2056 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 7
Hu et al.
(77.23 ppm) as reference. Coupling constants (J) are reported in
hertz (Hz). Thin layer chromatography (TLC) was performed on
silica gel plates detected by charring with phosphomolybdic acid
in EtOH or 5% H2SO4 in EtOH. Commercial anhydrous solvents
and reagents were used without further purification.
filtrate was washed with aqueous NaHCO3 and Na2S2O3 solutions
and brine sequentially. The organic layer was dried over Na2SO4,
filtered, and concentrated to give the crude product, which was
purified by silica gel chromatography to afford pure 14 (800 mg,
1
74%) as colorless oil. H NMR (400 MHz, CDCl3): δ 7.91-7.53
(m, 8 H), 7.40-7.20 (m, 15 H), 7.01-6.83 (m, 10 H), 5.34 (d, J )
8.8 Hz, 1 H), 5.17 (d, J ) 10.0 Hz, 1 H), 4.90 (d, J ) 12.8 Hz, 1
H), 4.87-4.76 (m, 2 H), 4.70 (d, J ) 10.8 Hz, 1 H), 4.62-4.35
(m, 7 H), 4.30-4.13 (m, 3 H), 4.06 (t, (t, J ) 9.6 Hz, 1 H), 3.87
(t, J ) 9.6 Hz, 1 H), 3.80-3.64 (m, 2 H), 3.57 (d, J ) 10.0 Hz, 1
H), 3.50-3.35 (m, 3 H). 13C NMR (125 MHz, CDCl3): δ 138.75,
138.53, 138.30, 133.99, 131.78, 128.68, 128.61, 128.54, 128.29,
128.15, 128.07, 127.97, 127.77, 127.67, 127.57, 127.17, 123.58,
97.18, 85.78, 79.86, 79.26, 77.04, 76.79, 75.37, 75.12, 75.06, 74.79,
73.48, 72.98, 68.23, 67.95, 56.93, 55.43. NMR data were consistent
with those reported.33 MALDI-TOF MS: calcd for C63H57N5O12Na
[M + Na]+ m/z, 1098.2; found, 1098.4.
3,4,6-tri-O-Benzyl-2-deoxy-2-phthalimido-ꢀ-D-glucopyranosyl
Azide (9). After 6 (1.0 g, 3.0 mmol), Bu4NI (100 mg, 0.25 mmol)
and BnBr (3 mL, 24.1 mmol) were dissolved in DMF (30 mL),
and NaH (500 mg, 20.8 mmol) was added slowly at 0 °C. The
reaction mixture was stirred at 0 °C for 1 h and then at rt overnight.
The reaction was quenched with saturated NH4Cl solution and
extracted with DCM. The organic phase was washed with NH4Cl
solution, brine and H2O, dried over Na2SO4, and then condensed
in vacuum to give crude product, which was purified by flash
column chromatography to give 1.2 g of pure 9 (66%) as a white
solid. 1H NMR (400 MHz, CDCl3): δ 7.92-7.73 (m, 4 H),
7.20-7.41 (m, 10 H), 6.80-7.00 (m, 5 H), 5.36-5.40 (d, J ) 10.0
Hz 1 H), 4.78-4.85 (m, 2 H), 4.58-4.70 (m, 3 H), 4.11 (t, J )
10.0 Hz, 1 H), 3.76-3.85 (m, 3 H), 3.72-3.75 (m, 1 H). 13C NMR
(100 MHz, CDCl3) δ 138.16, 138.04, 138.02, 128.77, 128.68,
128.33, 128.22, 128.17, 128.06, 127.97, 127.65, 123.67, 85.92,
79.35, 79.25, 77.55, 75.33, 75.16, 73.82, 68.45, 55.58. The NMR
data were consistent with those reported.32 ESI MS: calcd for
C35H32N4NaO6 [M + Na]+ m/z, 627.2; found, 627.3.
