G. Dekany et al. / Carbohydrate Research 341 (2006) 1737–1742
1741
1.8. 3,5,6-Tri-O-benzyl-1,2-O-isopropylidene-4-O-tosyl-
D-glucitol (15)
the organic layer was separated, dried (Na2SO4), filtered
and concentrated under reduced pressure. The remain-
ing residue was purified by chromatography on silica
gel (4:1, cyclohexane/EtOAc) to give compound 17
To a solution of 14 (1.25 g, 2.54 mmol) in dry CH2Cl2
(20 mL), pyridine (5.00 mL, 4.9 g, 62 mmol) and tosyl
chloride (3.40 g, 17.8 mmol) were added and the result-
ing reaction mixture was stirred for 3 days at ambient
temperature. The excess of reagent was quenched
by the addition of water (10 mL), the organic layer
was extracted consecutively with 5% aq HCl and satd
aq NaHCO3 and dried (Na2SO4). Filtration and re-
moval of the solvent under reduced pressure gave pure
20
(0.45 g, 1.04 mmol, 86%) as a colourless syrup. ½aꢀD
1
ꢁ70.4 (c 1.2, CH2Cl2); H NMR (CDCl3): d 4.84–4.44
(6H, 3 · CH2–Ph), 4.11 (dd, 1H, J = 11.2 Hz, J =
2.4 Hz), 4.05 (dd, 1H, J = 2.0 Hz, J = 2.0 Hz), 3.91–
3.82 (m, 3H), 3.79–3.74 (m, 3H), 1.70 (br s, 1H,
OH-2); 13C NMR: d 86.9, 84.6 (C-3, C-4), 77.4 (C-5),
75.1, 74.6 (C-1, C-2), 73.9, 73.7, 72.1 (3 · CH2–Ph),
70.9 (C-6). Anal. Calcd for C27H30O5: C, 74.63; H,
6.96. Found: C, 74.60; H, 7.00.
20
15 (1.61 g, 2.49 mmol, 98%) as a colourless syrup. ½aꢀD
1
+6.2 (c 2.1, CH2Cl2); H NMR (CDCl3): d 4.95 (dd,
1H, J3,4 = 4.4 Hz, J4,5 = 3.9 Hz, H-4), 4.68–4.36 (6H,
1.11. 1,4-Anhydro-3,5,6-tri-O-benzyl-D-tagatose (18)
0
3 · CH2–Ph), 4.30 (ddd, 1H, J1,2 = 6.3 Hz, J1 ;2
¼
0
6:8 Hz, J2,3 = 6.3 Hz, H-2), 3.96 (dd, 1H, J1;1
¼
To a solution of 17 (360 mg, 0.83 mmol) in dry CH2Cl2
(20 mL), Dess–Martin periodinane (530 mg, 1.25 mmol)
was added and the reaction mixture was stirred for 4 h
at ambient temperature. After extraction with satd aq
NaHCO3, the organic layer was separated, dried
(Na2SO4), filtered and concentrated under reduced pres-
sure. The remaining residue was subjected to column
chromatography on silica gel (10:1, cyclohexane/
EtOAc) to furnish compound 18 (319 mg, 0.74 mmol,
8:3 Hz, H-1), 3.93 (m, 1H, H-5), 3.73 (dd, 1H, H-10),
3.72 (dd, 1H, H-3), 3.67 (dd, 1H, J5,6 = 4.9 Hz,
0
0
J6;6 ¼ 10:3 Hz, H-6), 3.48 (dd, 1H, J5;6 ¼ 5:9 Hz, H-
60); 13C NMR: d 81.4, 78.4, 77.2, 76.7 (C-2, C-3, C-4,
C-5), 74.5, 73.4, 72.8 (3 · CH2–Ph), 69.4, 66.1 (C-1,
C-6). Anal. Calcd for C37H42O8S: C, 68.71; H, 6.55.
Found: C, 68.63; H, 6.60.
