Chemoenzymatic synthesis of n-hexyl and O-β-D-xylopyranosyl-(1→6) -β-D-glucopyranosides

Article abstract of DOI:10.1248/cpb.52.1105

Direct β-glucosidation between 1,6-octanediol (5) and D-glucose (3) using the immobilized β-glucosidase (EC 3.2.1.21) from almonds with the synthetic prepolymer ENTP-4000 gave a mono-β-glucoside (6) in 61.4% yield, which was converted into the n-hexyl β-D

Full text of DOI:10.1248/cpb.52.1105

September 2004
Chem. Pharm. Bull. 52(9) 1105—1108 (2004)
1105
b
Chemoenzymatic Synthesis of n-Hexyl and O- -D-Xylopyranosyl-
Æ b
(1 6)- -D-glucopyranosides
Masashi KISHIDA,a,b Miho NISHIUCHI,a Keisuke KATO,a and Hiroyuki AKITA*,a
a School of Pharmaceutical Sciences, Toho University; 2–2–1 Miyama, Funabashi, Chiba 274–8510, Japan: and b Tsukuba
Research Institute, Novartis Pharma K.K.; 8 Ohkubo, Tsukuba, Ibaraki 300–2611, Japan.
Received April 30, 2004; accepted June 11, 2004
Direct b-glucosidation between 1,6-octanediol (5) and D-glucose (3) using the immobilized b-glucosidase (EC
3.2.1.21) from almonds with the synthetic prepolymer ENTP-4000 gave a mono-b-glucoside (6) in 61.4% yield,
which was converted into the n-hexyl b-D-glucopyranoside (1) by means of a chemoenzymatic method. The cou-
pling of the n-hexyl b-D-glucopyranoside congener (13) and 2,3,4-tri-O-acetyl-b-D-xylosyl congener (14), followed
by deprotection, afforded the synthetic n-hexyl O-b-D-xylopyranosyl-(1Æ6)-b-D-glucopyranoside (2), which was
identical to the natural 2 with respect to the spectral data and specific rotation.
Key words b-glucosidase; b-glucosidation; lipase; natural product synthesis; n-hexyl b-D-glucopyranoside
Enzymatic synthesis of n-hexyl b-D-glucopyranoside (1)5)
and 6-hydroxyhexyl-b-D-glucopyranoside (6)6) using 4-nitro-
phenyl b-D-glucopyranoside as a glycosyl donor was re-
ported previously by us, while direct b-glycosidation using a
large amount of 1,6-hexanediol is reported to give a 6-hy-
droxyhexyl-b-D-glucopyranoside (6) in 61% yield.4) Those
reports are promising for the improved synthesis of n-hexyl
b-D-glucopyranoside (1) and its application to the total syn-
thesis of the natural congener (2). On the other hand, we re-
ported the effectiveness of immobilization of b-glucosidase
(EC 3.2.1.21) from almonds with a photocross-linkable resin
prepolymer (ENTP-4000) in the direct b-glucosidation be-
tween D-glucose (3) and 1,8-octanediol (5).7) Then we exam-
ined the direct b-glucosidation between D-glucose (3) and 1-
hexanol (4) or/and 1,6-hexanediol (5). Immobilization of b-
D-glucosidase from almonds on the photocross-linkable resin
prepolymer (ENTP-4000) was carried out following the re-
ported procedure.7)
When a large amount of 1-hexanol (4, 23.4 eq) was used
as an acceptor for D-glucose (3) in the presence of b-glucosi-
dase or the immobilized b-glucosidase, a low yield of n-
hexyl b-D-glucopyranoside (1) (entry 1 in Table 1; 13.5%
yield, entry 2 in Table 1; 9.4% yield) was obtained. When the
same b-glucosidation was carried out using the recovered
immobilized enzyme, the yield of 1 was almost the same as
in entry 2 in Table 1 (entry 3 in Table 1). When a large
amount of 1,6-hexanediol (5; 25.0 eq) was employed for b-
glucosidation using the native enzyme and the immobilized
enzyme, the yield of 6 was fairly high (entry 4 in Table 1;
67.8% yield, entry 5 in Table 1; 61.4% yield). The recovered
enzyme was also found to be effective (entry 6 in Table 1;
47.9% yield).
The Chinese natural medicine “Si Lie Hong Jing Tian”
prepared from the underground part of Rhodiola (R.) quadri-
fida (PALL.) FISCH. et MEY., has been prescribed for hemosta-
tic, antibechic, and tonic purposes in traditional Chinese
preparations and used as an endermic liniment for burns and
contusions. n-Hexyl b-D-glucopyranoside (1) was isolated as
one of chemical constituents of R. quadrifida by Yoshikawa
et al.1) and reported to increase blood pressure.2) Meanwhile,
n-hexyl O-b-D-xylopyranosyl-(1Æ6)-b-D-glucopyranoside
(2) was isolated from the dried roots of Rehmannia glutinosa
LIBOSH. var. purpurea MAKINO.3) In this paper, we describe
the synthesis of n-hexyl b-D-glucopyranoside (1) and its nat-
ural congener (2) based on the selective b-glycosidation be-
tween the nonprotected D-glucose (3) and primary alcohols
such as n-hexanol (4) and 1,6-hexanediol (5) catalyzed by the
immobilized b-glucosidase (EC 3.2.1.21) from almonds.
