fucopyranose (1392 mg, 4.11 mmol) in dry CH2Cl2 (20 mL),
trichloroacetonitrile (2.06 mL), and K2CO3 (2270 mg, 16.4 mmol)
were added. The reaction was stirred at room temperature until
completion, then it was filtered over a celite pad and the solvent
was evaporated. The crude was purified by flash chromatography
(eluent: 7/3 hexane/EtOAc) providing 1298 mg of the product
10R. Eluent: 95/5 toluene/EtOAc. 1H NMR (400 MHz,
CDCl3): δ 7.36-7.28 (m, 5H), 5.38-5.29 (m, 2H), 4.95 (d, 1H,
J ) 3.7 Hz), 4.70 (d, 1H, J ) 12.2 Hz), 4.61 (d, 1H, J ) 12.2 Hz),
4.22 (q, 1H, J ) 6.6 Hz), 3.88 (septuplet, 1H, J ) 6.0 Hz), 3.83
(dd, 1H, J ) 3.7, 10.0 Hz), 2.15 (s, 3H), 2.01 (s, 3H), 1.25 (d, 3H,
J ) 6.0 Hz), 1.19 (d, 3H, J ) 6.0 Hz), 1.11 (d, 3H, J ) 6.6 Hz).
13C NMR (300 MHz, CDCl3): δ 171.2, 170.8, 96.2, 74.0, 73.3,
(2.67 mmol, 65%). [R]D -52.4 (c 1.1, CHCl3). 1H NMR (400
22
MHz, CDCl3): δ 8.74 (s, 1H), 7.34-7.28 (m, 5H), 5.84 (d, 1H,
J ) 8.1 Hz), 5.28 (d, 1H, J ) 3.4 Hz), 5.10 (dd, 1H, J ) 3.4, J )
10.1 Hz), 4.91 (d, 1H, J ) 11.4 Hz), 4.68 (d, 1H, J ) 11.4 Hz),
3.98 (q, 1H, J ) 6.5 Hz), 3.91 (dd, 1H, J ) 8.2, J ) 10.1 Hz),
2.19 (s, 3H), 1.97 (s, 3H), 1.25 (d, 3H, J ) 6.5 Hz). 13C NMR
(400 MHz, CDCl3): δ 171.1, 170.5, 161.8, 98.9, 76.0, 75.6, 73.3,
71.0, 70.7, 21.3, 21.2, 16.6. FT IR (CHCl3) ν 1678, 1742, 3038
cm-1. Anal. Calcd for C19H22O7NCl3 (482.74): C, 47.27; H, 4.59;
N, 2.90. Found: C, 47.32; H, 4.52, N, 2.93.
72.4, 71.4, 64.8, 23.8, 22.0, 21.3, 16.5. FTIR (CHCl3): 1740 cm-1
.
Anal. Calcd for C20H28O7 (380.43): C, 63.14; H, 7.42. Found: C,
63.12; H, 7.40.
10â. Eluent: 95/5 toluene/EtOAc. 1H NMR (300 MHz,
CDCl3): δ 7.29 (m, 5H), 5.18 (d, 1H, J ) 3.4 Hz), 4.95 (dd, 2H,
J ) 3.4, 10.1 Hz), 4.88 (d, 1H, J ) 11.6 Hz), 4.61 (d, 1H, J )
11.6 Hz), 4.49 (d, 1H, J ) 7.8 Hz), 4.01 (septuplet, 1H, J ) 6.2
Hz), 3.74 (bq, 1H, J ) 6.5 Hz), 3.57 (dd, 1H, J ) 7.8, 10.1 Hz),
2.11 (s, 3H), 1.94 (s, 3H), 1.29 (d, 3H, J ) 6.2 Hz), 1.23 (d, 3H,
J ) 6.2 Hz), 1.18 (d, 1H, J ) 6.4 Hz). 13C NMR (300 MHz,
CDCl3): δ 170.6, 170.2, 102.1, 76.4, 72.7, 70.8, 68.7, 74.7, 23.6,
22.1, 20.7, 16.2. FTIR (CHCl3) 1740 cm-1. Anal. Calcd for
O-Isopropyl-2-azido-2-deoxy-3-O-benzil-4,6-O-benziliden-
22
R-D-glucopyranoside (9R). Eluent: 9/1 hexane/EtOAc. [R]D
+ 115.7 (c 0.51, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.52-
7.25 (m, 15H), 5.59 (s, 1H), 4.98 (d, 1H, J ) 3.5 Hz), 4.96 (d, 1H,
J ) 11.0 Hz), 4.80 (d, 1H, J ) 11.0 Hz), 4.27 (dd, 1H J ) 4.7,
10.1 Hz), 4.11 (t, 1H, J ) 9.3 Hz), 4.02-3.89 (m, 2H), 3.75 (t,
1H, J ) 10.1 Hz), 3.70 (t, 1H, J ) 9.3 Hz), 3.29 (dd, 1H, J ) 3.5,
9.3 Hz), 1.27-1.22 (m, 6H). 13C NMR (300 MHz, CDCl3): δ 101.3,
97.1, 83.0, 76.0, 75.0, 71.3, 68.9, 62.8, 23.3, 21.5. FT IR (CHCl3)
ν 1261, 2110, 2255, 2875, 2924, 2970 cm-1. Anal. Calcd for
C23H27O5N3 (425.48): C, 64.93; N, 9.88; H, 6.40. Found: C, 64.90;
N, 9.92; H, 6.35.
