´ ´
J. L. Lopez-Perez et al. / Tetrahedron 62 (2006) 2370–2379
2377
1
1617, 1588, 1506, 1480, 1463, 1245, 1127, 1037, 1008,
1478, 1460, 1245, 1128, 1036, 1009, 937 cmK1; H NMR
(400 MHz, CDCl3) d: 2.73 (m, H-8a), 3.06 (d, JZ6.0 Hz,
H-80), 3.58 (s, H-14), 3.74 (s, H-11, H-13), 3.82 (s, H-12),
4.49 (d, JZ6.0 Hz, H-70), 5.62 (sa, H-10), 5.97 (dd, JZ3.0,
5.0 Hz, H-8b), 6.24 (dd, JZ3.0, 5.0 Hz, H-8c), 6.31 (s, H-20,
H-60), 6.41 (s, H-3), 7.53 (s, H-6). 13C NMR (100 MHz,
CDCl3) d: 35.50 (C-9), 42.56 (C-8d), 46.53 (C-8a), 46.78
(C-70), 48.11 (C-08e), 51.8 (C-14), 51.86 (C-8), 56.12 (C-11
13), 56.12 (C-8 ),0 60.83 (C-12), 101.70 (C-10), 105.74
(C-6), 106.29 (C-2 60), 108.97 (C-03), 127.79 (C-1), 134.70
(C-8b), 136.94 (C-40), 139.0 (C-1 ), 139.29 (C-8c), 139.3
(C-2), 147.49 (C-4), 151.82 (C-5), 153.19 (C-30 50), 173.15
(C-90), 198.91 (C-7). HRFABMS m/z 492.1788 (calcd for
C28H28O8, 492.1784).
1
935 cmK1; H NMR (400 MHz, CDCl3) d: 1.40 (d, JZ
8.0 Hz, H-8ea), 1.50 (d, JZ8.0 Hz, H-8eb), 1.70 (dd, JZ
3.6, 12.0 Hz, H-9a), 2.86 (s, H-8d), 3.00 (dd, JZ2.04,
12.0 Hz, H-9b), 3.19 (s, H-8a), 3.46 (d, JZ10.8 Hz, H-8 ),
3.57 (s, COOMe), 3.77 (s, H-11, H-13), 3.83 (s, H-12), 4.84
(d, JZ10.8 Hz, H-70), 5.60 (dd, JZ3.0, 5.5 Hz, H-8b), 5.98
(dd, JZ1.0, 4.8 Hz, H-10), 6.25 (dd, JZ3.0, 5.6 Hz, H-8c),
6.30 (s, H-20, H-60), 6.32 (s, H-3), 7.22 (s, H-6). 13C NMR
(100 MHz, CDCl3) d: 31.00 (C-9), 42.26 (C-8d), 46.51 (C-
8a), 46.78 (C-70), 48.42 (C-8e), 51.80 (COOMe), 55.98 (C-
80), 56.13 (C-8), 56.13 (C-11, C-13), 60.79 (C-12), 101.64
(C-10), 105.71 (C-6), 106.36 (C-20, C-600), 108.67 (C-3),
127.82 (C-1), 132.91 (C-8b), 137.01 (C-4 ), 139.01 (C-10),
139.54 (C-2), 0139.68 (C-8c), 147.16 (C-4), 151.95 (C-5),
153.16 (C-3 , C-50), 172.23 (C-90), 197.23 (C-7).
HRFABMS m/z 492.1792 (calcd For C28H28O8, 492.1784).
3.3.7. Adducts of Diels–Alder reaction from 1 in
presence of AlCl3. To a solution of thuriferic acid
(50 mg, 0.12 mmol) in anhydrous CH2Cl2 (10 mL) at
K78 8C under nitrogen atmosphere, 5 mg of AlCl3 and
freshly cracked distilled ciclopentadiene (0.1 mL,
1.3 mmol) was added dropwise. After 4 days the reaction
was over and HPLC analysis showed that the reaction
products were the same in a similar proportion to that
observed without catalyst.
