1320
A. Pastore et al. / Carbohydrate Research 345 (2010) 1316–1323
solution of 2,5-dihydroxybenzoic acid in 7:3 CH3CN–H2O or, in the
case of trifluoroacetimidate derivatives, with a 10 mg/mL solution
of trihyroxyacetophenone in 1:1 MeOH–H2O. Analytical thin layer
chromatography (TLC) was performed on aluminium plates pre-
coated with Silica Gel 60 F254 as the adsorbent. The plates were
developed with 5% H2SO4 ethanolic solution and then heating to
130 °C. Column chromatography was performed on silica gel
4.5. Methyl 3,4,6-tri-O-benzyl-2-O-fluorenylmethoxycarbonyl-
-mannopyranosyl-(1?2)-3-O-benzyl-4,6-O-benzylidene-
glucopyranoside 7
a-D
a-D-
a
1H NMR (400 MHz, CDCl3) d 7.87–7.03 (m, Ar), 5.58 (s, 1H, ben-
zylidene –CHPh), 5.37 (br d, 1H, H-20), 5.17 (s, 1H, H-10), 4.96 (d,
J1,2 = 3.2, 1H, H-1), 5.00–4.38 (m, 4 ꢂ AB, 8H, 4 ꢂ –CH2Ph), 4.50–
4.45 (m, 1H, Fmoc –CHCH2O–), 4.40 (d, J = 12.0 Hz,1H, Fmoc –
CHCHaHbO–), 4.35–4.28 (m, 3H, H-6a, and Fmoc –CHCH2O–),
4.25–4.20 (m, 1H, H-50), 4.14 (dd, J2,3 = 2.8 Hz, J3,4 = 9.6 Hz, 1H, H-
30), 4.07 (t, J3,4 = 9.6 Hz, 1H, H-40), 4.00–3.95 (m, 2H, H-2 and H-
3), 3.88 (td, J5,6a = 4.6 Hz, J5,6b = 9.8 Hz, 1H, H-5), 3.76 (t,
(63–200 mesh). [a]
values are given in 10ꢁ1 deg cm2 gꢁ1. Glycos-
D
idations were performed with commercial anhydrous solvents. Bis-
muth(III) triflate was coevaporated three times in toluene and
dried under vacuum for 30–45 min and then dissolved in dioxane
in the presence of freshly activated 4 Å MS.
J5,6b = J6a,6b = 10.0 Hz,1H, H-6b), 3.73 (dd, J5,6b = 4.0 Hz, J6a,6b
=
4.2. General procedure of glycosidation with donor 3
10.2 Hz, 1H, H-60a), 3.67–3.57 (m, 2H, H-4 and H-60b), 3.49 (s,
3H, –OMe). 13C NMR (50 MHz, CDCl3) d 154.8 (–OCO2–), 143.5,
143.1, 141.25, 141.20 (Fmoc aromatic C), 138.6, 138.3, 137.9,
137.8, 137.3 (aromatic C), 129.0–119.9 (aromatic CH), 101.2 (ben-
zylidene –CHPh), 97.0, 94.3 (anomeric CH), 82.1, 79.1, 78.0, 75.6,
75.2, 74.1, 73.6, 73.0, 72.7, 71.8, 71.2, 70.2, 68.9, 68.5, 62.2, 55.4
(–OMe), 46.5 (Fmoc –CHCH2). MALDI-TOF MS: calcd for [M+Na]+
1049.41. Found 1049.3. Anal. Calcd for C63H62O13: C, 73.67; H,
6.08. Found: C, 73.45; H, 6.15.
A mixture of donor 3 (0.13–0.16 mmol) and an acceptor
(0.10 mmol) was coevaporated three times with anhydrous tolu-
ene (3 ꢂ 2 mL), and then dried in vacuo for 30 min. After adding
4 Å AW 300 MS, the mixture was dissolved under argon with 4:1
toluene–Et2O (4.1 mL), cooled to ꢁ30 °C, and stirred for 15 min. A
solution of Bi(OTf)3 in dioxane (14.5 mg–mL, 10 lmol, 0.45 mL)
was then added, and the temperature was allowed to slowly raise
to room temperature. On completion of the glycosidation (TLC
analysis, 15–180 min for entries in Table 1), a few drops of pyridine
were added and the reaction mixture was filtered on a short plug of
silica gel repeatedly washed with CH2Cl2–MeOH–CH3CN 85:10:5.
