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C. Jia et al. / Tetrahedron: Asymmetry 14 (2003) 2195–2199
3 (b configuration) 1H NMR (300 MHz, CDCl3): l
ppm 3.42 (s, 3H, OCH3), 4.03 (m, 2H, H2, H3), 4.53 (m,
4H, 2PhCH2), 4.64 (m, 1H, H4), 4.91 (d, J1,2=1.5 Hz,
1H, H1), 5.26 (d, J5,6a=10.2 Hz, 1H, H6a), 5.38 (d,
76.74 (C3), 79.67 (C5), 79.89 (C4), 119.70 (C7), 127.76–
128.58 (10C, aromatic C), 131.28 (C6), 136.84, 136.97
(2C-ipso), 172.53 (C2). HRFAB-MS (m/z): calcd for
C20H20O4Na [M+Na]+ 347.1254, found 347.1252.
J
5,6b=17.4 Hz, 1H, H6b), 6.11 (m, 1H, H5), 7.24–7.36
(m, 10H, aromatic H). 13C NMR (75 MHz, CDCl3): l
ppm 55.62 (OCH3), 71.97, 72.01 (2PhCH2), 82.32 (C4),
82.47 (C3), 87.10 (C2), 107.92 (C1), 118.37 (C6), 127.69–
128.40 (10C, aromatic C), 134.88 (C5), 137.54, 137.72
(2C-ipso). HRFAB-MS (m/z): calcd for C21H24O4Na
[M+Na]+ 363.1567, found 363.1565.
3.6. 1,5,6-Trideoxy-1-methylidene-3,4-di-O-benzyl-5-ene-
D
-glucofuranose 6
When the solution of compound 5 (0.208 g, 0.64 mmol)
in THF/Py (20 ml/20 ml) was cooled down to −78°C,
Tebbe’s reagent (0.5 mol/l, 2.7 ml) was dropped into
the solution. The reaction mixture was stirred from
−78°C to rt. When TLC showed the absence of material
5, the mixture was cooled with ice water bath and
quenched with NaOH solution of water (10%, 0.88 ml)
and then filtered. The filtrate was concentrated and the
residue was purified with a silica gel column eluting by
petroleum ether and ethyl acetate (100:1) with 0.03%
Et3N (V/V). The product 6 was colorless oil (0.151 g,
3 (a-configuration), 1H NMR (300 MHz, CDCl3): l
ppm 3.41 (s, 3H, OCH3), 4.01 (dd, J1,2=4.5 Hz, J2,3
=
6.0 Hz, 1H, H2), 4.29 (t, J=6.0 Hz, 1H, H3), 4.53, 4.55
(2d, 2H, PhCH2), 4.63 (m, 2H, PhCH2), 4.64 (m, 1H,
H4), 4.80 (d, J1,2=4.2 Hz, 1H, H1), 5.27 (d, J5,6a=10.2
Hz, 1H, H6a), 5.33 (d, J5,6b=17.1 Hz, 1H, H6b), 5.99
(m, 1H, H5), 7.25–7.36 (m, 5H, aromatic H) 13C NMR
(75 MHz, CDCl3): l ppm 55.23 (OCH3), 72.25, 72.59
(PhCH2), 78.57 (C4), 82.40 (C3), 83.58 (C2), 100.51 (C1),
118.63 (C6), 127.64ꢀ128.37 (10C, aromatic C), 134.16
(C5), 137.69, 137.93 (2C-ipso). HRFAB-MS (m/z):
calcd for C21H24O4Na [M+Na]+ 363.1567, found
363.1567.
1
73.0%). [h]2D0=+2.9 (c 1.2, MeOH), H NMR: l ppm
3.95 (dd, J3,4=3.9 Hz, J3,1=1.8 Hz, 1H, H3), 4.28, 4.88
(2d, 2H, H1), 4.30, 4.34 (2d, J=12.1 Hz, 2H, PhCH2),
4.37 (s, 1H, H5), 4.43, 4.69 (2d, J=11.6 Hz, 2H,
PHCH2), 4.98 (q, J4,3=3.9 Hz, J4,5=7.5 Hz, 1H, H4),
5.18 (d, J6,7a=10.8 Hz, 1H, H7a), 5.35 (d, J6,7b=17.2
Hz, 1H, H7b), 6.24 (m, 1H, H6), 7.17-7.36 (m, 10H,
aromatic H). 13C NMR (100 MHz, Benzene-d6): l ppm
70.01, 71.80 (2PhCH2), 80.90 (C5), 83.39 (C3), 84.19
(C4), 85.85 (C1), 118.57 (C7), 127.39–128.36 (10C-aro-
matic), 133.30 (C6), 138.02, 138.19 (2C-ipso), 159.97
(C2). HRFAB-MS (m/z): calcd for C21H23O3 [M+H]+
323.1647, found 323.1613.