C
20H28O7 (380.43): C, 63.14; H, 7.42. Found: C, 63.10; H, 7.45.
1
Low-Temperature (-78 °C) H NMR Experiments. Glu-
cosyl imidate 1â (or 1R) was dissolved in CD2Cl2 in a 5 mm NMR
tube, at -78°, in the presence of 1.5 equiv of [emim][OTf]. The
mixture was stable at these conditions, and therefore the
shimming of the sample (lock on the 2H nuclei of CD2Cl2 solvent)
and the acquisition of the first 1H spectrum (labeled with t ) 0)
was performed using a 500 MHz spectrometer, equipped with a
5 mm QNP probe (13C, 13P, 19F/1H coils) and with an N2
evaporator cooling system unit. The donor was activated by
addition at -78° of 0.01 equiv of TMSOTf, and a second spectrum
was acquired after the necessary manipulation and lock stabi-
O-Isopropyl-2-azido-2-deoxy-3-O-benzil-4,6-O-benziliden-
22
â-D-glucopyranoside (9â). Eluent: 9/1 Hexane/EtOAc. [R]D
-61.3 (c 1, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.49-7.25
(m, 15H), 5.57 (s, 1H), 4.91 (d, 1H, J ) 11.4 Hz), 4.79 (d, 1H,
J ) 11.4 Hz), 4.44 (d, 1H, J ) 7.8 Hz), 4.32 (dd, 1H, J ) 4.9,
10.3 Hz), 3.99 (septuplet, 1H, J ) 6.2 Hz), 3.80 (t, 1H, J ) 10.3
Hz), 3.70 (t, 1H, J ) 8.9 Hz), 3.54-3.33 (m, 3H), 1.27-1.25 (m,
6H). 13C NMR (300 MHz, CDCl3): δ 101.2, 81.5, 78.9, 66.2, 73.1,
74.9, 68.7, 23.5, 21.9. FTIR (CHCl3 solution) ν 2115, 2245, 2880,
2968, 3010 cm-1. Anal. Calcd for C23H27O5N3 (425.48): C, 64.93;
N, 9.88; H, 6.40. Found: C, 64.92; N, 9.86; H, 6.38
1
lization time (t ) 5 min). H experiments (35 s each one) were
subsequently acquired at regular time intervals (see Supporting
Information) until the spectrum appearance was stable.
Acknowledgment. This work was supported by
MIUR (COFIN 2004, protocol number 2004039212).
A.R. is grateful to Regione Lombardia (Assessorato alla
Sanita`) for financial support.
O-Isopropyl-3,4-di-O-acetyl-2-O-benzyl-R-L-fucopyrano-
side (10R) and O-Isopropyl-3,4-di-O-acetyl-2-O-benzyl-â-L-
fucopyranoside (10â). The two compounds were obtained in
a R/â anomeric mixture that could not be separated by flash
chromatography. The ratio between the anomers was deter-
mined by NMR, and the peaks of the major component of a 72/
28 and 18/82 R/â mixture are reported, respectively, to describe
the R- and â-anomer.
Supporting Information Available: General experimen-
tal methods, NMR spectral data for [emim][OTf], [bmim][PF6],
and compounds 9R, 9â, 5â, 10R, and 10â, and 1H NMR spectra
of low-temperature experiments. This material is available free
JO050704X
7768 J. Org. Chem., Vol. 70, No. 19, 2005