3.3.6.2. Adduct (1a-ex). Mp 150–152 8C (colourless
crystals); [a]22 C54 (Na 589), C59 (Hg 578), C62 (546),
C106 (436) (c 1%, CDCl3); IR (film) gmax: 3057, 2958,
2836, 1734, 1680, 1617, 1589, 1505, 1481, 1463, 1246,
1126, 1037, 1009, 935 cmK1; 1H NMR (400 MHz, CDCl3)
d: 0.60 (dd, JZ3.0, 6.0 Hz, H-9a), 1.10 (d, JZ8.5 Hz,
H-8ea), 1.70 (d, JZ8.6 Hz, H-8eb), 2.70 (s, H-8d), 2.74 (d,
JZ3.8 Hz, H-8a), 2.80 (dd, JZ4.0, 8.0 Hz, H-9b), 3.08 (d,
JZ1.5 Hz, H-80), 3.59 (s, COOMe), 3.77–3.82 0(br s, H-11,
H-13), 3.83 (s, H-12), 4.46 (d, JZ1.5 Hz, H-7 ), 4.60 (dd,
JZ3.0, 4.0 Hz, H-8b), 5.96 (d, JZ1.1 Hz, H-10), 5.96 (dd,
JZ3.0, 4.0 Hz, H-8c), 6.30–6.45 (br s, H-20, H-60), 6.51 (s,
H-3), 7.62 (s, H-6). 13C NMR (100 MHz, CDCl3) d: 35.45
(C-9), 41.34 (C-8a), 46.00 (C-8e), 46.18 (C-70), 50.99
(C-8d), 52.03 (COOMe), 53.44 (C-8), 56.42 (C-11, C-13),
58.07 (C-80), 60.97 (C-12), 101.70 (C-10), 106.75 (C-3),
107.08 (C-20, C-60), 109.33 (C-6), 127.94 (C-10), 135.34
(C-2), 135.59 (C-8b), 137.29 (C-40), 138.92 (C-1 ), 139.12
(C-8c), 147.69 (C-4), 151.63 (C-5), 153.03 (C-30, C-50),
174.43 (C-90), 197.01 (C-7). HRFABMS m/z 492.1786
(calcd for C28H28O8, 492.1784).
3.3.8. Adducts of Diels–Alder reaction from 2. To a
solution of epithuriferic acid (200 mg, 0.49 mmol) in
anhydrous CH2Cl2 (20 mL) at K18 8C under nitrogen
atmosphere, freshly distilled cyclopentadiene (0.1 mL,
1.3 mmol) was added dropwise. After 3 days, HPLC showed
that the reaction was over. The reaction mixture was
concentrated in vacuo and diluted with EtOAc (20 mL). The
organic layer was washed with saturated aqueous NaHCO3
(100 mL), dried with anhydrous Na2SO4, and evaporated
under reduced pressure. The reaction crude was trated with
diazomethane and then chromatograpied eluting with hexane/
ethyl acetate to give the adducts 2b-ex (98 mg; hexane/AcOEt
2:1) (41.2%) and 2b-en (7 mg; hexane/AcOEt 1:2) (3.0%).
