Synthesis of p-trifluoroacetamidophenyl (4,6-dideoxy-4-formamido-3-C-methyl-2-O-methyl-α-L-mannopyran osyl)-(1→3)-(2-O - methyl-α-D-rhamnopyranosyl)-(1→3)-(2-O-methyl-α-L-fucopyran osyl)-(1 →3)-(α-L-rhamnopyranosyl)-(1 →2)-6-deoxy-α-L-talopyranoside: A sp

Article abstract of DOI:10.1016/S0008-6215(98)00074-3

Syntheses of p-trifluoroacetamidophenyl glycosides of the haptenic pentasaccharide and the non-reducing disaccharide unit of the title pentasaccharide are reported. The synthesis of the terminal N-formylkansosamine unit started from methyl 6-deoxy-2,3-O-i

Full text of DOI:10.1016/S0008-6215(98)00074-3

Carbohydrate Research 308 (1998) 247±258
Synthesis of p-tri¯uoroacetamidophenyl
(4,6-dideoxy-4-formamido-3-C-methyl-2-O-
methyl-ꢀ-l-mannopyranosyl)-(1!3)-(2-O-
methyl-ꢀ-d-rhamnopyranosyl)-(1!3)-(2-O-
methyl-ꢀ-l-fucopyranosyl)-(1!3)-(ꢀ-l-
rhamnopyranosyl)-(1!2)-6-deoxy-ꢀ-l-
talopyranoside: a spacer-armed pentasaccharide
glycopeptidolipid antigen of
Mycobacterium avium serovar 14
Istvan Bajzaa,*, Katalin E. Koverb, Andras Liptaka, c,
*
a Research Group for Carbohydrates of the Hungarian Academy of Sciences, Debrecen, P.O.B 55,
H-4010 Hungary
b Institute of Organic Chemistry, L. Kossuth University, Debrecen, P.O.B. 20, H-4010 Hungary
c Institute of Biochemistry, L. Kossuth University, Debrecen, P.O.B 55, H-4010 Hungary
Received 19 September 1997; accepted 6 February 1998
Abstract
Syntheses of p-tri¯uoroacetamidophenyl glycosides of the haptenic pentasaccharide and the non-
reducing disaccharide unit of the title pentasaccharide are reported. The synthesis of the terminal N-
formylkansosamine unit started from methyl 6-deoxy-2,3-O-isopropylidene-ꢀ-l-lyxo-hexopyran-4-
uloside which, after C-3 methylation, was transformed into a glycosyl donor [3-O-benzyl-4-N-ben-
zylformamido-4,6-dideoxy-3-C-methyl-2-O-methyl-ꢀ,ꢁ-l-mannopyranosyl
(20), and used for the synthesis of p-tri¯uoroacetamidophenyl (4-formamido-4,6-dideoxy-3-C-
trichloroacetimidate
methyl-2-O-methyl-ꢀ-l-mannopyranosyl)-(1!3)-6-deoxy-2-O-methyl-ꢀ-d-mannopyranoside (29).
Ethyl
(3-O-benzyl-4-N-benzylformamido-4,6-dideoxy-3-C-methyl-2-O-methyl-ꢀ-l-mannopyra-
nosyl)-(1!3)-4-O-benzyl-6-deoxy-2-O-methyl-l-thio-ꢀ-d-mannopyranoside (31), prepared by gly-
cosylation of ethyl 4-O-benzyl-6-deoxy-2-O-methyl-1-thio-ꢀ-d-mannopyranoside with 20, served
as glycosyl donor in a 2+3 block synthesis of the title pentasaccharide. # 1998 Elsevier Science
Ltd. All rights reserved
Keywords: Branched-chain sugar; Spacer, p-tri¯uoroacetamidophenyl; Oligosaccharide synthesis; Block synthesis
* Corresponding authors.
0008-6215/98/$19.00 # 1998 Elsevier Science Ltd. All rights reserved
PII S0008-6215(98)00074-3

248
I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
Two trisaccharide segments (C±B±A with the o-
1. Introduction
aminopropyl [14] and p-nitrophenyl aglycons [12],
and E±D±C [4] with the allyl aglycon), and the
tetrasaccharide D±C±B±A [12] with the p-nitro-
phenyl aglycon have also been prepared.
The pioneering work of Brennan [1] and Aspi-
nall et al. [2] laid the foundation of the molecular
basis of the exact serodiagnosis of infections
caused by mycobacteria. Many pulmonary infec-
tions, especially in patients su€ering from acquired
immunode®ciency syndrome (AIDS), are con-
nected with mycobacteria of the Mycobacterium
avium±Mycobacterium scrofulaceum complex. Dif-
ferent serovars of this complex possess highly anti-
genic glycopeptidolipids (GPLs) on their cell
surface. Thus the outer oligosaccharide haptens,
after conjugation with suitable proteins, might aid
the serodiagnosis of mycobacterial infections.
Among these haptens, the pentasaccharide of M.
avium serovar 14 has the most complex structure
[3,4] (Scheme 1). Here rhamnose occurs in both
enantiomeric forms and the terminal N-formyl-ꢀ-l-
2. Results and discussion
For the synthesis of N-formyl-l-kansosamine on
a preparative scale we applied two known synthetic
strategies [15,16]. Firstly, the addition of methyl
magnesium iodide to 2 (Scheme 2) obtained by
oxidation of methyl 4-O-benzyl-2-O-methyl-ꢀ-l-
rhamnopyranoside [17] (1) with pyridinium chloro-
chromate [18] gave diastereomers 3 and 4 in a
molar ratio of 1:1.2. The stereochemical
assignment of compounds 3 and 4 was based on
homonuclear NOE measurements [19]. In com-
pound 3, the irradiation of the 3-C-methyl protons
resulted in the signal enhancement of H-2 (14%)
and H-5 (8%), while no e€ect was observed at the
resonance frequency of H-4. These spectral data
showed the proximity of the 3-C-Me group to H-5,
con®rming its axial position. In the case of com-
pound 4, signal intensity enhancements were
observed at H-4 (9%) and at H-2 (11%) indicating
the equatorial orientation of the 3-C-Me group.
The low yields of 3 (19%) and 4 (13%) prompted
us to proceed with our second synthetic strategy.
Methyl 6-deoxy-2,3-O-isopropylidene-ꢀ-l-lyxo-
hexopyran-4-uloside (5) was C-methylated [20] with
methyl iodide in the presence of strong inorganic or
organic bases, to give methyl 6-deoxy-2,3-O-iso-
propylidene-3-C-methyl-ꢀ-l-lyxo-hexopyran-4-ulo-
side (6). Reduction of compound 6 with NaBH4
yielded exclusively 6-deoxy-talopyranoside deriva-
tive 7, which was converted into 4-O-tri¯ate 8.
Treatment of compound 8 with sodium azide
a€orded methyl 4,6-dideoxy-2,3-O-isopropylidene-
3-C-methyl-ꢀ-l-erythro-hex-4-enopyranoside (9),
instead of the desired 4-azido-l-rhamnopyranoside
derivative. The reason of this elimination may have
been the presence of the axial 3-C-Me group, which
prevented the attack of the nucleophile, since
successful azide displacements of the 4-O-tri-
¯uoromethanesulphonyl derivative in 6-deoxy-ꢀ-l-
talopyranoside [21] and d-talopyranoside [22] were
reported to yield 4-azido-l-rhamno- and 4-azido-
d-mannopyranoside derivatives. Catalytic reduc-
tion (Pd-C) of oxime 10, prepared from 6, gave
exclusively the 6-deoxy-talo isomer (11), but the
kansosamine
(4-N-formamido-4,6-dideoxy-3-C-
methyl-2-O-methyl-ꢀ-l-mannopyranose)
is
a
highly functionalised branched-chain aminosugar.