Retrosynthetically, the synthesis of 2 can be achieved by the
coupling reaction of the protected n-hexyl b-D-glucopyra-
noside congener and the protected b-D-xylosyl congener.
Enzymatic b-Glycosidation In case of the direct b-gly-
cosidation between D-glucose (3) and primary alcohols using
b-glucosidase (EC 3.2.1.21) from almonds under thermo-
dynamic conditions, a high concentration of alcohol or a
medium with low water activity is reported to be effective.4)
b
Synthesis of n-Hexyl -D-Glucopyranoside (1) and n-
Hexyl O-b-D-Xylopyranosyl-(1Æ6)-b-D-glucopyranoside
(2) As the yield of n-hexyl b-D-glucopyranoside (1) from
Chart 1
Fig. 1
* To whom correspondence should be addressed. e-mail: akita@phar.toho-u.ac.jp
© 2004 Pharmaceutical Society of Japan

1106
Vol. 52, No. 9
Table 1
Entry
R3OH (g)
b-Glucosidase
Time (d)
Product (1 or 6), yield (%)
1
Me(CH2)5OH 4 (14.6)
Me(CH2)5OH 4 (14.6)
Me(CH2)5OH 4 (14.6)
HO(CH2)6OH 5 (18.0)
HO(CH2)6OH 5 (18.0)
HO(CH2)6OH 5 (18.0)
Native
A
Recovered A
Native
4
4
4
6
6
6
1
1
1
6
6
6
(13.5)
(9.4)
(9.0)
(67.8)
(61.4)
(47.9)
2
3a)
4
5
A
6b)
Recovered A
A immobilized b-glucosidase with ENTP-4000. a) The same immobilized enzyme in entry 2 was employed again after filtration. b) The same immobilized enzyme in
entry 5 was employed again after filtration.
direct b-glucosidation was low, conversion of 6 into the de-
sired b-glucoside (1) was carried out in five steps, including
the chemoenzymatic method. Acetylation of 6 gave quantita-
tively a pentaacetate (7), which was treated with the lipase
Amano P from Pseudomonas sp. to provide a monoalcohol
(8) in 80% yield along with the starting material (7). In this
enzymatic hydrolysis, the terminal acetyl group in the side
chain was selectively hydrolyzed and other acetyl groups in
the sugar moiety were found to be intact. Treatment of 8 with
iodine (I2) in the presence of triphenylphosphine (Ph3P) gave
quantitatively the corresponding iodide (9), which was sub-
jected to reduction with NaBH4 to give a tetraacetate (10) in
88% yield. Finally, treatment of 10 with K2CO3 in MeOH
provided the desired b-glucoside (1) in 87% yield. Conse-
quently, the overall yield (41.6% yield) of 1 from D-glucose
(3) via six steps is considerably improved in comparison to
that (8.8—13.5% yield) with the direct b-glucosidation of 1-
hexanol (4).
Tritylation of 1 gave a trityl ether (11; 79% yield) along
with the starting material (1; 20% recovery). Benzoylation of
11 afforded a benzoate (12) in 97% yield, which was sub-
jected to hydrogenolysis in the presence of 20% Pd(OH)2-C
to provide the desired 13 in 97% yield. On the other hand,
Chart 2
methylthio 2,3,4-tri-O-acetyl-b-D-xylopyranoside (14) was
synthesized by applying the reported method8) based on the chemoenzymatic method. The coupling of the n-hexyl b-D-
reaction of (methylthio)trimethylsilane and tetra-O-acetyl-b- glucopyranoside congener (13) and methylthio-2,3,4-tri-O-
D-xylopyranoside obtained by acetylation of D-xylose. By acetyl-b-D-xylopyranoside (14), followed by deprotection, af-
following the reported procedure,9) the coupling reaction of forded the synthetic n-hexyl O-b-D-xylopyranosyl-(1Æ6)-b-
n-hexyl b-D-glucopyranoside congener (13) and methylthio D-glucopyranoside (2), which was consistent with the natural
2,3,4-tri-O-acetyl-b-D-xylopyranoside (14) in the presence of 2 with respect to the spectral data and specific rotation.
silver triflate (AgOTf) and phenylselenochloride (PhSeCl)
Experimental
gave the coupled product (15) in 69% yield. Finally, treat-
ment of 15 with K2CO3 in MeOH provided quantitatively the
1H- and 13C-NMR spectra were recorded on a JEOL EX 400 spectrometer
(Tokyo, Japan). Spectra were recorded with 5—10% (w/v) solution in
CDCl3 with Me4Si as an internal reference. Melting points were determined
on a Yanaco MP-3S micromelting point apparatus and are uncorrected. Opti-
cal rotations were measured on a JASCO DIP-370 digital polarimeter. The
synthetic n-hexyl O-b-D-xylopyranosyl-(1Æ6)-b-D-glucopy-
ranoside (2). The spectral data (1H-, 13C-NMR) and specific
rotation ([a]D ꢀ50.0 (MeOH)) of the synthetic (2) were
identical with those (1H-, 13C-NMR and [a]D ꢀ48.0
FAB mass spectra were obtained with a JEOL JMS-AX 500 (matrix; glyc-
erol) spectrometer. IR spectra were recorded on a JASCO FT/IR-300 spec-
(MeOH)) of the natural product 2.3)
trometer. All evaporations were performed under reduced pressure. For col-
umn chromatography, silica gel (Kieselgel 60) was employed.
