Regioselective and stereoselective benzoylation of 2-N-protected 4,6-O-ketal derivatives of D-glucosamines with 1-(benzoyloxy)benzotriazole

Article abstract of DOI:10.1016/S0008-6215(00)00282-2

A highly regioelective and stereoselective benzoylation of the 2-N-protected 4,6-O-ketal derivatives of D-glucosamines with 1-(benzoyloxy)benzotriazole that affords the corresponding β anomeric benzoates in excellent yields is described herein.

Full text of DOI:10.1016/S0008-6215(00)00282-2

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Carbohydrate Research 330 (2001) 177–182
Regioselective and stereoselective benzoylation of
2-N-protected 4,6-O-ketal derivatives of
D-glucosamines
with 1-(benzoyloxy)benzotriazole
Shang-Cheng Hung,* Shankar R. Thopate, Cheng-Chung Wang
Institute of Chemistry, Academia Sinica, Taipei 115 Taiwan, ROC
Received 22 September 2000; accepted 23 October 2000
Abstract
A highly regioelective and stereoselective benzoylation of the 2-N-protected 4,6-O-ketal derivatives of
D
-glu-
cosamines with 1-(benzoyloxy)benzotriazole that affords the corresponding b anomeric benzoates in excellent yields
is described herein. © 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Benzoylation; 1-(Benzoyloxy)benzotriazole; Glucosamines
glucosamines with 1-(benzoyloxy)benzotri-
azole (BzOBT)4 at the anomeric (C-1) posi-
tion.
1. Introduction
N-Acetyl- -glucosamine (GlcNAc) is a key
D
component of numerous biologically impor-
tant oligosaccharides. For example, Lewis
group antigens1 and hyaluronic acid2 possess
linkages of GlcNAc with various sugar units
at C-1 and C-3, respectively. A convenient
route to generate a free 3-hydroxyl for further
glycosylation from the inexpensive, commer-
2. Results and discussion
Typical benzoylation of 1, which is gener-
ated from
D-glucosamine in two steps via
transformation of an amino group into an
azido group,5 followed by O-benzylidene
protection6 and benzoylation with benzoyl
chloride in pyridine at 0 °C, led to a mixture
of 1-O-Bz, 3-O-Bz and 1,3-di-O-Bz products.
When the diols 1–5 were treated with BzOBT
in dichloromethane at room temperature us-
ing triethylamine as a base, the b anomeric
benzoates 7–11 were afforded in good yields
(Table 1), respectively. Due to the poor solu-
bility of 6, the reaction concentration was
dilute and the adduct 12 was isolated in 42%
yield (entry 6). The b configurations of 7–12
were determined by the trans-diaxial coupling
constants of anomeric protons (J1,2 7.5–8.8
cially available
D
-glucosamine requires a
three-step transformation that includes the
protection of the primary amine, cyclic ketal
protection at O-4 and O-6, and regioselective
protection at the anomeric hydroxyl group.
Distinguishing between the hydroxyl groups at
C-1 and C-3 is, however, a challenge for
chemists.3 We have explored herein a highly
regioselective and stereoselective benzoylation
of 2-N-protected 4,6-O-ketal derivatives of
D-
* Corresponding author. Tel.: +886-2-27898646; fax: +
886-2-27831237.
E-mail address: schung@chem.sinica.edu.tw (S.-C. Hung).
0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(00)00282-2

178
S.-C. Hung et al. / Carbohydrate Research 330 (2001) 177–182
Table 1
Regioselective and stereoselective benzoylation of 2-N-protected 4,6-O-ketal derivatives of
D-glucosamines with 1-(benzoy-
loxy)benzotriazole
Entry
Starting material
Time (h)
Product
Yield (%)
J1,2 (Hz)
1
2
3
4
5
6
1: R=N3, X=H, Y=Ph
2: R=N3, X=H, Y=p-OMeꢀPh
3: R=N3, X=Y=Me
4: R=NHAc, X=H, Y=Ph
5: R=NHAc, X=Y=Me
6: R=NHTroc, X=H, Y=Ph
36
48
48
24
24
24
7
8
9
10
11
12
89
96
88
84
93
42
8.4
8.4
7.5
8.7
8.7
8.4
Fig. 1. The stereo ORTEP drawing of 8.
