19[14] (648 mg, 2.39 mmol), dissolved in glacial acid (20 mL) and
stirred for 18 h at RT. The solution was concentrated, and the
crude product dissolved in pyridine (5 mL) and treated with
Ac2O (1.13 mL, 11.9 mmol, 5 equiv) at RT for 52 h under N2 at-
mosphere. The solution was concentrated and co-evaporated
with toluene. The residual was purified by flash column chro-
matography (EtOAc/cyclohexane, pure EtOAc!1:1) to yield
protected glycoside 22 as an orange solid (1.25 g, 2.13 mmol,
89%): mp: 558C; Rf =0.5 (MeOH/EtOAc, 1:2); [a]2D0 = +1.83 (c=
1211 cmꢁ1; MS (ESI): m/z [M+Na]+ calcd for C26H28N2O11:
567.51, found: 567.16.
28: mp: 167–1698C; Rf =0.15 (cyclohexane/EtOAc, 1:1); [a]2D0 =
1
+0.89 (c=1.0, CH2Cl2); H NMR (500 MHz, CDCl3): d=7.89 (dd,
J=9.0 Hz, 4H, H-9, H-11, H-14, H-18), 7.22 (d, J=9.0 Hz, 4H, H-
8, H-12, H-15, H-17), 5.61 (d, J1,2 =1.7 Hz, 2H, 2 H-1), 5.58 (dd,
J3,4 =10.0, J2,3 =3.5 Hz, 2H, 2 H-3), 5.48 (dd, J2,3 =3.5 Hz, J1,2 =
1.8 Hz, 2H, 2 H-2), 5.38 (dd~t, J3,4 =J4,5 =10.1 Hz, 2H, 2 H-4),
4.31–4.26 (m, 2H, 2 H-6a), 4.11-4.07 (m, 4H, 2 H-5, 2 H-6b),
2.21, 2.06, 2.05, 2.03 (each s, each 6H, 8OAc); 13C NMR
(150 MHz, CDCl3): d=170.5, 169.9, 169.9, 169.7 (8 C=O), 157.5
(C-7, C-16), 148.4 (C-13, C-10), 124.5 (C-9, C-11, C-14, C-18),
116.8 (C-8, C-12, C-15, C-17), 95.7 (C-1), 69.5 (C-5), 69.3 (C-2),
68.8 (C-3), 65.9 (C-4), 62.1 (C-6), 20.9, 20.7, 20.7, 20.7
(8CO2CH3C); IR (ATR): v˜ =2992, 1748, 1599, 1582, 1496, 1368,
1213 cmꢁ1; MS (ESI): m/z [M+Na]+ calcd for C40H46N2O20:
897.26, found: 897.23.
1
0.26, DMSO);); H NMR (500 MHz, CDCl3): d=7.91 (d, J=8.9 Hz,
2H, H-9, H-11), 7.81 (mc, 1H, H-15), 7.58 (mc, 2H, H-17, H-18),
7.47 (ddd, J=7.7, 6.4, 2.2 Hz, 1H, H-16), 7.22 (d, J=8.9 Hz, 2H,
H-8, H-12), 5.83 (d, J1,2 =3.6 Hz, 1H, H-1), 5.72 (dd, J2,3 =10.0,
J
3,4 =9.6 Hz, 1H, H-3), 5.18 (dd, J3,4 =9.5 Hz, J4,5 =10.1 Hz, 1H,
H-4), 5.08 (dd, J1,2 =3.6 Hz, J2,3 =10.2 1H, H-2), 4.26 (dd, J5,6a
12.3, J6a,6b =4.52 Hz, 1H, H-6a), 4.11 (mc, 1H, H-5), 4.07 (dd,
5,6b =12.2, J6a,6b =2.3 Hz, 1H, H-6b), 3.91 (s, 3H, CO2CH3), 2.08,
=
J
2.06, 2.05, 2.04 (each s, each 3H, 4OAc); 13C NMR (125 MHz,
CDCl3): d=170.5, 170.2, 169.5, 167.9 (4 C=O), 158.9 (C-7), 151.9
(C-13), 148.5 (C-10), 131.9 (C-17), 129.7 (C-15). 129.6 (C-16),
125.1 (C-9, C-11), 118.8 (C-18), 116.8 (C-8, C-12), 94.7 (C-1), 70.3
(C-2), 69.9 (C-3), 68.3 (C-5), 68.2 (C-4), 61.5 (C-6), 52.3 (C-20),
20.7, 20.66, 20.63, 20.59 (4CO2CH3); IR (ATR): v˜ =1741, 1596,
1498, 1367, 1214 cmꢁ1; MS (ESI): m/z [M+Na]+ calcd for
C28H30N2O12: 609.169, found: 609.167.