Although kansosamine has not been isolated in free
form, its derivatives were found in the surface anti-
gen of M. kansasii [5] [4-(2-O-methyl)propionamido]
and in the antibiotic sibiromycin [6] (4-N-methy-
lated). For the preparation of N-formyl-ꢀ-l-kan-
sosamine, four di€erent methods have been
published [4,7±9], and the synthesis of some oligo-
saccharide fragments of the pentasaccharide have
also been reported. The B±A disaccharide (with
benzyl [10], methyl [11], and p-nitrophenyl [12,13]
aglycons), and the E±D [4] and D±C [4] disac-
charides (with the allyl aglycon) were also reported.
Scheme 1.

I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
249
Scheme 2.
LiA1H4 reduction of 10 resulted in a 1:1 mixture of
6-deoxy-l-talo- (11) and 6-deoxy-l-manno-isomers
(12) [23]. Compound 12 was isolated in 41% yield.
After N-formylation of 12 with acetic-formic
anhydride (!13) and N-benzylation (!14), the
2,3-O-isopropylidene group was removed (!15)
and the HO-2 function was selectively methylated
to give compound 16. The remaining free HO-3
group of 16 was benzylated to yield the fully pro-
tected N-formyl-ꢀ-l-kansosamine derivative (17).
Acetolysis of compound 17 (!18), followed by
deacetylation (!19) and imidation in the presence
of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) [24]
gave donor 20.
For the preparation of p-nitrophenyl 4-O-benzyl-
2-O-methyl-ꢀ-d-rhamnopyranoside (26), p-nitro-
phenyl 2,3-O-isopropylidene-ꢀ-d-mannopyranoside
[25] was selectively tosylated at HO-6 (!21), and
the tosyloxy group was transformed into a 6-
deoxy-6-iodo function (22). Compound 22 was
reduced by LiA1H4 to give 23, and the latter was
benzylated and deisopropylidenated to give 25.
Treatment of 25 with methyl iodide under phase-
transfer condition [26] gave 26. The structure of all
these compounds was veri®ed by 1H and 13C NMR
data, and the physical parameters of compounds
23±25 were compared with those of their l-enan-
tiomers [27].
The glycosylation of compound 26 with tri-
chloroacetimidate 20 (Scheme 3), catalysed by tri-
methylsilyl tri¯ate, yielded the fully protected
disaccharide 27 in 35% yield, whose structure was
con®rmed by 1H and 13C NMR spectroscopy
(Table 1). The nitro group in 27 was catalytically
reduced, and the amine formed was tri¯uoro-
acetylated to give 28. Deprotection of 28 was
achieved by catalytic hydrogenolysis yielding the
spacer-armed disaccharide 29 (for NMR data, see
Table 2).
Ethyl 4-O-benzyl-2-O-methyl-1-thio-ꢀ-d-rham-
nopyranoside [12] (30) was glycosylated with donor
20, yielding disaccharide 31 (75%) as the E±D
synthon (Scheme 1; Table 1) for the block synthesis
of the target pentasaccharide. The considerable dif-
ference in yields of the glycosylations of 26 and 30
with donor 20 may have been due to the di€erent
electronic e€ects of the aglycons since the substitu-
tion pattern of the two acceptors was the same.
Previously, we have reported [12] the synthesis of
the p-nitrophenyl glycoside of the tetrasaccharide
hapten isolated from M. avium serovar 20. This
tetrasaccharide was the D±C±B±A part of our
target pentasaccharide. An intermediate of the
unprotected tetrasaccharide [12], p-nitrophenyl (3-
O-acetyl-4-O-benzyl-2-O-methyl-ꢀ-d-rhamnopyra-
nosyl)-(1!3)-(4-O-benzyl-2-O-methyl-ꢀ-l-fuco-

250
I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
Scheme 3.
Table 1
NMR data for disaccharides 27 and 31 in CDCl3 (ꢂ in ppm)
Atom no.
27a
27b
31a
31b
1
1
1
1
ꢂ
13C
ꢂ H
ꢂ
13C
ꢂ H
ꢂ
13C
ꢂ H
ꢂ
13C
ꢂ H
1
2
3
4
95.88
76.39
73.98
79.54
69.51
18.33
94.45
81.03
78.5
62.50
65.27
17.35
17.50
59.20
58.94
74.38
63.36
50.2
5.64
96.22
77.2
5.60
80.61
77.96
74.38
80.02
68.38
18.12
93.44
80.90
78.5
62.50
65.14
17.33
17.33
58.83
57.94
74.43
63.26
50.09
161.71
25.48
14.98
126.0
140.0
5.38
80.61
78.70
74.78
80.33
68.20
18.03
95.49
82.25
80.23
65.43
63.89
18.58
18.30
59.37
57.78
74.94
63.52
55.92
163.27
25.36
15.02
126.0
140.0
5.34
3.84
4.20
3.54
3.76
1.30
5.11
3.46
3.81
4.27
3.55
3.71
1.23
5.08
3.77
3.75
3.97
3.48
4.10
1.33
5.00
3.45
3.71
4.04
3.47
4.0
1.26
4.99
3.66
74.16
80.09
69.30
18.13
96.76
82.53
80.15
65.81
63.77
18.69
18.30
59.68
58.94
74.73
63.72
55.97
163.32
5
6
10
20
30
40
4.40
4.13
0.63
1.45
3.58
3.51
4.69+4.75
4.45+4.48
3.85+5.40
7.49
3.23
5.04
0.73
1.53
3.55
3.56
4.57+4.98
4.45
4.40
4.04
0.62
1.40
3.48
3.48
4.71+4.73
4.43
3.83+5.4
7.49
2.63
1.29
7.1 7.4
3.21
5.00
0.71
1.54
3.52
3.46
4.54+4.98
4.40
4.40
8.33
2.61
1.26
7.1 7.4
50
60
30-CMe
2-OMe
20-OMe
4-OCH2Ph
30-OCH2Ph
NCH2Ph
NCHO
SCH2CH3
SCH2CH3
Ph
4.58+4.98
8.36
161.61
126.0
140.0
126.0
140.0
PNP-C1
161.14
116.33
125.83
142.72
161.45
116.38
125.76
142.53
PNP-C2,C6
PNP-C3,C5
PNP-C4
7.15
8.19
7.13
8.17
pyranosyl)-(1!3)-(2,4-di-O-benzyl-ꢀ-l-rhamno-
pyranosyl)-(1!2)-endo-3,4-O-benzylidene-6-deoxy-
ꢀ-l-talopyranoside, was saponi®ed to a€ord the
tetrasaccharide acceptor for the preparation of our
target pentasaccharide. Unfortunately neither imi-
date 20 nor the previously prepared phenyl 4-(N-
benzylformamido)-4,6-dideoxy-3-C-methyl-2-O-
methyl-1-thio-ꢀ-l-mannopyranoside reacted with
this acceptor.
3,4-O-benzylidene-6-deoxy-ꢀ-l-talopyranoside [12]
(32) reacted readily with the disaccharide donor 31 in
the presence of NIS/TfOH as promotor [28], yielding
the fully protected pentasaccharide 33 in a yield of
1
55% (Scheme 4). The complete H and 13C NMR
assignment of compound 33 was not possible since
signals of the CH2 protons of the benzyl groups
1
appeared in the informative region of the H NMR
spectrum. The E and Z isomerism of the N-CHO
group also made the interpretation of the spectrum
more dicult. The assignable chemical shift values
for compound 33 are presented in Table 3.