Hz). The absolute structure of 8 was firmly
determined by single-crystal X-ray analysis.
An ORTEP drawing of the structure is shown
in Fig. 1. The crystal data, data collection
parameters, and refinement results for 8 are
listed in Table 2, and atomic coordinates and
their isotropic thermal parameters are pro-
vided in Table 3.
benzoylation of N-protected 4,6-O-ketal
derivatives of
D
-glucosamines with BzOBT to
afford the corresponding b anomeric ben-
zoates in good yields.
3. Experimental
Since the proton of the 1-hydroxy group is
more acidic than the 3-hydroxy group, the
high regioselectivity is perhaps induced by the
formation of a higher concentration of the
anomeric species in the presence of triethy-
lamine, which predominantly reacts with the
mild benzoylating reagent BzOBT. Due to the
kinetic stereoelectronic effect or 1,3-diaxial re-
pulsion,7 the O− is oriented in the equatorial
position and only the b anomer is formed.
In conclusion, we have successfully devel-
oped a highly regioselective and stereoselective
General methods.—Solvents were purified
and dried by distillation. Flash chromatogra-
phy was carried out as recommended with
Silica Gel 60 (230–400 mesh, E. Merk). TLC
was performed on precoated glass plates of
Silica Gel 60 F254 (0.25 mm, E. Merck); detec-
tion was carried out by spraying with a solu-
tion of Ce(NH4)2(NO3)6, (NH4)6Mo7O24, as
well as H2SO4 in water and subsequent heat-
ing on a hot plate. Melting points were deter-
mined with a Bu¨chi B-540 apparatus and are

S.-C. Hung et al. / Carbohydrate Research 330 (2001) 177–182
179
uncorrected. Optical rotations were measured
with a JASCO DIP-370 polarimeter at ꢀ
25 °C. 1H and 13C NMR spectra were
recorded with Bruker AC 300 and AMX 400
instruments. Chemical shifts are in ppm from
Me4Si, generated from the CHCl3 lock signal
at l 7.26. Mass spectra were obtained with a
VG 70-250S mass spectrometer in the EI and
FAB modes. IR spectra were taken with a
Perkin–Elmer Paragon 1000 FT-IR spectrom-
eter. Elemental analyses were determined with
a Perkin–Elmer 2400 CHN instrument.
EtOAc–hexanes); mp 190–191 °C; [h]D27
−118° (c 1.0, CHCl3); IR (CHCl3) 3522, 2871,
2114, 1738, 1452, 1262, 1082, 991, 760 cm−1
;
1H NMR (400 MHz, CDCl3) l 8.09 (d, 2 H, J
7.4 Hz, BzH), 7.61 (t, 1 H, J 7.4 Hz, BzH),
7.49–7.45 (m, 4 H, BzH, PhH), 7.40–7.36 (m,
3 H, PhH), 5.82 (d, 1 H, J1,2 8.4 Hz, H-1),
5.54 (s, 1 H, PhCH), 4.37 (dd, 1 H, J6eq,6ax
10.2 Hz, H-6eq), 3.86 (dt, 1 H, J3,OH 2.6, J3,4
9.2 Hz, H-3), 3.77 (dd, 1 H, J2,3 9.2 Hz, H-2),
3.74 (t, 1 H, H-6ax), 3.64 (dd, 1 H, J4,5 10.2
Hz, H-4), 3.62 (dt, 1 H, J5,6ax 10.2, J5,6eq 4.0
13
Hz, H-5), 2.75 (d, 1 H, OH-3); C NMR (100
General procedure for regioselecti6e benzoy-
lation.—To a solution of the diol (3.0 mmol)
in CH2Cl2 (10 mL) was sequentially added
BzOBT (3.9 mmol) and Et3N (9.0 mmol) at rt
under nitrogen. After stirring for 24–48 h
(Table 1), the mixture was concentrated at
reduced pressure, and the residue was purified
by flash column chromatography on silica gel
to afford the desired adduct (the yields were
listed in Table 1).