E-p-(p-Hydroxyphenylazo)phenyl 2,3,4,6-tetra-O-acetyl-b-d-
glucopyranoside (25): BF3·Et2O (280 mL, 2.16 mmol) was added
at 08C under N2 atmosphere to a solution of the glucosyl
donor 11 (907 mg, 1.84 mmol) and p,p’-dihydroxyazoben-
zene[16] (23, 304 mg, 1.42 mmol) in dry THF (5 mL). The reaction
mixture was stirred at RT overnight, and saturated aq NaHCO3
(5 mL) was added to quench the reaction. The solution was ex-
tracted with CH2Cl2 (3ꢃ5 mL). The combined organic phases
were washed with H2O (2ꢃ5 mL), dried over MgSO4, filtered
and concentrated under reduced pressure. Purification by flash
column chromatography (cyclohexane/EtOAc, 1:1) gave the
monoglycosylated product 25 as a yellow solid (239 mg,
0.440 mmol, 31%): mp: 89–918C; Rf =0.46 (cyclohexane/EtOAc,
E-p-(o-Hydroxyphenylazo)phenyl 2,3,4,6-tetra-O-acetyl-a-d-
mannopyranoside (24) and E-p-[p-(2,3,4,6-tetra-O-acetyl-a-d-
mannopyranosyloxy)]phenylazophenyl
acetyl-a-d-mannopyranoside (28):
2,3,4,6-tetra-O-
BF3·Et2O (260 mL,
2.01 mmol) was added at 08C under N2 atmosphere to a solu-
tion of mannosyl donor 10 (1.00 g, 2.03 mmol) and p,p’-dihy-
droxyazobenzene[16] (23, 200 mg, 0.93 mmol) in dry CH3CN
(15 mL). The reaction mixture was stirred at RT overnight, and
saturated aq NaHCO3 (5 mL) was added to quench the reac-
tion. After dilution with EtOAc (100 mL), the phases were sepa-
rated. The organic phase was washed with H2O (2ꢃ15 mL),
dried over Na2SO4, filtered and concentrated under reduced
pressure. Purification by flash column chromatography (cyclo-
hexane/EtOAc, 6:4) gave the monoglycosylated product 24
(190 mg, 0.349 mmol, 37%) as the first fraction, followed by
the divalent glycoside 28 (268 mg, 0.307 mmol, 31%) as pale
yellow solids.