The trisaccharide acceptor p-nitrophenyl (4-O-
benzyl-2-O-methyl-ꢀ-l-fucopyranosyl)-(1!3)-(2,4-
di-O-benzyl-ꢀ-l-rhamnopyranosyl)-(1!2)-endo-

I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
251
Table 2
NMR data for disaccharide 29 in CD3OD (ꢂ in ppm)
3. Experimental
General.ÐMelting points (uncorrected) were
determined on a Ko¯er hot-sꢀtage apparatus. NMR
spectra were recorded at 25 C with a Bruker WP
200 SY (1H, 200 MHz; 13C, 50 MHz) or a Bruker
Avance DRX 500 (1H, 500.13 MHz; 13C,
125.76 MHz) spectrometer for solutions in CDCl3
(internal Me4Si) or in CD3OD. Proton chemical
shifts (ꢂ) are given in ppm relative to the signal for
internal Me4Si (CDCl3). Carbon chemical shifts
were referenced to the solvent signal. Column
chromatography was performed on Kieselgel 60
(Merck, 230 mesh) and fractions were monitored
by TLC on Kieselgel 60 F254 (Merck) by detection
with UV light and then charring with H2SO4.
Unless noted otherwise, optical rotations were
Atom no.
ꢂ1H
ꢂ13C
29a
29b
29a
29b
1
2
3
4
5.60
3.88
4.06
3.49
3.68
1.24
96.3
76.8
75.1
71.0
69.5
17.2
5
6
OMe
3.30±3.32
7.56±7.11
ꢁ58.9
Ph
10
122.8±117
5.04
3.12
5.15
3.17
94.6
94.8
20
84.3
60.3
67.5
17.7
ꢁ58.9
40
3.26
50
4.00
1.17
4.05
1.20
60
OMe
NCHO
CH3(30)
3.49±3.52
8.16
1.32
8.55
1.39
136.9
131
19
ꢀ
measured for solutions in CHCl3 at 20 C with a
Perkin Elmer 241 polarimeter, using a 10 cm
(1 mL) cell. Concentration of solutions was per-
formed at 40 ꢀC.
Methyl 4-O-benzyl-2-O-methyl-a-l-arabino-hexo-
pyranosid-3-ulose (2).ÐMethyl 4-O-benzyl-6-deoxy-
The fully protected pentasaccharide 33 was con-
verted into p-tri¯uoroacetamidophenyl glycoside
34, and then deprotected as described for disac-
1
charide 29. Full assignment of the H and 13C
2-O-methyl-ꢀ-l-mannopyranoside
(1)
(1.96 g,
spectra of the pentasaccharide 35 was achieved by
1H-1H COSY and TOCSY experiments as well as
1H/13C HSQC and HSQC±TOCSY experiments
[29,30] (Table 4). The spectral parameters were in
full accord with the target structure.
6.94 mmol) was dissolved in CH2Cl2 (200 mL), pyri-
dinium chlorochromate (6.5 g, 34.7 mmol) was
added, and the mixture was stirred for 12 h at room
temperature. The mixture was chromatographed
(7:3 hexane±EtOAc) to yield 2 (1.62 g, 83%) as a
Scheme 4.

252
I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
Table 3
NMR data for pentasaccharide 33 in CDCl3 (ꢂ in ppm)
Table 4
NMR data for pentasaccharide 35 in CD3OD (ꢂ in ppm)
Residue
Atom no.
ꢂ13C
ꢂ1H
Residue
Atom no.
ꢂ1H
ꢂ13C
6d-ꢀ-l-Talp
1
2
3
6
98.7
71.44
74.84
17-19
104.74
5.64
4.26
4.60
1.2-1.4
5.85
6d-ꢀ-l-Talp
1
2
3
4
5
6
5.62
4.03
4.12
3.63
3.80
1.25
98.1
77.8
71
70.6
69.8
17.2
benzylidene
JC1,H1
175.1 Hz
ꢀ-l-Rhap
ꢀ-l-Fucp
1
2
3
6
94.40
77.5
76.82
17-19
5.11
3.68
4.27
1.2-1.4
ꢀ-l-Rhap
ꢀ-l-Fucp
ꢀ-d-Rhap
1
2
3,4
5
5.03
4.10
3.82,3.79
3.63
1.12
103.44
75.1
78.3
72.1
16.7
JC1,H1
168.2 Hz
6
1
2
3
4
5
98.97
79.85
79.50
78.33
67.58
18
5.08
3.85
3.55
3.83
3.90
0.95
3.12
1
2
5.17
3.73
3.93,3.98,4.03
1.21
3.49,3.52,3.54
99.3
77.5
75,67.1,70
17.4
58.8-59
3,4,5
6
2-OMe
6
1
2
3
4
5
6
5.39
3.67
4.05
3.75
4.02
1.20
98.7
78.2
76.3
72.3
68.3
17.5
58.8-59
2-OMe
JC1,H1
58.89
167.3 Hz
ꢀ-d-Rhap
1
2
3
4
5
98.45
80.30
74.09
76.32
68.78
17-19
5.26
3.47
4.09
3.68
3.90
1.2-1.4
2-OMe
3.49,3.52,3.54
ꢀ-Kanp-4NFo
1
2
4
5
5.08
3.11 3.15
3.24 3.28
4.08
94.9
84.6
53.5
70.6
6
2-OMe
JC1,H1
58.89 or 58.38 3.45 or 3.41
172.1 Hz
ꢀ-Kanp-4NFo
1
6
93.50
17-19
58.89 or 58.38 3.45 or 3.41
5.07
1.2-1.4
6
1.22
15.8
2-OMe
NCHO
CH3(3)
3.49,3.52,3.54
8.2 and 8.0
1.37 and 1.31
58.8-59
131 and 137
19.1
2-OMe
CHO
N-Bzl
JC1,H1
162.31
50.03
8.32
3.84
166.3 Hz
EtOAc) gave pure 3 (40 mg, 19%) and 4 (28 mg,
13%), isolꢀated as colourless syrups. Compound 3:
[ꢀ]d 67.1 (c 0.43); 1H NMR: ꢂ 7.40 (m, 5 H, Ph),
4.72 (d, 1 H, J1,2 1 Hz, H-1), 3.61 (dd, 1 H, J4,5 10,
J5,Me(6) 6 Hz, H-5), 3.48 and 3.36 (2 s, each 3 H, 2
OCH3), 3.20 (d, 1 H, H-4), 3.08 (d, 1 H, H-2), 1.38
(s, 3 H, CH3), 1.25 (d, 3 H, CH3); Compound 4:
colourless syrup; [ꢀ]d
183.5ꢀ (c 0.45); IR:
1
1
1730 cm (C=O); H NMR: ꢂ 7.20±7.30 (m, 5 H,
Ph), 4.79 (d, 1 H, J1,2 2 Hz, H-1), 4.01 (d, 1 H, J4,5
9.2 Hz, H-4), 3.88 (dd, 1 H, J5,Me(6) 6 Hz, H-5), 3.55
(d, 1 H, H-2), 3.28 and 3.26 (2 s, each 3 H, 2
OCH3), 1.32 (d, 3 H, CH3). Anal. Calcd for
C15H20O5: C, 64.27; H, 7.19. Found: C, 64.11; H,
7.05.