MHz, CDCl3) l 164.43 (C), 136.62 (C), 134.02
(CH), 130.10 (CH), 129.48 (CH), 128.62 (CH),
128.42 (CH), 126.27 (CH), 102.11 (CH), 93.70
(CH), 80.40 (CH), 72.37 (CH), 68.26 (CH2),
66.96 (CH), 65.55 (CH); FABHRMS (MH+):
Anal. Calcd for C20H20N3O6 398.1352. Found
398.1337. Anal. Calcd for C20H19N3O6: C,
60.45; H, 4.82; N, 10.57. Found: C, 60.44; H,
4.65; N, 10.62.
2-Azido-1-O-benzoyl-2-deoxy-4,6-O-(p-
2-Azido-1-O-benzoyl-2-deoxy-4,6-O-benzyl-
methoxybenzylidene)-i- -glucopyranose (8).—
D
idene-i- -glucopyranose (7).—Rf 0.26 (1:4
D
Rf 0.36 (1:2 EtOAc–hexanes); mp 194–
195 °C; [h]2D9 −115.0° (c 0.5, CHCl3); IR
(CHCl3) 3528, 2930, 2118, 1740, 1613, 1514,
Table 2
Crystal data, data collection parameters, and refinement re-
1
1085, 816, 712 cm−1; H NMR (400 MHz,
sults for 8 a
CDCl3) l 8.08 (d, 2 H, J 8.0 Hz, BzH), 7.39 (t,
1 H, J 8.0 Hz, BzH), 7.47 (t, 2 H, J 8.0 Hz,
BzH), 7.40 (d, 2 H, J 6.8, ArH), 6.89 (d, 2 H,
J 6.8 Hz, ArH), 5.81 (d, 1 H, J1,2 8.4 Hz, H-1),
5.51 (s, 1 H, PhCH), 4.36 (dd, 1 H, J6eq,6ax 9.8
Hz, H-6eq), 3.85 (td, 1 H, J3,4 9.8, J3,OH 2.8
Hz, H-3), 3.79 (s, 3 H, OMe), 3.73 (dt, 1 H,
J5,6eq 3.7, J5,6ax 9.8 Hz, H-5), 3.71 (dd, J2,3 9.6
Hz, H-2), 3.63 (t, 1 H, J4,5 9.8 Hz, H-4), 3.60
8
Formula
C42H42N6O14
854.82
Formula weight
Crystal dimensions (mm3)
Crystal system
Space group
0.45×0.38×0.26
orthorhombic
P212121
8.2825(21)
13.3590(13)
38.155(7)
4221.7(14)
4
1.345
1792
0.1
50.0
,
a (A)
,
b (A)
,
c (A)
13
(t, 1 H, H-6ax), 2.76 (d, 1 H, OH); C NMR
3
,
V (A )
Z
(100 MHz, CDCl3) l 164.43 (C), 160.37 (C),
133.98 (CH), 130.07 (CH), 129.10 (C), 128.59
(CH), 128.46 (C), 127.63 (CH), 113.77 (CH),
102.00 (CH), 93.67 (CH), 80.35 (CH), 72.28
(CH), 68.19 (CH2), 66.93 (CH), 65.50 (CH),
55.28 (CH3); FABHRMS (MH+): Anal. Calcd
for C21H22N3O7 428.1459. Found 428.1424.
Anal. Calcd for C21H21N3O7: C, 59.01; H,
4.95; N, 9.83. Found: C, 59.10; H, 4.93; N,
9.83.
Dcalcd (g cm−3
F(000)
)
v (Mo Ka) (mm−1
2qmax (°)
)
Measured reflections
Unique reflections
Observed reflections
(I\2.0|(I))
Variables
Min, max in final difference
4240
4240
2492
561
−0.24, 0.29
−3
,
map (e A
R; wR
)
2-Azido-1-O-benzoyl-2-deoxy-4,6-O-iso-
0.064, 0.075
propylidine-i- -glucopyranose (9).—Rf 0.32
D
(1:2 EtOAc–hexanes); mp 160–161°C; [h]D30
−115° (c 0.7, CHCl3); IR (CHCl3) 3424, 2992,
a T=298 K; diffractometer, Nonius CAD-4; radiation, Mo
,
Ka; u=0.7107 A.

