The Journal of Organic Chemistry
Page 6 of 7
2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-D-glucopyranose
mg, 23 %). C10H25N2O4P; TLC (H2O/i-PrOH/EtOAc = 1:2:4) Rf
(7).15 To a solution of penta-acetate compound 6 (2.0 g, 5.137
mmol) in anhydrous THF (17 mL) was added benzylamine
(0.67 mL, 6.16 mmol). The mixture was stirred at room temper-
ature for 16 h, concentrated under reduced pressure, and puri-
fied by silica gel chromatography (EtOAc/hexane = 3:1 to 1:0)
to yield compound 7 (1.685 g, 95%). C14H21NO9; TLC
(EtOAc/hexane = 3:1) Rf = 0.21. Spectral values were in accord-
ance with literature.15
= 0.29. Spectral values were in accordance with literature.21
1
2
3
4
5
6
7
8
(2E,6E,10E,14E,18E,22E,26E,30E)-
3,7,11,15,19,23,27,31,35-nonamethylhexatriaconta-
2,6,10,14,18,22,26,30,34-nonaen-1-yl
phosphate
(11b,
solanesyl phosphate as the ammonium salt).15 To a solution
of LiCl (212 mg, 5 mmol), 2,4,6-collidine (1.1 mL, 8 mmol),
and solanesol (316 mg, 0.5 mmol) in DMF (20 mL) at 0 oC was
added CH3SO2Cl (0.23 mL, 3 mmol). The mixture was stirred
o
2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyra-
nosyl dibenzyl phosphate (8).15 Method A: To a solution of
compound 7 (1.78 g, 5.13 mmol) and dibenzyl N,N-diiso-
propylphosphoramidite (3.37 mL, 10.25 mmol) in anhydrous
THF (28 mL) was added 1H-tetrazole solution (45.6 mL, 0.45
M in anhydrous MeCN). The mixture was stirred for 14 h at
room temperature, cooled to –50 ℃ (electronic cooling system),
and hydrogen peroxide (1.0 mL, 30%) was added dropwise. The
mixture was stirred for another 1 h, and gradually warmed to
room temperature. Saturated aqueous Na2SO3 solution was
added to quench the reaction, and the mixture was extracted
with Et2O and brine. The organic phase was dried over Na2SO4,
concentrated under reduced pressure, and purified by silica gel
chromatography (Me2CO/hexane = 2:3) to yield a phosphate
compound 8 as the α-anomer (1.8 g, 58%).
at 0 C for 1 h. Ice water (20 mL) was added, and the mixture
9
was extract with hexane. The combined organic phase was
washed with saturated Cu(NO3)2 (aq), brine, and saturated Na-
HCO3 (aq). The organic phase was collected and dried over
MgSO4, filtered, and concentrated under reduced pressure to
give solanesyl chloride (10b) as a yellow oil. The crude chloride
product was dissolved in anhydrous MeCN (4 mL), and pow-
dered 4 Å molecular sieves and tetrabutylammonium dihydro-
gen phosphate (509 mg, 1.5 mmol) were added. The mixture
was stirred for 18 h, Et2O (10 mL) was added, and the solids
were filtered through a pad of Celite. The filtrate was concen-
trated under reduced pressure to give a yellow oil, which was
re-dissolved in MeOH and purified by ion-exchange chroma-
tography on DEAE anionic exchange resin with elution of
MeOH, water and 1 M aqueous NH4HCO3. The fractions con-
taining the desired product 11b (as the ammonium salt) were
collected and lyophilized to furnish colorless syrup (161 mg,
27%). C45H81N2O4P; TLC (H2O/i-PrOH/EtOAc = 1:2:4) Rf =
0.30. Spectral values were in accordance with literature.15
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Method B: To a solution of compound 7 (1.37 g, 3.94 mmol)
and 1H-tetrazole (828 mg, 11.83 mmol) in anhydrous CH2Cl2
(39 mL) was added dropwise dibenzyl N,N-diiso-
o
propylphosphoramidite (2.58 mL, 7.89 mmol) at –15 C. The
mixture was stirred for 1 h, and then concentrated under reduced
pressure. The residue was dissolved in THF (39 mL) and cooled
P1-2-Acetamido-2-deoxy-α-D-glucopyranosyl-P2-geranyl
diphosphate (3a, GlcNAc-GPP as the ammonium salt). To a
solution of geranyl phosphate (11a, 111 mg, 0.41 mmol) in an-
hydrous DMF (5.0 mL) was added carbonyldiimidazole (CDI,
335 mg, 2.07 mmol) in anhydrous DMF (5.0 mL). The mixture
was stirred at room temperature for 3 h. Anhydrous methanol
(67 μL) was added to destroy excess CDI, and the mixture was
stirred for additional 30 min. The mixture was concentrated un-
der reduced pressure, and a solution of 9 (392 mg, 0.74 mmol)
in DMF (5 mL) was added. The mixture was stirred at room
temperature for 3 days, concentrated under reduce pressure, and
purified by silica gel chromatography (H2O/i-PrOH/EtOAc =
1:2:4). The eluate was concentrated under reduced pressure.