20
1.9. 3,5,6-Tri-O-benzyl-4-O-tosyl-D-glucitol (16)
89%) as a colourless syrup. ½aꢀD ꢁ83.9 (c 2.0, CH2Cl2);
1H NMR (CDCl3): d 4.90–4.40 (6H, 3 · CH2–Ph) 4.18
(dd, 1H, J3,4 = 6.8 Hz, J4,5 = 2.0 Hz, H-4), 4.18 (d,
To a solution of 15 (0.87 g, 1.35 mmol) in CH3CN/H2O
(10 mL, 9:1 v/v), p-toluenesulfonic acid monohydrate
(200 mg, 1.1 mmol) was added and the reaction mixture
was stirred for 16 h at ambient temperature. CH2Cl2
(100 mL) was added to the reaction mixture, which
was then extracted with satd aq NaHCO3. The organic
layer was separated, dried (Na2SO4), filtered and con-
centrated under reduced pressure. Column chromato-
graphy on silica gel (2:1, cyclohexane/EtOAc) yielded
compound 16 (0.79 g, 1.30 mmol, 97%) as a colourless
1H, J1;1 ¼ 17:6 Hz, H-1), 4.02 (d, 1H, H-10), 3.98 (d,
0
1H, H-3), 3.78 (m, 3H, H-5, H-6, H-60); 13C NMR: d
213.6 (C-2), 81.4, 77.0, 76.7 (C-3, C-4, C-5), 73.8, 73.4,
72.5 (3 · CH2–Ph), 70.9, 69.8 (C-1, C-6). Anal. Calcd
for C27H28O5: C, 74.98; H, 6.53. Found: C, 75.00; H,
6.59.
1.12. 1,4-Anhydro-3,5,6-tri-O-benzyl-D-tagatose diethyl
acetal (19)
20
1
syrup. ½aꢀD +21.3 (c 3.0, CH2Cl2); H NMR (CDCl3):
d 5.16 (dd, 1H, J3,4 = 6.5 Hz, J4,5 = 2.4 Hz, H-4),
4.74–4.38 (6H, 3 · CH2–Ph), 3.97 (m, 1H, H-5*), 3.78
(m, 2H, H-2*, H-3), 3.68 (dd, 1H, J5,6 = 6.4 Hz,
To a solution of 18 (240 mg, 0.56 mmol) in dry ethanol
(20 mL), p-toluenesulfonic acid monohydrate (200 mg,
1.1 mmol) was added, and the reaction mixture was stir-
red overnight at ambient temperature. After neutralisa-
tion with NaHCO3 and filtration, the solvent was
removed under reduced pressure. The remaining residue
was purified by column chromatography on silica gel
(13:1, cyclohexane/EtOAc), yielding compound 19
J6;6 ¼ 10 Hz, H-6), 3.55 (dd, 1H, J5;6 ¼ 6:3 Hz, H-60),
0
0
0
3.53 (dd, 1H, J1;1 ¼ 11 Hz, J1,2 = 6.3 Hz, H-1), 3.37
(dd, 1H, J1 ;2 ¼ 4:4 Hz, H-10), 2.50 (br s, 2H, OH-1,
0
OH-2); 13C NMR: d 81.3, 77.8, 77.7 (C-3, C-4, C-5),
74.7, 73.5, 73.3 (3 · CH2–Ph), 70.4 (C-2), 69.4 (C-6),
64.0 (C-1). *may be interchanged. Anal. Calcd for
C34H38O8S: C, 67.31; H, 6.31. Found: C, 67.27; H, 6.35.
20
(260 mg, 0.51 mmol, 92%) as a colourless syrup. ½aꢀD
1
ꢁ7.7 (c 1.3, CH2Cl2); H NMR (CDCl3): d 4.80–4.40
(6H, 3 · CH2–Ph), 4.06 (dd, 1H, J3,4 = 4.4 Hz,
0
1.10. 1,4-Anhydro-3,5,6-tri-O-benzyl-D-galactitol (17)
J4,5 = 4.4 Hz, H-4), 3.98 (d, 1H, J1;1 ¼ 9:3 Hz, H-1),
3.79 (m, 2H, H-3, H-5), 3.73 (dd, 1H, J5,6 = 3.9 Hz,
J6;6 ¼ 10:7 Hz, H-6), 3.70 (m, 1H, H-60), 3.69 (d, 1H,
0
A solution of 16 (0.73 g, 1.20 mmol) in dry CH2Cl2
(15 mL) containing Et3N (5 mL) was stirred at 40 ꢁC
for 48 h, until TLC indicated complete conversion of
the starting material. The reaction mixture was washed
consecutively with 5% aq HCl and satd aq NaHCO3,
H-10), 3.66–3.42 (m, 4H, 2 · OCH2Me), 1.22, 1.15
(2 · t, 2 · 3H, 2 · OCH2Me); 13C NMR: d 107.3 (C-2),
85.1, 79.6, 77.7 (C-3, C-4, C-5), 73.6, 73.5, 71.9
(3 · CH2–Ph), 71.6, 71.3 (C-1, C-6), 58.9, 57.1 (2 ·