evaporated. The resulting solid was dissolved in CHCl (100 mL) and washed with saturated sodium thiosulfate solution
3
(2 × 2 mL) and H O (20 mL). The organic layer was dried over anhydrous Na SO and evaporated. The solid was purified by
2
2
4
CC (gradient elution, C H → C H –i-PrOH, 100:1→50:1). Yield of glycoside 2a, 1.53 g (49%); oily compound, [α] +92°
6
6
6
6
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1
(ñ 1.0, CHCl ). Í NMR spectrum (300 MHz, ÑDCl , δ, ppm, J/Hz): 1.45–1.80 (14Í, m, 7 CÍ ), 1.95 (3Í, s, NAc), 2.03,
3
3
2
2.04, 2.10 (3Í each, s, OÀc), 3.77 (1Í, qt, H-1′), 4.03 (1Í, ddd, J = 9.5, 2.5, 5, H-5), 4.10 (1Í, dd, J = 2.5, 12.5, Í-6a), 4.22
(1Í, dd, J = 5, 12.5, Í-6b), 4.31 (1Í, m, Í-2), 4.93 (1Í, d, J = 4, H-1), 5.10 (1Í, dd, J = 9.5, 9.5, H-4), 5.20 (1Í, dd, J = 10.5,
9.5), 5.63 (1Í, d, J = 9.5, NH).
Cyclopentadecyl-2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyranoside (2b) was prepared analogously,
1
yield 1.75 g (46%); mp 112–114°Ñ, [α] +104° (ñ 1.0, CHCl ). Í NMR spectrum (300 MHz, ÑDCl , δ, ppm, J/Hz): 1.33,
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3
3
1.48–1.62 (28Í, m, 14 CÍ ), 1.95 (3Í, s, NAc), 2.03, 2.04, 2.10 (3Í each, s, OÀc), 3.65 (1Í, qt, H-1′), 4.04 (1Í, ddd, J = 9.5,
2
2.5, 5, H-5), 4.07 (1Í, dd, J = 2.5, 12.5, Í-6a), 4.24 (1Í, dd, J = 5, 12.5, Í-6b), 4.32 (1Í, m, Í-2), 4.94 (1Í, d, J = 4, H-1),
5.10 (1Í, dd, J = 9.5, 9.5, H-4), 5.20 (1Í, dd, J= 10, 9.5, H-3), 5.64 (1Í, d, J = 9.5, NH).
Version 2. A reaction mixture consisting of α-D-glucopyranosyl chloride (1, 2.50 g, 6.84 mmol), anhydrous ZnCl
2
(0.93 g, 6.84 mmol), cyclooctanol (875 mg, 6.84 mmol), Bu NBr (2.20 g, 6.83 mmol), and anhydrous CH Cl (30 mL) was
4
2
2
held for 48 h at room temperature, diluted with CH Cl (20 mL), and washed with H O (5 mL). The organic layer was dried
2
2
2
over anhydrous Na SO and evaporated. The solid was purified analogously to version 1 to afford 2a (1.53 g, 49%). Glycoside
2
4
2b (1.94 g, 51%) was also synthesized analogously.
Cyclooctyl-2-acetamido-2-deoxy-α-D-glucopyranoside (3a). Acetate 2a (1.50 g, 3.3 mmol) was dissolved in
anhydrous MeOH (30 mL) and treated with NaOMe in MeOH (0.5 mL, 0.1 M). When the reaction was finished
+
(TLC monitoring using systems 1 and 2), the solution was neutralized by KU-2 cation exchanger (H ). The resin was rinsed
with MeOH. The filtrate was evaporated to afford 3a (1.0 g, 92%), mp 109–111°C, [α] +168° (c 1.0, EtOH).
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Cyclopentadecyl-2-acetamido-2-deoxy-α-D-glucopyranoside (3b, 1.3 g, 88%) was prepared analogously;
mp 212–218°C, [α] +131° (c 1.0, EtOH).
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Cyclooctyl-2-acetamido-2-deoxy-4,6-O-isopropylidene-α-D-glucopyranoside (4a). A suspension of 3a (0.95 g,
2.87 mmol) in anhydrous THF (20 mL) was stirred, heated to 50–55°C, treated with 2,2-dimethoxypropane (1.0 mL) and
anhydrous p-toluenesulfonic acid (10 mg), cooled after 1 h (TLC monitoring using system 3), neutralized with Py (~50 μL),
and evaporated. The solid was purified by CC (gradient elution, C H –i-PrOH, 50:1→10:1). Yield of 4a, 0.85 g (80%);
6
6
glassy compound, [α] +102° (c 1.0, CHCl ).
546
3
Cyclopentadecyl-2-acetamido-4,6-O-isopropylidene-α-D-glucopyranoside (4b, 1.25 g, 91%) was prepared
analogously; glassy compound, [α] +83° (c 1.0, CHCl ).
546
3
Benzyl Ester of O-(Cyclooctyl-2-acetamido-2,3-dideoxy-4,6-O-isopropylidene-α-D-glucopyranosid-3-yl)-D-
lactyl-L-alanyl-D-isoglutamine (6a). A suspension of 4a (740 mg, 1.99 mmol) in anhydrous dioxane (20 mL) was stirred,
treated in portions with a suspension of NaH (320 mg, 7.96 mmol, 60%), heated to 95°C, held at that temperature for 1 h,
cooled to 65°C, treated with (S)-2-bromopropanoic acid (0.27 mL, 3.00 mmol), held at 65°C for 3 h, and cooled. The excess
of NaH was decomposed by EtOH. The mixture was concentrated, poured into cold H O (50 mL), and acidified with HCl
2
(2 M) to pH 3–4. Muramic acid was extracted with CHCl (3 × 30 mL). The extract was dried over anhydrous Na SO and
3
2
4
evaporated.
The resulting partially protected muramic acid 5a (800 mg, 1.8 mmol, 90%) was used without further purification by
dissolving in anhydrous THF (10 mL), stirring, and treating with N-hydroxysuccinimide (HOSu, 250 mg, 2.16 mmol) and
N,N′-dicyclohexylcarbodiimide (DCC, 445 mg, 2.16 mmol). The precipitate of dicyclohexylurea was filtered off after 3 h and
rinsed with solvent. The filtrate was treated with L-alanyl-D-isoglutamine benzyl ester trifluoroacetate [prepared by treating
the corresponding Boc-derivative with trifluoroacetic acid (730 mg, 1.79 mmol) followed by evaporating to dryness] and Et N
3
to pH 8. When the reaction was finished (TLC monitoring using system 3), the mixture was evaporated. The solid was
dissolved in CHCl (70 mL). The solution was washed with HCl (25 mL, 1 M), saturated NaHCO solution (25 mL), and H O
3
3
2
(25 mL). The organic layer was dried over anhydrous Na SO and evaporated. The solid was purified by CC (gradient
2
4
elution, CHCl –i-PrOH, 50:1→10:1) to afford 6a (1.15 g, 87%), mp 68–72°C, [α] +54° (c 1.0, CHCl ). Table 1 lists the
3
546
3
PMR spectral data.
The benzyl ester of O-(cyclopentadecyl-2-acetamido-2,3-dideoxy-4,6-O-isopropylidene-α-D-glucopyranosid-
3-yl)-D-lactyl-L-alanyl-D-isoglutamine (6b, 560 mg, 60%) was synthesized analogously, amorphous compound, [α] +80°
546
(c 0.6, CHCl ). Table 1 lists the PMR spectral data.
3
1141