045 mmol).
The reaction mixture was stirred at room temperature for 12 h. The solvent was removed and
compound 17 was purified by recrystallization from ethyl acetate affording a white solid in 44% yield
(0.064 g, 0.20 mmol). The structure of the compound is supported by the following data: TLC Rf = 0.54
(hexane-ethyl acetate 1:1 v/v). mp. 175.9–177.8 °C. IR (ATR, cm−1)
: 1756, 1611, 1465, 1369,
max
1
1285, 1170, 1023, 975; H-NMR (200 MHz, DMSO-d6): 2.01 (brs, 6H, 2 × -COCH3), 6.85 (s, 1H,