August 2014
783
pyranoside (11) According to the reported method,16,17) (1H, d, J=7.2Hz), 3.00 (1H, dd, J=11.2, 4.4Hz), 2.90 (1H, dd,
diglycoside 11 was obtained as white crystals on chromatog- J=14.4, 3.6Hz), 1.40 (3H, s), 1.25 (3H, s), 1.11, 1.02, 0.91, 0.89,
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raphy (CH2Cl2 :CH3OH=200:1) from 10, yield 92%. H-NMR 0.84, 0.79, 0.64 (3H each, 21H, s each). MS m/z: 1255 [M+
(CDCl3) δ: 7.50 (3H, m), 7.37 (7H, m), 5.59 (1H, s), 5.29 (1H, H]+. Anal. Calcd for C79H98O13: C, 75.57; H, 7.87. Found: C,
s), 5.08 (1H, d, J=12.8Hz), 5.03 (1H, d, J=12.8Hz), 4.64 (1H, 75.68; H, 7.90.
d, J=7.6Hz), 4.43 (1H, d, J=7.6Hz), 4.31 (2H, m), 4.19 (1H, t,
J=7.6Hz), 4.02 (1H, d, J=13.2, 4.0Hz), 3.81 (1H, t, J=9.2Hz), rhamnopyranosyl-(1→2)-3″,4″,6″-O-benzyl-β-
Benzyl
Oleanolate
3-O-2‴,3‴,4‴-Tri-O-benzoyl-α-L-
-gluco
D
-
3.78 (3H, m), 3.57 (2H, m), 3.45 (1H, m), 3.11 (1H, dd, J=11.6, pyranosyl-(1→2)-3′,4′-O-isopropylidene-α-L-arabino-
4.4Hz), 2.89 (1H, d, J=10.4Hz), 1.55 (3H, s), 1.36 (3H, s), 1.10, pyranoside (23) Diglycoside 20 was dissolved in dry
1.00, 0.91, 0.87, 0.88, 0.81, 0.60 (3H each, 21H, s each). MS CH2Cl2 :MeOH (1:2, 18mL), to which a newly prepared
m/z: 969 [M+H]+. mp 92–94°C. [α]D20 +37.5 (c=0.5, CH2Cl2). NaOMe in MeOH solution (1.0mol/L, 0.8mL) was added.
Anal. Calcd for C58H80O12: C, 71.87; H, 8.32. Found: C, 72.02; The mixture was stirred at rt. for 2h and then neutralized
H, 8.45.
with Et3N resin to pH 7. The mixture was then filtered and
3,4,6-Tri-O-acetyl-D-glucosyl-1,2-ortho-ester (14) 2,3,4,6- the filtrate was concentrated to dryness to afford crude 21
Tetra-O-acetyl-1-bromoglucose (13) (2.0g, 4.9mmol), tetrabu- as colorless oil. Triglycoside 23 was prepared from crude
tylammonium bromide, (0.6g, 0.2mmol), triethylamine (3mL, 21 and rhamnosyl trichloroacetimidate 22 according to the
19.6mmol) and dry ethanol (2mL, 30.0mmol) were stirred same procedure described for diglycoside 9 as white crystals
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at rt. for 24h in dry CH2Cl2 (20mL). The solution was then on chromatography (PE:EtOAc=10:1), yield 82%. H-NMR
concentrated and subjected to a silica gel chromatography (CDCl3) δ: 8.01 (2H, d, J=7.2Hz), 7.92 (2H, d, J=7.6Hz), 7.79
(PE:EtOAc=5:1) to furnish the product 14 (1.0g, 53%) as (2H, d, J=7.2Hz), 7.61 (1H, m), 7.20–7.41 (22H, m), 7.09 (3H,
1
white foam. H-NMR (CDCl3) δ: 5.71 (1H, d, J=5.2Hz), 5.21 m), 5.86 (1H, d, J=10.0Hz), 5.74 (1H, dd, J=3.2, 1.6Hz), 5.60
(1H, t, J=2.8Hz), 4.90 (1H, m), 4.32 (1H, dd, J=5.2, 2.8Hz), (1H, t, J=10.0Hz), 5.47 (2H, m), 5.26 (1H, s), 5.08 (1H, d,
4.20 (2H, m), 3.96 (1H, m), 3.55 (2H, q, J=7.2Hz), 2.11, 2.10, J=12.4Hz), 5.03 (1H, d, J=12.4Hz), 4.95 (1H, d, J=10.8 Hz),
2.09 (3H each, 9H, s each), 1.72 (3H, s), 1.18 (3H, t, J=7.2Hz). 4.90 (1H, d, J=7.6Hz), 4.85 (1H, d, J=10.8Hz), 4.79 (1H, d,
MS m/z: 377 [M+H]+.