Methyl 4-O-benzyl-6-deoxy-3-C-methyl-2-O-
methyl-a-l-manno-(3) and altro-pyranoside (4).Ð
A solution of compound 2 (196 mg, 0.7 mmol) in
Et2O (2 mL) was added dropwise to a solution of
Grignard reagent prepared from CH3I (875 mg,
14.1 mmol) and Mg (343 mg, 14.1 mmol) in Et2O
(5 mL), and the mixture was stirred for 1 h at room
temperature. The reaction was quenched by addi-
tion of a chilled NH3-solution (10 mL), then the
mixture was diluted with Et2O (20 mL), extracted
with water (2Â10 mL), dried, and concentrated.
Chromatography of the residue (8:2 hexane±
[ꢀ]d 56.1ꢀ (c 0.3); H NMR: ꢂ 7.4 (m, 5 H, Ph),
1
4.72 (d, 1 H, J1,2 1.5 Hz, H-1), 4.66 (s, 2 H,
CH2Ph), 3.92 (dd, 1 H, J4,5 9.5, J5,6 6 Hz, H-5),
3.46 and 3.41 (2 s, each 3 H, 2 OCH3), 3.19 (d, 1 H,
H-4), 3.09 (d, 1 H, H-2), 1.15 (s, 3 H CH3), 1.14 (d,
3 H, CH3). Anal. Calcd for C16H24O5: C, 64.84; H,
8.16. Found: C, 64.90; H, 8.05.
Methyl 6-deoxy-2,3-O-isopropylidene-a-l-lyxo-
hexopyran-4-uloside (5).ÐTo a solution of methyl
6-deoxy-2,3-O-isopropylidene-ꢀ-l-mannopyrano-
side (1.0 g, 4.6 mmol) in dry CH2Cl2 (50 mL) was
added
23 mmol), and the mixture was stirred for 3.5 h at
pyridinium
chlorochromate
(5.0 g,
room temperature. Conventional work-up (see 2)

I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
253
yielded pure 5 (0.92 g, 91%), isolated as a colour-
less syrup; [ꢀ]d 35.8ꢀ (c 0.77); IR: 1740 cm
was added dropwise tri¯ic anhydride (210 mL,
1.24 mmol) at 70 C, and the mixture was stirred
1
ꢀ
1
(C=O); H NMR: ꢂ 4.85 (s, 1 H, H-1), 4.44 (s, 2
H, H-2,3), 4.26 (d, 1 H, J5,Me(6) 7 Hz, H-5), 3.47 (s,
3 H, OCH3), 1.49 and 1.37 (2 s, each 3 H, Ip CH3),
1.41 (d, 3 H, CH3). Anal. Calcd for C10H16O6: C,
55.54; H, 7.46. Found: C, 55.03; H, 7.18.
for 90 min. After work-up via extractions and puri-
®cation on a short column of silica (9:1 hexane±
EtOAc) pure 8 was obtained as a colourless syrup
(304 mg, 88%); [ꢀ]d 17.8ꢀ (c 0.95); H NMR: ꢂ
1
4.94 (s, 1 H, H-1), 4.35 (s, 1 H, H-4), 4.03 (d, 1 H,
J5,Me(6) 6 Hz, H-5), 3.78 (s, 1 H, H-2), 3.40 (s, 3 H,
OCH3), 1.55 and1.40 (2 s, each 3 H, Ip CH3), 1.50
(s, 3 H, CH3), 1.38 (d, 3 H, CH3). Anal. Calcd for
C12H19F3O7S: C, 39.56; H, 5.26. Found: C, 39.16;
H, 5.02.
Methyl 6-deoxy-2,3-O-isopropylidene-3-C-methyl-
a-l-lyxo-hexopyran-4-uloside (6).ÐA solution of
BuLi (15% in hexane; 2.1 mL, 4.8 mmol) was
ꢀ
added dropwise at 40 C under Ar to a solution
of diisopropylamine (672 mL, 4.8 mmol) in dry
THF (50 mL). The light-yellow mixture was stirred
for 20 min at 40 ꢀC, then cooled to 78 ꢀC, and a
solution of 5 (0.91 g, 4.2 mmol) in dry THF (5 mL)
was added dropwise. After stirring for 1 h at
Methyl 4,6-dideoxy-2,3-O-isopropylidene-3-C-
methyl-a-l-erythro-hex-4-enopyranoside (9).ÐTo
the solution of 8 (300 mg, 0.82 mmol) in dry DMF
(5 mL) was added NaN3 (150 mg, 2.46 mmol) and
dicyclohexyl-18-crown-6 (10 mg, 0.03 mmol), and
the mixture was stirred for 6 h at room tempera-
ture. The mixture was then poured into 0.1 M HCl
(10 mL), extracted with Et2O (2Â20 mL), and the
combined organic layer was washed with water
until neutral, dried, and concentrated. Chromato-
graphy (95:5 hexane±EtOAc) of the residue yielded
9 (150 mg, 87%), isolated as a colourless oil; [ꢀ]d
18.3ꢀ (c 0.65); 1H NMR: ꢂ 5.02 (d, 1 H, J1,2 2 Hz,
H-1), 4.60 (s, 1 H, H-4), 3.81 (d, 1 H, H-2), 3.45 (s,
3 H, OCH3), 1.80, 1.48, 1.42, and 1.43 (4 s, each 3
H, 4 CH3). Anal. Calcd for C11H19O4: C, 61.37; H,
8.90. Found: C, 60.56; H, 8.92.
ꢀ
78 C, hexamethylphosphoric triamide (1.1 mL)
and CH3I (2.2 mL, 34 mmol) was added, and the
mixture was allowed to warm up to room tem-
perature. Then, an aqueous solution of NH4Cl
(10%, 12 mL) was added, the mixture was diluted
with CH2Cl2 (200 mL), the organic layer was
washed with water, dried, and concentrated. The
residue was chromatographed (8:2 hexane±EtOAc)
to yield pure 6 (800 mg, 83%), isolated as a col-
ourless syrup; [ꢀ]d 65.8ꢀ (c 0.38); IR: 1740 cm
1
(C=O); 1H NMR: ꢂ 4.92 (d, 1 H, J1,2 1.3 Hz, H-1),
4.34 (d, 1 H, J5,Me(6) 6.8 Hz, H-5), 4.07 (d, 1 H, H-
2), 350 (s, 3 H, OCH3), 1.49 and 1.37 (2 s, each 3
H, Ip CH3), 1.43 (s, 3 H, CH3), 1.41 (d, 3 H, CH3).
Anal. Calcd for C11H18O5: C, 57.38; H, 7.88.
Found: C, 56.96; H, 7.70.
Methyl 6-deoxy-2,3-O-isopropylidene-3-C-methyl-
a
a-l-lyxo-hexopyran-4-uloside-oxime (10).ÐTo
solution of 6 (5.8 g, 25.2 mmol) in EtOH (150 mL)
was added hydroxylamine hydrochloride (8.85 g,
127.4 mmol) and Na2CO3 (15 g, 141.5 mmol), and
the mixture was stirred for 15 h at 80 ꢀC. Inorganic
salts were ®ltered o€, the ®ltrate was concentrated,
and CH2Cl2 (300 mL) was added. The organic
layer was washed with water until neutral, dried,
and concentrated to yield 10 (6.2 g, 99%) as a col-
ourless oil which was suciently pure for the next
Methyl 6-deoxy-2,3-O-isopropylidene-3-C-methyl-
a-l-talopyranoside (7).ÐTo the chilled solution of
6 (500 mg, 2.18 mmol) in MeOH (10 mL) was
added NaBH4 (150 mg, 3.9 mmol), and the mixture
was stirred for 1 h, then boiled under re¯ux for
20 min, and concentrated. CH2Cl2 (50 mL) was
added, the organic layer was washed with water
until neutral, dried, and concentrated to yield 7
(480 mg, 95%), isolated as a colourless syrup; [ꢀ]d
58.0ꢀ (c 0.35); 1H NMR: ꢂ 4.93 (s, 1 H, H-1), 3.88
(dd, 1 H, J4,5 1, J5,Me(6) 6.5 Hz, H-5), 3.75 (s, 1 H,
H-2), 3.40 (s, 3 H, OCH3), 3.17 (dd, 1 H, J4,OH
5 Hz, H-4), 2.48 (d, 1 H, OH), 1.57 and 1.38 (2 s,
each 3 H, Ip CH3), 1.42 (s, 3 H, CH3), 1.34 (d, 3 H,
CH3). Anal. Calcd for C11H20O5: C, 56.88; H, 8.68.