3.3.8.1. Adduct (2b-ex). (Yellow oil); [a]22 C106 (Na
589), C109 (Hg 578), C126 (546), C236 (436) (c 1%,
CDCl3); IR (film) gmax: 2970, 2945, 2839, 1731, 1675,
1616, 1590, 1504, 1481, 1461, 1423, 1253, 1126, 1037,
1007, 935, 756 cmK1; 1H NMR (400 MHz, CDCl3) d: 1.20
(dd, JZ3.6, 12.0 Hz, H-9b), 1.60 (dd, JZ1.0, 8.7 Hz,
H-8eb), 1.80 (dd, JZ1.0, 8.7 Hz, H-8ea), 2.30 (dd, JZ2.5,
12.0 Hz, H-9b), 2.96 (br s, H-8d), 3.13 (br s, H-8a), 3.32 (s,
COOMe), 3.36 (d, JZ6.2 Hz, H-80), 3.60–3.85 (br s, H-11,
H-13), 3.85 (s, H-12), 4.80 (d, JZ6.2 Hz, H-70), 5.6 (dd, JZ
2.9, 5.8 H0z, H-8b), 5.99 (d, JZ1.82 Hz, H-10), 6.20–6.40
(br s, H-2 , H-60), 6.30 (dd, JZ2.6, 5.5 Hz, H-8c), 6.43 (s,
H-3), 7.44 (s, H-6). 13C NMR (100 MHz, CDCl3) d: 32.39
(C-9), 42.55 (C-8d), 45.23 (C-8e), 46.86 (C-70), 49.52
(C-8a), 51.25 (COOMe), 56.17 (C-11, C-13), 56.84 (C-8),
59.14 (C-80), 60.81 (C-12), 101.57 (C-10), 106.42 (C-3),
108.46 (C-60), 128.24 (C-1), 132.53 (C-8b), 135.96 (C-2),
137.17 (C-1 ), 137.39 (C-400), 141.06 (C-8c), 147.43 (C-5),
151.39 (C-4), 153.32 (C-3 , C-50), 173.22 (C-90), 196.84
(C-7), 106.42 br s (C-20, C-60). HRFABMS m/z 492.1779
(calcd for C28H28O8, 492.1784).
3.3.6.3. Adduct (1a-en). Mp 156–158 8C (white solid);
[a]22 C106 (Na 589), C109 (Hg 578), C126 (546), C236
(436) (c 1%, CDCl3); IR (film) gmax: 3059, 2953, 1734,
1681, 1617, 1589, 1505, 1480, 1463, 1246, 1128, 1037,
1
1009, 935 cmK1; H NMR (400 MHz, CDCl3) d: 1.30 (d,
JZ8.8 Hz, H-8e-b), 1.50 (dd, JZ3.0, 12.0 Hz, H-9a), 1.70
(d, JZ8.5 Hz, H-8e-a), 1.98 (d, JZ12 Hz, H-9b), 2.70 (s,
H-8d), 2.90 (s, H-8a), 3.54 (d, JZ3.5 Hz, H-80), 3.60 (s,
COOMe), 3.77 (s, H-11, H-13), 3.83 (s, H-12), 4.54 (d, JZ
3.5 Hz, H-70), 5.70 (dd, JZ2.8, 5.0 Hz, H-8b), 5.9 (dd, JZ
3.4 Hz, H-10), 6.13 (dd, JZ3.0, 5.0 Hz, H-8c), 6.41 (s, H-20,
H-60), 6.48 (s, H-3), 7.39 (s, H-6). 13C NMR (100 MHz,
CDCl3) d: 35.65 (C-9), 42.77 (C-8d), 46.18 (C-70), 47.33
(C-8e), 48.50 (C-8a), 52.07 (COOMe), 54.58 (C-8), 56.42
(C-11, C-13), 58.06 (C-80), 60.97 (C-12), 101.65 (C-10),
106.31 (C-20, C-60), 106.38 (C-6), 109.30 (C-3), 128.55
(C-1), 133.40 (C-8b), 135.90 (C-2), 137.10 (C-40), 137.76
(C-8c), 139.79 (C-10), 147.43 (C-4), 151.40 (C-5), 153.21
(C-30, C-50), 173.91 (C-90), 196.48 (C-7). HRFABMS m/z
492.1788 (calcd for C28H28O8, 492.1784).
3.3.6.4. Adduct (1b-ex). (Amorphous white solid); IR
(film) gmax: 3061, 2954, 1736, 1680, 1614, 1588, 1503,
3.3.8.2. Adduct (2b-en). (Yellow oil); [a]22 C106 (Na
589), C109 (Hg 578), C126 (546), C236 (436) (c 1%,