O-(2-Acetamido-3,4,6-tri-O-benzyl-2-deoxy-ꢀ-D-glucopyranosyl)-
(1f4)-2-acetamido-3,6-di-O-benzyl-2-deoxy-ꢀ-D-glucopyranosyl
Azide (15). After the mixture of 14 (200 mg, 0.19 mmol),
NH2CH2CH2NH2 (1 mL), and n-butanol (5 mL) was stirred at 90
°C overnight, it was concentrated to dryness in vacuum. The residue
was dissolved in Ac2O and pyridine (3 mL, 1:2) and stirred at rt
overnight. The reaction mixture was diluted with EtOAc (50 mL),
and the solution was washed with saturated NaHCO3 and brine,
dried over Na2SO4, and concentrated in vacuum. The residue was
purified on a silica gel column to give 15 as a white solid (156
2-Acetamido-3,4,6-tri-O-benzyl-2-deoxy-ꢀ-D-glucopyranosyl Azide
(10). After a solution of 9 (500 mg, 0.83 mmol), NH2CH2CH2NH2
(5 mL), and n-butanol (25 mL) was stirred at 90 °C overnight, it
was concentrated to dryness under vacuum. The residue was
dissolved in Ac2O and pyridine (12 mL, 1:2) and stirred at rt
overnight. The reaction mixture was diluted with EtOAc (50 mL),
and the solution was washed with saturated NaHCO3 and brine,
dried over Na2SO4, and concentrated in vacuum. The residue was
purified on a silica gel column to give 10 as a white solid (403
1
mg, 91.2%). H NMR (400 MHz, CDCl3): δ 7.40-7.16 (m, 25
H), 6.33 (d, J ) 7.2 Hz, 1 H), 5.01 (d, J ) 7.8 Hz, 1 H), 4.85-4.72
(m, 3 H), 4.71-4.62 (m, 2 H), 4.63-4.54 (m, 3 H), 4.53-4.43
(m, 3 H), 4.35 (d, J ) 7.2 Hz, 1 H) 4.01 (t, J ) 6.4 Hz, 1 H),
3.92 (m, 1 H), 3.83-3.57 (m, 8 H), 3.55-3.45 (m, 1 H), 3.38-3.31
(m, 1 H). 2.01 (s, 3 H) 1.73 (s, 3 H). 13C NMR (100 MHz, CDCl3):
δ 170.88, 170.83, 138.65, 138.40, 138.16, 138.12, 138.08, 128.88,
128.80, 128.72, 128.64, 128,56, 128.50, 128.30, 128.22, 128.15,
128.03, 127.97, 127.92, 127.76, 100.10, 88.58, 81.15, 78.71, 78.06,
76.61, 75.12, 75.06, 74.66, 73.94, 73.86, 73.71, 72.99, 69.29, 68.77,
55.70, 52.15, 23.73, 23.35. NMR data were consistent with those
reported.33 MALDI-TOF MS: calcd for C51H57N5O10Na [M + Na]+
m/z, 922.5; found, 922.8.
1
mg, 94%). H NMR (500 MHz, CDCl3): δ 7.35-7.19 (m, 15 H),
5. 42 (d, J ) 9.6 Hz, 1 H), 4.93 (d, J ) 6.8 Hz, 1 H), 4.85-4.78
(m, 2 H), 4.64-4.54 (m, 4 H), 3.97 (t, J ) 7.6 Hz, 1 H), 3.80-3.71
(m, 2 H), 3.70 (t, J ) 7.6 Hz, 1 H), 3.63-3.55 (m, 1 H), 3.45 (dd,
J ) 7.2 Hz, 1 H), 1.85 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ
170.85, 1 38.42, 138.15, 138.04, 128.81, 128.70, 128.66, 128.31,
128.18, 128.15, 128.07, 127.95, 80.71, 78.43, 77.33, 75.07, 75.00,
73.79, 68.63, 56.42, 23.68. The NMR data were consistent with
those reported.32 ESI MS: calcd for C35H32N4NaO6 [M + Na]+ m/z,
539.2; found, 539.1.
Preparation of Glycosyl Amino Acids 4a-c (Common Proce-
dures). To a solution of 11 in DCM (10 mL) and NMP (1 mL)
was subsequently added HOBt and DCC, and the mixture was
stirred at rt for 1 h to form the active ester of 11. Meanwhile, a
mixture of glycosyl azide 10, 15, or 18 and Lindlar catalyst in
MeOH was stirred at rt for 2.5 h under a H2 atmosphere. After
filtration of the reaction mixture through celite to remove the catalyst
and then concentration of the solution in vacuum, to the resulting
residue were added DCM (2 mL) and the freshly prepared solution
of the active ester. The mixture was stirred at rt overnight,
concentrated in vacuum, and directly applied to silica gel column
chromatography to give 12, 16, and 19, respectively, as white solids.
p-Methylphenyl 3,4,6-tri-O-Benzyl-2-deoxy-2-phthalimido-1-
thio-ꢀ-D-glucopyranoside (13). After the solution of 8 (5 g, 9.23
mmol) in 40 mL of 0.05 M NaOMe in methanol was stirred at rt
for 2 h, it was neutralized to pH 6-7 using Amberlyst H+ resin.