180
S.-C. Hung et al. / Carbohydrate Research 330 (2001) 177–182
Table 3 (Continued)
Table 3
Atomic coordinates and isotropic thermal parameters for
compound 8
Atom
x
y
z
Biso
4.6(5)
6.2(5)
6.4(6)
8.6(8)
8.1(8)
6.0(5)
Atom
x
y
z
Biso
5.7(3)
C45
C46
C47
C48
C49
C50
C51
Ho3
Ho33
H1
H2
H3
H4
H5
H6a
H6b
H9
H10
H11
H12
H13
H14
H16
H17
H19
H20
H21a
H21b
H21c
H31
H32
H33
H34
H35
H36a
H36b
H39
H40
H41
H42
H43
H44
H46
H47
H49
H50
H51a
0.1682(10) 0.7946(7) 1.03265(23)
0.1241(12) 0.8921(8) 1.04305(28)
0.0900(15) 0.9146(9) 1.07807(28)
0.0988(16) 0.8426(12) 1.10209(36)
0.1406(16) 0.7451(12) 1.09318(24)
0.1735(12) 0.7225(8) 1.05875(28)
O1
O3
O4
O5
0.3935(8)
0.3204(9)
0.3796(7)
0.3845(8)
0.4054(8)
0.0658(5) 0.8522(2)
0.3791(4) 0.9072(1)
0.3786(4) 0.9733(1)
0.0705(4) 0.9110(1)
0.1291(4) 1.0045(1)
6.3(3)
4.2(3)
4.8(3)
5.1(4)
8.2(4)
6.0(3)
4.9(3)
4.5(3)
4.0(3)
4.1(3)
5.0(3)
7.1(4)
12.2(7)
6.9(5)
11.6(9)
20.3(15)
5.9(4)
9.6(6)
14.7(10)
4.9(5)
4.6(4)
3.9(4)
3.9(4)
4.2(4)
4.9(4)
5.9(6)
5.6(5)
8.9(8)
O6
0.0405(22) 0.9291(21) 1.15234(43) 17.7(18)
O7
0.6055(11) −0.0373(6) 0.8580(2)
0.303
0.034
0.567
0.262
0.521
0.226
0.545
0.440
0.260
0.607
0.503
0.292
0.176
0.239
0.206
0.326
0.395
0.443
0.384
0.508
0.399
0.588
0.388
0.443
0.124
0.222
0.300
0.216
0.136
0.005
0.050
−0.171
−0.245
−0.173
−0.025
0.038
0.211
0.157
0.240
0.506
0.420
0.546
0.569
0.545
0.680
0.533
0.586
0.644
0.772
0.821
0.900
0.765
0.715
0.586
0.508
0.552
0.754
0.946
0.983
0.692
0.652
0.937
0.963
0.977
0.881
0.964
0.882
0.872
0.914
0.939
0.943
0.975
0.971
0.811
0.754
0.725
0.743
0.799
1.001
1.070
1.120
1.066
0.013
0.159
0.125
0.120
0.880
0.892
0.944
0.948
0.929
0.938
0.925
0.758
0.699
0.690
0.740
0.796
0.996
1.025
1.084
1.112
1.053
1.178
1.140
1.145
7.0
5.3
5.6
5.4
4.7
4.7
5.0
5.7
5.7
9.7
11.0
12.5
11.5
8.4
5.0
5.6
5.9
5.9
5.2
7.2
7.2
7.2
5.2
4.8
4.7
4.3
4.5
6.3
6.3
7.8
9.6
10.6
10.9
7.7
5.1
7.0
7.2
8.9
6.8
18.5
18.5
18.5
O8
0.4520(9)
0.0932(8)
0.1263(7)
0.1186(7)
0.1630(7)
0.1832(8)
0.4231(5) 1.1304(1)
0.6396(4) 0.8428(1)
0.4841(4) 0.9550(1)
0.6881(4) 0.9842(1)
0.7309(4) 0.8905(1)
0.8561(4) 0.9750(1)
0.7607(6) 0.8246(2)
O31
O33
O34
O35
O36
O37
O38
N1
N2
N3
N31
N32
N33
C1
−0.0772(9)
0.0768(14) 0.8500(10) 1.1385(2)
0.4680(13) 0.2726(6) 0.8495(2)
0.3928(19) 0.3156(11) 0.8291(3)
