C18H28O4 requires C, 70.10; H, 9.15%); m/z 308 (Mϩ, 37%), 251
(41), 209 (64), 167 (100); νmax(NaCl)/cmϪ1 2980, 1621, 1579,
1420, 1130; δH 14.11 (1H, s), 5.95 (1H, s), 4.65 (1H, septet,
J 5.94), 4.58 (1H, septet, J 6.21), 2.92 (2H, d, J 7.02), 2.23 (1H,
septet, J 7.02), 2.00 (3H, s), 1.42 (6H, d, J 6.21), 1.36 (6H, d,
J 5.94), 0.96 (6H, d, J 6.48); δC 205.8, 164.2, 161.7, 158.9, 106.3,
92.3, 89.3, 70.4, 70.2, 53.4, 25.2, 22.7 (2C), 22.1 (2C), 21.9 (2C),
7.4; λmax(EtOH)/nm 204 (log ε/dmϪ3 molϪ1 cmϪ1 5.37), 294
(5.26).
Compound 16 was then allowed to stand at ambient
temperature in a solution of TiCl4 (2.0 cm3) in CH2Cl2 (10 cm3)
for 48 h to give 17 (yield 83.4%), red crystals, mp 154–155 ЊC
(Found: C, 64.1; H, 7.4; C12H16O4 requires C, 64.27; H, 7.19%);
m/z 224 (Mϩ, 31%), 209 (18), 167 (100); νmax(NaCl)/cmϪ1 3141,
2770, 1612, 1430; δH 5.83 (1H, s), 2.97 (2H, d, J 5.94), 2.23
(2H, septet, J 6.75), 2.04 (3H, s), 0.97 (6H, d, J 6.75); δC 206.0,
162.8, 159.7, 159.0, 105.0, 102.5, 94.8, 52.9, 25.3, 22.8 (2C), 7.0;
λmax(EtOH)/nm 204 (log ε/dmϪ3 molϪ1 cmϪ1 4.12), 292 (4.06).
To a solution of compound 17 in CH2Cl2 (5 cm3), 1.0 cm3 of
TiCl4 and 1.1 g of dichloromethyl methyl ether were added at
Ϫ20 ЊC under Ar, and the mixture was allowed to stand at
Ϫ20 ЊC for 2 h. The solution was then poured into crushed
ice, and extracted with AcOEt to give 10 (41.6%), pink crystals,
mp 113–114 ЊC (Found: C, 61.7; H, 6.6; C13H16O5 requires C,
61.89; H, 6.39%); m/z 252 (Mϩ, 18%), 237 (22), 185 (100), 167
(35), 69 (24); νmax(NaCl)/cmϪ1 3359, 2968, 1630; δH 15.5 (1H, s),
14.32 (1H, s), 10.11 (1H, s), 3.00 (2H, d, J 6.75), 2.26 (1H,
septet, J 6.48), 2.05 (3H, s), 0.99 (6H, d, J 6.48); δC 206.6, 191.9,
171.8, 167.8, 161.5, 104.3, 103.4, 100.0, 52.9, 25.1, 22.8, 6.4;
λmax(EtOH)/nm 214 (log ε/dmϪ3 molϪ1 cmϪ1 3.43), 246 (4.47).
100.88, 87.60, 54.87, 52.75, 40.66, 40.28, 34.14, 28.78, 28.21,
27.90, 25.03, 22.78, 19.94; λmax(EtOH)/nm 278 (log ε/dmϪ3
molϪ1 cmϪ1 4.57).
Electrochemical synthesis of euglobal-T1 7 and -IIc 8
Euglobal-T1 and -IIc were synthesized by the above method
using α-phellandrene instead of α-pinene (yield 78.6%, 7:8
9:5).
Euglobal-T1 7; an oil, [α] Ϫ139Њ (c 0.01) (lit.,10b Ϫ143.7Њ)
(Found: C, 71.6; H, 8.0; C23H30O5 requires C, 71.48; H, 7.82%);
m/z 386 (Mϩ, 32%), 343 (36), 256 (64), 251 (75), 236 (61), 137
(100), 123 (49); νmax(NaCl)/cmϪ1 2920, 1615, 1450; δH 15.40
(1H, s), 13.21 (1H, s), 10.19 (1H, s), 5.78 (1H, dd, J 10.2, 2.9),
5.71 (1H, br d, J 10.2), 2.96 (1H, dd, J 7.2, 14.4), 2.86 (1H, dd,
J 7.2, 14.4), 2.69 (1H, dd, J 1.67, 6.3), 2.41 (1H, dd, J 16.7, 7.8),
2.20 (1H, m), 2.14 (1H, m), 2.08 (1H, m), 1.74 (1H, h, J 6.6),
1.71 (2H, m), 1.53 (3H, s), 0.98 (6H, d, J 6.6), 0.96 (3H, d, J
7.8), 0.93 (3H, d, J 7.8); δC 206.01, 192.42, 169.99, 167.08,
162.09, 133.47, 130.42, 104.46, 104.00, 99.66, 79.20, 53.19,
38.73, 32.65, 31.77, 27.62, 27.34, 25.46, 22.75, 22.68, 20.14,
20.06, 19.83; λmax(EtOH)/nm 280 (log ε/dmϪ3 molϪ1 cmϪ1 4.30).
