M. Dubernet et al. / Tetrahedron 61 (2005) 4585–4593
4589
4.75 (2H, s, N–CH2), 3.79–3.41 (8H, m, 4CH2CH3), 1.22
(12H, t, JZ7.0 Hz, 4CH2CH3); dC (200 MHz, CDCl3) 169.1
(2C]O), 155.3 (2C), 145.5 (2C), 136.3 (C), 128.6
(2CHarom.), 128.4 (2CHarom.), 128.4 (2CHvinyl.), 127.7
(CHarom.), 120.3 (2CHvinyl.), 119.9 (2CHfuran.), 117.9 (2C),
112.1 (2CHfuran.), 100.0 (2CH(OEt)2), 60.9 (4CH2), 41.8
(N–CH2), 15.2 (4CH3); m/z 576 (MC1), 598 (MC23);
(Anal. Calcd for C33H37NO8: C, 68.85; N, 2.43; H, 6.48.
Found: C, 68.79; N, 2.41; H, 6.39).
8.7 Hz, Harom.), 6.83 (2H, d, JZ8.7 Hz, Harom.), 6.61 (2H, d,
JZ3.5 Hz, Hfuran.), 5.65 (2H, s, 2CH(OEt)2), 4.68 (2H, s,
N–CH2), 3.76 (3H, s, O–CH3), 3.64 (8H, dq, JZ7.1, 1.5 Hz,
4CH2CH3), 1.22 (12H, t, JZ7.1 Hz, 4CH2CH3); dC
(200 MHz, CDCl3) 168.7 (2C]O), 158.7 (C–O), 155.0
(2C), 144.6 (2C), 129.5 (2CHarom.), 128.1 (C), 118.3
(2CHfuran.), 118.2 (2C), 113.5 (2CHarom.), 110.5 (2CHfuran.),
95.6 (2CH(OEt)2), 60.9 (4CH2), 54.8 (N–CH2), 40.8 (CH2),
14.7 (4CH3); m/z 508 (MK[OEt]), 571 (MC18), 576
(MC23); (Anal. Calcd for C30H35NO9: C, 65.09; N, 2.53;
H, 6.37. Found: C, 65.01; N, 2.49; H, 6.44).
4.2.4. 3,4-Bis[(5-diethoxymethyl)fur-2-yl]-2,5-dihydro-1-
benzyl-1H-pyrrol-2,5-dione (4d). Red solid (73%), mp
107–109 8C; nmax (KBr)/cmK1 3054, 2979, 2932, 1769,
1706, 1679, 1434, 1401, 1114, 1057, 1018; dH (200 MHz,
CDCl3) 7.54 (2H, d, JZ3.5 Hz, Hfuran.), 7.41–7.21 (5H, m,
Harom.), 6.65 (2H, d, JZ3.5 Hz, Hfuran.), 5.68 (2H, s,
2CH(OEt)2), 4.75 (2H, s, N–CH2), 3.64 (8H, dq, JZ1.6,
7.0 Hz, 4CH2CH3), 1.24 (12H, t, JZ7.0 Hz, 4CH2CH3); dC
(200 MHz, CDCl3) 168.9 (2C]O), 155.4 (2C), 144.9 (2C),
136.1 (C), 128.5 (2CHarom.), 128.3 (2CHarom.), 127.6
(CHarom.), 118.7 (2CHfuran.), 118.4 (2C), 110.9 (2CHfuran.),
95.9 (2CH(OEt)2), 61.2 (4CH2), 41.6 (N–CH2), 15.0
(4CH3); m/z 524 (MC1), 541 (MC18), 546 (MC23);
(Anal. Calcd for C29H33NO8: C, 66.53; N, 2.68; H, 6.35.
Found: C, 66.63; N, 2.61; H, 6.29).
4.2.8. 3,4-Bis[(5-diethoxymethyl)furan-2-yl]-2,5-di-
hydro-1-(4-hydroxybenzyl)-1H-pyrrol-2,5-dione (4h).
