6514
M. T. Barros et al. / Tetrahedron 56 (2000) 6511±6516
135.50 (Ar), 169.40, 169.70, 169.80, 169.90, 170.00, 170.50
(CO).
described in the literature.15 [a]D154.4 (c 1, CHCl3),
1
Lit.15 154.0 (c 1.2, CHCl3); H NMR (CDCl3) d 7.66±
7.60 (m, 8H, Ar), 7.43±7.27 (m, 12H, Ar), 5.65 (d,
J3.5 Hz, 1H, H-1), 5.38 (m, 4H, H-3, H-4, H-30 and
H-40), 4.82 (dd, J9.5, 3.5 Hz, 1H, H-2), 4.31 (d, J
12.0 Hz, 1H, H-10a), 4.23 (d, 1H, H-10b), 4.00 (d, J
9.0 Hz, 1H, H-50), 3.81 (m, 2H, H-60a and H-60b), 3.63 (d,
J11.5 Hz, 1H, H-6a), 3.52 (d, 1H, H-6b), 2.11, 2.09, 2.07,
2.04, 2.02, 1.84 (6s, 3H each, OCOMe), 1.02 (s, 18H, tBu).
13C NMR (CDCl3) d 19,11 (CMe3), 20.17, 20.47, 20.57,
20.74 (Me), 26.65, 26.67 (CMe3), 61.30, 62.20, 63.90
(C-6, C-10 and C-60), 68.00, 70.20, 70.50, 70.60 (C-2,
C-3, C-4 and C-5), 75.10, 76.20 (C-30 and C-40), 81.90
(C-50), 90.50 (C-1), 104.50 (C-20), 127.60, 127.62, 127.70,
129.50, 129.60, 129.70, 132.90, 135.40, 135.60, 135.63
(Ar), 169.10, 169.62, 169.64, 170.10, 170.20, 170.60
(CO); Anal. Calcd for C56H70O17Si2 (1070.42): C, 62.78;
H, 6.59. Found C, 62.71; H, 6.86.
2,3,4,6,10,30,40-Hepta-O-acetylsucrose (3). To a solution of
2 (250.0 mg, 0.29 mmol) in dry THF (7 mL) was added,
under argon, tetrabutylammonium ¯uoride (1.8 equiv.,
135.0 mg). When the reaction mixture showed no more
starting material (TLC in AcOEt/hexane, 3/2), the THF
was evaporated. Water was then added, and the organic
compounds were extracted with dichloromethane. After
drying and concentration, a puri®cation by ¯ash chroma-
tography gave the expected but unstable 60-free sucrose 3
(91.0 mg, 50%). 1H NMR (CDCl3) d 5.68 (d, J3.5 Hz, 1H,
H-1), 5.47 (m, 3H, H-3, H-30 and H-40), 5.09 (t, J9.4 Hz,
1H, H-4), 4.88 (dd, J12.0, 3.5 Hz, 1H, H-2), 4.18 (d,
J11.7 Hz, 1H, H-10a), 4.16 (m, 4H, H-5, H-6a, H-6b and
H-50), 4.10 (d, 1H, H-10b), 3.84 (dd, J12.8, 2.8 Hz, 1H,
H-60a), 3.68 (dd, J12.8, 4.4 Hz, 1H, H-60b), 2.70 (wide
signal, 1H, OH), 2.19, 2.13, 2.11, 2.10, 2.08, 2.05, 2.02 (7s,
3H each, OCOMe). 13C NMR (CDCl3) d 20.41, 20.45,
20.47, 20.50, 20.55, 20.61, 20.87 (Me), 61.10, 61.40,
63.80 (C-6, C-10 and C-60), 67.90, 68.60, 69.30, 70.10
(C-2, C-3, C-4 and C-5), 73.70, 76.00 (C-30 and C-40),
81.60 (C-50), 89.90 (C-1), 103.20 (C-20), 169.40, 169.80,
169.90, 170.00, 170.40, 170.50, 170.60 (CO).
2,3,6,10,30,40-Hexa-O-acetylsucrose (6). To a solution of 5
(0.5 g, 0.5 mmol) in anhydrous THF (10 mL) under argon
was added 0.3 mg (2.5 equiv.) of tetrabutylammonium
¯uoride. After 2.5 h of stirring, TLC (AcOEt/hexane, 2/1)
showed no trace of the starting material. Evaporation of the
solvent followed by puri®cation on silica gel (AcOEt/
hexane, 2/1, then AcOEt) gave the title compound 6
(219.0 mg, 79%). [a]D136.9 (c 1, CHCl3); 1H NMR
(CDCl3) d 5.55 (d, J3.6 Hz, 1H, H-1), 5.40 (m, 2H, H-30
and H-40), 5.23 (t, J4.8±5.2 Hz, 1H, H-3), 4.76 (dd,
J10.4, 3.6 Hz, 1H, H-2), 4.48 (dd, J12.8, 3.6 Hz, 1H,
H-6a), 4.26 (dd, J12.8, 2.4 Hz, 1H, H-6b), 4.10 (d,
J11.6±12.0 Hz, 1H, H-10a), 4.04 (m, 2H, H-5 and H-50),
4.00 (d, 1H, H-10b), 3.77 (dd, J12.8, 2.8 Hz, 1H, H-60a),
3.60 (dd, J12.8, 4.0 Hz, 1H, H-60b), 3.46 (t, J9.6 Hz, 1H,
H-4), 2.11, 2.07, 2.05, 2.04, 2.03, 2.03 (6s, 3H each,
OCOMe). 13C NMR (CDCl3**) d 20.28, 20.35, 20.37,
20.44, 20.47, 20.56 (Me), 61.26, 62.43, 63.53 (C-6, C-10
and C-60), 68.47, 70.17, 71.11, 71.62 (C-2, C-3, C-4 and
C-5), 73.89, 76.03 (C-30 and C-40), 81.69 (C-50), 90.26
(C-1), 103.28 (C-20), 170.12, 170.24, 170.29, 170.81,
171.13, 171.80 (CO); Anal. Calcd for C24H34O17 (594.18):
C, 48.49; H, 5.76. Found C, 48.17; H, 5.65.