Euglobal-IIc 8; an oil [α] Ϫ135Њ (c 0.01) (lit.,2 Ϫ144Њ) (Found:
C, 71.5; H, 7.6; C23H30O5 requires C, 71.48; H, 7.82%); m/z 386
(Mϩ, 16%), 355 (26), 256 (33), 167 (51), 149 (100); νmax(NaCl)/
cmϪ1 2925, 1620, 1260; δH 15.40 (1H, s), 14.50 (1H, s), 10.04
(1H, s), 5.75 (1H, dd, J 2.4, 10.2), 5.69 (1H, d, J 10.2), 2.97
(2H, d, J 7.8), 2.66 (1H, dd, J 6.6, 16.2), 2.38 (1H, dd, J 7.2,
16.8), 2.25 (1H, h, J 6.6), 2.13 (1H, m), 2.05 (1H, m), 1.72 (1H,
m), 1.68 (2H, m), 1.49 (3H, s), 0.98 (6H, d, J 6.6), 0.95 (3H, d,
J 6.0), 0.94 (3H, d, J 6.6); δC 206.39, 191.88, 171.39, 168.11,
160.88, 133.19, 130.90, 103.73, 103.41, 100.49, 78.48, 52.68,
38.71, 33.22, 27.56, 27.48, 25.10, 22.77, 20.43, 20.05, 19.82;
λmax(EtOH)/nm 278 (log ε/dmϪ3 molϪ1 cmϪ1 4.51).
Electrochemical synthesis of euglobal-G1 1 and -G2 2
Grandinol 10 (504 mg) and (ϩ)-α-pinene (816 mg) were dis-
solved in 10 cm3 of 50 m Et4OTs–CH3NO2 at ambient
temperature. To this solution was added DDQ and the mixture
was electrolysed using a PTFE-fibre coated glassy carbon
anode and a Pt cathode at a constant potential under Ar. After
the reaction was complete (2.2 F), the reaction mixture was
poured into AcOEt and the AcOEt solution was washed
successively with 5% aq. NaHCO3 and brine. The organic layer
was washed and dried over anhydrous MgSO4. After filtration
and evaporation under reduced pressure, the residue was puri-
fied by silica gel column chromatography (hexane–AcOEt) to
give a mixture of euglobal-G1 1 and -G2 2 (6:5, yield 79.0%).
The mixture was further separated by HPLC (hexane–AcOEt)
to give purified 1 and 2, respectively.
Euglobal-G1 1; white crystals, mp 112 ЊC, [α]D ϩ129Њ (c 0.01)
(lit.,10a ϩ116Њ) (Found: C, 71.2; H, 8.0; C23H30O5 requires C,
71.48; H, 7.82%); νmax(NaCl)/cmϪ1 3650–3200, 1710, 1620,
1360; m/z 386 (Mϩ, 85), 343 (22), 251 (100), 195 (33), 193 (31),
93 (64); δH 15.44 (1H, s), 13.15 (1H, s), 10.21 (1H, s), 3.01
(1H, dd, J 6.21, 15.39), 2.76 (1H, d, J 2.70), 2.71 (1H, m), 2.58
(1H, dd, J 7.56, 15.39), 2.43 (1H, m), 2.41 (1H, dd, J 12.45,
5.67), 2.23 (1H, m), 2.13 (1H, m), 1.91 (1H, m), 1.35 (1H, m),
1.51 (3H, s), 2.77 (1H, d, J 2.31), 1.31 (3H, s), 1.10 (3H, s), 0.99
(3H, d, J 6.59), 0.94 (3H, d, J 6.60), 0.80 (1H, d, J 10.56);
δC 205.79, 192.48, 170.47, 166.93, 166.18, 104.67, 104.02,
100.59, 89.30, 55.38, 52.68, 40.42, 40.30, 33.74, 32.30, 29.16,
28.17, 27.60, 24.90, 23.05, 22.76, 22.44, 19.92; λmax(EtOH)/nm
278 (log ε/dmϪ3 molϪ1 cmϪ1 4.56).
Acknowledgements
This work was supported by a Grant-in-Aid for Scientific
Research on Priority Areas (No. 283, “Innovative Synthetic
Reactions”) from the Ministry of Education, Science, Sports
and Culture, Government of Japan.
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Euglobal-G2 2; an oil, [α] ϩ98.0Њ (c 0.01) (lit.,10a ϩ103Њ)
(Found: C, 71.2; H, 7.9; C23H30O5 requires C, 71.48; H, 7.82%);
m/z 368 (Mϩ, 72%), 343 (22), 251 (100), 195 (35), 193 (28), 93
(60); νmax(NaCl)/cmϪ1 3650–3200, 1625, 1300; δH 15.35 (1H, s),
14.36 (1H, s), 9.93 (1H, s), 2.99 (1H, d, J 6.48), 2.98 (1H, d,
J 6.48), 2.68 (1H, m), 2.59 (1H, m), 2.45 (1H, dd, J 6.48, 16.2),
2.24 (1H, t, J 5.67), 2.14 (1H, t, J 5.28), 2.08 (2H, m), 1.88 (1H,
m), 1.46 (3H, s), 1.30 (3H, s), 1.26 (1H, m), 1.10 (3H, s), 1.03
(3H, d, J 1.35), 0.98 (3H, d, J 1.35), 0.82 (1H, d, J 10.53);
δC 206.32, 191.69, 171.30, 168.24, 164.41, 103.71, 103.52,
Paper 8/02306I
Received 24th March 1998
Accepted 25th June 1998
2942
J. Chem. Soc., Perkin Trans. 1, 1998