T. Kato et al. / Tetrahedron: Asymmetry 12 (2001) 2695–2701
2699
tive HPLC (m-porasil; hexane:EtOH 300:1; flow 3.0
mL/min) to obtain a yellowish oily product (21 mg) of
allylic alcohol 15 and cyclopropane alcohol 17 (R=H)
as an inseparable mixture by HPLC under several
conditions.
and 0.5N aq. oxalic acid solution was added to make
the pH 3–4. After usual work-up, excess CH2N2 in
ether was added and volatile materials were removed to
obtain a residue. The residue was passed through a
SiO2 column eluting with hexane:AcOEt 20:1 and then
subjected to preparative HPLC (m-porasil; hex-
ane:EtOH 300:1; flow 3.0 mL/min) to obtain a yellow-
ish oily allylic alcohol 14 (10 mg, 81%). Similarly, the
(16R)-benzoate of 15 (15 mg) was treated to obtain
(16R)-allylic alcohol 15 (9 mg, 73%). Allylic alcohols 14
and 15 lH (300 MHz, CDCl3) 0.94 (3H, t, J=7.4 Hz),
1.31 (8H, brs), 1.62 (4H, brs), 2.04 (2H, m), 2.30 (2H, t,
J=7.5 Hz), 2.93 (2H, t, J=7.0 Hz), 3.67 (3H, s), 4.09
(1H, m), 5.39 (3H, m), 5.67 (1H, dd, J=6.8, 15.1 Hz),
5.98 (1H, t, J=10.8 Hz), 6.52 (1H, dd, J=11.0, 15.1
Hz). lC (76 MHz, CDCl3) 174.4 (s), 136.0 (d), 130.7 (d),
130.6 (d), 127.8 (d), 127.1 (d), 125.6 (d), 74.1 (d), 51.5
(q), 34.1 (t), 30.2 (t), 29.5 (t), 29.1 (t), 29.1 (t), 29.0 (t),
27.2 (t), 27.1 (t), 24.9 (t), and 9.7 (q). HRMS of 14 and
15 calcd for C19H32O3: 308.2351. Observed: 308.2342
for 14 and 308.2360 for 15. [h]2D7 +19.0 (c 0.5, CHCl3)
for 14 and −18.5 (c 0.5, CHCl3) for 15.
A solution of Et3N (27 mL, 0.2 mmol) in CH2Cl2 (1
mL) was added to the mixture of 15 and 17 (21 mg) and
then benzoic anhydride (44 mg, 0.2 mmol) was added.
After stirring for 25 h at rt under an argon atmosphere,
aq. NH4Cl solution was dropped to make the pH 6–7,
and then the mixture was treated as usual. The resulting
residue was first passed through a SiO2 (4 g) column
eluted with hexane:AcOEt 40:1 and then subjected to a
preparative HPLC (m-porasil; hexane:AcOEt 40:1, flow
3.0 mL/min) to isolate the yellowish oily methyl ester of
the benzoates of 15 (16 mg, 56%) and 17 (R=Bz, 10
mg, 37%), respectively.
Similarly, (15R,16S)-epoxy-a-linolenic acid 12 (R=H,
29 mg, 0.1 mmol) provided a mixture of allylic alcohol
14 and cyclopropane alcohol 16 (R=H) (15 mg) as a
single peak in HPLC analysis. The benzoylation of the
mixture (20 mg) under the same conditions followed by
HPLC separation afforded the corresponding methyl
ester benzoates of 14 (18 mg, 89%) and 16 (2 mg, 10%)
as yellow oil, respectively. Benzoates of 14 and 15: lH
(270 MHz, CDCl3) 0.98 (3H, t, J=7.4 Hz), 1.29 (8H,
brs), 1.61 (2H, m), 1.80 (2H, m), 2.02 (2H, m), 2.30
(2H, t, J=7.4 Hz), 2.92 (2H, t, J=6.4 Hz), 3.66 (3H, s),
5.37 (4H, m), 5.73 (1H, dd, J=7.3, 15.2 Hz), 5.98 (1H,
t, J=11.1 Hz), 6.64 (1H, dd, J=11.1, 15.0 Hz), 7.52
(3H, m) and 8.08 (2H, m). lC (68 MHz, CDCl3) 174.3
(s), 165.9 (s), 132.8 (d), 131.5 (d), 131.1 (d), 130.8 (d),
130.7 (s), 129.6 (d)×2, 128.3 (d)×2, 127.8 (d), 127.5 (d),
127.0 (d), 76.4 (d), 51.4 (q), 34.1 (t), 29.45 (t), 29.1 (t),
29.1 (t), 29.0 (t), 27.7 (t), 27.2 (t), 26.1 (t), 24.9 (t), and
9.6 (q). HRMS of benzoates of 14 and 15 calcd for
C26H36O4: 412.2614. Observed: 412.2607 for 14 and