Found: C, 56.16; H, 8.42.
transformation; [ꢀ]d 78.0ꢀ (c 0.55); H NMR: ꢂ
1
4.72 (dd, 1 H, J5,6 5 Hz, H-5), 4.57 (s, 1 H, H-1),
3.92 (s, 1 H, H-2), 3.87 (s, 3 H, OCH3), 3.38 (s, 3
H, OCH3), 1.55 (s, 3 H, CH3), 1.53 and 1.45 (2 s,
each 3 H, Ip CH3), 1.44 (d, 3 H, CH3). Anal. Calcd
for C11H19NO5: C, 53.86; H, 7.81. Found: C,
54.16; H, 7.92.
Methyl 4-amino-4,6-dideoxy-2,3-O-isopropylidene-
3-C-methyl-a-l-mannopyranoside (12).ÐA solution
of 10 (6.0 g, 24.5 mmol) and LiAlH4 (8.83 g,
233 mmol) iꢀn 1,4-dioxane (400 mL) was stirred for
4 h at 100 C. The mixture was chilled, and the
Methyl 6-deoxy-2,3-O-isopropylidene-3-C-methyl-
4-O-tri¯uoromethanesulfonyl-a-l-talopyranoside
(8).ÐTo the solution of 7 (220 mg, 0.95 mmol) in
dry CH2Cl2 (8 mL) containing pyridine (400 mL)

254
I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
excess of hydride was decomposed by addition of
EtOAc (200 mL) and water. Then the organic layer
was washed with water until neutral, dried, and
concentrated. Chromatography (9:1 hexane±
EtOAc) of the residue yielded 12 (2.27 g, 41%),
isolated as a syrup. The corresponding l-talo iso-
mer was isolated in 38% yield; [ꢀ]d 40.1ꢀ (C
0.99); 1H NMR: ꢂ 4.87 (d, 1 H, J1,2 1 Hz, H-1), 3.79
(d, 1 H, H-2), 3.51 (dd, 1 H, J4,5 10, J5,Me(6) 6.5 Hz,
H-5), 3.38 (s, 3 H, OCH3), 2.84 (d, 1 H, H-4), 1.51
and 1.37 (2 s, each 3 H, Ip CH3), 1.31 (s, 3 H,
CH3). Anal. Calcd for C11H21NO4: C, 57.12; H,
9.15; N, 6.05. Found: C 57.10; H, 9.00; N, 5.95.
Methyl 4,6-dideoxy-4-formamido-2,3-O-isopropy-
lidene-3-C-methyl-a-l-mannopyranoside (13).ÐTo
a solution of 12 (880 mg, 3.8 mmol) in MeOH
(20 mL) was added acetic±formic anhydride (3 mL,
35.6 mmol) and the mixture was stirred for 30 min,
then concentrated. Chromatography (8:2 hexane±
acetone) of the residue gave 13 (980 mg, 99%),
graphed (9:1 CH2Cl2±MeOH) to yield syrupy 15
(208 mg, 84%); [ꢀ]d 11.41ꢀ (c 0.60); H NMR: ꢂ
1
8.35 and 8.05 (2 s, 1 H, CHO), 7.2±7.3 (m, 5 H,
Ph), 5.40 (bs, 1 H, OH), 4.64 and 4.62 (2 s, 1 H, H-
1), 4.0 (dd, 1 H, J4,5 10, J5,Me(6) 6 Hz, H-5), 3.57
and 3.52 (2 s, 1 H, H-2), 3.30 (s, 3 H, OCH3), 2.90
(d, 1 H, H-4), 1.40 and 1.39 (2 s, 3 H, CH3), 1.25 (s,
1 H, OH), 0.80 (d, 3 H, CH3). Anal. Calcd for
C16H23NO5: C, 62.12; H, 7.49. Found: C, 62.16; H,
7.52.
Methyl 4-N-benzylformamido-4,6-dideoxy-3-C-
methyl-2-O-methyl-a-l-mannopyranoside (16).ÐTo
a solution of 15 (200 mg, 0.65 mmol) in dry DMF
(10 mL) was added NaH (29 mg, 0.98 mmol), and
the mixture was stirred at room temperature for
40 min, then chilled, and CH3I (52 mL, 0.85 mmol)
was injected. After 15 min, MeOH (0.5 mL) was
added, the mixture was concentrated, and the resi-
due was chromatographed (7:3 hexane±acetone) to
yield 16 (169 mg, 80%), isolated as a syrup; [ꢀ]d
isolated as a syrup; [ꢀ]d 76.0ꢀ (c 0.72); H NMR:
32.01ꢀ (c 0.87); H NMR: ꢂ 8.40 and 8.15 (2 s, 1
1
1
ꢂ 8.18 and 7.98 (2 d, 1 H, CHO), 7.22 and 6.70 (2 m,
1 H, NH), 4.64 and 4.54 (2 d, 1 H, J1,2 1 Hz, H-1),
3.05 and 3.04 (2 d, 1 H, J4,5 10 Hz, H-4), 3.75 and
3.65 (2 dd, 1 H, J5,Me(6) 6 Hz, H-5), 3.43 (d, 1 H, H-
2), 3.30 and 3.28 (2 s, 3 H, OCH3), 1.49 and 1.40 (2
s, each 3 H, Ip CH3), 1.23 and 1.22 (2 s, 3 H, CH3),
1.19 and 1.17 (2 d, 3 H, CH3). Anal. Calcd for
C12H21NO5: C, 55.58; H, 8.16. Found: C, 55.04; H,
8.01.
Methyl 4-N-benzylformamido-4,6-dideoxy-2,3-
O-isopropylidene-3-C-methyl-a-l-mannopyranoside
(14).ÐA solution of 13 (980 mg, 1.77 mmol), ben-
zyl bromide (1 mL, 3.9 mmol) and powdered KOH
(2 g) in dry DMF (20 mL) was stirred for 1.5 h at
room temperature. Then the mixture was diluted
with EtOAc (200 mL), washed with water until
neutral, dried, and concentrated. Chromatography
(8:2 hexane±EtOAc) of the residue yielded 14
(1.0 g, 75%), isolated as a syrup; [ꢀ]d 2.9ꢀ (c 0.6);
1H NMR: ꢂ 8.2 and 8.05 (2 d, 1 H, CHO), 7.3±7.2
(m, 5 H, Ph), 4.64 and 4.59 (2 s, 1 H, H-1), 4.08
(dd, J4,5 10, J5,6 6 Hz, H-5), 3.58 and 3.51 (2 s, 1 H,
H-2), 332 (s, 3 H, OCH3), 2.91 (d, 1 H, H-4), 1.41
and 1.40 (2 s, 3 H, CH3), 0.85 (d, 3 H, CH3). Anal.
