and donor 10 (353 mg, 0.59 mmol) in anhyd. CH2Cl2 (20 mL) was
stirred with activated, powdered molecular sieves (4 A, 200 mg)
3H, CH3-acetal), 1.20 (d, 3H, J = 6.9, Tg ); 13C NMR (100.6 MHz,
CDCl3, DEPT, HMQC), d = 198.0, 170.4, 170.3, 156.4 (C O),
143.6 (C1a-, C8a-Fmoc), 141.4 (C4a-, C5a-Fmoc), 127.9 (C3-,
C6-Fmoc), 127.1 (C2-, C7-Fmoc), 125.0, 124.9 (C1-, C8-Fmoc),
120.1 (C4-, C5-Fmoc), 110.6 (Cq-acetal), 100.1 (C1), 83.4 (Cq-
tBu), 76.9 (Tb), 74.6 (C3), 73.3 (C5), 72.5 (C4), 67.0 (CH2-Fmoc),
58.7 (Ta), 49.8 (C2), 47.3 (CH-Fmoc), 28.1 (CH3-tBu), 27.7 (CH3-
acetal), 26.6 (CH3-NHAc), 23.4 (CH3-acetal), 18.6 (Tg ); FD-MS,
m/z: 638.78 [M+H]+; HR-MS (ESI-TOF), m/z: found: 661.2722
[M+Na]+, C34H42N2NaO10 calcd.: 661.2737.
˚
for 1 h at room temperature under an argon atmosphere. The
suspension was cooled to 0 ◦C, and TMSOTf (15 mL, 0.08 mmol)
was added. After being stirred for 20 h, the reaction mixture
was neutralized with solid NaHCO3. The organic phase was
concentrated in vacuo and purified by flash chromatography on
silica gel (cHex–EtOAc, 2 : 1) to afford 11 as a colorless amorphous
solid (303 mg, 0.29 mmol, 61%, a/b = 1 : 2.5); b-11: Rf 0.22, 0.29
(rotamer) (cHex–EtOAc, 1 : 1); RP-HPLC (Jupiter, H2O–MeOH,
20 : 80 → 0 : 100, 30 min): tR = 12.4 min, 13.4 min (rotamer);
[a]2D3 = 31.5 (c = 1, CHCl3); 1H NMR (400 MHz, CDCl3, COSY),
d = 7.80–7.76 (m, 2H, 4-H-, 5-H-Fmoc), 7.64 (d, 2H, J = 7.4, 1-H-,
8-H-Fmoc), 7.40 (t, 2H, J = 7.6, 3-H-, 6-H-Fmoc), 7.38–7.25 (m,
17 H, 2-H-, 7-H-Fmoc, Har-Bn), 5.78 (d, 1H, J = 9.6, NHAc),
5.44 (d, 1H, J = 9.4, NH-Fmoc), 4.91 (d, 1H, J = 11.4, CH2-Bn),
4.87 (d, 1H, J = 3.2, 1-H), 4.83–4.64 (m, 4H, CH2-Bn {4.78, d,
J = 12.2}, 2¢-H, 6a/b-H, CH2-Bn), 4.63–4.43 (m, 6H, 1¢-H, CH2-
Fmoc {4.49, d, J = 6.7}, CH2-Bn, 2-H, 6a/b-H), 4.43–4.40 (m, 2H,
CH2-Bn), 4.28 (t, 1H, J = 6.7, CH-Fmoc), 4.24–4.20 (m, 1H, Ta),
4.19–4.11 (m, 1H, Tb), 4.10–3.99 (m, 3H, 4-H, 5-H, 5¢-H), 3.72–
3.64 (m, 1H, 3-H), 3.54 (dd, 1H, J = 3.1/6.2, 3¢-H), 3.88–3.85 (m,
1H, 4¢-H), 3.60–3.52 (m, 2H, 3-H, 6a/b¢-H), 3.50–3.45 (m, 1H,
6a/b¢-H), 2.01 (s, 3H, CH3-NHAc), 1.46 (s, 9H, tBu), 1.30 (d, 3H,
J = 6.5, Tg ); 13C NMR (100.6 MHz, HMQC, CDCl3), d = 170.4,
170.1, 156.4 (C O), 143.8, 143.7 (C1a-, C8a-Fmoc), 141.3 (C4a-,
C5a-Fmoc), 137.9, 137.8, 137.5 (Cq-Bn), 128.5, 128.4, 128.3, 127.9,
127.8, 127.5, 127.1 (Car-Bn, C2-, C3-, C6-, C7-Fmoc), 125.0, 125.0
(C1-, C8-Fmoc), 120.0 (C4-, C5-Fmoc), 102.5 (d, J = 24.0, C1¢),
100.4 (C1), 91.3 (d, J = 185.0, C2¢), 83.2 (d, J = 167.6, C6), 83.1 (Cq-
tBu), 80.0 (C3), 79.7 (d, J = 13.7, C3¢), 76.9 (Tb), 74.8 (CH2-Bn),
74.0 (C4¢), 73.6, 72.7 (CH2-Bn), 69.2 (d, J = 20.9, C5), 68.7 (C6¢),
68.3 (C5¢), 68.0 (d, J = 7.0, C4), 67.0 (CH2-Fmoc), 59.1 (Ta), 47.4
(C2), 47.2 (CH-Fmoc), 28.1 (CH3-tBu), 23.3 (CH3-NHAc), 18.8
(Tg ); 19F NMR (376.6 MHz, CDCl3), d = -228.9 (dt, J = 15.0/47.1,
6-F), -204.5 – -204.8 (m, 2¢-F); MS-ESI (positive), m/z: 1059.46
[M+Na]+; HR-MS (ESI-TOF), m/z: found: 1059.4435 [M+Na]+,
C58H66F2N2NaO13 calcd.: 1059.4431.