2-O-Benzoyl-3,4,6-tri-O-benzyl-D-glucopyranose
J=11.2Hz), 4.65 (3H, m), 4.55 (2H, m), 4.39 (2H, m), 4.09 (1H,
(18) t, J=5.2Hz), 3.95 (1H, dd, J=12.8, 5.2Hz), 3.60–3.85 (5H, m),
ortho-Ester 14 (6.2g, 16.5mmol) was dissolved in dry THF 3.47 (1H, d, J=9.2Hz), 2.98 (1H, dd, J=11.2, 4.4Hz), 2.89 (1H,
(40mL), to which powdered KOH (10.2g, 0.2mol) and benzyl d, J=10.0Hz), 1.50 (3H, s), 1.42 (3H, s), 1.31 (3H, d, J=6.0Hz),
bromine (6mL, 53.0mmol) was added. The reaction mixture 1.11, 0.96, 0.90, 0.89, 0.83, 0.78, 0.61 (3H each, 21H, s each).
was heated under reflux for 3h, and then cooled to room IR (KBr) cm−1: 3742, 3449, 2943, 1725, 1662, 1459, 1382,
temperature. The mixture was washed with water and sat. 1092. MS m/z: 1609 [M+H]+. mp 87–90°C. Anal. Calcd for
NaHCO3 and dried to get the 3,4,6-tribenzyl-1,2-glucosyl or- C99H116O19: C, 73.86; H, 7.26. Found: C, 73.22; H, 7.08.
thoester 15 (7.2g, 84%). ortho-Ester 15 was dissolved in 80%
Benzyl
Oleanolate
3-O-2‴,3‴,4‴-Tri-O-benzoyl-α-L-
HOAc (30mL). After stirred at rt. for 1h, this solution was rhamnopyranosyl-(1→2)-3″,4″,6″-tri-O-benzyl-β-D -
diluted with CH2Cl2, and washed with water and sat. NaHCO3 glucopyranosyl-(1→2)-α-L-arabinopyranoside
(24) Ac-
and dried to get the mixture of monoacetylated intermedi- cording to the reported method,15) compound 24 was obtained
ates 16 and 17 in the ratio of 1:3. According to the reported as white amorphous solid from starting material 23, yield
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method,15,22) the product 18 was obtained as white crystals on 86%. H-NMR (CDCl3) δ: 8.01 (4H, dd, J=8.8, 7.2Hz), 7.79
chromatography (CH2Cl2 :CH3OH=5:1) from the mixture of (2H, d, J=6.8Hz), 7.61 (1H, t, J=7.6Hz), 7.20–7.51 (27H,
16 and 17 in a one-pot procedure by a rapid sequence of three m), 7.09 (3H, m), 5.82 (1H, dd, J=10.4, 3.2Hz), 5.70 (1H, dd,
reactions, without any purification of intermediates, yield 72% J=3.2, 1.6Hz), 5.62 (1H, t, J=10.0Hz), 5.54 (2H, m), 5.28 (1H,
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for three steps. H-NMR (CDCl3) δ: 7.96–7.20 (20H, m), 5.38 s), 5.09 (1H, d, J=12.4Hz), 5.04 (1H, d, J=12.4Hz), 4.95 (2H,
(1H, d, J=10.0Hz), 4.82 (3H, m), 4.65 (1H, d, J=12.0Hz), 4.58 d, J=8.0Hz), 4.80 (2H, t, J=11.2Hz), 4.60 (5H, m), 4.15 (3H,
(1H, m), 4.52 (1H, d, J=12.0Hz), 4.26 (1H, d, J=9.6Hz), 4.07 m), 3.50–3.88 (7H, m), 3.07 (1H, dd, J=11.6, 4.4Hz), 2.91 (1H,
(2H, m), 3.96 (1H, d, J=9.6Hz), 3.84 (1H, d, J=11.2Hz), 3.73 d, J=9.6Hz), 1.33 (3H, d, J=6.4Hz), 1.11, 0.92, 0.90, 0.89,
(1H, d, J=11.2Hz). MS m/z: 555 [M+H]+.
