6
X. Zhang et al. / Carbohydrate Research 388 (2014) 1–7
with CH2Cl2 (about 50 mL), filtered through Celite, washed with
saturated brine (3 Â 10 mL), dried over anhydrous MgSO4, and
concentrated under reduced pressure. The residue was purified
by silica gel column chromatography eluting with a hexanes/EtOAc
system to give the coupling products.
3.3 Hz, 1H, H-3 eq), 2.13 (s, 3H), 2.12 (t, J = 12.7 Hz, 1H), 2.05
(s, 3H), 1.92 (s, 3H), 1.25 (m, 2H) ppm; 13C NMR (100 MHz, CDCl3):
3
d = 171.4, 170.4, 169.7, 168.6(C1, JC1,H3ax = 5.7 Hz), 159.1, 139.0,
138.1, 128.4, 128.1, 127.7, 127.6, 127.5, 104.7, 99.1, 76.6, 76.3,
74.7, 73.8, 73.6, 72.5, 69.1, 69.0, 68.0, 67.2, 61.8, 57.9, 56.9, 52.1,
36.5, 29.7, 21.0, 20.6, 20.4 ppm; HRMS (ESI-TOF): m/z calcd for
4.3. General sialylation procedure with NIS/TfOH as promoter
C
38H48NO17 [M+H]+ 790.2922, found: 790.2939.
A solution of sialyl donors (D1–D4, 37.2/40.1 mg, 0.069 mmol,
1.0 equiv), acceptor (1.1–2.0 equiv), NIS (37.3 mg, 0.1656 mmol,
2.4 equiv) and activated 4 Å powdered sieves in anhydrous
CH2Cl2–CH3CN (2:1, 2.67/2.40 mL) was stirred for 10 min at room
temperature under Ar. Then the mixture was stirred at À40 °C
for 20 min, followed by the addition of CH2Cl2–CH3CN (2:1) solu-
tion of TfOH (0.33/0.60 mL, 1.1/2.0 equiv). After stirred for another
1.0 h at À40 °C, the reaction was quenched with Et3N (0.1 mL). The
mixture was diluted with CH2Cl2 (about 50 mL), filtered through
Celite, washed with 20% aq Na2S2O3 solution (2 Â 10 mL) and
saturated brine (2 Â 10 mL), dried over anhydrous MgSO4, and
concentrated under reduced pressure. The residue was purified
by silica gel column chromatography eluting with a hexanes/EtOAc
system to give the coupling products.
4.7. Methyl (cyclohexyl 5-acetamido-7,8,9-tri-O-acetyl-5-N,
4-O-carbonyl-3,5-dideoxy- -glycero- -galacto-non-2-
ulopyranoside) onate (24
D
a-D
a)
1H NMR (400 MHz, CDCl3): d = 5.58 (d, J = 8.0 Hz, 1H), 5.40–5.42
(m, 1H), 4.56 (d, J = 9.2 Hz, 1H), 4.37 (dd, J = 12.2, 2.4 Hz, 1H), 4.06
(dd, J = 12.2, 6.8 Hz, 1H), 3.92–3.99 (m, 1H), 3.80 (s, 3H), 3.67–3.74
(m, 2H), 2.89 (dd, J = 11.9, 3.3 Hz, 1H, H-3eq), 2.50 (s, 3H), 2.15 (s,
3H), 2.14 (s, 3H), 2.04 (s, 3H), 1.94 (s, 1H), 1.16–1.70 (m, 10H) ppm;
13C NMR (100 MHz, CDCl3): d = 172.0, 170.6, 170.1, 169.3 (C1,
JC1,H3ax = 5.7 Hz), 153.8, 99.2, 75.24, 75.18, 71.9, 69.3, 63.1, 59.2,
52.7, 37.0, 34.9, 33.1, 25.4, 24.7, 24.3, 24.1, 21.2, 20.9, 20.8 ppm;
HRMS (ESI-TOF): m/z calcd for C25H35NO13 [M+H]+ 558.2187,
found: 558.2184.
4.4. Methyl (octyl 7,8,9-tri-O-acetyl-5-N,4-O-carbonyl-3,5-
Acknowledgments
dideoxy-D-glycero-a-D-galacto-non-2-ulopyranoside)onate
(12
a
)
The project was financially supported by the National Natural
Science Foundation of China (21272027, 20502002), Beijing
National Natural Science Foundation (2122031), and Beijing
Municipal Commission of Education.