Conclusion
Immobilization of b-D-Glucosidase Using a Prepolymer b-D-Glucosi-
dase (EC 3.2.1.21) from almonds was purchased from Sigma Chemical Co.
(G-0395, 2.5—3.6 U/mg). Immobilization of b-D-glucosidase from almonds
on the photocross-linkable resin prepolymer (ENTP-4000) was carried out
using the following procedure. One gram of ENTP-4000 was mixed with
10 mg of a photosensitizer, benzoin ethyl ether, and 110 mg of b-D-glucosi-
dase from almonds (3.4 units/mg). The mixture was layered on a sheet of
In conclusion, direct b-glucosidation between 1,6-hexane-
diol (5) and D-glucose (3) using the immobilized b-glucosi-
dase from almonds with the synthetic prepolymer ENTP-
4000 gave a mono-b-glucoside (6) in 61.4% yield, which was
converted into the n-hexyl b-D-glucopyranoside (1) using the

September 2004
1107
transparent polyester film (thickness, ca. 0.5 mm). The layer was covered 171.2 (s), 170.7 (s), 170.4 (s), 169.5 (s), 169.3 (s), 100.8 (d), 72.9 (d), 71.8
with transparent thin film and then illuminated with chemical lamps (wave- (d), 71.4 (d), 70.0 (t), 68.5 (d), 64.4 (t), 62.0 (t), 29.3 (t), 28.6 (t), 25.6 (t),
length range, 300—400 nm) for 3 min. The gel film thus obtained was cut
into small pieces (0.5ꢁ5ꢁ5 mm) and used for the bioconversion reaction.
Enzymatic Transglycosylation. Synthesis of n-Hexyl b-D-Glucopyra-
noside (1) 1) Entry 1: A mixture of D-glucose 3 (1.1 g, 6.1 mmol), 1-hexa-
nol (14.6 g, 143.1 mmol), water (2 ml) and b-glucosidase 100 mg (250 units)
was incubated for 4 d at 50 °C. The reaction mixture was directly chro-
matographed on silica gel (35 g) to give 1-hexanol (12.0 g, 82.1% recovery)
from the CHCl3 eluent and b-glucoside (1, 218.7 mg, 13.5% yield) as color-
less crystals from the CHCl3/MeOHꢂ10 : 1 eluent. 1: mp 88—89 °C; [a]D27
25.5 (t), 21.0 (q), 20.8 (q), 20.7 (q), 20.6 (q), 20.6 (q); FAB-MS m/z: 513
(MꢃNa)ꢃ, 491 (MꢃH)ꢃ.
2) A suspension of 7 (504 mg, 1.03 mmol), lipase Amano P (504 mg) in
water-saturated i-Pr2O (50 ml) was incubated for 47 h at 33 °C. The reaction
mixture was filtered with the aid of celite and the filtrate was evaporated to
give a residue. It was chromatographed on silica gel (20 g) to afford 7
(96 mg, 19% recovery) from the n-hexane/AcOEt (2 : 1) eluent and 8
(369 mg, 80% yield) as a colorless syrup from the n-hexane/AcOEt (2 : 1)
1
eluent. 8: [a]D25 ꢀ18.1° (cꢂ0.43, CHCl3); IR (KBr): 3561, 1753 cmꢀ1, H-
ꢀ34.9° (cꢂ0.5, H2O); IR (KBr): 3410, 2927, 1075, 1030 cmꢀ1 1H-NMR NMR (CDCl3): d 5.20 (1H, t, Jꢂ9.5 Hz), 5.09 (1H, t, Jꢂ9.5 Hz), 4.98 (1H,
,
(DMSO-d6): d 4.93 (1H, d, Jꢂ4.9 Hz), 4.90 (2H, dd, Jꢂ4.9, 12.7 Hz), 4.46
(1H, t, Jꢂ5.9 Hz), 4.09 (1H, d, Jꢂ7.8 Hz), 3.75 (1H, sixtet, Jꢂ6.8 Hz), 3.66
(1H, dd, Jꢂ5.9, 11.7 Hz), 0.86 (3H, t, Jꢂ6.8 Hz); 13C-NMR (MeOH-d4): d
dd, Jꢂ7.8, 9.5 Hz), 4.49 (1H, d, Jꢂ7.8 Hz), 4.26 (1H, dd, Jꢂ4.8, 12.3 Hz),
4.14 (1H, dd, Jꢂ2.3, 12.3 Hz), 3.87 (1H, dt, Jꢂ6.6, 9.5 Hz), 3.69 (1H, ddd,
Jꢂ2.3, 4.8, 12.3 Hz), 3.63 (2H, t, Jꢂ6.6 Hz), 3.49 (1H, dt, Jꢂ6.6, 9.5 Hz),
104.4, 78.1, 77.9, 75.1, 71.7, 70.9, 62.8, 32.9, 30.8, 26.8, 23.7, 14.4; FAB- 2.09 (3H, s), 2.04 (3H, s), 2.02 (3H, s), 2.00 (3H, s), 1.59—1.54 (4H, m),
MS m/z: 265 (Mꢃ1)ꢃ; Anal. Found: C, 54.28; H, 9.25. Calcd for C12H24O6:
C, 54.53; H, 9.15%.