1
1:3) [a]2D0 =ꢁ1.27 (c=0.92, MeOH); H NMR (500 MHz, CDCl3):
d=7.77 (d, J=9.0 Hz, 2H, H-9, H-11), 7.75 (d, J=8.9 Hz, 2H, H-
14, H-18), 7.00 (d, J=9.0 Hz, 2H, H-8, H-12), 6.86 (d, J=8.9 Hz,
2H, H-15, H-17), 6.19 (s, br, 1H, OH), 5.25 (mz, 2H, H-2, H-3),
5.12 (t, J=9.8 Hz, 1H, H-4), 5.09 (d, J1,2 =7.2 Hz, 1H, H-1), 4.30
(dd, J=12.3, 5.3 Hz, 1H, 1H-6a), 4.13 (dd, J=2.5, 12.3, 1H, H-
6b), 3.84 (ddd, J=10, 5.4, 2.5 Hz, 1H, H-5), 2.02 (s, 3H, OAc-6),
2.01, (s, 3H, OAc-2), 1.99, (s, 3H, OAc-4), 1.98 (s, 3H, OAc-3);
13C NMR (150 MHz, CDCl3): d=170.8 (CO2CH3-6) 170.4 (CO2CH3-
4), 169.5 (CO2CH3-2), 169.5 (CO2CH3-4), 158.6 (C-16), 158.3 (C-7),
148.7 (C-10), 146.9 (C-13), 124.8 (C-14, C-18), 124.2 (C-9, C-11),
117.1 (C-8, C-12), 115.8 (C-15, C-17), 98.8 (C-1), 72.7 (C-2), 72.2
(C-5), 71.2 (C-3), 68.3 (C-4), 62.0 (C-6), 20.7, 20.6, 20.6, 20.5
(4CO2CH3); IR (ATR): v˜ =3367, 2940, 2874, 1743, 1586, 1366,
1211 cmꢁ1; MS (ESI): m/z [M+H]+ calcd for C26H28N2O11: 545.2,
found: 545.3.
24: mp: 109–1108C; Rf =0.26 (cyclohexane/EtOAc, 1:1); [a]2D0 =
1
+0.75 (c=1.0, CH2Cl2); H NMR (600 MHz, CDCl3): d=7.85 (d,
J=9.0 Hz, 2H, H-14, H-18), 7.83 (d, J=8.9 Hz, 2H, H-9, H-11),
7.19 (d, J=9.0 Hz, 2H, H-15, H-17), 6.94 (d, J=8.8 Hz, 2H, H-8,
H-12), 5.61 (d, J1,2 =1.6 Hz, 1H, H-1), 5.59 (dd, J3,4 =10.0, J3,2
=
3.4 Hz, 1H, H-3), 5.48 (dd, J2,3 =3.5 Hz, J1,2 =1.8 Hz, 1H, H-2),
5.39 (dd~t, J3,4 =J4,5 =10.1 Hz, 1H, H-4), 4.30 (dd, J5,6a =12.1,
E-p-(p-Hydroxyphenylazo)phenyl a-d-mannopyranoside (26):
Protected mannoside 24 (100 mg, 0.184 mmol) was dissolved
in dry MeOH (2 mL), and a catalytic amount of NaOMe was
added. The reaction mixture stirred at RT overnight and then
neutralized with Amberlite IR 120 ion exchange resin. After fil-
tration, the filtrate evaporated under reduced pressure to yield
pure 26 as a light orange solid (61 mg, 0.162 mmol, 88%): mp:
206–2078C; Rf =0.18 (CH2Cl2/MeOH, 9:1); [a]2D0 = +1.02 (c=1.0,
J6a,6b =5.3 Hz, 1H, H-6a), 4.12–4.08 (m, 2H, H-5, H-6b), 2.22,
2.07, 2.06, 2.04 (each s, each 3H, 4OAc); 13C NMR (150 MHz,
CD3OD): d=170.7, 170.3, 170.1, 169.8 (4C=O), 158.3 (C-7),
157.2 (C-16), 148.5 (C-13), 147.1 (C-10), 124.8 (C-14, C-18), 124.3
(C-9, C-11), 116.8 (C-15, C-17), 115.8 (C-8, C-12), 95.7 (C-1), 69.4
(C-5), 69.3 (C-2), 68.9 (C-3), 65.9 (C-4), 62.1 (C-6), 20.9, 20.7,
20.7, 20.7 (CO2CH3); IR (ATR): v˜ =3407, 1744, 1587, 1498, 1368;
1
MeOH); H NMR (500 MHz, CD3OD): d=7.82 (d, J=9.0 Hz, 2H,
ꢀ 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemistryOpen 2014, 3, 99 – 108 107