Calcd for C19H27NO5: C, 65.31; H, 7.79. Found: C,
64.90; H, 7.80.
H, CHO), 7.20±7.40 (m, 5 H, Ph), 4.50 (d, 1 H, J1,2
1 Hz, H-1), 4.00 (dd, 1 H, J4,5 10, J5,Me(6) 6 Hz, H-
5), 3.50 and 3.48 (2 s, 3 H, OCH3), 3.37 and 3.34 (2
s, 3 H, OCH3), 3.10 and 3.03 (2 d, 1 H, H-2), 2.58
(bs, 1 H, OH), 1.41 and 1.32 (2 s, 3 H, CH3), 0.77
(d, 3 H, CH3). Anal. Calcd for C17H27NO5: C,
63.14; H, 7.79. Found: C, 63.06; H, 7.90.
Methyl 3-O-benzyl-4-N-benzylformamido-4,6-
dideoxy-3-C-methyl-2-O-methyl-a-l-mannopyrano-
side (17).ÐTo a solution of 16 (1.56 g, 4.8 mmol) in
dry DMF (70 mL) was added NaH (300 mg,
9.6 mmol), and the mixture was stirred for 2 h at
room temperature. Benzyl bromide (1.5 mL,
6.2 mmol) was added and the mixture was stirred
for 3 h. After processing (see 16) pure 17 (1.0 g,
50%) was isolated as a colourless glass; [ꢀ]d 48.0ꢀ
(c 0.35); 1H NMR: ꢂ 8.32 and 8.15 (2 s, 1 H, CHO),
7.20 and 7.43 (2 m, 10 H, 2 Ph), 4.91 and 4.05 (2
dd, 1 H, J4,5 11, J5,Me(6) 6 Hz, H-5), 4.72 and 4.70
(2 d, 1 H, J1,2 1 Hz, H-1), 4.50 and 4.42 (2 d, each 1
H, PhCH2), 4.49 (s, 2 H, PhCH2), 3.47 and 3.45 (2
s, 3 H, OCH3), 3.41 (d, 1 H, H-2), 3.37 and 3.50 (2
s, 3 H, OCH3), 3.21 (d, 1 H, H-4), 1.60 and 1.45 (2
s, 3 H, CH3), 0.78 (d, 3 H, CH3). Anal. Calcd for
C24H31NO5: C, 69.71; H, 7.56. Found: C, 70.06; H,
7.82.
Methyl 4-N-benzylformamido-4,6-dideoxy-3-C-
methyl-a-l-mannopyranoside (15).ÐCompound 14
(280 mg, 0.8 mmol) was dissolved in aq 70% HOAc
(20 mL) and the solution was kept for 4 h at 80 ꢀC,
then concentrated. The residue was chromato-
1-O-Acetyl-3-O-benzyl-4-N-benzylformamido-
4,6-dideoxy-3-C-methyl-2-O-methyl-a-l-mannopyra-
nose (18).ÐTo
a
solution of 17 (300 mg,
0.72 mmol) in Ac2O (2 mL) was added H2SO4 in
Ac2O (4%, 2 mL), and the mixture was stirred for

I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
255
30 min at room temperature. The solution was
poured into ice-cold aq NaHCO3, extracted with
CH2Cl2 (20 mL), and the organic layer was sepa-
rated, dried, and concentrated. Chromatography
(97:3 CH2Cl2-EtOAc) of the residue yielded syrupy
18 (221 mg, 70%); [ꢀ]d 28.0ꢀ (c 0.55); 1H NMR: ꢂ
8.32 and 8.13 (2 s, 1 H, CHO), 7.20±7.50 (m, 10 H,
Ph), 6.12 and 6.20 (2 d, 1 H, J1,2 1 Hz, H-1), 5.08
and 4.20 (2 dd, 1 H, J4,5 10, J5,Me(6) 6 Hz, H-5),
4.50 (d, 1 H, H-2), 4.50-4.43 (m, 4 H, PhCH2), 3.52
and 3.51 (2 s, 3 H, OCH3), 3.32 (d, 1 H, H-4), 2.10
and 2.12 (2 s, 3 H, Ac), 1.52 and 1.60 (2 s, 3 H,
CH3), 0.75 (d, 3 H, CH3). Anal. Calcd for
C25H31NO6: C 68.01; H, 7.08. Found: C, 67.76; H,
7.02.
5.78 (s, 1 H, H-1), 4.38 (d, 1 H, J2,3 5 Hz, H-2), 4.3
(m, 3 H, H-3,4,5), 3.50 (m, 2 H, H-6a,6b), 2.90 (s, 1
H, OH), 2.45 (s, 3 H, p-Ts CH3), 1.55 and 1.42 (2 s,
each 3 H, Ip CH3); 13C NMR: ꢂ 115.66 (acetalic
C), 94.71 (C-1), 67.63 (C-6), 25.1 and 26.82 (2 Ip
CH3), 20.32 (p-Ts CH3). Anal. Calcd for
C22H25NO10S: C, 57.01; H, 5.44. Found: C, 56.96;
H, 5.12.
p-Nitrophenyl 6-deoxy-6-iodo-2,3-O-isopropy-
lidene-a-d-mannopyranoside (22).ÐA solution of
21 (580 mg, 1.2 mmol) and NaI (4 g, 24 mmol) in
ꢀ
dry DMF (10 mL) was kept for 5 h at 100 C, then
cooled, diluted with CH2Cl2 (200 mL), extracted
with water, and concentrated. Chromatography
(7:3 hexane±EtOAc) of the residue a€orded 22
(380 mg, 73%), isolated as a syrup; [ꢀ]d +85.3ꢀ (c
0.36); 1H NMR: ꢂ 8.22 and 7.20 (2 m, each 2 H, p-
subst. Ph), 5.90 (d, 1 H, J1,2 1 Hz, H- 1), 4.42 (dd, 1
H, J2,3 6 Hz, H-2), 4.32 (dd, 1 H, J3,4 7 Hz, H-3),
3.50 (ni, 2 H, H-5,6a), 3.31 (dd, 1 H, J5,6a 7, J6a,6b
11 Hz, H-6b), 3.12 (ddd, 1 H, J4,5 7, J4,OH 2 Hz, H-
4), 2.05 (s, 1 H, OH), 1.60 and 1.42 (2 s, each 3 H,
Ip CH3); 13C NMR: ꢂ 116.82 (acetalic C), 96.17 (C-
1), 26.2 and 27.95 (2 Ip CH3), 5.11 (C-6). Anal.
Calcd for C15H18INO7: C, 39.93; H, 4.02. Found:
C, 40.16; H, 3.92.