1.38—1.35 (4H, m); 13C-NMR (CDCl3): d 170.7 (s), 170.4 (s), 169.4 (s),
169.3 (s), 100.8 (d), 72.9 (d), 71.8 (d), 71.4 (d), 70.0 (t), 68.5 (d), 62.7 (t),
62.0 (t), 32.6 (t), 29.3 (t), 25.6 (t), 25.4 (t), 20.7 (q), 20.6 (q), 20.6 (q), 20.6
2) Entry 2: A mixture of D-glucose 3 (1.1 g, 6.1 mmol), 1-hexanol (14.6 g,
143.1 mmol), water (2 ml), and the immobilized b-glucosidase was incu- (q); FAB-MS m/z: 449 (Mꢃ1)ꢃ. Anal. Found: C, 53.07; H, 7.27. Calcd for
bated for 4 d at 50 °C. The reaction mixture was filtered off and the filtrate
was directly chromatographed on silica gel (35 g) to give 1-hexanol (10.4 g,
71.2% recovery) from the CHCl3 eluent and b-glucoside (1, 152 mg, 9.4%
yield) as colorless crystals from the HCl3/MeOHꢂ10 : 1 eluent.
C20H32O11: C, 53.56; H, 7.19%.
3) To a solution of 8 (540 mg, 1.21 mmol), Ph3P (948 mg, 3.62 mmol), and
imidazole (246 mg, 3.62 mmol) in THF (10 ml) was added a solution of I2
(810 mg, 3.19 mmol) in THF (2 ml). The whole mixture was stirred for 2 h at
room temperature. The reaction mixture was diluted with water and ex-
3) Entry 3: A mixture of D-glucose 3 (1.1 g, 6.1 mmol), 1-hexanol (14.6 g,
143.1 mmol), water (2 ml), and the recovered immobilized b-glucosidase tracted with AcOEt. The organic layer was dried over MgSO4 and evapo-
was incubated for 4 d at 50 °C. The reaction mixture was filtered off and the
filtrate was directly chromatographed on silica gel (35 g) to give 1-hexanol
(11.0 g, 75.3% recovery) from the CHCl3 eluent and b-glucoside (1,
145.7 mg, 9.0% yield) as colorless crystals from the CHCl3/MeOHꢂ10 : 1
eluent.
rated to give a residue. It was chromatographed on silica gel (15 g, n-
hexane/AcOEt (3 : 1)) to afford 9 (599 mg, 89% yield) as a colorless amor-
phous solid. 9: mp 96—98 °C; [a]D26 ꢀ16.3° (cꢂ0.41, CHCl3); IR (KBr):
1752 cmꢀ1 1H-NMR (CDCl3): d 5.20 (1H, t, Jꢂ9.6 Hz), 5.09 (1H, t,
,
Jꢂ9.6 Hz), 4.98 (1H, dd, Jꢂ8.0, 9.6 Hz), 4.49 (1H, d, Jꢂ8.0 Hz), 4.27 (1H,
dd, Jꢂ4.4, 12.4 Hz), 4.15 (1H, dd, Jꢂ2.4, 12.4 Hz), 3.87 (1H, dt, Jꢂ6.5,
9.8 Hz), 3.68 (1H, ddd, Jꢂ2.4, 4.4, 12.4 Hz), 3.49 (1H, dt, Jꢂ6.7, 9.8 Hz),
3.18 (2H, t, Jꢂ6.8 Hz), 2.09 (3H, s), 2.04 (3H, s), 2.02 (3H, s), 2.01 (3H, s),
1.85—1.78 (2H, m), 1.61—1.56 (2H, m), 1.38—1.35 (4H, m); 13C-NMR
(CDCl3): d 170.5 (s), 170.2 (s), 169.3 (s), 169.1 (s), 100.8 (d), 72.9 (d), 71.8
(d), 71.3 (d), 69.9 (t), 68.5 (d), 62.0 (t), 33.4 (t), 30.1 (t), 29.2 (t), 24.8 (t),
Synthesis of 6-Hydroxyhexyl b-D-Glucopyranoside (6) 4) Entry 4: A
mixture of D-glucose
3 (1.1 g, 6.1 mmol), 1,6-hexanediol (18.0 g,
152.5 mmol), and b-glucosidase 100 mg (250 unit) was incubated for 6 d at
50 °C. The reaction mixture was filtered off and the filtrate was directly
chromatographed on silica gel (150 g) to give 1,6-octanediol (17.0 g, 94.4%
recovery) from the CHCl3/MeOHꢂ20 : 1 eluent and b-glucoside (6, 1.16 g,
67.8% yield) as colorless crystals from the CHCl3/MeOHꢂ9 : 1 eluent. 6: 20.8 (q), 20.7 (q), 20.7 (q), 20.6 (w), 20.6 (q), 6.9 (t); FAB-MS m/z: 597
mp 109—111 °C; [a]D28 ꢀ32.5° (cꢂ0.46, MeOH); IR (KBr): 3374, 2934, (MꢃK)ꢃ.
