A R T I C L E S
Pratt and Bertozzi
syl)-(1f4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-1-â-D-
glucopyranosyl Azide (20). Compound 19 (380 mg, 0.214 mmol) was
dissolved in pyridine, and Ac2O (40 µL, 0.428 mmol) was added. The
reaction was stirred for 16 h and then concentrated under high vacuum.
Silica gel chromatography (30% ethyl acetate in hexanes) yielded 377
mg (95%) of 20 as a colorless oil. 1H NMR (500 MHz, CDCl3) δ 7.87-
7.69 (m, 8 H), 7.47-7.46 (app d, 2 H, J ) 6.5 Hz), 7.35-7.13 (m, 30
H), 7.03-6.97 (m, 10 H), 6.79-6.76 (m, 3 H), 5.49 (s, 1 H), 5.41 (d,
1 H, J ) 2.8 Hz), 5.32 (s, 1 H), 5.26 (d, 1 H, J ) 8.2 Hz), 5.16 (d, 1
H, J ) 9.4 Hz), 4.87-4.80 (m, 3 H), 4.74 (s, 1 H), 4.65 (d, 1 H, J )
12.2 Hz), 4.58-4.38 (m, 9 H), 4.29-4.13 (m, 10 H), 4.05 (app t, 1 H,
J ) 9.6 Hz), 3.92-3.88 (m, 3 H), 3.82 (app t, 1 H, J ) 9.3 Hz), 3.75-
3.64 (m, 5 H), 3.58-3.52 (m, 3 H), 3.22 (app d, 1 H, J ) 9.9 Hz),
3.11-3.09 (m, 2 H), 2.03 (s, 3 H);13C NMR (125 MHz, CDCl3) δ
171.23, 170.61, 170.09, 169.55, 169.44, 138.98, 138.60, 138.57, 138.48,
138.41, 138.35, 138.29, 138.20, 138.05, 138.01, 137.94, 137.86, 137.22,
133.79, 131.51, 129.41, 129.27, 129.11, 129.03, 128.65, 128.44, 128.39,
128.35, 128.25, 128.22, 128.16, 128.13, 128.09, 128.05, 128.01, 127.95,
127.88, 127.86, 127.78, 127.73, 127.70, 127.66, 127.63, 127.56, 127.43,
127.25, 127.02, 126.88, 126.31, 126.25, 123.30, 102.08, 101.41, 99.14,
96.95, 85.56, 78.74, 78.44, 77.72, 76.77, 76.46, 75.59, 75.14, 75.05,
74.60, 74.53, 74.44, 74.34, 73.40, 73.28, 73.08, 72.89, 72.78, 72.14,
71.04, 70.74, 69.15, 68.51, 67.69, 67.54, 66.59, 56.54, 55.19, 47.32,
20.87; FAB-HRMS calcd for C105H101N5O22S (M + Na+) 1838.6557,
found 1838.6662; IR (thin film) cm-1 2923.3, 2112.4, 1716.0, 1650.7,
1557.8.6, 1073.2, 728.0.
to rt over 16 h. The mixture was then filtered through a pad of Celite,
and the filtrate was washed with concentrated NaHCO3, H2O, and brine.
The organic layer was dried over Na2SO4, filtered, and concentrated.
Silica gel chromatography (30% ethyl acetate in hexanes) yielded 600
mg (85%) of 22 as a colorless oil. 1H NMR (500 MHz, CDCl3) δ 7.83-
7.57 (m, 8 H), 7.31-7.07 (m, 45 H), 6.94-6.92 (m, 5 H), 6.75-6.74
(m, 10 H), 5.39 (d, 1 H, J ) 1.2 Hz), 5.26 (d, 1 H, J ) 1.1 Hz), 5.22
(d, 1 H, J ) 8.0 Hz), 5.14 (d, 1 H, J ) 9.3 Hz), 4.87-4.83 (m, 3 H),
4.74-4.67 (m, 4 H), 4.65 (s, 1 H), 4.58-4.32 (m, 14 H), 4.26-4.11
(m, 6 H), 4.08-4.02 (m, 2 H), 3.90-3.88 (m, 5 H), 3.83-3.47 (m, 15
H), 3.36 (app d, 2 H, J ) 9.3 Hz), 3.25-3.20 (m, 2 H), 3.06 (m, 2 H),
2.03 (s, 3 H); 13C NMR (125 MHz, CDCl3) δ 169.75, 169.53, 169.21,
167.56, 138.84, 138.54, 138.48, 138.42, 138.38, 138.28, 138.24, 138.21,
138.19, 138.18, 138.11, 138.08, 138.04, 138.03, 137.96, 137.94, 137.88,
133.80, 131.81, 131.54, 129.24, 129.19, 129.16, 129.08, 128.78, 128.60,
128.59, 128.58, 128.56, 128.53, 128.49, 128.48, 128.45, 128.40, 128.36,
128.34, 128.31, 128.30, 128.27, 128.25, 128.17, 128.03, 128.00, 127.94,
127.91, 127.89, 127.87, 127.81, 127.79, 127.76, 127.75, 127.74, 127.73,
127.69, 127.65, 127.61, 127.59, 127.56, 127.55, 127.52, 127.48, 127.20,
127.17, 127.12, 127.11, 127.01, 123.38, 102.46, 100.60, 99.20, 96.95,
85.54, 81.47, 78.82, 78.42, 77.42, 76.80, 75.63, 75.56, 75.22, 75.07,
74.87, 74.63, 74.52, 73.52, 73.40, 73.36, 73.30, 72.87, 71.99, 71.51,
71.33, 69.13, 55.23, 37.07, 36.72, 21.19; ESI-HRMS calcd for
C
132H131N5O26S2 (M + 2Na+/2) 1156.4170, found 1156.4198; IR (thin
film) cm-1 3340.8, 2924.3, 2115.3, 1725.9.3, 1650.7, 1553.8, 1072.3,
720.8.