Red oil (62%); nmax(film)/cmK1 3054, 2986, 1708, 1680,
1614, 1517, 1422, 1156, 1053; dH (200 MHz, CDCl3) 7.51
(2H, d, JZ3.5 Hz, Hfuran.), 7.21 (2H, d, JZ8.4 Hz, Harom.),
6.73 (2H, d, JZ8.4 Hz, Harom.), 6.61 (2H, d, JZ3.5 Hz,
Hfuran.), 5.65 (2H, s, 2CH(OEt)2), 4.63 (2H, s, N–CH2), 3.62
(8H, dq, JZ1.5, 7.1 Hz, 4CH2CH3), 1.21 (12H, t, JZ
7.1 Hz, 4CH2CH3); dC (200 MHz, CDCl3) 169.2 (2C]O),
155.9 (C–O), 155.4 (2C), 145.1 (2C), 130.0 (2CHarom.),
127.9 (C), 118.8 (2CHfuran.), 118.7 (2C), 115.5 (2CHarom.),
111.0 (2CHfuran.), 96.1 (2CH(OEt)2), 61.5 (4CH2), 41.4
(N–CH2), 15.1 (4CH3); m/z 540 (MC1), 562 (MC23);
(Anal. Calcd for C29H33NO9: C, 64.55; N, 2.60; H, 6.16.
Found: C, 64.32; N, 2.49; H, 6.05).
4.2.5. 3,4-Bis[(5-diethoxymethyl)thien-2-yl]-2,5-dihydro-
1-benzyl-1H-pyrrol-2,5-dione (4e). Red oil (65%);
nmax(film)/cmK1 1741, 1699, 1284; dH (200 MHz, CDCl3)
7.75 (2H, d, JZ3.9 Hz, Hthiophen.), 7.27–7.44 (5H, m,
Harom.), 7.08 (2H, d, JZ3.9 Hz, Hthiophen), 5.76 (2H, s,
2CH(OEt)2), 4.75 (2H, s, N–CH2), 3.64 (8H, q, JZ7.1 Hz,
4CH2CH3), 1.25 (12H, t, JZ7.1 Hz, 4CH2CH3); dC
(200 MHz, CDCl3) 169.5 (2C]O), 148.5 (2C), 136.0
(2C), 131.1 (C), 129.5 (2CHarom.), 128.5 (2CHarom.), 128.4
(CHarom.), 127.6 (2CHthiopen.), 126.9 (2C), 125.3
(2CHthiophen.), 97.9 (2CH(OEt)2), 60.8 (4CH2), 41.9 (N–
CH2), 14.9 (4CH3); m/z 556 (MC1), 578 (MC23); (Anal.
Calcd for C29H33NO6S2: C, 62.68; N, 2.52; H, 5.99. Found:
C, 62.55; N, 2.55; H, 6.07).
4.3. 4-Bis[(5-formyl)heteroar-2-yl]-2,5-dihydro-1-(substi-
tuted)-1H-pyrrol-2,5-dione (5a–h). General procedure
A solution of 4a–h (1.59 mmol) and trifluoroacetic acid
(1.21 mL, 15.90 mmol) in THF (15 mL) was stirred at room
temperature during 2 h. Then, the mixture was taken up in
pentane (30 mL), filtered and the precipitate was washed
with pentane to give the title compounds 5a–h.
4.3.1. 3,4-Bis[(5-formyl)fur-2-yl]-2,5-dihydro-1H-pyr-
rol-2,5-dione (5a). Red solid (86%), mp 249 8C;
nmax(KBr)/cmK1 3055, 2987, 1738, 1681, 1653, 1551,
1436, 1345, 1185, 1032, 814; dH (200 MHz, CDCl3) 9.92
(2H, s, CHO), 7.78 (2H, d, JZ3.8 Hz, Hfuran.), 7.55 (1H, br
s, NH), 7.4 (2H, d, JZ3.8 Hz, Hfuran.); dC (200 MHz,
CDCl3) 179.6 (2CHO), 169.2 (2C]O), 153.4 (2C), 148.3
(2C), 122.1 (2CHfuran.), 121.6 (2C), 120.0 (2CHfuran.); m/z
286 (MC1), 308 (MC23), 318 (MC33); (Anal. Calcd for
C14H7NO6: C, 58.96; N, 4.91; H, 2.47. Found: C, 58.93; N,
4.71; H, 2.49).
