SMQ-V047 N-002_ligas_size.pdf - Journal of the Mexican Chemical ...
SMQ-V047 N-002_ligas_size.pdf - Journal of the Mexican Chemical ...
SMQ-V047 N-002_ligas_size.pdf - Journal of the Mexican Chemical ...
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138 Rev. Soc. Quím. Méx. Vol. 47, Núm. 2 (2003) Howard G. Pentes et al.<br />
26: IR 3449, 1752, 1638 cm –1 ; 1 H NMR: δ 5.80 (dd, 1H, C 1 -<br />
H, J = 11, 17 Hz); 5.00 (m, 4H, C 2 -Ha,b, C 3 -Ha,b); 4.60 (dd,<br />
1H, C 6 -H, J = 10, 11Hz); 2.20 (d, 1H, C 5 -H, J = 12 Hz); 1.79<br />
(s, 3H, C 15 -CH 3 ); 1.46 (s, 3H, C 13 -CH 3 ); 1.10 (s, 3H, C 14 -<br />
CH 3 ); MS m/z (relative intensity) 250 (M + ) (0.3), 204 (M-46 + )<br />
(0.4), 121 (M-129 + ) (3.2).<br />
27: IR 3353, 1770, 1638 cm –1 ; 1 H NMR: 8.68 (s, 1H, OOH);<br />
5.80 (dd, 1H, C 1 -H, J = 11, 17 Hz); 5.00 (m, 4H, C 2 -Ha,b, C 3 -<br />
Ha,b); 4.17 (dd, 1H, C 6 -H, J = 11 Hz); 2.32 (d, 1H, C 5 -H, J =<br />
11 Hz); 1.78 (s, 3H, C 15 -CH 3 ); 1.39 (s, 3H, C 13 -CH 3 ); 1.08 (s,<br />
3H, C 14 -CH 3 ); MS m/z (relative intensity) 266 (M + ) (0.5), 216<br />
(M-50 + ) (0.5), 166 M-100 + ) (0.9).<br />
28: IR 3466, 1708, 1638 cm –1 ; 1 H NMR: δ 5.76 (dd, 1H, C 1 -H,<br />
J = 11, 17 Hz); 4.90 (m, 4H, C 2 -Ha,b, C 3 -Ha,b); 4.10 (dd, 1H,<br />
C 6 -H, J = 11 Hz); 2.25 (s, 3H, C 13 -CH 3 ); 1.78 (s, 3H, C 15 -CH 3 );<br />
1.04 (s, 3H, C 14 -CH 3 ); MS m/z (relative intensity) 222 (M + )<br />
(2.0), 204 (M-18 + ) (1.5), 189 (M-33 + ) (1.0), 161 (M-61 + ) (3.6).<br />
Oxidation <strong>of</strong> <strong>the</strong> enolate anion <strong>of</strong> dihydropar<strong>the</strong>nolide (4)<br />
with (-)-(2S,8aR)-(camphorylsulfonyl)oxaziridine.<br />
Dihydropar<strong>the</strong>nolide (4) (200 mg, 0.8 mmol) dissolved in 5<br />
mL <strong>of</strong> dry THF was added slowly over 15 min by syringe to a<br />
stirred solution <strong>of</strong> 0.7 mL (1.04 mmol) <strong>of</strong> LDA in 5 mL <strong>of</strong><br />
THF under argon at –70 °C. After stirring <strong>the</strong> solution for an<br />
additional 15 min, a THF solution <strong>of</strong> (-)-(2S,8aR)-(camphorylsulfonyl)oxaziridine<br />
(30, 370 mg, 1.6 mmol) was added to <strong>the</strong><br />
reaction flask by syringe over a 5 min period at –70 °C. After<br />
5 more min, <strong>the</strong> reaction was quenched with <strong>the</strong> addition <strong>of</strong> 5<br />
mL <strong>of</strong> a saturated aqueous NH 4 Cl solution. The reaction mixture<br />
was extracted with diethyl e<strong>the</strong>r (6 × 10 mL). The e<strong>the</strong>r<br />
solution was dried over anhydrous Na 2 SO 4 , filtered, and <strong>the</strong><br />
solvent was evaporated.<br />
Attempted precipitation <strong>of</strong> <strong>the</strong> unreacted oxaziridine and<br />
its reduced form, <strong>the</strong> imine, at –78 °C in diethyl e<strong>the</strong>r only<br />
removed 60-70 % <strong>of</strong> <strong>the</strong>se reagents. Repeated precipitations<br />
did not fur<strong>the</strong>r purify <strong>the</strong> product. Dry column (silica gel)<br />
chromatography [19] was used to separate <strong>the</strong> product mixture<br />
eluting with DCM/acetone (9:1). The oxaziridine and <strong>the</strong><br />
imine eluted in <strong>the</strong> very early fractions. Dihydropar<strong>the</strong>nolide<br />
(4) (58 mg) was recovered and 100 mg (66 %) <strong>of</strong> 11β-hydroxydihydropar<strong>the</strong>nolide<br />
(6) was isolated. The 1 H NMR data <strong>of</strong><br />
compound 6 was identical with <strong>the</strong> data for <strong>the</strong> product isolated<br />
from <strong>the</strong> reaction <strong>of</strong> oxygen with <strong>the</strong> enolate anion <strong>of</strong> dihydropar<strong>the</strong>nolide<br />
(4). The norsesquiterpene ketone 13 and 11αhydroxydihydropar<strong>the</strong>nolide<br />
(5) were not detected.<br />
References<br />
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Oxidation <strong>of</strong> enolate anion <strong>of</strong> dihydropar<strong>the</strong>nolide (4) with<br />
(+)-(2R,8aS)-(camphorylsulfonyl)oxaziridine. Dihydropar<strong>the</strong>nolide<br />
(4) (200 mg) was oxidized as described above with (+)-<br />
(2R,8aS)-(camphorylsulfonyl)oxaziridine 29. The product mixture<br />
was separated by dry column (silica gel) chromatography<br />
[19] eluting with DCM/acetone (9:1). Dihydropar<strong>the</strong>nolide (4)<br />
(56 mg) was recovered and 110 mg (72 %) <strong>of</strong> 11β-hydroxydihydropar<strong>the</strong>nolide<br />
(6) was isolated as <strong>the</strong> only product.