3-O-Benzyl-4-N-benzylformamido-4,6-dideoxy-3-
C-methyl-2-O-methyl-a-l-mannopyranosyl trichloro-
acetimidate (20).ÐTo a solution of 18 (100 mg,
0.23 mmol) in dry DMF (5 mL) was added hydra-
zine acetate (30 mg, 0.3 mmol), and the solution
was kept for 30 min at 50 ꢀC. Then, EtOAc (20 mL)
was added, and the organic layer was washed with
water, dried, and concentrated to give 19 (80 mg,
87%) which was used without puri®cation ([ꢀ]d
+33.2ꢀ (c 0.29)). A solution of the foregoing
material (80 mg, 0.2 mmol), trichloroacetonitrile
(190 mL, 1.9 mmol) and DBU (50 mL, 0.34 mmol)
in dry CH2Cl2 (5 mL) was stirred for 10 min at
room temperature, then concentrated. The resi-
due was chromatographed (7:3 hexane±acetone
+1% Et3N) to yield 20 (100 mg, 91%; 6:4, E:Z)
p-Nitrophenyl 6-deoxy-2,3-O-isopropylidene-a-
d-mannopyranoside (23).ÐTo a solution of 22
(380 mg, 0.84 mmol) in dry THF (15 mL) was
added LiAlH4 (96 mg, 2.5 mmol), and the mixture
was stirred for 20 h at room temperature. The
excess of hydride was decomposed by addition of
EtOAc (100 mL) and water, and the organic layer
was washed with water until neutral, dried, con-
centrated. Chromatography (7:3 CH2Cl2±acetone)
of the residue yielded 23 (144 mg, 53%), isolated as
ꢀ
1
as a syrup; [ꢀ]d 21.3 (c 0.42); H NMR: ꢂ 8.68
and 8.56 (2 s, 1 H, NH), 8.34 and 8.13 (2 s, 1 H,
CHO), 7.20±7.50 (m, 10 H, Ph), 6.35 and 6.29 (2
d, 1 H, J1,2 2 Hz, H-1), 5.17 and 4.29 (2 dd, 1 H,
J4,5 10, J5,Me(6) 6 Hz, H-5), 4.50 (bs, 4 H, PhCH2),
3.72 and 3.65 (2 bs, 1 H, H-2), 3.56 and 3.54 (2 s,
3 H, OCH3), 3.30 (d, 1 H, H-4), 1.60 (s, 3 H,
CH3), 0.79 (d, 3 H, CH3). Anal. Calcd for
C25H29C13N2O5: C, 55.21; H, 5.38. Found: C,
55.16; H, 5.12.
a syrup; [ꢀ]d + 115.4ꢀ (c 0.24); H NMR: ꢂ 8.20
1
and 7.28 (2 m, each 2 H, p-subst. Ph), 5.82 (d, 1 H,
J1,2 1 Hz, H-1), 4.45 (dd, 1 H, J2,3 6, J3,4 6.5 Hz, H-
3), 4.39 (dd, 1 H, H-2), 3.75 (dd, 1 H, J4,5 9.5,
J5,Me(6) 6 Hz, H-5), 3.40 (dd, 1 H, H-4), 1.55 and
1.40 (2 s, each 3 H, Ip CH3), 1.21 (d, 1 H, CH3).
Anal. Calcd for C15H19NO7: C, 55.38; H, 5.89.
Found: C, 55.16; H, 5.92.
p-Nitrophenyl 4-O-benzyl-6-deoxy-2,3-O-iso-
propylidene-a-d-mannopyranoside (24).ÐTo a chil-
led solution of 23 (140 mg, 0.43 mmol) and benzyl
bromide (67 mL, 0.56 mmol) in DMF (10 mL) was
added KOH ꢀ(2.5 g), and the mixture was stirred for
40 min at 0 C. EtOAc (100 mL) was added, and
the organic layer was washed with water until
neutral, dried, and concentrated. Chromatography
p-Nitrophenyl 2,3-O-isopropylidene-6-O-p-tol-
uenesulfonyl-a-d-mannopyranoside (21).Ðp-Tolue-
nesulfonyl chloride (290 mg, 1.5 mmol) was added
to a solution of p-nitrophenyl 2,3-O-isopropy-
lidene-ꢀ-d-mannopyranoside (100 mg, 0.3 mmol) in
dry pyridine (8 mL), and the solution was kept for
1.5 h at 60 ꢀC. After concentration, chromato-
graphy (7:3 hexane±acetone) of the residue yielded
21 (96 mg, 70%), isolated as a syrup; [ꢀ]d +52.6ꢀ
1
(c 0.63); H NMR: ꢂ 8.15 and 7.10 (2 m, each 2 H,
p-subst. Ph), 7.70 and 7.32 (2 m, each 2 H, p-Ts),

256
I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
(95:5 hexane±EtOAc) of the residue yielded 24
(133 mg, 75%), isolated as a syrup; [ꢀ]d +121ꢀ (c
0.17); 1H NMR: ꢂ 8.19 and 7.13 (2 m, each 2 H, p-
subst. Ph), 7.32 (m, 5 H, Ph), 5.79 (d, 1 H, J1,2
1 Hz, H-1), 4.92 and 4.66 (2 d, each 1 H, PhCH2),
4.45 (t, 1 H, J2,3 6, J3,4 6 Hz, H-3), 4.38 (dd, 1 H,
H-2), 3.72 (dd, 1 H, J4,5 9.5, J5,Me(6) 6 Hz, H-5),
3.31 (dd, 1 H, H-4), 1.56 and 1.42 (2 s, each 3 H, Ip
CH3), 1.22 (d, 1 H, CH3). Anal. Calcd for
C22H25NO7: C, 63.60; H, 6.07. Found: C, 63.46; H,
6.22.
p-Nitrophenyl 4-O-benzyl-6-deoxy-a-d-manno-
pyranoside (25).ÐTo a solution of 24 (500 mg,
1.2 mmol) in CH2Cl2 (10 mL) were added
CF3CO2H (1 mL) and water (0.5 mL), and the
mixture was stirred vigorously for 10 min at room
temperature. After concentration, ¯ash chromato-
graphy (7:3 hexane±EtOAc) of the residue gave 25
(405 mg, 90%), isolated as a syrup; [ꢀ]d +105.2ꢀ (c
0.58); 1H NMR: ꢂ 8.20 and 7.28 (2 m, each 2 H, p-
subst. Ph), 7.32 (m, 5 H, Ph), 5.90 (d, 1 H, J1,2
1 Hz, H-1), 4.91 and 4.60 (2 d, each 1 H, CH2Ph),
5.2 and 3.2 (2 s, each 1 H, OH). Anal. Calcd for
C19H21NO7: C, 60.79; H, 5.64. Found: C, 61.0; H,
5.88.
p-Nitrophenyl 4-O-benzyl-6-deoxy-2-O-methyl-
a-d-mannopyranoside (26).ÐA mixture of 25
(200 mg, 0.53 mmol), Bu4NBr (300 mg), and CH3I
(3 mL, 9.3 mmol) in CH2Cl2 (10 mL) and aq 20%
NaOH (6 mL) was stirred vigorously overnight.
The organic layer was separated, washed with
water, concentrated, and the residue was chroma-
tographed (7:3 hexane±EtOAꢀc) to yield 26 (186 mg,
90%) as a syrup; [ꢀ]d +118.0 (c 0.15); 1H NMR: ꢂ
8.20 and 7.30 (2 m, each 2 H, p-subst. Ph), 7.32 (m,
5 H, Ph), 5.85 (d, 1 H, J1,2 2 Hz, H-1), 5.21 (d, 1 H,
JOH,3 7 Hz, OH), 4.88 and 4.58 (2 d, each 1 H,
PhCH2), 3.95 (m, 1 H, J2,3 3.5, J3,4 9 Hz, H-3), 3.58
(dd, 1 H, H-2), 3.47 (dd, 1 H, J5,6 6, J4,5 9.5 Hz, H-
5), 3.46 (s, 3 H, OCH3), 3.30 (t, 1 H, H-4), 1.1 (d, 3
H, CH3). Anal. Calcd for C20H23NO7: C, 61.69; H,
5.95. Found: C, 61.50; H, 5.92.
quenched with pyridine (0.5 mL). Then the mixture
was diluted with CH2Cl2 (20 mL), ®ltered, and
concentrated. Chromatography (7:3 hexane±
EtOAc) of the residue yielded ꢀ27 (20 mg, 35%),
13C NMR data (500 and 125 MHz, respectively)
are presented in Table 1. ``a'' and ``b'' denote the
two isomers present due to the formamido group.