N -(9H -Fluoren-9-yl)-methoxycarbonyl-O-(2-acetamido-2,6-
dideoxy-6,6-difluoro-3,4-isopropylidene-a-D -galactopyranosyl)-
L-threonine tert-butyl ester (16). A solution of 17 (340 mg,
0.53 mmol) in anhyd. CH2Cl2 (20 mL) was stirred for 3 h at room
temperature with DAST (0.14 mL, 1.16 mmol). The reaction was
quenched by addition of MeOH (2 mL) and the solvents were
removed in vacuo. Flash chromatography on silica gel (cHex–
EtOAc, 1 : 2) gave 16 (244 mg, 0.37 mmol, 70%) as a colorless
amorphous solid; Rf 0.62 (cHex–EtOAc, 1 : 2); RP-HPLC (Luna,
H2O–MeCN, 50 : 50 → 20 : 80, 30 min → 0 : 100, 10 min): tR
=
22.1 min; [a]2D3 = 83.5 (c = 1, CHCl3); 1H NMR (400 MHz, CDCl3,
COSY), d = 7.76 (d, 2H, J = 7.4, 4-H-, 5-H-Fmoc), 7.59 (d, 2H, J =
7.3, 1-H-, 8-H-Fmoc), 7.43–7.36 (m, 2H, 3-H-, 6-H-Fmoc), 7.34–
7.28 (m, 2H, 2-H-, 7-H-Fmoc), 6.10 (ddd, 1H, J = 6.7/11.2/54.3,
6-H), 5.97 (d, 1H, J = 9.7, NHAc), 5.29 (d, 1H, J = 7.6, NH-
urethane), 4.78 (s, 1H, 1-H), 4.57–4.41 (m, 2H, CH2-Fmoc), 4.35–
4.26 (m, 1H, 2-H), 4.26–4.15 (m, 3H, 4-H, CH-Fmoc, Ta), 4.14–
4.01 (m, 2H, 5-H, Tb), 4.02 (dd, 1H, J = 9.0/4.9, 3-H) 2.02 (s,
3H, CH3-NHAc), 1.59 (s, 3H, CH3-acetal), 1.44 (s, 9H, tBu),
1.33 (s, 3H, CH3-acetal), 1.26 (d, 3H, J = 6.4, Tg ); 13C NMR
(100.6 MHz, CDCl3, HMQC), d = 170.2, 170.0, 156.3 (C O),
143.8, 143.6 (C1a-, C8a-Fmoc), 141.4 (C4a-, C5a-Fmoc), 127.8
(C3-, C6-Fmoc), 127.1 (C2-, C7-Fmoc), 125.0, 124.9 (C1-, C8-
Fmoc), 120.1 (C4-, C5-Fmoc), 114.3 (dd, J = 238.3/245.5, C6)
110.5 (Cq-acetal), 100.2 (C1), 83.3 (Cq-tBu), 77.5 (Tb), 74.6 (C3),
70.8 (d, J = 6.5, C4), 68.0 (dd, J = 22.7/31.6, C5), 66.9 (CH2-
Fmoc), 58.8 (Ta), 49.8 (C2), 47.3 (CH-Fmoc), 28.1 (CH3-tBu),
27.7 (CH3-acetal), 26.6 (CH3-NHAc), 23.4 (CH3-acetal), 18.5 (Tg );
19F NMR (376.5 MHz, CDCl3), d = -130.7 (dd, J = 53.8/298.1,
6aF), -127.1 (ddd, J = 11.2/58.0/298.1, 6bF); ESI-MS (positive),
m/z: 683.27 [M+Na]+; HR-MS (ESI-TOF), m/z: found: 683.2767
[M+Na]+, C34H42F2N2NaO9 calcd.: 683.2756.