2864, 1079, 1024 cmꢀ1 1H-NMR (DMSO-d6): d 4.92 (1H, d, Jꢂ4.9 Hz),
4) A mixture of 9 (750 mg, 1.34 mmol) and NaBH4 (102 mg, 2.68 mmol)
4.88 (2H, dd, Jꢂ4.9, 11.7 Hz), 4.45 (1H, t, Jꢂ5.9 Hz), 4.33 (1H, t, in DMSO (15 ml) was stirred for 40 min at room temperature. The reaction
,
Jꢂ4.6 Hz), 4.09 (1H, d, Jꢂ7.8 Hz), 3.75 (1H, q, Jꢂ6.8 Hz), 3.66 (1H, dq, mixture was diluted with water and extracted with AcOEt. The organic layer
Jꢂ1.6, 5.9 Hz); 13C-NMR (D2O, acetone): d 103.0, 76.7, 76.7, 74.0, 71.4, was dried over MgSO4 and evaporated to give a residue. It was chro-
70.5, 62.6, 61.6, 32.0, 29.5, 25.7, 25.6; FAB-MS m/z: 281 (Mꢃ1)ꢃ; Anal.
Found: C, 51.04; H, 9.01. Calcd for C12H24O7: C, 51.42; H, 8.63%.
5) Entry 5: A mixture of D-glucose 3 (1.1 g, 6.1 mmol), 1,6-hexanediol
matographed on silica gel (10 g, n-hexane/AcOEt (1 : 1)) to afford 10
(574 mg, 99% yield) as colorless needles. 10: mp 51—53 °C (n-
1
hexane/AcOEt); [a]D27 ꢀ20.2° (cꢂ0.41, CHCl3); IR (KBr): 1746 cmꢀ1, H-
(18.0 g, 152.5 mmol), water (2 ml), and the immobilized b-glucosidase was NMR (CDCl3): d 5.20 (1H, t, Jꢂ9.6 Hz), 5.08 (1H, t, Jꢂ9.6 Hz), 4.98 (1H,
incubated for 6 d at 50 °C. The reaction mixture was filtered off and the fil-
trate was directly chromatographed on silica gel (35 g) to give 1,6-hexaediol
(17.0 g, 94.4% recovery) from the CHCl3/MeOHꢂ20 : 1 eluent and b-gluco-
side (6, 1.05 g, 61.4% yield) as colorless crystals from the CHCl3/
MeOHꢂ9 : 1 eluent.
6) Entry 6: A mixture of D-glucose 3 (1.1 g, 6.1 mmol), 1,6-hexanediol
(18.0 g, 152.51 mmol), water (2 ml), and the recovered immobilized b-glu-
cosidase was incubated for 6 d at 50 °C. The reaction mixture was filtered off
and the filtrate was directly chromatographed on silica gel (35 g) to give 1,6-
hexaediol (17.1 g, 95.0% recovery) from the CHCl3/MeOHꢂ20 : 1 eluent
and b-glucoside (6, 820 mg, 47.9% yield) as colorless crystals from the
CHCl3/MeOHꢂ9 : 1 eluent.
Conversion of 6 into n-Hexyl b-D-Glucopyranoside (1) 1) A mixture
of 6 (300 mg, 1.07 mmol), Ac2O (874 mg, 8.5 mmol), and 4-N,N-dimethyl-
aminopyridine (DMAP; 10 mg, 0.08 mmol) in pyridine (1 ml, 12.4 mmol)
was stirred for 1 h at room temperature. The reaction mixture was diluted
with water and extracted with AcOEt. The organic layer was washed with
10% aqueous HCl, 7% aqueous NaHCO3, and brine. The organic layer was
dried over MgSO4 and evaporated to give a residue, which was chro-
matographed on silica gel (15 g, n-hexane/AcOEt (2 : 1)) to afford 7
(525 mg, quantitative yield) as a colorless syrup. 7: [a]D23 ꢀ16.6. (cꢂ0.62,
CHCl3); IR (KBr): 1753 cmꢀ1, 1H-NMR (CDCl3): d 5.21 (1H, t, Jꢂ9.4 Hz),
5.09 (1H, t, Jꢂ9.4 Hz), 4.98 (1H, dd, Jꢂ8.0, 9.4 Hz), 4.50 (1H, d, Jꢂ8 Hz),
4.27 (1H, dd, Jꢂ4.8, 12.2 Hz), 4.14 (1H, dd, Jꢂ2.4, 12.2 Hz), 4.05 (2H, t,
Jꢂ6.8 Hz), 3.87 (1H, dt, Jꢂ6.4, 9.8 Hz), 3.71—3.67 (1H, m), 3.48 (1H, dt,
Jꢂ6.4, 9.8 Hz), 2.09 (3H, s), 2.04 (3H, s), 2.04 (3H, s), 2.03 (3H, s), 2.01
(3H, s), 1.65—1.55 (4H, m), 1.40—1.30 (4H, m); 13C-NMR (CDCl3): d
dd, Jꢂ8.0, 9.6 Hz), 4.49 (1H, d, Jꢂ8.0 Hz), 4.26 (1H, dd, Jꢂ4.4, 12.2 Hz),
4.14 (1H, dd, Jꢂ2.4, 12.2 Hz), 3.87 (1H, dt, Jꢂ6.4, 9.6 Hz), 3.69 (1H, ddd,
Jꢂ2.4, 4.4, 12.2 Hz), 3.47 (1H, dt, Jꢂ6.8, 9.6 Hz), 2.08 (3H, s), 2.04 (3H,
s), 2.02 (3H, s), 2.00 (3H, s), 1.60—1.52 (2H, m), 1.34—1.24 (6H, m), 0.88
(3H, t, Jꢂ6.8 Hz); 13C-NMR (CDCl3): d 170.7 (s), 170.3 (s), 169.4 (s),
169.3 (s), 100.9 (d), 72.9 (d), 71.8 (d), 71.4 (d), 70.2 (t), 68.5 (d), 62.1 (t),
31.5 (t), 29.4 (t), 25.5 (t), 22.6 (t), 20.7 (q), 20.6 (q), 20.6 (q), 20.6 (d), 14.0
(q); FAB-MS m/z: 471 (MꢃK)ꢃ. Anal. Found: C, 54.94; H, 7.47. Calcd for
C20H32O10· 1/3H2O: C, 54.73; H, 7.51%.
