S. Paul et al. / Carbohydrate Research 344 (2009) 177–186
185
tus. The solvents were evaporated to half of the volume, then BnBr
(182 L, 1.5 mmol) and Bu4NBr (0.36 g, 1.1 mmol) were added.
After refluxing for 4 h, the solvents were evaporated, and the crude
1.29 (t, 3H, J 7.4 Hz, CH3); 13C NMR (CDCl3, 100 MHz): d 170.5,
170.3, 170.1, 169.6 (CO), 136.7, 129.0, 128.1, 126.7, 126.1 (aro-
matic-C), 101.5 (PhCH), 96.4 (C-1G), 79.3 (C-1D), 78.8, 76.0, 75.4,
73.3, 70.9, 68.5, 68.4, 63.5 (C-3D to C-6D, C-2G to C-6G), 36.3 (C-
2D), 25.0 (SCH2), 21.1, 20.7, 20.5 (COCH3), 14.9 (CH3). HRESIMS:
m/z [M+Na]+ calcd for C29H38O13S: 649.1931; found: 649.1942.
l
product was purified to obtain 13 (0.7 g, 80%, b only) as a pale-yel-
low gum. Rf 0.42 (1:4 EtOAc–PhMe); ½a D24
ꢂ
+8.2 (c 1.0, CHCl3); 1H
NMR (CDCl3, 300 MHz): d 7.31–7.16 (band, 25H, aromatic-H),
5.86 (d, 1H, J 3.6 Hz, H-1G), 4.93 (d, 1H, J 12.0 Hz, PhCH2), 4.71–
4.36 (band, 10H, H-1D, PhCH2), 4.00 (t, 1H, J 9.6 Hz, H-4D), 3.89
(ddd, 1H, J 5.0, 9.0, 11.8 Hz, H-3D), 3.80–3.63 (band, 7H, H-3G, H-
4G, H-5G, H-6aG, H-6Gb , H-6aD, H-6Db ), 3.59–3.55 (m, 1H, H-5D), 3.46
(dd, 1H, J 3.0, 9.0 Hz, H-2G), 2.80–2.64 (m, 2H, SCH2), 2.44 (ddd,
1H, J 1.5, 5.0, 12.1 Hz, H-2De ), 1.70 (ddd, 1H, J 9.5, 11.8, 12.1 Hz,
3.14. Ethyl 3,6-di-O-acetyl-4-O-(2,3-di-O-acetyl-6-O-benzoyl-
a-
D-glucopyranosyl)-2-deoxy-1-thio-
a/b-D-arabino-
hexopyranoside (15)
Compound 14 (0.65 g, 1 mmol) was dissolved in 1:1 MeOH–THF
(15 mL), and p-TsOH (0.18 g, 1.2 mmol) was added. After 3 h, the
reaction mixture was quenched with Et3N (0.5 mL) and concen-
trated. The crude product was purified by column chromatography
(SiO2, 100–200 mesh) to afford ethyl 3,6-di-O-acetyl-4-O-(2,3-di-
H-2D), 1.26 (t, 3H, J 7.6 Hz, CH3); 13C NMR (CDCl3, 75 MHz): d
a
138.7, 138.4, 137.9, 137.8, 128.7, 128.3, 128.2, 127.8, 127.7,
127.6, 127.5, 127.4, 126.9 (aromatic-C), 96.4 (C-1G), 81.7, 81.0,
79.5 (C-1D), 78.9, 75.3, 73.5, 73.3, 72.2, 72.1, 70.9, 70.5, 70.0,
69.5, 69.4 (C-3D to C-6D, C-2G to C-6G, PhCH2), 36.3 (C-2D), 24.2
(SCH2), 15.2 (CH3). HRESIMS: m/z [M+Na]+ calcd for C49H56O9S:
843.3543; found: 843.3555. Anal. Calcd for C49H56O9S: C, 71.70;
H, 6.83; S, 3.90. Found: C, 71.70; H, 7.07; S, 3.74.
O-acetyl-
a
-D
-glucopyranosyl)-2-deoxy-1-thio-
a/b-D-arabino-hexo-
pyranoside (0.514 g, 92%,
a
/b 9:1) as a foamy solid. Rf 0.54 (EtOAc).