60-O-(Tri-O-methylgalloyl)-2,3,4,6,10,30,40-hepta-O-acetyl-
sucrose (4). First way: general procedure. To a solution of
TMEDA (2.0 equiv., 94.2 mL) in dry dichloromethane
Ê
(1 mL), was added molecular sieves 3 A (165 mg), and
then a solution of 200.0 mg of 3 dissolved in dry dichloro-
methane (6 mL) under argon. The mixture was cooled to
2788C, and then tri-O-methylgalloyl chloride (2.5 equiv.,
179 mg) in dry dichloromethane (1 mL) was added. The
reaction mixture was allowed to warm until room tempera-
ture, then stirred overnight. After neutralization by a
solution of phosphate buffer (pH 7) and extraction with
dichloromethane, the combined organic phases were
washed with brine, dried and concentrated. A puri®cation
of the crude by ¯ash chromatography (AcOEt/hexane, 1/1)
led to the expected 4 (135.0 mg, 52%). [a]D136.9 (c 0.4,
1
CHCl3); H NMR (CDCl3) d 7.33 (m, 2H, Ar), 5.76 (d,
J3.6 Hz, 1H, H-1), 5.47 (m, 3H, H-3, H-30 and H-40),
5.07 (t, J9.6 Hz, 1H, H-4), 4.87 (dd, J11.8, 3.4 Hz,
1H, H-2), 4.63 (dd, J11.6, 6.8 Hz, 1H, H-60a), 4.51 (dd,
J11.6, 5.6 Hz, 1H, H-60b), 4.40±4.13 (m, 6H, H-5, H-6a,
H-6b, H-50, H-10a and H-10b), 3.93 (s, 6H, ArOMe), 3.91 (s,
3H, ArOMe), 2.18, 2.12, 2.11, 2.10, 2.08, 2.03, 2.02 (7s, 3H
each, OCOMe). 13C NMR (CDCl3) d 20.38, 20.46 (Me),
56.15 (ArOMe), 60.75 (ArOMe), 61.64, 62.78, 64.31 (C-6,
C-10 and C-60), 68.00, 68.49, 69.39, 70.16 (C-2, C-3, C-4
and C-5), 75.53, 75.80 (C-30 and C-40), 79.07 (C-50), 90.03
(C-1), 104.15 (C-20), 107.08, 124.40, 142.66, 153.07 (Ar),
165.76, 169.59, 169.77, 169.90, 170.08, 170.21, 170.71
(CO); HRMS Calcd for C36H46O22: 830.2480. Found:
830.2484.
60-O-(Tri-O-methylgalloyl)-2,3,6,10,30,40-hexa-O-acetyl-
sucrose (7). The reaction of galloylation of 6 (133.0 mg,
0.2 mmol) was carried out according to the general pro-
cedure given for compound 3 (149 mg, 84%). [a]D
1
128.7 (c 1.2, CHCl3); H NMR (CDCl3) d 7.31 (m, 2H,
Ar), 5.64 (d, J3.6 Hz, 1H, H-1), 5.46 (m, 2H, H-30 and
H-40), 5.40 (t, J9.6 Hz, 1H, H-3), 4.79 (dd, J10.4, 3.2±
3.6 Hz, 1H, H-2), 4.47 (dd, J14.0, 4.8 Hz, 1H, H-6 or
H-60), 4.40 (m, 2H, H-6 and H-60, or H-5 and H-50), 4.31
(dd, J12.4, 1.6 Hz, 1H, H-6 or H-60), 4.22 (d, J12.4 Hz,
1H; H-10a), 4.18 (d, 1H, H-10b), 4.12 (m, 1H, H-5, H-50, H-6
or H-60), 4.10 (m, 1H, H-5, H-50, H-6 or H-60), 3.92 (s, 6H,
OMe), 3.91 (s, 3H, OMe), 3.53 (t, 1H, H-4), 3.39 (s, 1H,
OH), 2.15, 2.12, 2.11, 2.10, 2.08, 2.04 (6s, 3H each,
OCOMe). 13C NMR (CDCl3) d 20.23, 20.36, 20.41,
20.48, 20.62 (Me), 56.17, 56.19 (ArOMe), 60.77
(ArOMe), 62.55, 62.73, 64.68 (C-6, C-10 and C-60), 68.84,
70.30, 70.96, 71.82 (C-2, C-3, C-4 and C-5), 75.65, 75.83
(C-30 and C-40), 79.39 (C-50), 90.44 (C-1), 104.31 (C-20),
107.15, 124.40, 142.71, 153.07 (Ar), 166.03, 169.82,
Second way. Acetylation of 7 in the presence of 4-DMAP,
followed by a puri®cation on silica gel (AcOEt/hexane, 2/1)
gave the previously reported 4 (90%).
6,60-Di-O-tert-butyldiphenylsilyl-2,3,4,10,30,40-hexa-O-
acetylsucrose (5). This compound was prepared as