2
K. MIYAMOTO ET AL.
Materials and methods
gel flash chromatography (2.6 × 15 cm) using ethyl
acetate-n-hexane (3:7, v/v) as the eluent to isolate
the fast-moving N-((3R)-jasmonoyl)-(4S)-4-isopro-
pyl-2-oxazolidinone (4), and slow-moving N-((3S)-
jasmonoyl)-(4S)-4-isopropyl-2-oxazolidinone (3).
General experimental precedures
1
13
H- and C-NMR were recorded on an ECA-500
spectrometer (JEOL) at 500 MHz and 125 MHz,
respectively. Specific optical rotations were recorded
on a DIP-300 polarimeter (JASCO, Hachioji, Japan).
The R values of compounds 3 and 4 were 0.26 and
f
0.36, respectively, on thin layer chromatography
under the following conditions: adsorbent,
Silica gel 60 F254 (Merck, Darmstadt, Germany);
solvent system, ethyl acetate-n-hexane (3: 7, v/v).
Chemicals
2
Racemic MeJA (1) and [9,10- H ]-JA were purchased
Compound 3: 0.168 g, 22% yield. [α] = +79.4
2
D
1
from Wako Pure Chemical Co. Ltd (Osaka, Japan)
and Tokyo Chemical Industry Co. Ltd (Tokyo,
Japan), respectively. (+)-JA-Ile and (−)-JA-Ile were
(c = 1.47, methanol). H NMR δ (CDCl ) 0.87
3
(3H, d, J = 6.9 Hz), 0.91 (3H, d, J = 7.0 Hz), 0.91
(3H, t, J = 7.7 Hz), 1.49 (1H, m), 1.95 (1H, m), 2.02
(2H, m), 2.10 (1H, m), 2.26 (1H, m), 2.34 (4H, m),
2.41 (1H, m), 3.08 (1H, dd, J = 17.0 Hz, J = 9.0 Hz),
3.17 (1H, dd, J = 17.0 Hz, J = 4.5 Hz), 4.20 (1H, dd,
J = 9.2 Hz, J = 3.0 Hz), 4.27 (1H, t, J = 8.7 Hz), 4.43
1
3
synthesized as previously described [7]. [ C ]- (+)-
6
1
3
JA-Ile and [ C ]-(−)-JA-Ile were similarly synthe-
6
1
3
sized using [ C ]-Ile (Cambridge Isotope
6
Laboratories Inc., Tewksbury, MA, USA) [9].
1
3
(
(
1H, m), 5.26 (1H, m), 5.41 (1H, m). C-NMR δ
CDCl ) 14.27, 14.90, 18.12, 20.76, 25.69, 27.34,
3
(± ±)-J (2±
2
8.62, 37.58, 37.87, 39.98, 54.16, 58.64, 63.62,
Racemic MeJA (1) (2.24 g, 10.0 mmol) was dissolved in
125.17, 134.17, 154.30, 171.88, 219.44. Compound
a mixture of THF (60 mL) and water (20 mL), and
4: 0.081 g, 13% yield. [α] = +28.6 (c = 1.73, metha-
D
1
1
M NaOH (20 mL) was added dropwise to the solution.
nol). H-NMR δ (CDCl ) 0.85 (3H, d, J = 6.8 Hz),
3
After stirring overnight at room temperature, the reac-
tion mixture was concentrated under reduced pressure,
and the residue was acidified to pH 2 with 6 M HCl. The
mixture was extracted three times with diethyl ether,
and the combined extracts were washed with water and
brine successively. After drying over anhydrous sodium
sulfate, the solvent was evaporated to obtain (±)-JA (2)
0.90 (3H, d, J = 6.8 Hz), 0.90 (3H, t, J = 7.5 Hz), 1.44
(1H, m), 1.93 (1H, m), 2.01 (2H, m), 2.09 (1H, m),
2.25 (1H, m), 2.35 (4H, m), 2.42 (1H, m), 2.92 (1H,
dd, J = 17.1 Hz, J = 9.7 Hz), 3.28 (1H, dd, J = 17.1 Hz,
J = 4.0 Hz), 4.20 (1H, dd, J = 9.1 Hz, J = 2.8 Hz), 4.27
(1H, t, J = 8.7 Hz), 4.43 (1H, m), 5.25 (1H, m), 5.41
1
3
(1H, m). C-NMR δ (CDCl ) 14.23, 14.80, 18.10,
3
(
2.03 g, 97% yield). This material was used for the next
20.73, 25.56, 27.52, 28.55, 37.24, 37.93, 40.31, 54.12,
58.58, 63.62, 125.13, 134.15, 154.24, 171.80, 219.36.
reaction without further purification.
N)((3S±)jasmonoyl±)(4S±)4)isopropyl)2)oxazolidinone
(−±)-J (5±
(
2
3± and n)((3R±)jasmonoyl±)(4S±)4)isopropyl)
)oxazolidinone (4±
Compound 3 (0.147 g, 0.46 mmol) and lithium
hydroxide monohydrate (0.0384 g, 0.91 mmol) were
dissolved in a mixture of THF (7 mL) and water
(2 mL). To this solution, 30% H O aq (0.183 mL,
A solution of 1.6 M n-butyllithum in n-hexane
(
(
in THF (10 mL) at −78°C under argon with stirring,
and the stirring was continued for 30 min at the
same temperature. To this solution, a mixed acid
anhydride suspension, which had been prepared by
adding isobutyl chloroformate (0.300 g, 2.20 mmol)
to a solution of N-methylmorpholine (0.222 mL,
1.36 mL, 2.00 mmol) was added to a solution of
S)-4-isopropyl-2-oxazolidione (0.258 g, 2.00 mmol)
2
2
1.79 mmol) was added dropwise at 0°C. The mixture
was stirred for 30 min at 0°C and then overnight at
room temperature. The reaction mixture was washed
with dichloromethane, and acidified to pH 2 with
1 M HCl. The solution was extracted three times
with diethyl ether, and the combined ether layers
were washed with water and brine. The organic
layer was dried over anhydrous Na SO . The product
2
.20 mmol) and (±)-JA (2) (0.420 g, 2.00 mmol) in
2
4
THF (5 mL) at −15°C with stirring, was added and
stirred for 30 min at −78°C, and then for 2 h at 0°C.
The reaction was stopped by adding saturated NH4
Cl aq (2.5 mL) and the resultant reaction mixture
was extracted three times with ethyl acetate. The
combined organic layers were washed with water
and saturated NaCl aq, and then dried over anhy-
drous Na SO . The solvent was evaporated under
was purified by silica gel flash chromatography
(1.0 × 15 cm) eluted with ethyl acetate-n-hexane
(4:6, v/v) followed by solvent evaporation to obtain
5 (39.1 mg, 40% yield). [α] = -88.2 (25°C, c = 0.820,
D
13
1
methanol, Lit. -81.4 ). H NMR δ (CDCl ) 0.94 (3H,
3
t, J = 7.6 Hz), 1.51 (1H, m), 1.91 (1H, m), 2.03
(2H, m), 2.11 (H, m), 2.31 (3H, m,), 2.35 (3H, m),
2.75 (1H, m), 5.24 (1H, m), 5.44 (1H, m), 8.26 (1H,
2
4
13
reduced pressure. The residue was purified by silica
br). C-NMR δ (CDCl ) 14.28, 20.76, 25.63, 27.34,
3