0.3132(24) 0.2645(17) 0.8091(4)
−0.0468(11) 0.4849(5) 0.8872(2)
−0.0317(16) 0.4477(6) 0.8592(2)
−0.0278(22) 0.4034(9) 0.8329(3)
0.4462(11) 0.1187(7) 0.88151(25)
0.3798(12) 0.2249(6) 0.87782(21)
0.4029(11) 0.2871(6) 0.91131(20)
C2
C3
C4
0.3449(9)
0.2267(6) 0.94144(21)
C5
C6
C7
C8
0.4258(10) 0.1246(6) 0.94232(22)
0.3770(12) 0.0682(6) 0.97270(21)
0.4976(16) −0.0125(7) 0.84110(29)
0.4344(14) −0.0566(7) 0.80899(25)
0.5129(17) −0.1444(9) 0.79792(33)
−0.061
0.187
−0.048
0.275
0.009
0.348
0.214
−0.095
−0.015
0.164
0.292
0.217
0.328
0.123
0.051
0.145
0.203
0.034
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
C41
C42
C43
C44
0.4513(23) −0.1839(10) 0.76400(39) 10.2(9)
0.3306(24) −0.1379(16) 0.74637(41) 11.7(12)
0.2576(19) −0.0567(12) 0.75866(38) 10.7(10)
0.3049(16) −0.0185(9) 0.78907(32)
0.3245(11) 0.2228(6) 1.00288(21)
0.3567(10) 0.2791(6) 1.03555(21)
0.3533(12) 0.2301(6) 1.06814(23)
0.3871(13) 0.2784(7) 1.09764(21)
0.4204(12) 0.3834(7) 1.09766(23)
0.4164(12) 0.4331(6) 1.06735(23)
0.3840(11) 0.3809(6) 1.03515(20)
0.4893(14) 0.5262(8) 1.13360(24)
0.0544(11) 0.6595(6) 0.87781(22)
0.0774(10) 0.5600(6) 0.89819(20)
0.0679(10) 0.5718(6) 0.93811(20)
0.1582(10) 0.6621(6) 0.94948(19)
0.1250(10) 0.7528(6) 0.92609(21)
0.2302(13) 0.8378(6) 0.93975(24)
0.0140(14) 0.6968(7) 0.81785(22)
0.0566(14) 0.6639(8) 0.78192(25)
0.0146(15) 0.7100(8) 0.75394(27)
0.0312(19) 0.6829(11) 0.72026(33)
0.1344(23) 0.6090(13) 0.71419(34)
7.6(7)
4.2(4)
4.0(4)
4.8(5)
5.2(5)
4.7(4)
5.1(5)
4.4(4)
6.4(6)
4.4(4)
4.1(4)
3.9(4)
3.5(4)
3.7(4)
5.5(5)
5.1(5)
5.8(5)
7.0(6)
8.8(8)
9.8(10)
H51b −0.052
H51c 0.127
2117, 1734, 1602, 1271, 1077, 840, 713 cm−1
;
1H NMR (400 MHz, CDCl3) l 8.06 (d, 2 H, J
7.2 Hz, BzH), 7.60 (t, 1 H, J 7.2 Hz, BzH),
7.46 (t, 2 H, J 7.2 Hz, BzH), 5.77 (d, 1 H, J1,2
7.9 Hz, H-1), 3.95 (dd, 1 H, H-6eq), 3.76 (t, 1
0.2076(19) 0.5608(10) 0.74376(33) 10.1(9)
0.1684(16) 0.5873(8) 0.77596(22)
0.2107(10) 0.7714(6) 0.99686(24)
6.9(7)
4.3(4)

S.-C. Hung et al. / Carbohydrate Research 330 (2001) 177–182
181
13
(s, 3 H, Me); C NMR (100 MHz, CDCl3) l
171.66 (C), 165.47 (C), 133.97 (CH), 130.20
(CH), 128.62 (CH), 128.61 (C), 100.03 (C),
93.59 (CH), 73.98 (CH), 72.94 (CH), 68.10
(CH), 61.75 (CH2), 56.03 (CH), 28.96 (CH3),
23.33 (CH3), 19.03 (CH3).