5) A mixture of 10 (400 mg, 0.93 mmol) and K2CO3 (128 mg, 0.93 mmol)
in MeOH (10 ml) was stirred for 25 min at room temperature. The reaction
mixture was evaporated to give a residue, which was chromatographed on
silica gel (10 g, CHCl3/MeOH (9 : 1)) to afford 1 (213 mg, 87% yield) as a
colorless amorphous crystals. The 1H- and 13C-NMR spectra of the present 1
were identical to those of enzymatic b-glucoside 2.
Conversion of 2 into the n-Hexyl b-D-Glucopyranoside Congener (13)
1) A mixture of 1 (1.02 g, 3.86 mmol) and TrCl (1.6 g, 5.73 mmol) in pyri-
dine (3 ml, 37.2 mmol) was stirred for 12 h at room temperature. The reac-
tion mixture was diluted with toluene (100 ml) and evaporated under re-
duced pressure to give a residue, which was chromatographed on silica gel
(20 g) to afford 11 (1.55 g, 79% yield) as a colorless amorphous solid from
the CHCl3/MeOH (20 : 1) eluent and starting material 1 (204 mg, 20% re-
covery) from the CHCl3/MeOH (5 : 1) eluent. 11: mp 51—53 °C; [a]D24
ꢀ46.5° (cꢂ0.56, CHCl3); IR (KBr): 3236 cmꢀ1 1H-NMR (CDCl3): d
,
7.46—7.43 (6H, m), 7.31—7.21 (9H, m), 4.26 (1H, d, Jꢂ7.6 Hz), 3.88 (1H,
dt, Jꢂ6,8, 9.4 Hz), 3.56—3.50 (3H, m), 3.45—3.42 (4H, m), 3.15 (3H, br s),
1.66—1.60 (2H, m), 1.37—1.26 (6H, m), 0.87 (3H, t, Jꢂ6.8 Hz); 13C-NMR

1108
Vol. 52, No. 9
(1 g) in 1,2-dichloroethane (3 ml) was added silver triflate (AgOTf; 216 mg,
0.83 mmol) with stirring at 0 °C under an argon atmosphere. To the above-
mentioned reaction mixture was added a solution of 13 (338 mg, 0.58 mmol)
and 14 (350 mg, 1.14 mmol) in 1,2-dichloroethane (2 ml) and the whole mix-
ture was stirred for 2 h at the same temperature. The reaction mixture was
cooled at 0 °C and quenched with AcOEt (15 ml) and 7% aqueous NaHCO3
solution (15 ml). The reaction mixture was filtered with the aid of celite and
the filtrate was extracted with AcOEt and dried over MgSO4. Evaporation of
the organic solvent gave a residue, which was chromatographed on silica gel
(20 g, n-hexane/AcOEt (4 : 1)) to afford 15 (339 mg, 69% yield) as a color-
less amorphous solid. 15: [a]D31 ꢀ27.81° (cꢂ0.41, CHCl3); IR (KBr):
(CDCl3): d 143.7 (s, Ph-4°), 128.3 (d, Ph-3°), 127.6 (d, Ph-3°), 126.91 (d,
Ph-3°), 102.3 (d), 86.9 (s), 76.8 (d), 73.7 (d), 73.5 (d), 72.0 (d), 70.0 (t), 64.3
(t), 31.5 (t), 29.6 (t), 25,6 (t), 22.5 (t),14.0 (q); FAB-MS m/z: 529 (MꢃK)ꢃ.
Anal. Found: C, 72.29; H, 7.51. Calcd for C31H38O6·1/2H2O: C, 72.21; H,
7.62%.
2) A mixture of 11 (1.0 g, 1.92 mmol), BzCl (1.332 g, 9.45 mmol), and
pyridine (2 ml, 25.3 mmol) in CHCl3 (5 ml) was stirred for 45 min at 0 °C.