The filtrate was concentrated, and the residue purified by silica-
gel flash-chromatography (eluent: n-hexane–EtOAc or toluene–
EtOAc).
4.6. Methyl 3,4,6-tri-O-benzyl-2-O-fluorenylmethoxycarbonyl-
b-D-mannopyranosyl-(1?2)-3-O-benzyl-4,6-O-benzylidene-a-D-
glucopyranoside 7b
1H NMR (400 MHz, CDCl3) d 7.87–7.06 (Ar), 5.59 (s, 1H, benzyl-
idene H), 5.35 (d, 1H, J2,3 = 2.8 Hz, H-20), 5.01–4.37 (4 ꢂ –CH2Ph,
8H), 4.94 (d, 1H, J1,2 = 3.9 Hz, H-1), 4.78 (s, 1H, H-10), 4.50–4.35
(m, 2H, Fmoc –CHCH2O–), 4.36–4.28 (m, 2H, H-6a and Fmoc –
CHCH2O–), 4.08 (t, J2,3 = J3,4 = 9.6 Hz 1H, H-3), 3.91–3.71 (m, 6H),
3.64 (t, J4,5 = 9.6 Hz, 1H, H-4), 3.49 (dd, 1H, J3,4 = 9.2 Hz, H-30),
3.47–3.43 (m, 1H, H-50), 3.30 (s, 3H, –OMe). 13C NMR (50 MHz,
CDCl3) d 155.0 (–OCO2–), 143.6, 143.5, 141.2, 141.1 (Fmoc aromatic
C), 138.8, 138.2, 138.0, 137.5, 137.3 (aromatic C), 128.9–119.9 (aro-
matic CH), 101.3 (benzylidene CH), 100.2, 100.1 (anomeric CH),
82.4, 80.5, 79.5, 78.5, 75.5, 75.3, 74.1, 73.5, 72.1, 71.5, 70.2, 69.3,
69.1, 67.0, 62.3, 55.3 (–OMe), 46.7 (Fmoc –CHCH2). [M+Na]+
1049.41. Found 1049.3. Anal. Calcd for C63H62O13: C, 73.67; H,
6.08. Found: C, 73.50; H, 6.15.
4.3. Ethyl 3,4,6-tri-O-benzyl-2-O-fluorenylmethoxycarbonyl-
-mannopyranosyl-(1?2)-3,4,6-tri-O-benzyl-1-thio-
mannopyranoside 5
a-
D
a-D-
a
1H NMR (300 MHz, CDCl3) d 7.91–7.00 (Ar), 5.45 (s, 1H, H-1),
5.40 (br d, 1H, H-20), 5.21 (s, 1H, H-10), 5.00–4.41 (m, 6 ꢂ AB,
12H, 6 ꢂ –CH2Ph), 4.40–4.23 (m, 3H, –CH2O and H-9 Fmoc),
4.20–4.01 (m, 4H, H-2, H-5, H-30 and H-50), 4.00–3.78 (m, 6H),
3.72 (d, J6a,6b = 11.1 Hz, 1H, H-6b), 2.64–2.49 (m, 2H, –SCH2CH3),
1.24 (t, 3H, J = 7.2 Hz, –SCH2CH3). 13C NMR (50 MHz, CDCl3) d
154.7 (–OCO2–), 143.7, 143.4, 141.3, 141.2 (Fmoc aromatic C),
138.6 (ꢂ2), 138.5, 138.4, 138.2, 138.1 (aromatic C), 128.3–120.0
(aromatic CH), 99.4 (C-10), 80.2 (C-1), 78.2, 75.9, 75.6, 75.2, 75.1,
75.0, 74.6, 73.4, 73.3, 72.8, 72.3 (ꢂ3), 72.0, 70.3, 69.3 (ꢂ2), 46.7
(Fmoc –CHCH2), 25.5 (–SCH2CH3), 15.0 (–SCH2CH3). MALDI-TOF
MS: calcd for [M+Na]+ 1171.47. Found 1171.4. Anal. Calcd for
4.7. p-Methoxyphenyl 3,4,6-tri-O-benzyl-2-O-fluorenylmethoxy
carbonyl-
a-D-mannopyranosyl-(1?2)-3,4,6-tri-O-benzyl-a-D-
mannopyranoside 9
a
C
71H72O12S: C, 74.19; H, 6.31. Found: C, 74.45; H, 6.25.