H, J6a,6b 10.4 Hz, H-6ax), 3.72 (dt, 1 H, J3,4
10.4, J3,OH 2.0 Hz, H-3), 3.66 (dd, 1 H, J2,3
10.4 Hz, H-2), 3.62 (t, 1 H, J4,5 10.4 Hz, H-4),
3.44 (dt, 1 H, J5,6eq 5.6, J5,6ax 10.4 Hz, H-5),
2.79 (d, 1 H, OH-3), 1.51 (s, 3 H, Me), 1.43 (s,
3 H, Me); 13C NMR (100 MHz, CDCl3) l
164.45 (C), 134.00 (CH), 130.11 (CH), 128.62
(CH), 128.52 (C), 100.12 (C), 93.78 (CH),
73.19 (CH), 72.79 (CH), 67.98 (CH), 65.76
(CH), 61.66 (CH2), 28.90 (CH3), 19.05 (CH3);
FABHRMS (MH+): Anal. Calcd for
C16H20N3O6 350.1352. Found 350.1344. Anal.
Calcd for C16H19N3O6: C, 55.01; H, 5.48.
Found: C, 54.96; H, 5.44.
2 - (2,2,2 - Trichloroethoxycarbonylamino) - 1-
O-benzoyl-2-deoxy-4,6-O-benzylidine-i- - glu-
D
copyranose (12).—Rf 0.32 (4:7 EtOAc–hex-
anes); mp 201–202 °C; [h]3D0 –57o (c 0.7,
CHCl3); IR (CHCl3) 3636, 3315, 2867, 1739,
1704, 1684, 1534, 1265, 1081, 1026, 820, 750,
706 cm−1; H NMR (400 MHz, CDCl3) l
1
8.08 (dd, 2 H, J 7.4, 1.2, BzH), 7.60 (tt, 1 H,
J 7.4, 1.2 Hz, BzH), 7.53–7.51 (m, 2 H, BzH),
7.47–7.40 (m, 5H, PhH), 5.93 (d, 1 H, J1,2 8.4
Hz, H-1), 5.59 (s, 1 H, PhCH), 5.18 (d, 1 H,
NH), 4.85 (d, 1 H, J 12.0 Hz, CCl3CH2O),
4.54 (d, 1 H, CCl3CH2O), 4.41 (dd, 1 H,
J6eq,6ax 10.4 Hz, H-6eq), 4.04 (q, 1 H, J2,3 8.4,
J2,NH 8.4 Hz, H-2), 3.99 (dd, 1 H, J3,4 7.6 Hz,
H-3), 3.80 (dt, 1 H, J5,6ax 10.4, J5,6eq 4.4 Hz,
H-5), 3.71 (dd, 1 H, J4,5 10.4 Hz, H-4), 3.69
(dd, 1 H, H-6ax), 2.91 (s, 1 H, OH-3); 13C
NMR (100 MHz, CDCl3): l 165.01 (C),
154.74 (C), 136.82 (C), 133.97 (CH), 130.25
(CH), 129.59 (CH), 128.54 (CH), 128.40 (C),
126.40 (CH), 102.05 (CH), 95.25 (C), 93.45
(CH), 81.08 (CH), 74.49 (CH2), 71.39 (CH),
68.34 (CH2), 67.02 (CH), 57.02 (CH);
FABHRMS (MH+): Anal. Calcd for
C23H23Cl3NO8 546.0489. Found 546.0482.