Anal. Calcd for C43H50N2O11: C, 66.99; H, 6.54;
N, 3.64. Found: C, 66.85, H, 6.48, N, 3.65.
1
isolated as a syrup; [ꢀ]d +52.9 (c 1.03). H and
p-Tri¯uoroacetamidophenyl (4-formamido-4,6-
dideoxy-3-C-methyl-2-O-methyl-a-l-mannopyrano-
syl)-(1!3)-6-deoxy-2-O-methyl-a-d-mannopyrano-
side (29).ÐCompound 27 (15 mg, 0.03 mmol) in
EtOAc (10 mL) was treated with H2 in the presence
of Adam's catalyst (PtO2, 10 mg) for 2 h at room
temperature. Pyridine (200 mL) and tri¯uoroacetic
anhydride (150 mL) were added, and the mixture
was stirred for an additional 1 h. After ®ltration,
the ®ltrate was concentrated and the residue was
chromatographed (7:3 hexane±EtOAc) to yield 28
(11 mg). A mixture of 28 (11 mg) and Pd(OH)2
(40 mg) in MeOH (5 mL) was stirred vigorously
under H2 overnight. After ®ltration and con-
centration, the residue was puri®ed on a short col-
umn of silica gel (98:2 CH2Cl2±MeOH) to yield 29
(4 mg, 24%) as a glass; [ꢀ]d 4.52ꢀ (c 0.24; MeOH).
1H and 13C NMR data (recorded in CD3OD at 500
and 125 MHz, respectively) are presented in Table 2.
Ethyl (3-O-benzyl-4-N-benzylformamido-4,6-
dideoxy-3-C-methyl-2-O-methyl-a-l-mannopyrano-
syl)-(1!3)-4-O-benzyl-6-deoxy-2-O-methyl-1-thio-
a-d-mannopyranoside (31).ÐA mixture of ethyl 4-
O-benzyl-6-deoxy-2-O-methyl-1-thio-ꢀ-d-manno-
pyranoside (30) (23 mg, 0.074 mmol), 20 (50 mg,
0.09 mmol) and 4 A molecular sieves (100 mg) ꢀin
dry CH2Cl2 (3 mL) was stirred for 30 min ꢀat 0 C
under Ar. The mixture was cooled to 30 C, and
TMSOTf (17 mL, 0.3 equiv.) in CH2Cl2 (1 mL) was
injected. After 15 min, pyridine (500 mL) was
added, and the mixture was diluted with CH2Cl2,
®ltered, and the ®ltrate was concentrated. Chro-
matography (7:3 hexane±EtOAc) of the residue
gave 31 (38 mg, 75%), isolated as a syrup; [ꢀ]d
p-Nitrophenyl (3-O-benzyl-4-N-benzylformamido-
4,6-dideoxy-3-C-methyl-2-O-methyl-a-l-mannopy-
ranosyl)-(1!3)-4-O-benzyl-6-deoxy-2-O-methyl-a-
d-mannopyranoside (27).ÐA mixture of 26 (29 mg,
0.074 mmol) and 20 (50 mg, 0.09 mmol) in dry
CH2Cl2 (5 mL), containing 4 A molecular sieves
ꢀ
1
+56.8 (c 0.37). H and 13C NMR data (500 and
125 MHz, respectively) are presented in Table 1.
``a'' and ``b'' denote the two isomers present due to
the formamido group. Anal. Calcd for C39H51
NO8S: C, 67.50; H, 7.41. Found: C, 67.42; H, 7.23.
p-Nitrophenyl (3-O-benzyl-4-N-benzylformamido-
4,6-dideoxy-3-C-methyl-2-O-methyl-a-l-mannopy-
ranosyl)-(1!3)-(4-O-benzyl-6-deoxy-2-O-methyl-a-
ꢀ
(100 mg) was stirred for 30 min at 0 C under Ar,
ꢀ
then cooled to 30 C. A solution of TMSOTf
(17 mL, 0.3 equiv.), in dry CH2Cl2 (1 mL) was
injected and after 15 min the reaction was

I. Bajza et al./Carbohydrate Research 308 (1998) 247±258
257
d-mannopyranosyl)-(1!3)-(4-O-benzyl-2-O-methyl-
a-l-fucopyranosyl)-(1!3)-(2,4-di-O-benzyl-6-deoxy-
a-l-mannopyranosyl)-(1!2)-3,4-O-endo-benzylidene-
a-l-talopyranoside (33).ÐA mixture of 31 (30 mg,
0.046 mmol), 32 [12] (48 mg, 0.074 mmol) and 4 A
molecular sieves (100 mg) in dry CH2Cl2 (5 mL)
was stirred for 30 min at 0 ꢀC, then cooled to 40 ꢀC.
A solution of NIS (14 mg, 0.055 mmol) and TfOH
(0.6 mL, 0.005 mmol) in CH2Cl2 (1 mL) was added
dropꢀwise and the mixture was allowed to warm up
to 0 C. After 40 min the mixture was diluted with
CH2Cl2 (20 mL), extracted with aq Na2S2O3 (10 mL)
and aq NaHCO3 (10 mL), and the organic layer was
dried and concentrated. The residue was chromato-
graphed (8:2 hexane±EtOAc) to yield 33 (40 mg,
55%), isolated as a syrup; [ꢀ]d 23.2 (c 0.19); H
and 13C NMR data (500 and 125 MHz, respec-
tively) are given in Table 3. Anal. Calcd for C90H104
N2O23: C, 68.34; H, 6.63. Found: C, 68.12; H, 6.58.
p-Tri¯uoroacetamidophenyl (4-formamido-4,6-
dideoxy-3-C-methyl-2-O-methyl-a-l-mannopyrano-
syl)-(1!3)-(6-deoxy-2-O-methyl-a-d-mannopyrano-
syl)-(1!3)-(2-O-methyl-a-l-fucopyranosyl)-(1!3)-
(6-deoxy-a-l-mannopyranosyl)-(1!2)-a-l-talopyr-
anoside (35).ÐA solution of 33 (35 mg, 0.02 mmol)
in EtOAc (10 mL) was stirred vigorously under H2
in the presence of Adam's catalyst (PtO2, 10 mg)
for 2 h at room temperature. Pyridine (200 mL) and
tri¯uoroacetic anhydride (150 mL) were added, and
the mixture was stirred for an additional 1 h. After
®ltration and concentration of the ®ltrate, resulting
34 (16 mg) was dissolved in MeOH (10 mL), and
Pd(OH)2 (50 mg) was added. The mixture was stir-
red vigorously under H2 overnight, then ®ltrated
followed by concentration of the ®ltrate. The resi-
due was puri®ed on a column of silica (98:2
CH2Cl2±MeOH) to yield pure 35 (5 mg, 25%), iso-
Liptak is also acknowledged. The purchase of the
DRX 500 NMR spectrometer used in this study
was supported by OMFB Mec-93-0098, Phare-
Accord H-9112-0198 and OTKA A084.
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Acknowledgements
This work was supported in part by an Interna-
tional Research Scholar's award from the Howard
Hughes Medical Institute. Support from the Hun-
garian Science Fund (OTKA F 019482) to I. Bajza,
(OTKA T 014982 and OTKA D 23749) to K.E.
Kover, from the Ministry of Education (FKFP
0500/1997) to K.E. Kover, and from the Hun-
garian Academy of Sciences (AKP96-121) to A.
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