N-(9H-Fluoren-9-yl)-methoxycarbonyl-O-(2-acetamido-2-deo-
xy - 3,4 - isopropylidene-a - D-galacto-hexodialdo-1,5-pyranosyl)-L-
threonine-tert-butyl ester (17). To a suspension of pyridinium
dichromate (420 mg, 1.12 mmol) and Ac2O (0.32 ml, 3.37 mmol)
in anhyd. CH2Cl2 (50 ml) was added protected TN antigen 7
(715 mg, 1.12 mmol), dissolved in anhyd. CH2Cl2 (15 ml). The
reaction mixture was refluxed for 3.5 h, neutralized with 3 drops of
NEt3, and concentrated in vacuo. Flash chromatography on silica
gel (cHex–EtOAc–NEt3, 1 : 2 : 0.001) afforded 17 as a colorless
amorphous solid (351 mg, 0.55 mmol, 49%); Rf 0.20 (cHex–EtOAc,
1 : 2); RP-HPLC (Luna, H2O–MeCN, 50 : 50, 10 min → 23 : 77,
15 min → 0 : 100, 35 min): tR = 11.6 min; [a]2D3 = 62.1 (c = 1,
N -(9H -Fluoren-9-yl)-methoxycarbonyl-O-(2-acetamido-2,6-
dideoxy-6,6-difluoro-a-D-galactopyranosyl)-L-threonine tert-butyl
ester (18). To a solution of 6,6F-TN analog 16 (220 mg,
0.33 mmol) in 20 mL MeOH were added Amberlyst-15 (30 mg).
The mixture was stirred at room temperature for 14 h and then
filtered. The solvents were removed in vacuo and the residue was
co-evaporated with dichloromethane (3 ¥ 10 mL) to yield 18 as
a colorless amorphous solid (171 mg, 0.28 mmol, 85%); Rf 0.40
(EtOAc); RP-HPLC (Luna, H2O–MeCN, 60 : 40 → 0 : 100, 60
min): tR = 19.6 min; [a]D23 = 31.7 (c = 1, CHCl3); 1H NMR (400 MHz,
CDCl3, COSY), d = 7.76 (d, 2H, J = 7.2, 4-H-, 5-H-Fmoc), 7.61
(d, 2H, J = 7.3, 1-H-, 8-H-Fmoc), 7.39 (t, 2H, J = 6.0, 3-H-, 6-
H-Fmoc), 7.32 (t, 2H, J = 7.4, 2-H-, 7-H-Fmoc), 7.21–7.13 (m,
1H, NHAc), 6.01 (dt, 1H, J = 6.4/56.0, 6-H), 5.74 (d, 1H, J = 8.7,
NH-urethane), 4.88 (d, 1H, J = 2.9, 1-H), 4.54–4.36 (m, 2H, CH2-
Fmoc), 4.36–4.28 (m, 1H, 2-H), 4.28–4.21 (m, 2H, CH-Fmoc, Ta),
1
CHCl3); H NMR (400 MHz, CDCl3, COSY), d = 9.66 (s, 1H,
6-H), 7.78–7.71 (m, 2H, 4-H-, 5-H-Fmoc), 7.58 (d, 2H, J = 7.3,
1-H-, 8-H-Fmoc), 7.42–7.34 (m, 2H, 3-H-, 6-H-Fmoc), 7.33–7.25
(m, 2H, 2-H-, 7-H-Fmoc), 6.07 (d, 1H, J = 9.6, NHAc), 5.40 (d,
1H, J = 9.1, NH-urethane), 4.89 (d, 1H, J = 2.8, 1-H), 4.55–4.42
(m, 3H, 4-H, CH2-Fmoc), 4.42–4.28 (m, 2H, 2-H, 5-H), 4.25–4.16
(m, 2H, CH-Fmoc, Ta), 4.15–4.03 (m, 2H, Tb, 3-H), 2.02 (s, 3H,
CH3-NHAc), 1.56 (s, 3H, CH3-acetal), 1.45 (s, 9H, tBu), 1.31 (s,
This journal is
The Royal Society of Chemistry 2011
Org. Biomol. Chem., 2011, 9, 5541–5546 | 5545
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