2-N-Acetyl-1-O-benzoyl-2-deoxy-4,6-O-ben-
zylidene-i- -glucopyranose (10).—Rf 0.28
D
(3:2 EtOAc–hexanes); mp 188–189 °C; [h]D32
−61° (c 0.5, 1:1 CHCl3–MeOH); IR (CHCl3)
3650, 3276, 3057, 2877, 1740, 1679, 1250,
1
1084, 753, 698 cm−1; H NMR (400 MHz, 1:1
CDCl3–CD3OD) l 8.07 (dd, 2 H, J 7.2, J 1.2
Hz, BzH), 7.62 (tt, 1 H, J 7.2, J 1.2 Hz, BzH),
7.54–7.46 (m, 4 H, BzH, PhH), 7.38–7.36 (m,
3 H, PhH), 5.85 (d, 1 H, J1,2 8.8 Hz, H-1),
5.62 (s, 1 H, PhCH), 4.37 (dd, 1 H, H-6eq),
4.23 (t, 1 H, J
8.8 Hz, H-2), 3.89 (t, 1 H,
2,3
J3,4 8.8 Hz, H-3), 3.83 (dt, 1 H, J5,6ax10.4, J5,6eq
4.4 Hz, H-5), 3.70 (dd, J4,5 10.4 Hz, H-4), 3.65
(dd, 1 H, J6ax,6eq 10.4 Hz, H-6ax), 1.94 (s, 3 H,
Ac); 13C NMR (100 MHz, CDCl3) l 172.37
(C), 165.17 (C), 137.03 (C), 133.60 (CH),
129.75 (CH), 128.79 (CH), 128.57 (C), 128.30
(CH), 127.81 (CH), 126.04 (CH), 101.65 (CH),
93.75 (CH), 81.04 (CH), 70.77 (CH), 68.10
(CH2), 66.99 (CH), 55.05 (CH), 21.91 (CH3);
FABHRMS (MH+): Anal. Calcd for
C22H24NO7 414.1553. Found 414.1584.
4. Supplementary material
Crystallographic data for the structural
analysis has been deposited with the Cam-
bridge Crystallographic Data Centre, CCDC
no. 147253. Copies of this information may be
obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: +44-1223-336033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http://www.
ccdc.cam.ac.uk).
2-N-Acetyl-1-O-benzoyl-2-deoxy-4,6-O-iso-
propylidene-i- -glucopyranose (11).—Rf 0.21
D
(EtOAc); mp 115–117 °C; [h]3D2 −37° (c 0.7,
CHCl3); IR (CHCl3) 3630, 3288, 2994, 1735,
1655, 1264, 1076, 1026, 940, 859, 755 cm−1
;
1H NMR (400 MHz, CDCl3) l 8.04 (d, 2 H, J
7.2 Hz, BzH), 7.58 (t, 1 H, J 7.2 Hz, BzH),
7.44 (d, 2 H, J 7.2 Hz, BzH), 5.92 (bs, 1 H,
NH), 5.89 (d, 1 H, J1,2 8.4 Hz, H-1), 4.23 (q,
1 H, J2,3 8.4 Hz, H-2), 3.95 (dd, 1 H, H-6eq),
3.83 (dd, 1 H, J3,4 9.6 Hz, H-3), 3.77 (t, 1 H,
J4,5 9.6 Hz, H-4), 3.69 (t, 1 H, J6ax,6eq 9.6 Hz,
H-6ax), 3.45 (dt, 1 H, J5,6ax 9.6, J5,6eq 5.2 Hz,
Acknowledgements
We thank Mr Yuh-Sheng Wen for the sin-
gle-crystal X-ray structural analysis.
H-5), 1.95 (s, 3 H, Ac), 1.52 (s, 3 H, Me), 1.43
.

182
S.-C. Hung et al. / Carbohydrate Research 330 (2001) 177–182
3. Clinch, K.; Vasella, A. Tetrahedron Lett. 1987, 28, 6425–
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