The reaction mixture was diluted with CHCl3 (5 ml) and 10% aqueous
H2SO4 (20 ml) and extracted with AcOEt. The organic layer was washed
with 7% aqueous NaHCO3 and brine and dried over MgSO4. Evaporation of
the organic solvent gave a residue, which was chromatographed on silica gel
(20 g, n-hexane/AcOEt (10 : 1)) to afford 12 (1.57 g, 97% yield) as a color-
1741 cmꢀ1 1H-NMR (CDCl3): d 7.95 (2H, t, Jꢂ7.6 Hz), 7.92 (2H, d,
,
less syrup. 12: [a]D31 ꢀ18.6° (cꢂ0.14, CHCl3); IR (KBr): 1731 cmꢀ1 1H-
,
Jꢂ7.6 Hz), 7.81 (2H, d, Jꢂ7.6 Hz), 7.53—7.48 (2H, m), 7.42—7.35 (5H,
m), 7.28—7.24 (2H, m), 5.86 (1H, t, Jꢂ9.6 Hz), 5.46 (1H, t, Jꢂ8.8 Hz),
5.42 (1H, t, Jꢂ9.2 Hz), 5.14 (1H, t, Jꢂ8.8 Hz), 4.94—4.87 (2H, m), 4.77
(1H, d, Jꢂ8.0 Hz), 4.60 (1H, d, Jꢂ6.8 Hz), 4.08 (1H, dd, Jꢂ5.0, 11.6 Hz),
4.00—3.91 (3H, m), 3.77 (1H, dd, Jꢂ7.4, 11.6 Hz), 3.53 (1H, dt, Jꢂ6.8,
9.4 Hz), 3.33 (1H, dd, Jꢂ8.8, 11.6 Hz), 2.07 (3H, s), 2.05 (3H, s), 2.03 (3H,
s), 1.60—1.46 (2H, m), 1.27—1.05 (6H, m), 0.74 (3H, t, Jꢂ6.8 Hz); 13C-
NMR (CDCl3): d 169.6, 169.4, 168.9, 165.4, 164.9, 164.7, 133.2, 132.9,
132.8, 129.5 (2C), 129.4 (2C), 129.1, 128.6, 128.5, 128.1 (2C), 128.0 (2C),
100.8, 100.4, 73.7, 72.8, 71.7, 71.1, 70.4, 70.0, 69.6, 68.6, 67.8, 61.8, 31.3,
29.3, 25.4, 22.4, 20.7 (3C), 13.9; FAB-MS m/z: 857 (MꢃNa)ꢃ. Anal. Found:
C, 61.91; H, 6.17. Calcd for C44H50O16·H2O: C, 61.96; H, 6.15%.
NMR (CDCl3): d 7.96 (2H, dd, Jꢂ1.2, 8.4 Hz), 7.82 (2H, dd, Jꢂ1.2,
8.4 Hz), 7.70 (2H, dd, Jꢂ1.2, 8.4 Hz), 7.52—7.35 (11H, m), 7.32—7.25
(4H, m), 7.18—7.08 (9H, m), 5.78 (1H, t, Jꢂ9.8 Hz), 5.68 (1H, t,
Jꢂ9.8 Hz), 5.53 (1H, dd, Jꢂ7.8, 9.8 Hz), 4.79 (1H, d, Jꢂ7.8 Hz), 3.99 (1H,
dt, Jꢂ6.5, 9.8 Hz), 3.85 (1H, ddd, Jꢂ2.5, 4.8, 10.5 Hz), 3.61 (1H, dt, Jꢂ6.8,
9.8 Hz), 3.34 (1H, dd, Jꢂ2.5, 10.5 Hz), 3.27 (1H, dd, Jꢂ4.8, 10.5 Hz),
1.65—1.54 (2H, m), 1.27—1.11 (6H, m), 0.76 (3H, t, Jꢂ7.0 Hz); 13C-NMR
(CDCl3): d 165.7, 164.9, 164.6, 143.5 (3C), 132.9 (3C), 129.7, 129.6, 129.5,
129.4, 129.1, 128.9, 128.5 (9C), 128.1, 128.1, 128.0, 127.6 (9C), 126.7 (3C),
101.2, 86.7, 73.9, 73.4, 72.2, 70.0, 69.7, 62.6, 31.6, 29.6, 25.7, 22.6, 14.1;
FAB-MS m/z: 841 (MꢃNa)ꢃ. Anal. Found: C, 76.37; H, 6.11. Calcd for
C52H50O9: C, 76.26; H, 6.15%.
3) A mixture of 15 (88 mg, 0.10 mmol) and NaOMe (11 mg, 0.20 mmol)
in MeOH (3 ml) was stirred for 1 h at room temperature. The reaction mix-
ture was evaporated to give a residue, which was chromatographed on silica
gel (8 g, CHCl3/MeOH (7 : 1)) to afford 2 (41 mg, 99% yield) as a colorless
amorphous solid. 2: [a]D22 ꢀ50.0° (cꢂ0.3, MeOH); IR (KBr): 3366,
3) A mixture of 12 (1.0 g, 1.22 mmol) and 20% Pd(OH)2–C (500 mg) in
MeOH (100 ml) was subjected to catalytic hydrogenolysis at ambient tem-
perature and the reaction mixture was filtered with the aid of celite to give
the filtrate. Evaporation of the filtrate gave a residue, which was chro-
matographed on silica gel (20 g, n-hexane/AcOEt (5 : 1)) to afford 13
1040 cmꢀ1 1H-NMR (MeOH-d4): d 4.32 (1H, d, Jꢂ7.6 Hz), 4.25 (1H, d,
,
(688 mg, 97% yield) as a colorless syrup. 13: IR (KBr): 3461, 1739 cmꢀ1
;
Jꢂ8.0 Hz), 4.08 (1H, dd, Jꢂ2.0, 11.6 Hz), 3.90—3.72 (2H, m), 3.74 (1H,
dd, Jꢂ5.6, 11.6 Hz), 3.57—3.40 (3H, m), 3.35 (2H, t (like)), 3.31—3.29
(2H, m), 3.23—3.16 (2H, m), 1.42—1.28 (8H, m), 0.91 (3H, t, Jꢂ6.8 Hz);
13C-NMR (MeOH-d4): d 105.3, 104.2, 77.9, 77.6, 76.8, 74.9, 74.7, 71.3,
71.1, 71.0, 69.6, 66.8, 32.9, 30.8, 26.8, 23.7, 14.5; FAB-MS m/z: 419
(MꢃNa)ꢃ.