a
anomer: 1H NMR (CDCl3, 400 MHz): d 5.42 (d, 1H, J 4.0 Hz, H-1G),
5.28 (app.d, 1H, J 4.7 Hz, H-1D), 5.16 (t, 1H, J 10.0 Hz, H-3G), 5.03
(ddd, 1H, J 4.0, 8.0, 12.0 Hz, H-3D), 4.68 (dd, 1H, J 4.1, 10.0 Hz, H-
2G), 4.35-4.20 (band, 4H, H-5D, H-5G, H-6aD, H-6Db ), 3.84–3.53 (band,
4H, H-4D, H-4G, H-6aG, H-6Gb ), 3.20–3.11 (br s, 2H, OH), 2.59–2.43 (m,
2H, SCH2), 2.21–1.77 (band, 14H, H-2D, H-2D, COCH3), 1.20 (t, 3H, J
3.13. Ethyl 3,6-di-O-acetyl-4-O-(2,3-di-O-acetyl-4,6-O-
benzylidene-a-D-glucopyranosyl)-2-deoxy-1-thio-a/b-D-
arabino-hexopyranoside (14)
a
e
7.4 Hz, CH3); Characteristic signals for b anomer: d 5.53 (d, 1H, J
4.0 Hz, H-1G), 4.82–4.74 (m, 1H, H-3D), 3.33 (t, 1H, J 9.0 Hz, H-
4G), 3.22 (t, 1H, J 9.0 Hz, H-4D), 1.42 (ddd, 1H, J 9.0, 11.2, 12.1 Hz,
H-2Da ); 13C NMR (CDCl3, 100 MHz): d 171.6, 171.4, 170.7, 170.0
(CO), 95.6 (C-1G), 79.3 (C-1D), 73.1, 73.0, 72.5, 72.3, 70.3, 70.0,
68.3, 63.6, 62.3 (C-3D to C-6D, C-2G to C-6G), 34.9 (C-2D), 24.9
(SCH2), 21.3, 20.9, 20.6 (COCH3), 14.7 (CH3). HRESIMS: m/z
[M+Na]+ calcd for C22H34O13S: 561.1618; found: 561.1613.
A mixture of 2-deoxy-1-thioglycoside 2 (3.75 g, 10.0 mmol),
a,a-dimethoxytoluene (2.9 mL, 17.0 mmol), and p-TsOH monohy-
drate (0.19 g, 1.0 mmol) in DMF (20 mL) was stirred at diminished
pressure with a rotary evaporator for 1.5 h (bath temperature
60 5 °C). The reaction was quenched with Et3N (1 mL). The sol-
vent was removed, and the residue was taken for the next step
without further purification.
To a mixture of Ac2O (8 mL) in pyridine (13 mL), crude ethyl 4-
O-(4,6-O-benzylidene-a-D-glucopyranosyl)-2-deoxy-1-thio-a/b-D-
arabino-hexopyranoside in DMF (5 mL) was added dropwise at
0 °C. After 24 h, the reaction mixture was diluted with CH2Cl2
(100 mL), washed with ice-cold HCl (5%, 3 ꢀ 50 mL) solution, satd
NaHCO3 solution (3 ꢀ 50 mL), and water (2 ꢀ 50 mL). The extract
was dried (Na2SO4) and concentrated, and purification of the crude
To a mixture of BzCl (306
7.4 mmol) in CH2Cl2 (15 mL), ethyl 3,6-di-O-acetyl-4-O-(2,3-di-O-
acetyl- -glucopyranosyl)-2-deoxy-1-thio- /b- -arabino-hexo-
pyranoside (1.3 g, 2.43 mmol) in CH2Cl2 (15 mL) was added drop-
wise at 0 °C. After 24 h, the reaction mixture was diluted with
CH2Cl2 (50 mL), washed with ice-cold HCl (5%, 2 ꢀ 50 mL) solution,
satd NaHCO3 solution (2 ꢀ 50 mL), and water (2 ꢀ 50 mL). The ex-
tract was dried (Na2SO4) and concentrated, and purification of the
lL, 2.6 mmol) and pyridine (600 lL,
a
-
D
a
D
residue afforded 14 (5.4 g, 85% after two steps, a/b 9:1), as a white
solid.