3.4. 2,3-Di-O-benzyl-5,6-dideoxy-5-ene-
D
-glucofuranose
4
Compound 3 (0.251 g, 0.74 mmol) was dissolved in a
solution of AcOH (7.4 ml) and TfOH (2 M, 1.48 ml)
and heated at 80°C. When TLC showed the absence of
the material, the reaction mixture was cooled down to
rt, added to CH2Cl2 (10 ml) and neutralized with
saturated solution of NaHCO3 at 4°C. The mixture was
extracted with CH2Cl2 (2×30 ml). The organic layer was
separated, then concentrated and purified through a
silica gel column eluting with petroleum ether and ethyl
acetate to obtain a colorless oily mixture (0.188 g,
78.4%, a:b=5:4).
3.7. (1S,6S,7S)-2,3-Dibenzyloxycyclohepta-4-en-1-ol 7
TIBAL (1 mol/l, 3.90 ml) in toluene was added to a
solution of compound 6 (0.122 g, 0.38 mmol) in toluene
(15 ml) at rt under argon. The mixture was heated to
80°C and stirred. When TLC showed the absence of
compound 6, the reaction solution was cooled down to
0°C and quenched with ice water (8 ml). The mixture
was filtered and the filtrate extracted with EtOAc. The
organic layers were combined, dried and concentrated.
The residue was purified on a silica gel column eluting
by petroleum and ethyl acetate (30:1). Two products 7
(colorless oil, 77 mg, 62.7%) and 8 (colorless oil, 24 mg,
19.6%) were obtained.
3.5. 1-Dehydro-2,3-di-O-benzyl-5,6-dideoxy-5-ene-D-glu-
cofuranose 5
,
PCC (0.55 g, 2.55 mmol) and 4 A MS (0.30 g) were
mixed in CH2Cl2 (20 ml) under argon. The solution of
compound 4 (0.165 g, 5.06 mmol) in CH2Cl2 was then
cooled to 0°C and stirred at rt. When TLC showed the
absence of the material of compound 4, the reaction
mixture was purified on a silica gel column eluting by
petroleum ether and ethyl acetate (10:1) to give a
colorless oil (0.136 g, 83.0%).
1
7: [h]2D0=−300.2 (c 0.5, CHCl3), H NMR (500 MHz,
CDCl3): l ppm 1.67–1.73, 1.76–1.85 (2m, 2H, H7),
1.94–2.01, 2.28–2.34 (2m, 2H, H6), 3.61 (dd, J2,3=8.5
Hz, J1,2=3.0 Hz, 1H, H2), 4.16 (m, J1,2=3.0 Hz, J1,7a
3.8 Hz, J1,7b=7.5 Hz, 1H, H1), 4.47 (dd, J3,4=4.0 Hz,
J3,2=8.5 Hz, J3,5=1.5 Hz, 1H, H3), 4.63, 4.66 (2d,
=
1
5: [h]2D0=+108.9 (c 2.2, MeOH). H NMR (400 MHz,
CDCl3): l ppm 4.22 (d, J2,3=6.4 Hz, 1H, H2), 4.27 (t,
J=6.4 Hz, 1H, H3), 4.56, 4.59 (2d, J=12 Hz, 2H,
PhCH2), 4.72, 4.97 (2d, J=12 Hz, 2H, PhCH2), 5.00
(m, J3,4=6.4 Hz, J4,5=6.2 Hz, J4,6=1.2 Hz, 1H, H4),
5.36, 5.39 (2t, J5,6a=10.4 Hz, J4,6=1.2 Hz, 1H, H6a),
5.41, 5.45 (2t, J5,6b=17.2 Hz, J4,6=1.2 Hz, 1H, H6b),
5.99 (m, J4,5=6.2 Hz, J5,6a=10.4 Hz, J5,6b=17.2 Hz,
1H, H5, 7.26ꢀ7.37 (m, 10H, aromatic H). 13C NMR
(100 MHz, CDCl3): l ppm 72.44, 72.59 (2PhCH2),
J=12 Hz, 2H, PhCH2), 4.64, 4.83 (2d, J=12 Hz, 2H,
PhCH2), 5.70 (dd, J4,5=11.5 Hz, J3,4=4.0 Hz, 1H, H4),
5.93 (m, J4,5=11.5 Hz, J5,6=6.0 Hz, J3,5=1.5 Hz, 1H,
H5), 7.25ꢀ7.34 (m, 10H, aromatic H). 13C NMR (125
MHz, CDCl3): l ppm 21.73 (C6), 30.68 (C7), 70.91 (C1),
72.21, 73.67 (2C, 2PhCH2), 75.56 (C3), 81.48 (C2),
127.43–128.39 (10C, aromatic C), 131.57 (C4), 133.10
(C5), 138.53, 138.71 (2C-ipso). HRFAB-MS (m/z):
calcd for C21H24O3Na [M+Na]+ 347.1618, found