The solution was filtered off and concentrated to afford a white
powder, which was directly used for next step. The crude product
(3.00 g, 7.22 mmol) was dissolved with TBAI (300 mg, 0.76 mmol)
and BnBr (5.71 mL, 45.88 mmol) in DMF (60 mL) at 0 °C, and
then NaH (1.6 g, 40.00 mmol) was added slowly. The reaction
mixture was stirred at 0 °C for 1 h and then at rt overnight. Workup
of the reaction was completed as described for 9, and the crude
product was purified by column chromatography to afford pure 13
(2.9 g, 59%) as a white solid. 1H NMR (400 MHz, CDCl3): δ 7.90-
7.60 (m, 4 H), 7.42-7.26 (m, 10 H), 7.04-6.82 (m, 5 H), 5.51 (d,
J ) 8.0 Hz, 1 H), 4.76-4.90 (m, 2 H), 4.74-4.56 (m, 3 H),
4.50-4.36 (m, 2 H), 4.26 (t, J ) 7.6 Hz, 1 H), 3.90-3.66 (m, 4
H), 2.29 (s, 3 H). 13C NMR (125 MHz, CDCl3): δ 138.56, 138.30,
138.22, 138.05, 134.06, 133.91, 133.65, 129.76, 128.57, 128.29,
128.18, 128.06, 127.92, 127.77, 127,58, 123.66, 123.50, 83.56,
80.54, 79.65, 79.63, 75.23, 75.19, 73.69, 69.11, 55.24, 21.34. ESI
MS: calcd. for C42H39NNaO6S [M + Na]+ m/z, 708.3; found, 708.4.
O-(-3,4,6-tri-O-Benzyl-2-deoxy-2-phthalimido-ꢀ-D-glucopyrano-
syl)-(1f4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-ꢀ-D-glucopyra-
nosyl Azide (14). To a mixture of 13 (1.0 g, 1.46 mmol), 7 (514
mg, 1.0 mmol), and MS 4 Å (1.0 g) in dry CH2Cl2 (50 mL) were
added NIS (520 mg, 2.31 mmol) and then slowly TfOH (41 µL,
0.46 mmol) under an Ar atmosphere at -30 °C. After the mixture
was stirred for 20 min, it was filtered off through celite, and the
1
12 (85%): H NMR (400 MHz, CDCl3) δ 7.76 (d, J ) 7.2 Hz, 2
H), 7.61 (d, J ) 7.2 Hz, 2 H), 7.42-7.14 (m, 19 H), 5.97 (d, J )
8.8 Hz, 1 H), 4.96-4.73 (m, 4 H), 4.59 (d, J ) 11.5 Hz, 1 H),
4.56 (d, J ) 12.5 Hz, 1 H), 4.48-4.34 (m, 4 H), 4.70-4.54 (m, 3
H), 4.53-4.32 (m, 3 H), 4.29 (t, J ) 8.0 Hz, 1 H), 4.22 (t, J ) 7.2
Hz, 1 H), 3.93-3.66 (m, 4 H), 3.54-3.40 (m, 2 H), 2.82 (ddd, J
) 16 and 4 Hz, 2 H), 1.71 (s, 3 H), 1.42 (s, 9 H). 13C NMR (100
MHz, CDCl3) δ 172.54, 171.06, 170.26, 156.36, 144.20, 144.12,
141.48, 138.20, 137.98, 129.18, 129.07, 128.73, 128.63, 128.32,
128.29, 128.21, 128.00, 127.89, 127.31, 125.49, 120.16, 82.22,
80.73, 78.56, 76.71, 75.26, 74.49, 73.86, 68.29, 67.37, 53.86, 51.25,
47.38, 38.05, 28.13, 23.33. NMR data were consistent with those
reported.39 MALDI-TOF MS: calcd for C52H57N3O10Na [M + Na]+
m/z, 906.4; found, 906.9. 16 (70%): 1H NMR (500 MHz, CD3OD/
CDCl3 1:5) δ 7.71 (d, J ) 8.0 Hz, 2 H), 7.56 (d, J ) 7.5 Hz, 2 H),
7.40-7.06 (m, 29 H), 4.79-4.67 (m, 4 H), 4.61-4.53 (m, 3 H),
4.51 (d, J ) 10.5 Hz, 1H), 4.42 (t, J ) 5 Hz, 1 H), 4.40-4.31 (m,
5 H), 4.23 (t, J ) 7.5 Hz, 1 H), 4.16 (t, J ) 7.0 Hz, 1 H), 4.04 (t,
J ) 7.0 Hz, 1 H), 3.96 (t, J ) 8.5 Hz, 1 H), 3.84 (t, J ) 10.0 Hz,