O-(3,4,6-Tri-O-benzyl-2-deoxy-2-thiobenzyl-r-D-mannopyrano-
syl)-(1f3)-O-(2-O-acetyl-â-D-mannopyranosyl)-(1f4)-O-(3,6-di-O-
benzyl-2-deoxy-2-phthalimido-â-D-glucopyranosyl)-(1f4)-3,6-di-O-
benzyl-2-deoxy-2-phthalimido-1-â-D-glucopyranosyl Azide (21).
Compound 20 (325 mg, 0.179 mmol) was placed in an ice bath, and a
precooled solution (0 °C) of 5% TFA in CH2Cl2 (15 mL) was added.
The reaction was stirred at 0 °C for 20 min, at which time the acid
was quenched with addition of aqueous NaHCO3. The resulting mixture
was washed with H2O and brine. The organic layer was dried over
Na2SO4, filtered, and concentrated. Silica gel chromatography (40%
ethyl acetate in hexanes) yielded 200 mg (65%) of 21 as a yellow oil.
1H NMR (500 MHz, CDCl3) δ 7.89-7.55 (m, 8 H), 7.38-7.15 (m, 25
H), 7.01-6.94 (m, 7 H), 6.77-6.73 (m, 3 H), 5.37 (d, 1 H, J ) 3.1
Hz), 5.26 (d, 1 H, J ) 8.1 Hz), 5.16 (d, 1 H, J ) 9.4 Hz), 5.13 (d, 1
H, J ) 4.0 Hz), 4.87 (d, 1 H, J ) 12.0 Hz), 4.86 (d, 1 H, J ) 12.9
Hz), 4.67-4.32 (m, 16 H), 4.26-4.03 (m, 8 H), 3.83-3.63 (m, 6 H),
3.57-4.48 (m, 5 H), 3.43-3.38 (m, 4 H), 3.22 (app d, 1 H, J ) 9.8
Hz), 3.04 (app t, 2 H, J ) 9.9 Hz), 2.05 (s, 3 H); 13C NMR (125 MHz,
CDCl3) δ 171.23, 170.61, 170.09, 169.55, 169.53, 138.39, 138.36,
138.16, 138.14, 138.13, 138.09, 138.03, 137.85, 129.12, 128.58, 128.56,
128.37, 128.34, 128.32, 128.29, 128.21, 128.15, 128.08, 127.89, 127.86,
127.82, 127.81, 127.78, 127.74, 127.68, 127.65, 127.63, 127.58, 127.57,
127.34, 127.19, 126.96, 102.22, 98.23, 96.95, 85.51, 79.58, 78.32, 77.86,
77.29, 76.75, 76.68, 76.48, 75.36, 75.19, 75.14, 74.65, 74.44, 74.41,
73.30, 73.06, 72.88, 71.82, 71.21, 69.03, 67.65, 67.43, 64.35, 62.29,
56.45, 55.18, 47.85, 21.06; FAB-HRMS calcd for C98H97N5O22S (M
+ Li+) 1734.6506, found 1734.6483; IR (thin film) cm-1 3339.8,
2923.5, 2115.2, 1715.9, 1657.7, 1557.8, 1073.3, 719.8.