4.2.6. 3,4-Bis[(5-diethoxymethyl)fur-2-yl]-2,5-dihydro-1-
(phenylethyl)-1H-pyrrol-2,5-dione (4f). Red solid (60%),
mp 45–46 8C; nmax(KBr)/cmK1 2976, 2931, 1764, 1705,
1618, 1583, 1527, 1438, 1362, 1115, 1017; dH (200 MHz,
CDCl3) 7.51 (2H, d, JZ3.5 Hz, Hfuran.), 7.34–7.21 (5H, m,
Harom.), 6.63 (2H, d, JZ3.5 Hz, Hfuran.), 5.67 (2H, s,
2CH(OEt)2), 3.82 (2H, t, JZ7.3 Hz, CH2), 3.65 (8H, dq,
JZ1.9, 7.0 Hz, 4CH2CH3), 2.94 (2H, t, JZ7.3 Hz, CH2),
1.24 (12H, t, JZ7.0 Hz, 4CH2CH3); dC (200 MHz, CDCl3)
169.1 (2C]O), 155.5 (2C), 145.1 (2C), 138.0 (C), 128.8
(2CHarom.), 128.5 (2CHarom.), 126.5 (CHarom.), 118.7
(2CHfuran.), 118.4 (2C), 110.9 (2CHfuran.), 96.1
(2CH(OEt)2), 61.4 (4CH2), 39.5 (N–CH2), 34.5 (CH2),
15.1 (4CH3); m/z 555 (MC18), 560 (MC23); (Anal. Calcd
for C30H35NO8: C, 66.53; N, 2.68; H, 6.35. Found: C, 66.69;
N, 2.75; H, 6.46).
4.3.2. 3,4-Bis[(5-formyl)fur-2-yl]-2,5-dihydro-1-phenyl-
1H-pyrrol-2,5-dione (5b). Red solid (87%), mp 257 8C;
nmax(KBr)/cmK1 3055, 2987, 1713, 1675, 1600, 1549,
1404, 1339, 1166, 1028, 828; dH (200 MHz, CDCl3) 9.94
(2H, s, CHO), 7.85 (2H, d, JZ3.8 Hz, Hfuran.), 7.54–7.25
(7H, m, Hfuran., Harom.); dC (200 MHz, CDCl3) 178.8
(2CHO), 167.4 (2C]O), 153.9 (2C), 148.5 (2C), 131.8
(C), 129.4 (2CHarom.), 128.8 (CHarom.), 127.6 (2CHarom.),
122.6 (2CHfuran.), 121.5 (2C), 120.7 (2CHfuran.); m/z 362
(MC1), 379 (MC18); (Anal. Calcd for C20H11NO6: C,
66.49; N, 3.88; H, 3.07. Found: C, 65.21; N, 4.10; H, 3.00).
4.2.7. 3,4-Bis[(5-diethoxymethyl)fur-2-yl]-2,5-dihydro-1-
(4-methoxybenzyl)-1H-pyrrol-2,5-dione (4g). Red solid
(58%), mp 58–59 8C; nmax(KBr)/cmK1 3164, 3054, 2986,
1708, 1683, 1662, 1514, 1430, 1399, 1032; dH (200 MHz,
CDCl3) 7.51 (2H, d, JZ3.5 Hz, Hfuran.), 7.33 (2H, d, JZ
4.3.3. 3-(5-{1-Benzyl-2,5-dioxo-4-[5-(3-oxopropenyl) fur-
2-yl]-2,5-dihydro-1H-pyrrol-3-yl}fur-2-yl)-propenal