1H NMR (400 MHz, CDCl3) d 7.90–7.12 (Ar), 6.97 (d, J = 9.1 Hz,
2H, Ar-HPMP), 6.74 (d, J = 9.1 Hz, 2H, Ar-HPMP), 5.59 (d,
J1,2 = 2.0 Hz, 1H, H-1), 5.41 (dd, J2,3 = 3.0 Hz, H-20), 5.25 (d,
J1,2 = 1.6 Hz,1H, H-10), 4.97–4.43 (m, 6 ꢂ AB, 12H, 6 ꢂ –CH2Ph),
4.32 (d, J = 8.0 Hz, 1H, Fmoc –CHCHaCHaO–), 4.30 (d, J = 7.9 Hz,
1H, Fmoc –CHCHaCHbO–), 4.25 (t, 1H, Fmoc –CHCHaCHbO–), 4.21
(t, J2,3 = 2.5 Hz, 1H, H-2), 4.14 (dd, 1H, J2,3 = 3.0 Hz, J3,4 = 8.8 Hz,
H-3), 4.11–4.02 (m, 2H, H-50 and H-30), 3.97 (t, 1H, J = 9.3 Hz),
3.94–3.86 (m, 2H), 3.84–3.72 (m, 3H), 3.74 (s, 3H, –OMe), 3.69
(dd, J5,6 = 1.6 Hz, J6a,6b = 11.2 Hz, 1H, H-6). 13C NMR (50 MHz,
CDCl3) d 155.0 (p-methoxyphenyl aromatic C), 154.7 (–OCO2),
150.1 (p-methoxyphenyl aromatic C), 143.6, 143.3, 141.3, 141.2
(Fmoc aromatic C), 138.5, 138.4, 138.3(3), 138.3(0), 138.2, 138.0
(aromatic C), 128.4–120.0 (aromatic CH), 117.9, 114.6 (p-methoxy-
phenyl aromatic CH), 99.3, 97.7 (C-10 and C-1), 79.5, 78.2, 75.24,
75.20, 75.0, 74.6, 74.5, 73.3, 73.2, 72.7, 72.5, 72.4, 72.2, 72.0,
70.2, 69.2 (ꢂ2), 55.6 (–OMe), 46.7 (Fmoc –CHCH2). [M+Na]+
1233.50. Found 1233.6. Anal. Calcd for C76H74O14: C, 75.35; H,
6.16. Found: C, 75.20; H, 6.05.
4.4. Ethyl 3,4,6-tri-O-benzyl-2-O-fluorenylmethoxycarbonyl-b-
-mannopyranosyl-(1?2)-3,4,6-tri-O-benzyl-1-thio-
mannopyranoside 5b
D
a-D-
1H NMR (300 MHz, CDCl3) d 7.80–6.90 (Ar), 5.57 (d, J1,2 = 2.7 Hz,
1H, H-1), 5.43 (d, J2,3 = 1.5 Hz, 1H, H-20), 5.07–4.77 (m, 4H, –CH2Ph
and H-10), 4.76–4.43 (m, 4 ꢂ AB, 8H, 4 ꢂ –CH2Ph), 4.42–4.19 (m,
4H), 4.18–4.05 (m, 2H), 3.94 (t, J = 9.4 Hz, 1H), 3.93–3.58 (m, 7H),
3.57–3.48 (m, 1H, H-50), 2.77–2.43 (m, 2H, –SCH2CH3), 1.26 (t,
3H, J = 7.5 Hz, –SCH2CH3). 13C NMR (50 MHz, CDCl3) d 155.1 (–
OCO2–), 143.9, 143.4, 141.2, 141.1 (Fmoc aromatic C), 138.6,
138.5, 138.4, 138.3 (ꢂ2), 137.6 (aromatic C), 128.4–119.8 (aro-
matic CH), 95.8 (C-10), 81.1 (C-1), 80.1, 78.2, 75.9, 75.2, 75.1,
74.5, 74.4, 73.6, 73.4, 73.1, 72.3, 71.8, 71.4, 70.6, 70.3, 69.6, 69.4,
46.8 (Fmoc –CHCH2), 25.5 (–SCH2CH3), 15.0 (–SCH2CH3). MALDI-
TOF MS: calcd for [M+Na]+ 1171.47. Found 1171.7. Anal. Calcd
for C71H72O12S: C, 74.19; H, 6.31. Found: C, 74.40; H, 6.20.