0.87, 0.79, 0.59 (3H each, 21H, s each). MS m/z: 1569 [M+H]+.
Benzyl Oleanolate 3-O-2″-Benzoyl-3″,4″,6″-tri-O-benzyl- Anal. Calcd for C96H112O19: C, 73.45; H, 7.19. Found: C, 73.06;
β-D-glucopyranosyl-(1→2)-3′,4′-O-isopropylidene-α-L- H, 7.04.
arabinopyranoside (20) According to the reported meth-
Benzyl Oleanolate 3-O-α-L-Rhamnopyranosyl-(1→2)-
od,15) 2-benzoyl-3,4,6-tri-O-benzyl-glucosyl trichloroacetimi- 3″,4″,6″-tri-O-benzyl-β-D-glucopyranosyl-(1→2)-α-L-
date 19 was obtained as white amorphous solid from 18, arabinopyranoside (25) Compound 25 was prepared as
yield 91%. Compound 20 was prepared from benzyl ester 7 white crystals from triglycoside 24 according to the same
and glucosyl trichloroacetimidate 19 according to the same procedure described for diglycoside 21 form on chromatogra-
procedure described for diglycoside 9, yield 81%. 1H-NMR phy (CH2Cl2 :CH3OH=20:1), yield 76%. H-NMR (CDCl3) δ:
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(CDCl3) δ: 8.07 (2H, m), 7.55 (1H, dt, J=7.2, 1.6Hz), 7.43 7.26–7.36 (14H, m), 7.18 (2H, m), 5.28 (1H, m), 5.22 (1H, s),
(2H, t, J=7.6Hz), 7.18–7.39 (20H, m), 5.27 (1H, t, J=3.6Hz), 5.19(1H, d, J=12.4Hz), 5.04 (1H, d, J=12.8Hz), 4.91 (1H, m),
5.23 (1H, d, J=8.4Hz), 5.09 (1H, d, J=12.4Hz), 5.04 (1H, d, 4.87 (1H, d, J=7.2Hz), 4.76 (1H, d, J=10.8Hz), 4.68 (1H, d,
J=12.4Hz), 4.94 (1H, d, J=4.0Hz), 4.82 (1H, d, J=10.8 Hz), J=11.2Hz), 4.56 (3H, m), 4.43 (1H, d, J=7.2Hz), 3.98 (4H, m),
4.73 (1H, d, J=11.6Hz), 4.63 (3H, d, J=11.6Hz), 4.53 (1H, 3.60–3.75 (9H, m), 3.37 (2H, m), 3.04 (1H, d, J=11.2, 4.0Hz),
d, J=12.0Hz), 4.35 (1H, d, J=6.0Hz), 4.06 (1H, dd, J=11.2, 2.91 (1H, d, J=10.0Hz), 1.27 (3H, d, J=6.0Hz), 1.30, 0.91,
4.4Hz), 3.78–3.92 (6H, m), 3.62 (1H, dd, J=12.8, 4.4Hz), 3.51 0.89, 0.84, 0.83, 0.74, 0.61 (3H each, 21H, s each). MS m/z: