B. Pelotier et al. / Tetrahedron: Asymmetry 16 (2005) 1513–1520
1517
of dicyclohexylcarbodiimide (194 mg, 0.94 mmol) in
4.5. (R)-(1,2:5,6-Di-O-isopropyliden-a-D-glucofuranose-
3-O-yl) 2-propyloctanoate 5
dichloromethane (1 mL) was then added dropwise.
The mixture was allowed to warm upto rt and stirred
overnight. The white precipitate was filtered off and
the solvent evaporated. The residue was purified by flash
chromatography (ethyl acetate/petroleum ether, 5/95) to
yield ester 3 (288 mg, 0.68 mmol, 79%, E/Z, 90/10) as a
A solution of ester 4 (106 mg, 0.25 mmol) in diethyl
ether (3 mL) was hydrogenated over PtO2 (balloon,
1 atm) for 12 h. The crude mixture was filtered through
a short plug of silica and eluted with ethyl acetate/petro-
1
colourless oil. H NMR: E-isomer: d 6.77 (br t,
leum ether 5/95 to give compound 5 (107 mg,
20
D
J = 7.5 Hz, 1H, HC@C), 5.88 (d, J = 3.7 Hz, 1H, O–
0.25 mmol, quantitative). ½a ¼ ꢀ28:0 (c 1.23,
1
CH–O), 5.28 (d, J = 2.3 Hz, 1H, CH–O–C@O), 4.52
CH Cl ). H NMR: d 5.86 (d, J = 3.6 Hz, 1H, O–CH–
2
2
(
O–CH–CH–CH O), 4.13–4.06 (m, 1H, 1/2 ABX,
d, J = 3.7 Hz, 1H, CH–CH(O) ), 4.28–4.18 (m, 2H,
O), 5.29 (d, J = 2.1 Hz, 1H, CH–O–C@O), 4.43 (d,
2
J = 3.6 Hz, 1H, CH–CH(O) ), 4.26–4.16 (m, 2H, O–
CH–CH–CH O), 4.16–4.08 (m, 1H, 1/2 ABX,
2
2
OCH H ), 4.04–3.98 (m, 1H, 1/2 ABX, OCH H ),
A
B
A
B
2
2
.28 (td, J = 7.1, 1.9 Hz, 2H, CH –C–CO ), 2.19 (br q,
2
OCH H ), 4.05–3.98 (m, 1H, 1/2 ABX, OCH H ),
A
2
B
A
B
J = 7.5 Hz, 2H, CH –CH@C), 1.54 (s, 3H, CH C(O) ),
2.38 (tt, J = 8.9, 5.3 Hz, 1H, CH–C@O), 1.53 (s, 3H,
2
3
2
1
1
.42 (s, 3H, CH C(O) ), 1.31 (s, 6H, 2 · CH C(O) ),
CH C(O) ), 1.41 (s, 3H, CH C(O) ), 1.32 (s, 3H,
CH C(O) ), 1.30 (s, 3H, CH C(O) ), 1.70–1.20 (m,
3 2 3 2
3
2
3
2
3
2
3
2
.50–1.20 (m, 8H, 4 · CH ), 0.90 (t, J = 7.1 Hz, 3H,
2
CH ), 0.89 (t, J = 6.8 Hz, 3H, CH ); [Z-isomer: d 5.73
14H, 7 · CH ), 0.91 (t, J = 7.2 Hz, 3H, CH ), 0.88 (t,
3
3
2
3
1
3
13
(
t, J = 7.3 Hz, 1H, HC@C)]. C NMR E-isomer: d
J = 6.8 Hz, 3H, CH ). C NMR: d 175.2, 112.6, 109.6,
3
1
7
2
66.9, 144.6, 131.9, 112.4, 109.5, 105.3, 83.6, 80.4,
6.4, 72.8, 67.6, 31.8, 28.9, 28.8, 28.7, 27.0, 26.9, 26.4,
5.4, 22.7 (2C), 14.2 (2C). MS (LSIMS): m/z (%) = 449
105.4, 83.8, 80.4, 75.9, 72.6, 67.8, 46.0, 34.9, 32.8, 31.9,
29.5, 27.5, 27.1 (2C), 26.5, 25.4, 22.9, 20.9, 14.3 (2C).
+
MS (LSIMS): m/z (%) = 451 (M+Na , 44), 413 (56),
+
(
M+Na , 20), 411 (50), 369 (65), 266 (16), 167 (100),
371 (100), 176 (50), 147 (68), 109 (90). HRMS calcd
for C H O Na : 541.2672. Found: 541.2671.
+
01 (51). HRMS calcd for C H O Na : 449.2515.
+
1
Found: 449.2516.
