C.-L. Schengrund, P. Ko6a´c
'
/ Carbohydrate Research 319 (1999) 24–28
27
J5,F 23.4 Hz, C-5), 70.68 (C-3), 67.70 (C-2),
and 66.70 (d, J4,F 5.8 Hz, C-4), 20.69, 20.56,
20.51, 20.46 (4 CH3). Anal. Calcd for
C14H19FO9: C, 48.00; H, 5.47. Found: C,
48.04; H, 5.46.
The mother liquor from crystallization of 4
was combined with material that was unre-
solved by chromatography, deacetylated with
NaOMe–MeOH (Zemple´n), and reprocessed
as described above.
treated with 50% aq trifluoroacetic acid (86
mL) for 5 h at 100 °C. After concentration
and co-evaporation with water to remove
TFA, chromatography on silica gel, using a
step gradient of 12:15:1 CH2Cl2–CH3OH,
gave first unchanged 2. Eluted next was 3.
Pure 3 was obtained upon crystallization
(H2O–EtOH, 1.1 g, 76% yield), mp 160–
1
162 °C, lit. [10], 160 °C; H NMR (D2O) for
the anomeric mixture (a:bꢀ1:1): l 5.28 (d,
J1,2 3.5 Hz, H-1a), 4.8–4.48 (m, H-6ab, incl. d
at 4.61, J1,2 7.9 Hz, H-1b), 4.32 (ddd, J4,5B1,
J5,6a 4.0, J5,6b 7.0, J5,F 16.6 Hz, H-5b), 4.04–
3.93 (m, H-4a,b,5a), 4.87 (dd, J2,3 10.1, J3,4 3.1
Hz, H-3a) 3.80 (dd, H-2a), 3.66 (dd, J2,3 10.1,
J3,4 3.8 Hz, H-3b), 3.50 (dd, J2,3 9.6 Hz, H-2b);
13C NMR (D2O) l 96.52 (C-1b), 92.45 (C-1a),
83.57, 83.22 (2d, J6,F 164.6 Hz, H-6a,b), 73.48
(d, J5,F 19.8 Hz, C-5b), 72.6 (C-3b), 71.8 (C-
2b), 69.06 (d, J5,F 18.9 Hz, C-5a), 69.06 (d, J4,F
7.4 Hz, C-4a), 68.94 (C-3a), 68.47 (d, J4,F 7.4
Hz, C-4b), and 68.29 (C-2a).
Preparation of 6-deoxy-6-fluoro-h- -galac-
D
topyranosyl phosphate (5).—The dipotassium
salt of 5 was prepared from 4 (414 mg, 1.18
mmol) as described by MacDonald [11] for
a-
purified by chromatography on silica gel using
step-gradient of 10:2:110:4:0.5 2-
D
-galactose 1-phosphate. The product was
a
propanol–water–CH3COOH. Yield, 354 mg,
88%: [h]D +74° (c 0.2 H2O), lit. [6], for the
analogous derivative of
D-galactose, +81° (c
1
0.2 H2O); H NMR (D2O): l 5.48 (dd, 1 H,
J1,2 3.6, J1,P 6.9 Hz, H-1), 4.67, 4.52 (2 m, 1 H
each, J6,F 46.6 Hz, H-6a,b), 4.33 (2 t, 1 H, J5,6
5.8, J5,F 17.2 Hz, H-5), 4.02 (dd, 1 H, J4,F 1.1
Hz, J3,4 3.3 Hz, H-4), 3.88 (dd, 1 H, J2,3 10.0
Hz, H-3), 3.74 (ddd, 1 H, J2,P 2.2 Hz, H-2);
13C NMR (D2O): l 94.4 (C-1, JC-1,P 5.7 Hz),
83.65 (C-6, JC-6,F 163.8 Hz), 69.67 (C-5, JC-5,F
19.5 Hz), 69.07 (C-3), 69.02 (C-4, JC-4,F 6.9
Hz), 68.45 (C-2, JC-2,P 8.0 Hz).
1,2,3,4-tetra-O-acetyl-6-deoxy-6-fluoro-i- -
D
galactopyranose (4).—Compound 3 (900 mg,
4.7 mmol) was added to a mixture of fused
sodium acetate (0.45 g) in acetic anhydride (9
mL) and stirred at 110 °C for 3 h, when TLC
(3.5:1 hexane–acetone) showed the reaction to
be complete. Excess Ac2O was destroyed by
stirring the mixture with aq NaHCO3. The
product was extracted into CH2Cl2, and the
organic phase was dried and concentrated.
TLC showed the presence of two major
Preparation of UDP-6-deoxy-6-fluoro-h-
galactose (6).—The dipotassium salt of 5 was
converted to UDP-6-deoxy-6-fluoro-a-
D-
1
D
-
bands. H NMR spectroscopy indicated the
galactose using the procedure described by
Wittmann and Wong [12] for the synthesis of
UDP-Gal. After purification on a Bio-Gel P-2
column with 0.25 M NH4HCO3 as the eluant,
the sample was lyophilized. Recovered UDP-
ratio of anomers present to be ap:bp:af:bf=
18.4:52.0:15.4:14.2. Upon chromatography on
silica gel (3.5:1 hexane–acetone), the second
zone eluted gave 4 in \90% purity (NMR,
730 mg). The material solidified upon standing
and crystallization from EtOH (twice) gave
pure 4, mp 94–96 °C, [h]D +27.6° (c 1.9
6-deoxy-6-fluoro-a- -galactose was dissolved
D
in water and converted to the disodium salt by
first adding Dowex 50W (H+) to adjust the
pH to ꢀ6, filtering to remove the Dowex,
and then adding NaOH to bring the pH to
ꢀ7. Excess salt was removed by filtration
through a YC05 membrane that had a molec-
1
CHCl3); H NMR (CDCl3) l: 5.74 (d, 1 H,
J1,2 8.3 Hz, H-1), 5.50 (bd, 1 H J3,4 ꢀ2.9 Hz,
H-4), 5.35 (dd, 1 H, J2,3 10.3 Hz, H-2), 5.10
(dd, 1 H, H-3), 4.53 (ddd, 1 H, J5,6a 6.3 Hz, 1
H, J6a,b 9.8 Hz, J6a,F 46.9 Hz, H-6a), 4.44
(ddd, 1 H, J5,6b 5.9 Hz, J6b,F 46.3 Hz, H-6b),
4.11 (m, 1 H, H-5), 2.17, 2.12, 2.05, 2.00 (4 s,
3 H each, 4 COCH3); 13C NMR (CDCl3) l:
169.97, 169.86, 169.33, 168.88 (4 CO), 92.05
(C-1), 80.19 (d, J6,F 171.9 Hz, C-6), 72.15 (d,
1
ular-weight cutoff of 500. 31P and H NMR
(D2O) spectral data agreed with those re-
ported previously [4]. Mass spectral analysis
of the disodium salt gave the anticipated m/z
peak at 613 [M+1]+.