The residue was dissolved in ammonia (33% NH3 (aq), 1 mL) and
stirred at room temperature for 8 h. After concentration under
reduced pressure, the residue was purified by silica gel chroma-
tography (H2O/i-PrOH/EtOAc = 1:2:4) to afford compound 3a
(56 mg, 15%). C18H39N3O12P2; TLC (H2O/i-PrOH/EtOAc =
o
to –78 C. Hydrogen peroxide (0.66 mL, 30%) was added
slowly at –78 oC. The mixture was stirred for 15 min, and then
quenched by addition of saturated aqueous Na2SO3 solution.
The mixture was stirred at 0 oC for 10 min, concentrated under
reduced pressure, and extracted by EtOAc and water. The or-
ganic phase was dried over Na2SO4, concentrated under reduced
pressure, and purified by silica gel chromatography
(EtOAc/hexane = 2:1) to yield a phosphate compound 8 as the
α-anomer (969 mg, 40%). C28H34NO12P; TLC (Me2CO/hexane
= 2:3) Rf = 0.32. Spectral values were in accordance with liter-
ature.15
2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyra-
nosyl phosphate triethylamine salt (9).15 To a solution of
compound 8 (969 mg, 1.60 mmol) in MeOH (15 mL) was added
10% Pd/C (169 mg). The mixture was stirred under 1 atm of H2
at room temperature for 1 h until compound 8 was completely
consumed according to the TLC analysis. Triethylamine (0.22
mL) was added, and the mixture was stirred for 5 min. The cat-
alyst was filtered through a pad of Celite, and the filtrate was
concentrated under reduced pressure to afford the phosphate
salt 9 (C26H52N3O12P, 884 mg, 87%). Spectral values were in
accordance with literature.15
1
1:2:4) Rf = 0.13; H NMR (400 MHz, D2O) δ 5.61–5.58 (1 H,
dd, J = 7.0, 3.1 Hz), 5.54–5.50 (1 H, t, J = 7.1 Hz), 5.30–5.27
(1 H, t, J = 6.5 Hz), 4.58–4.55 (2 H, d, J = 6.7 Hz), 4.09–4.05
(1 H, dt, J = 10.4, 2.8 Hz), 4.03–3.99 (1 H, dt, J = 10.0, 2.2 Hz),
3.98–3.94 (1 H, d, J = 1.9 Hz), 3.91–3.86 (2 H, m), 3.65–3.60
(1 H, t, J = 9.6 Hz), 2.24–2.21 (2 H, d, J = 6.7 Hz), 2.19–2.17
(2 H, m), 2.15 (3 H, s), 1.80 (3 H, s), 1.77 (3 H, s), 1.71 (3 H,
s); 13C{1H} NMR (100 MHz, D2O) δ 174.8, 143.2, 133.8, 124.1,
119.3, 94.5, 73.0, 70.9, 69.6, 63.1, 60.4, 53.7, 38.8, 25.6, 24.8,
22.2, 17.0, 15.7; 31P NMR (D2O) δ –10.8, –13.0; ESI–HRMS
calcd for C18H32NO12P2: 516.1400, found: m/z 516.1419 [M – 2
NH3 – H]–.
(E)-3,7-Dimethylocta-2,6-dien-1-yl phosphate (11a, gera-
nyl phosphate as the ammonium salt).21 To a solution of tet-
rabutylammonium dihydrogen phosphate (1.63 g, 4.80 mmol)
in anhydrous CH3CN (10 mL) was slowly added geranyl bro-
mide (10a, 521 mg, 2.40 mmol). The mixture was stirred for 10
h, filtered through Dowex 50 resin (NH4+ form), and purified by
ion-exchange chromatography on a column of DEAE anionic
exchange resin with elution of MeOH, water and 1 M aqueous
NH4HCO3. The eluate containing the desired product 11a (as
the ammonium salt) was lyophilized to give white solids (147
P1-2-Acetamido-2-deoxy-α-D-glucopyranosyl-P2-solane-
syl diphosphate (3b, GlcNAc-SPP as the ammonium salt).15
To a solution of solanesyl phosphate (11b, 234.6 mg, 0.476
mmol) in anhydrous DMF (11.8 mL) was added CDI (386 mg,
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