1H-NMR (CDCl3): d 7.95 (4H, t, Jꢂ7.6 Hz), 7.84 (2H, d, Jꢂ7.6 Hz), 7.51
(2H, q, Jꢂ7.6, 13.6 Hz), 7.43—7.35 (5H, m), 5.93 (1H, t, Jꢂ9.4 Hz), 5.49
(1H, t, Jꢂ9.4 Hz), 4.82 (1H, d, Jꢂ8.0 Hz), 3.94 (1H, dt, Jꢂ6.8, 9.6 Hz),
3.87—3.74 (4H, m), 3.54 (1H, dd, Jꢂ6.8, 16.0 Hz), 2.58 (1H, s), 1.58—1.45
(2H, m), 1.27—1.20 (6H, m), 0.74 (3H, t, Jꢂ6.8 Hz); 13C-NMR (CDCl3): d
165.8, 165.6, 164.8, 133.5, 133.0 (2C), 129.8, 129.6 (3C), 129.3 (2C), 128.7,
128.5, 128.3, 128.2 (2C), 128.1 (2C), 101.2, 74.6, 72.8, 71.9, 70.3, 69.6,
61.4, 31.5, 29.5, 25.5, 22.5, 14.0. High (FAB)-MS (matrix; m-nitrobenzyl al-
cohol) m/z: 577.2446. Calcd for C33H36O9: 577.2438.
References
1) Yoshikawa M., Shimada Hirom., Shimada Hiros., Murakami N.,
Yamahara J., Matsuda H., Chem. Pharm. Bull., 44, 2086—2091
(1996).
2) Matsubara Y., Mizuno T., Sawabe A., Iizuka Y., Okamoto K., Nippon
Nogeikagaku Kaishi, 63, 1373—1377 (1989).
3) Nishimura H., Sasaki H., Morota T., Chin M., Mitsuhashi H., Phyto-
chemistry, 29, 3303—3306 (1990).
4) Vic G., Crout D. H. G., Tetrahedron: Asymmetry, 5, 2513—2516
(1994).
5) Kurashima K., Fujii M., Ida Y., Akita H., J. Mol. Cat. B: Enzymatic,
26, 87—98 (2003).
6) Kurashima K., Fujii M., Ida Y., Akita H., Chem. Pharm. Bull., 52,
270—275 (2004).
7) Akita H., Kawahara E., Kato K., Tetrahedron: Asymmetry, 15, 1623—
1629 (2004).
8) Pozsgay V., Jennings H. J., Tetrahedron Lett., 28, 1375—1376 (1987).
9) Ito Y., Ogawa T., Numata M., Sugimoto M., Carbohydr. Res., 202,
165—175 (1990).
n-Hexyl O-b-D-Xylopyranosyl-(1Æ6)-b-D-Glucopyranoside (1) 1) To
a solution of tetra-O-acetyl-b-D-xylopyranoside (407 mg, 1.28 mmol) in
CH2Cl2 (5 ml) under an argon atmosphere was added (methylthio)trimethyl-
silane (Me3SiSMe; 382 mg, 3.2 mmol) and 45% BF3·Et2O (200 ml, 0.63 ml)
and the whole mixture was stirred for 2 h at room temperature. The reaction
mixture was diluted with 7% aqueous NaHCO3 (10 ml) and extracted with
AcOEt. The organic layer was washed with brine and dried over MgSO4.
Evaporation of the organic solvent gave a residue, which was chro-
matographed on silica gel (8 g, n-hexane/AcOEt (20 : 1)) to afford 14
(245 mg, 62% yield) as colorless needles. 14: [a]D31 ꢀ74.9° (cꢂ0.9, CHCl3);
IR (KBr): 1747 cmꢀ1 1H-NMR (CDCl3): d 5.20 (1H, t, Jꢂ8.8 Hz), 5.00
,
(1H, t, Jꢂ9.3 Hz), 4.97 (1H, dt, Jꢂ5.2, 9.3 Hz), 4.40 (1H, d, Jꢂ8.8 Hz), 4.21
(1H, dd, Jꢂ5.2, 11.6 Hz), 3.39 (1H, dd, Jꢂ9.3, 11.6 Hz), 2.16 (3H, s), 2.08
(3H, s), 2.05 (6H, s); 13C-NMR (CDCl3): d 169.7, 169.6, 169.3, 83.3, 72.5,
69.0, 68.8, 65.9, 20.8 (3C), 11.6; FAB-MS m/z: 307 (Mꢃ1)ꢃ. Anal. Found:
C, 47.08; H, 5.95. Calcd for C12H18O7S: C, 47.05; H, 5.92%.
2) To a mixture of PhSeCl (161 mg, 0.83 mmol) and 4A molecular sieves