1H NMR (400 MHz, CDCl3): d = 5.47 (d, J = 9.7 Hz, 1H), 5.34
(s, 1H), 5.13 (d, J = 9.7 Hz, 1H), 4.36–4.25 (m, 3H), 3.97–3.90
(m, 1H), 3.79 (s, 3H, COOCH3), 3.76–3.70 (m, 1H), 3.22–3.16 (m, 1H),
3.05 (t, J = 10.3 Hz, 1H), 2.89 (dd, J = 12.1, 3.2 Hz, 1H, H-3eq), 2.19
(s, 6H), 2.07 (s, 3H), 1.63 (br s, 1H), 1.55-1.50 (m, 2H), 1.27 (br s,
9H), 0.88 (t, J = 6.4 Hz, 3H) ppm; 13C NMR (100 MHz, CDCl3):
Supplementary data
Supplementary data (1H NMR spectra of sialyl donors D1–D4,
1H and 13C NMR spectra of new compounds) associated with this
3
d = 171.5, 170.5, 169.8, 168.7(C1, JC1,H3ax = 5.3 Hz), 159.3, 100.2,
76.8, 73.4, 68.9, 67.0, 65.6, 61.7, 58.0, 52.8, 37.6, 31.8, 29.5, 29.2,
25.8, 22.6, 21.0, 20.8, 20.7, 14.1 ppm; HRMS (ESI-TOF): m/z calcd
for C25H39NO12Na [M+Na]+ 568.2370, found: 568.2352.
References
4.5. Methyl (cyclohexyl 7,8,9-tri-O-acetyl-5-N,4-O-carbonyl-3,5-
dideoxy-
D-glycero-a-D-galacto-non-2-ulopyranoside)onate
(13a)
1H NMR (400 MHz, CDCl3): d = 5.42 (d, J = 9.7 Hz, 1H), 5.34
(s, 1H), 5.30 (s, 1H), 5.12 (dd, J = 9.8, 1.6 Hz, 1H), 4.35–4.26
(m, 2H), 4.21 (dd, J = 9.9, 1.6 Hz, 1H), 3.94–3.87 (m, 1H), 3.77 (s, 3H,
COOCH3), 3.57 (br s, 1H), 3.04 (t, J = 10.4 Hz, 1H), 2.90 (dd,
J = 12.0, 3.4 Hz, 1H, H-3eq), 2.19 (s, 3H), 2.18 (s, 3H), 2.06 (s, 3H),
1.89 (br s, 1H), 1.71–1.49 (m, 5H), 1.37–1.15 (m, 5H) ppm; 13C
NMR (100 MHz, CDCl3): d = 171.5, 170.5, 169.7, 169.0(C1,
3JC1,H3ax = 5.5 Hz), 159.4, 100.3, 76.9, 75.3, 73.4, 68.9, 67.2, 61.8,
57.9, 52.6, 37.9, 34.9, 33.0, 25.3, 24.3, 24.1, 21.0, 20.8, 20.6 ppm;
HRMS (ESI-TOF): m/z calcd for C23H33NO12Na [M+Na]+ 538.1901,
found: 538.1876.
4.6. Methyl 7,8,9-tri-O-acetyl-5-N,4-O-carbonyl-3,5-dideoxy-
glycero- -galacto-non-2-ulopyranosylonate-(2 ? 3)-methyl
2,6-di-O-benzyl-b- -galactopyranoside (15
D-
a-D
D
a)
1H NMR (400 MHz, CDCl3): d = 7.37–7.28 (m, 10 H), 5.52 (ddd,
J = 9.6, 3.2, 2.1 Hz, 1H), 5.31 (s, 1H), 5.09 (dd, J = 9.6, 1.8 Hz, 1H),
4.81 (d, J = 11.9 Hz, 1H), 4.70 (d, J = 11.9 Hz, 1H), 4.58 (s, 2H),
4.35 (d, J = 7.7 Hz, 1H), 4.24 (dd, J = 12.7, 1.9 Hz, 1H), 4.19–4.15
(m, 2H), 4.06 (dd, J = 9.6, 3.2 Hz, 1H), 3.96–3.89 (m, 1H), 3.81 (dd,
J = 9.9, 6.2 Hz, 1H), 3.76 (s, 3H, COOCH3), 3.74 (d, J = 5.6 Hz, 1H),
3.72 (d, J = 3.8 Hz, 1H), 3.61 (t, J = 5.9 Hz, 1H), 3.56 (s, 3H), 3.53
(dd, J = 9.6, 7.8 Hz, 1H), 3.02 (t, J = 10.4 Hz, 1H), 2.89 (dd, J = 12.2,