O-(3,4,6-Tri-O-benzyl-2-deoxy-2-thiobenzyl-r-D-mannopyrano-
syl)-(1f3)-O-[(3,4,6-tri-O-benzyl-2-deoxy-2-thiobenzyl-r-D-man-
nopyranosyl)-(1f6)]-O-(2-O-acetyl-â-D-mannopyranosyl)-(1f4)-O-
(2-acetamido-3,6-di-O-benzyl-2-deoxy-â-D-glucopyranosyl)-(1f4)-
2-acetamido-3,6-di-O-benzyl-2-deoxy-1-â-D-glucopyranosyl Azide
(23). Pentasaccharide 22 (130 mg, 0.06 mmol) was dissolved in n-BuOH
(10 mL) and ethylenediamine (2.5 mL). The reaction mixture was then
heated at 90 °C for 16 h. At this time, the reaction was concentrated
under high vacuum and evaporated from toluene (20 mL) 2 times. A
solution of pyridine/Ac2O (2:1, 20 mL) was then added, and the reaction
was stirred for 4 h. The solvent was removed under high vacuum, and
the resulting oil was purified by silica gel chromatography (66% ethyl
acetate in hexanes) to yield 115 mg (97%) of 23 as a colorless oil.1H
NMR (500 MHz, CDCl3) δ 7.31-7.21 (m, 55 H), 7.14-7.11 (m, 5
H), 6.15 (d, 1 H, J ) 12 Hz), 5.35 (d, 1 H, J ) 3.0 Hz), 5.12 (app t,
1 H, J ) 9.8 Hz), 4.99 (d, 1 H, J ) 3.7 Hz), 4.89 (d, 1 H, J ) 1 Hz),
4.83-4.76 (m, 4 H), 4.70 (d, 1 H, J ) 8.4 Hz), 4.67-4.58 (m, 7 H),
4.55-4.48 (m, 7 H), 4.43-4.32 (m, 8 H), 3.95 (app t, 1 H, J ) 5.4
Hz), 3.84-3.81 (m, 6 H), 3.71-3.54 (m, 15 H), 3.49 (d, 1 H, J ) 8.3
Hz), 3.45 (dd, 1 H, J ) 10.8, 1.0 Hz), 3.39 (dd, 1 H, J ) 7.8, 3.3 Hz),
3.20 (m, 2 H), 3.10 (dd, 1 H, J ) 2.6, 1.4 Hz), 2.99 (dd, 1 H, J ) 7.3,
3.6 Hz), 2.01 (s, 3 H), 1.85 (s, 3 H), 1.82 (s, 3 H), 1.65 (s, 3 H); 13C
NMR (125 MHz, CDCl3) δ 170.42, 170.39, 169.84, 169.57, 138.62,
138.58, 138.39, 138.38, 138.35, 138.29, 138.26, 138.22, 138.19, 138.17,
137.99, 137.89, 129.15, 129.05, 128.58, 128.55, 128.50, 128.48, 128.36,
128.32, 128.31, 128.30, 128.29, 128.28, 128.24, 128.19, 128.04, 127.94,
127.92, 127.89, 127.86, 127.79, 127.73, 127.70, 127.68, 127.65, 127.63,
127.61, 127.55, 127.50, 127.48, 127.12, 127.04, 103.24, 100.34, 99.73,
98.03, 88.19, 79.11, 79.05, 78.19, 77.83, 76.43, 75.88, 75.47, 75.10,
74.78, 74.41, 73.80, 73.56, 73.40, 73.35, 73.29, 73.24, 73.21, 72.80,
72.73, 72.16, 72.10, 71.89, 71.56, 71.03, 69.08, 69.01, 68.84, 68.42,
67.00, 23.40, 23.10, 21.02, 20.96; FAB-HRMS calcd for C122H133N5O25S2
(M + Na+) 2154.8629, found 2154.8541; IR (thin film) cm-1 2922.9,
2113.2, 1650.4, 1557.8, 1072.3, 719.5.
O-(3,4,6-Tri-O-benzyl-2-deoxy-2-thiobenzyl-r-D-mannopyrano-
syl)-(1f3)-O-[(3,4,6-tri-O-benzyl-2-deoxy-2-thiobenzyl-r-D-man-
nopyranosyl)-(1f6)]-O-(2-O-acetyl-â-D-mannopyranosyl)-(1f4)-O-
(3,6-di-O-benzyl-2-deoxy-2-phthalimido-â-D-glucopyranosyl)-(1f4)-
3,6-di-O-benzyl-2-deoxy-2-phthalimido-1-â-D-glucopyranosyl Azide
(22). Compounds 21 (537 mg, 0.311 mmol) and 18 (191 mg, 0.342
mmol) were combined and evaportated from toluene (50 mL) 3 times.
The mixture was placed under high vacuum for 1 h, and dry CH2Cl2
(20 mL) and freshly activated 4-Å molecular sieves were added. The
reaction mixture was cooled to 0 °C, and SnCl2 (106 mg, 0.560 mmol)
was added. The reaction was stirred for 15 min, at which time AgOTf
(144 mg, 0.560 mmol) was added. The reaction was allowed to warm
Nr-(tert-Butoxycarbonyl)-Nγ-{O-(3,4,6-tri-O-benzyl-2-deoxy-2-
thiobenzyl-r-D-mannopyranosyl)-(1f3)-O-[(3,4,6-tri-O-benzyl-2-
deoxy-2-thiobenzyl-r-D-mannopyranosyl)-(1f6)]-O-(2-O-acetyl-â-
D-mannopyranosyl)-(1f4)-O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-
â-D-glucopyranosyl)-(1f4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-1-
â-D-glucopyranosyl}-L-asparagine tert-Butyl Ester 26. Pentasaccharide
9
6156 J. AM. CHEM. SOC. VOL. 125, NO. 20, 2003