2
3
38
7
23 40
7
4.6. (R)-Arundic acid 6
4
3
.4. (R)-(1,2:5,6-Di-O-isopropyliden-a-D-glucofuranose-
-O-yl) 2-propyloct-3-enoate 4
4.6.1. Saponification of 5. To a solution of ester 5
(89 mg, 208 lmol) dissolved in methanol (2 mL) and
cooled to 0 ꢁC was added hydrogen peroxide (35% in
water, 81 mg, 0.83 mmol). An aqueous solution of lith-
ium hydroxide monohydrate (1 M, 18 mg, 0.42 mmol)
was then added dropwise. The cold bath was then
allowed to warm up. After 6 h, a saturated solution of
aqueous sodium hydrogen carbonate (10 mL) was added
and the mixture extracted with dichloromethane
(3 · 3 mL). The aqueous phase was acidified to pH 1
with 1 M HCl, the excess hydrogen peroxide quenched
with aqueous sodium sulfite (2 M) and extraction was
carried out with ethyl acetate (3 · 10 mL). The organic
To a solution of ester 3 (141 mg, 0.33 mmol) in dichloro-
methane (35 mL) was added N,N-dimethylethanolamine
(
30 mg, 0.33 mmol). The mixture was transferred into
quartz tubes (10 mm diameter) and deoxygenated with
nitrogen for 5 min. The tubes were placed around a
quartz tube in which a short wavelength OSRAM lamp
was introduced. The irradiation was carried out at
ꢀ
40 ꢁC and monitored by TLC. After 6 h, the solvent
was evaporated and the crude product purified by flash
chromatography (ethyl acetate/petroleum ether, 5/95) to
yield compound 4 (136 mg, 0.32 mmol, 97%) as a mix-
ture of diastereoisomers in a 28/72 ratio of E- and Z-iso-
phases were dried over MgSO and concentrated. The
4
crude acid was purified by flash chromatography (ethyl
acetate/petroleum ether, 10/90) to give (R)-6 as a colour-
less oil (17 mg, 91 lmol, 44%). 88% ee (ee determined
after conversion into the corresponding phenacyl ester
(phenacyl bromide, Et N, CH Cl ), Chiralcel OJ-H,
1
mers. H NMR: major isomer: d 5.86 (d, J = 3.7 Hz, 1H,
O–CH–O), 5.61–5.48 (m, 1H, CH@C), 5.45–5.28 (m,
1
4
2
H, CH@C), 5.26 (d, J = 1.5 Hz, 1H, CH–O–C@O),
.40 (d, J = 3.7 Hz, 1H, CH–CH(O) ), 4.25–4.15 (m,
H, O–CH–CH–CH O), 4.13–4.05 (m, 1H, 1/2 ABX,
2
3
2
2
heptane/isopropanol
99/1,
0.5 mL/min,
254 nm,
2
20
OCH H ), 4.03–3.95 (m, 1H, 1/2 ABX, OCH H ),
B
22.6 min (S) and 26.5 min (R)). ½a ¼ ꢀ5:4 (c 0.24,
A
B
A
D
5
a
20
D
2
2
1
.98 (br q, J = 7.5 Hz, 1H, CH–C@O), 2.10–1.95 (m,
CH Cl ), lit. ½a ¼ ꢀ6:1 (c 2.00, EtOH) for (R)-arun-
2
2
1
H, CH –CH@C), 1.80–1.65 (m, 2H, CH –CH–C@O),
dic acid. H NMR: d 2.37 (tt, J = 8.7, 5.3 Hz, 1H, CH–
C@O), 1.70–1.55 (m, 2H, 2 · CH–CH–C@O), 1.55–1.20
2
2
.52 (s, 3H, CH C(O) ), 1.40 (s, 3H, CH C(O) ), 1.30
3
2
3
2
(
(
(
s, 3H, CH C(O) ), 1.29 (s, 3H, CH C(O) ), 1.50–1.20
3
m, 6H, 3 · CH ), 0.90 (t, J = 7.1 Hz, 3H, CH ), 0.89
t, J = 7.3 Hz, 3H, CH ); [minor isomer: d 3.35 (br q,
(m, 12H, 2 · CH–CH–C@O and 5 · CH ), 0.91 (t,
2
3
2
2
J = 7.2 Hz, 3H, CH ), 0.88 (t, J = 7.0 Hz, 3H, CH ).
2
3
3
3
1
3
C NMR: d 183.3, 45.7, 34.7, 32.5, 32.0, 29.6, 27.7,
22.9, 20.9, 14.4, 14.3.
3
1
3
J = 7.1 Hz, 1H, CH–C@O)]. C NMR major isomer:
d 173.3, 134.2, 127.4, 112.6, 109.5, 105.4, 83.6, 80.4,
7
2
1
2
6.0, 72.5, 67.6, 49.5, 34.7, 32.4, 31.6, 27.0 (2C), 26.5,
5.5, 22.4, 20.5, 14.1, 14.0; [minor isomer: d 173.1,
33.4, 127.0, 80.5, 67.7, 44.3, 35.1, 31.9, 27.5, 25.4,
4.6.2. Hydrogenolysis of (R)-7. A solution of ester (R)-
7 (62 mg, 0.22 mmol) in methanol (6 mL) was hydroge-
nated over Pd/C 10% (10% w/w, 6 mg, H2 balloon,
1 atm) for 3 h. The solvent was then evaporated and
the residue purified by flash chromatography (ethyl ace-
tate/petroleum ether, 8/92) to give compound (R)-6
(39 mg, 0.21 mmol, 95%). 89% ee (ee determined after
2.5, 20.4, 14.2]. MS (LSIMS): m/z (%) = 449
+
(M+Na , 22), 411 (46), 369 (100), 139 (38), 101 (53).
HRMS calcd for C H O Na : 449.2515. Found:
4
+
2
3
38
7
49.2516.