crude product afforded 15 (1.24 g, 80%, /b 9:1) as an amorphous
solid. Rf 0.35 (1:1 EtOAc–pet ether). a
a
Compound 14
a
: mp 193–195 °C; ½a D24
ꢂ
+158.1 (c 1, CHCl3); Rf 0.5
anomer: 1H NMR (CDCl3,
(1:2 EtOAc–pet ether); 1H NMR (CDCl3, 400 MHz): d 7.45–7.34
(band, 5H, aromatic-H), 5.53–5.48 (band, 3H, H-1G, H-3G, PhCH),
5.36 (app.d, 1H, J 4.7 Hz, H-1D), 5.12 (ddd, 1H, J 5.2, 9.7, 11.0 Hz,
H-3D), 4.89 (dd, 1H, J 4.1, 10.0 Hz, H-2G), 4.45–4.33 (band, 3H, H-
5D, H-5G, H-6bD), 4.27 (dd, 1H, J 4.8, 10.2 Hz, H-6Da ), 3.93–3.82 (m,
2H, H-6Ga , H-6Gb ), 3.73 (t, 1H, J 10.0 Hz, H-4G), 3.63 (t, 1H, J 9.7 Hz,
H-4D), 2.65–2.52 (m, 2H, SCH2), 2.29 (ddd, 1H, J 1.2, 5.2, 13.2 Hz,
400 MHz): d 8.07–8.00 (band, 2H, aromatic-H), 7.61–7.43 (band,
3H, aromatic-H), 5.52 (d, 1H, J 3.8 Hz, H-1G), 5.36 (app.d, 1H, J
4.8 Hz, H-1D), 5.31 (t, 1H, J 10.0 Hz, H-3G), 5.13 (ddd, 1H, J 5.0,
9.0, 13.3 Hz, H-3D), 5.05 (dd, 1H, J 3.8, 10.0 Hz, H-2G), 4.81 (dd,
1H, J 4.0, 10.5 Hz, H-6Ga ), 4.77 (dd, 1H, J 2.7, 10.5 Hz, H-6Gb ), 4.50–
4.28 (band, 4H, H-5D, H-5G, H-6aD, H-6Db ), 3.97 (d, 1H, J 9.5, OH),
3.85 (t, 1H, J 9.0 Hz, H-4D), 3.65-3.61 (m, 1H, H-4G), 2.65–2.52
H-2D), 2.10 (s, 3H, COCH3), 2.05 (s, 3H, COCH3), 2.03–1.92 (band,
(m, 2H, SCH2), 2.27 (app.dd, 1H, J 5.0, 13.2 Hz, H-2D), 2.16–2.00
e
e
7H, COCH3, H-2D), 1.27 (t, 3H, J 7.4 Hz, CH3); 13C NMR (CDCl3,
(band, 13H, H-2D, COCH3), 1.28 (t, 3H, J 7.4 Hz, CH3); Characteristic
a
a
100 MHz): d 170.6, 170.3, 169.8, 169.6 (CO), 136.8, 129.0, 128.1,
126.2 (aromatic-C), 101.6 (PhCH), 96.4 (C-1G), 79.1 (C-1D), 78.9,
76.9, 73.8, 72.9, 70.9, 68.6, 68.5, 63.5, 63.3 (C-3D to C-6D, C-2G to
C-6G), 34.7 (C-2D), 24.8 (SCH2), 21.1, 20.7, 20.5 (COCH3), 14.6
(CH3). HRESIMS: m/z [M+Na]+ calcd for C29H38O13S: 649.1931;
found: 649.1928.
signals for b anomer: d 7.97–7.91 (band, 2H, aromatic-H), 7.39–
7.33 (band, 3H, aromatic-H), 4.99–4.90 (m, 1H, H-3D), 4.63 (dd,
1H, J 2.0, 10.0 Hz, H-1D), 4.25–4.17 (m, 2H, H-6aD, H-6Db ), 4.10 (t,
1H, J 9.0 Hz, H-4D), 2.41–2.37 (m, 1H, H-2De ), 1.64 (ddd, 1H, J
10.0, 11.2, 12.8 Hz, H-2aD); 13C NMR (CDCl3, 100 MHz): d 171.1,
170.6, 170.5, 169.8, 166.9 (CO), 133.3, 129.7, 129.5, 129.1, 128.4
(aromatic-C), 95.6 (C-1G), 79.1 (C-1D), 73.4, 72.9, 71.2, 70.2, 69.0,
68.3, 63.4, 62.8 (C-3D to C-6D, C-2G to C-6G), 34.7 (C-2D), 24.7
(SCH2), 21.0, 20.7, 20.5 (COCH3), 14.6 (CH3). HRESIMS: m/z
[M+Na]+ calcd for C29H38O14S: 665.1880; found: 665.1874.
Compound 14b: ½a D24
ꢂ
+130.9 (c 1.4, CHCl3); Rf 0.62 (1:2 EtOAc–
pet ether); 1H NMR (CDCl3, 400 MHz): d 7.43–7.33 (band, 5H, aro-
matic-H), 5.51–5.48 (band, 3H, H-1G, H-3G, PhCH), 4.97 (ddd, 1H, J
3.8, 9.0, 11.0 Hz, H-3D), 4.90 (dd, 1H, J 4.0, 9.6 Hz, H-2G), 4.64 (dd,
1H, J 1.8, 10.2 Hz, H-1D), 4.42 (dd, 1H, J 1.8, 10.2 Hz, H-6Db ), 4.34–
4.25 (m, 2H, H-5, H-6aD), 3.91–3.84 (m, 2H, H-6aG, H-6Gb ), 3.73 (t,
1H, J 9.6 Hz, H-4G), 3.65-3.60 (band, 2H, H-4D, H-5G), 2.78–2.64
3.15. General procedure for oligomerization of 13 and 15
(m, 2H, SCH2), 2.42 (ddd, 1H, J 1.8, 3.8, 12.7 Hz, H-2D), 2.11–2.03
The monomer (1 mmol) was dissolved in C6H6 (20 mL) and
freeze-dried. A solution of N-iodosuccinimide (1.1 mmol) in CH2Cl2
e
(band, 12H, COCH3), 1.64 (ddd, 1H, J 10.2, 11.0, 12.7 Hz, H-2D),
a