412.2611 for 15. [h]2D7 +96.5 (c 1.0, CHCl3) for benzoate
of 14 and −90.6 (c 1.0, CHCl3) for that of 15. Benzoates
of 16 and 17 (R=Bz) (270 MHz, CDCl3) lH 0.80 (1H,
dt, J=8.5, 5.4, 1H, dt, J=8.8, 5.1, C-14), 1.00 (3H, t,
J=7.3, C-18), 1.18 (1H, m, C-15), 1.23 (8H, brs, C-
4,5,6,7), 1.60 (1H, m, C-13), 1.61 (2H, m, C-3), 1.80
(2H, m, C-17), 2.12 (2H, m, C-8), 2.29 (2H, t, J=7.6,
C-2), 3.66 (3H, s, OMe), 4.64 (1H, dt, J=6.3, 8.1,
C-16), 5.20 (2H, m, C-9,12), 5.87 (1H, dd, J=10.1,
11.0, C-10), 6.32 (1H, dd, J=11.1, 14.9, C-11), 7.45
(3H, m, Ph), and 8.06 (2H, m, Ph). lC (100 MHz,
CDCl3) 174.4 (s), 166.3 (s), 136.1 (d), 133.7 (d), 132.8
(d), 130.7 (s), 130.2 (d), 129.9 (d), 129.6 (d), 128.5 (d),
128.2 (d), 124.1 (d), 78.7 (d), 51.5 (q), 34.1 (t), 29.6 (t),
29.1 (t), 29.0 (t)×2, 27.7 (t), 27.6 (t), 24.9 (d), 24.8 (t),
20.0 (d), 12.2 (t), and 9.8 (q). HRMS of benzoates of 16
and 17 calcd for C26H36O4: 412.2614. Observed:
412.2616 for 16 and 412.2616 for 17. [h]D of benzoates
of 16 and 17, not measured.
3.3. DL-9- and 13-Hydroxylinoleic methyl esters
A solution of methyl 9-epoxylinoleic ester 18 (180 mg,
0.57 mmol) in 0.5N LiOH/dioxane H2O (1:1, 11.4 mL)
was stirred at rt for 24 h, dioxane was removed under
reduced pressure at 40°C and the residue was diluted
with water and then 0.5N aq. oxalic solution was added
to make the pH 3ꢀ4. The usual work-up afforded the
crude epoxy acid. A solution of the crude 9-epoxyli-
noleic acid 18 (H instead of Me) in THF (1.62 mL) was
added at −78°C under an argon atmosphere to an LDA
solution, freshly prepared by treatment of a solution of
diisopropylamine (0.66 mL, 5.1 mmol) in THF (3 mL)
with n-BuLi in hexane (2.45 mL, 4.01 mmol) at 0°C for
5 min, and the mixture was stirred for 1 h at 0°C. After
addition of aq. NH4Cl solution to make the pH 6ꢀ7,
the mixture was worked up as usual. An excess CH2N2
in ether was added to the resulting residue. After evap-
oration of volatile materials, the residue was passed
through a SiO2 (18 g) column eluted with hex-
ane:AcOEt 20:1 and then subjected to a preparative
HPLC (m-porasil; hexane:EtOH 300:1; flow 3.0 mL/
min) to afford allylic alcohol 20 (R=H, 140 mg, 78%)
as a yellowish oil.
By similar treatment, 12-epoxylinoleic methyl ester 19
(134 mg, 0.45 mmol) provided the allylic alcohol 21
(R=H, 106 mg, 76%). Compound 20 (R=H) lH (270
MHz, CDCl3) 0.89 (3H, t, J=6.5 Hz), 1.31 (14H, brs),
1.61 (4H, m), 2.16 (2H, m), 2.30 (2H, t, J=7.4 Hz),
3.66 (3H, s), 4.13 (1H, dt, J=6.1, 6.4 Hz), 5.44 (1H, m),
5.67 (1H, dd, J=6.8, 15.1 Hz), 5.97 (1H, t, J=11.1
Hz), and 6.48 (1H, dd, J=10.9, 15.1 Hz). lC (68 MHz,
CDCl3) 174.3 (s), 135.7 (d), 133.0 (d), 127.6 (d), 125.8
(d), 72.8 (d), 51.4 (q), 37.3 (t), 34.0 (t), 31.4 (t), 29.3
(t)×2, 29.1 (t), 29.0 (t), 27.7 (t), 25.3 (t), 24.9 (t), 22.5 (t),
and 14.0 (q). Compound 21 (R=H) lH (500 MHz,
CDCl3) 0.89 (3H, t, J=6.6 Hz), 1.31 (12H, brs), 1.39
(2H, m), 1.59 (4H, m), 2.17 (2H, m), 2.30 (2H, t, J=7.4
Hz), 3.66 (3H, s), 4.14 (1H, dt, J=6.6, 6.4 Hz), 5.44
A mixture of the methyl ester of the (16S)-benzoate of
14 (18 mg, 0.04 mmol) and 0.5N KOH in dioxane/H2O
(1:1, 0.8 mL) was stirred at rt for 30 min under an
argon atmosphere, the mixture was diluted with water