Stereocontrolled palladium(0)-catalyzed preparation of unsaturated azidosugars: An easy access to 2- and 4-aminoglycosides

Article abstract of DOI:10.1016/j.tet.2005.06.041

The palladium-catalyzed substitution of alkyl 4,6-di-O-acetyl-α-d- erythro-hex-2-eno-pyranosides using NaN₃ as the nucleophile gave predominantly the corresponding alkyl 2-azido-2,3,4-trideoxy-α-d-threo- hex-2-enopyranosides in the presence of

Full text of DOI:10.1016/j.tet.2005.06.041

Tetrahedron 61 (2005) 8271–8281
Stereocontrolled palladium(0)-catalyzed preparation of
unsaturated azidosugars: an easy access to 2- and 4-aminoglycosides
b,
Ronaldo N. de Oliveira,a,b Louis Cottier,a Denis Sinoua, and Rajendra M. Srivastava
*
*
a
` ´ ´
Laboratoire de Synthese Asymetrique, UMR 5181, ESCPE Lyon, Universite Claude Bernard Lyon 1, 43 boulevard du 11 Novembre 1918,
69662 Villeurbanne Cedex, France
bDepartamento de Quimica Fundamental, Universidade Federal de Pernambuco, Cidade Universitaria, 50740-540 Recife, PE, Brazil
Received 26 April 2005; revised 7 June 2005; accepted 8 June 2005
Available online 1 July 2005
Abstract—The palladium-catalyzed substitution of alkyl 4,6-di-O-acetyl-a-D-erythro-hex-2-eno-pyranosides using NaN3 as the nucleophile
gave predominantly the corresponding alkyl 2-azido-2,3,4-trideoxy-a-D-threo-hex-2-enopyranosides in the presence of Pd(PPh3)4. However,
alkyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-erythro-hex-2-enopyranosides were obtained as the major products using Pd(PPh3)4 as the
catalyst in the presence of dppb as the added ligand. Conversely, alkyl 6-O-(tert-butyldimethylsilyl)-4-O-methoxycarbonyl-2,3-dideoxy-a-D-
hex-2-enopyranosides gave exclusively alkyl 4-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-trideoxy-a-D-erythro-hex-2-enopyranosides in
the presence of Pd2(dba)3/PPh3 as the catalyst and Me3SiN3 as the nucleophile. The bis-hydroxylation followed by hydrogenation of
ethyl 4-azido-2,3,4-trideoxy-a-D-erythro-hex-2-enopyranoside afforded the corresponding 4-amino-a-D-mannopyranoside, when propyl
2-azido-2,3,4-trideoxy-a-D-threo-hex-3-enopyranoside gave the 2-amino-a-D-altropyranoside under the same conditions.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
In connection with our interest on the valorisation of
unsaturated carbohydrates as starting materials for the
synthesis of biologically active compounds, and particularly
the metal-catalyzed functionalization of these unsaturated
compounds,44–55 we expected that the azido group could be
introduced stereospecifically at position 4 of 2,3-unsaturated
substrates under very mild conditions using a palladium-
catalyzed reaction. Secondary and tertiary amines have
already been introduced on this position under palladium-
catalysis.56,57 Palladium-catalyzed azidation of allylic esters
has also been investigated using sodium azide58,59 or
trimethylsilyl azide as the nucleophile.60–62 These unsaturated
4-azido-2,3-dideoxyhexopyranosides would be valuable start-
ing materials for the synthesis of 4-amino-2,3-dideoxyhexo-
pyranosides or various 4-aminohexopyranosides.
Various aminosugars are present in nature.1,2 They also repre-
sent an important class of carbohydrate units, some of them
being found in numerous oligosaccharides and glycoconju-
gates.3–14 For instance 4-aminosugars are major structural
elements in some compounds exhibiting very important
biological properties such as pyranmycin,15,16 acarbose,17–20
apramycin,21 apicamycin,22 aebramycin,21,23,24 and trehalo-
samine derivatives.25–28
Due to the very large spectrum of their possible applications
in chemistry, biochemistry, medicine, as well as pharma-
ceutical fields,3,15,16,29–34 extensive studies have thus been
performed towards the synthesis of these aminosugars.
In this paper, we described the methodologies used for
the introduction of the azido function at C-4 and C-2 on
2,3-dideoxyhex-2-enopyranosides and the transformation of
the latter to some aminosugars.
One of the most convenient routes to aminosugars is the
introduction on the appropriate carbohydrate of a nitrogen
substituent via the use of a tethered nitrogen nucleophile.35
The amino group was most often introduced and masked via
a nucleophilic displacement of halides or sulfonates as an
azido group, which was finally converted into the amino
group at the end of the synthesis.15,16,36–43
2. Results and discussion
The starting alkyl 2,3-dideoxy-a-D-erythro-hex-2-eno-
pyranosides 1a–c were prepared via a Ferrier reaction of
3,4,6-tri-O-acetyl-D-glucal with the corresponding alcohol
(Scheme 1).63,64 Deacetylation of unsaturated carbohydrates
Keywords: Palladium catalyst; Azidation; Alkyl azidohexenopyranoside;
Amino carbohydrate.
*
Corresponding authors. Tel.: C33 4 72448183; fax: C33 4 78898914;
e-mail: sinou@univ-lyon1.fr
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.06.041

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R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
Scheme 1. Reagents and conditions: i: cat. MeONa, MeOH; ii: tert-BuMe2SiCl, imidazole, DMF, 0 8C; iii: CH3OCOCl, pyridine, DMAP, CH2Cl2, 0 8C; iv:
PPh3, ClCH2CO2H, diethyl azodicarboxylate, toluene, then cat. MeONa, MeOH.
`
1a–c with sodium methoxide in methanol (Zemplen pro-
results summarized in Table 1 showed that azidation occurred
in 72–78% yields after column chromatography, affording a
mixture of three unsaturated azides 7–9 a–c in a quite similar
ratio whatever the aglycon present; however, the expected
4-azidocompound7wastheminoroneand2-azidocompound
9 was the major product (Table 1, entries 1–3). Even
performing the azidation reaction in the presence of
Pd(PPh3)4 and 5 equiv of PPh3 gave practically the same
results (Table 1, entries 4 and 5). Fortunately, substitution
of PPh3 by the chelating bidentate ligand dppb [or 1,4-
bis(diphenylphosphino)butane] (2 equiv of ligand per palla-
dium) resulted in a very highly regio-and stereoselectivity, the
expected unsaturated azide 7 being obtained with chemical
yields up to 92%, the two other allylic azides 8 and 9 being
observed as traces (Table 1, entries 6–8). It is noteworthy that
adding more dppb (Table 1, entry 9) gave the same ratio of
isomers 7c–9c, although the catalyst seemed more sluggish.
The same behaviour was observed using Pd2(dba)3 and 4 dppb
as the catalyst (Table 1, entry 10).
cedure65) afforded quantitatively the corresponding unsatur-
ated diols 2a–c. The regioselective monoprotection of the
primary hydroxyl function of compounds 2a–c with
TBDMSCl gave the corresponding monosilylated unsatur-
ated derivatives 3a–c in quite good yields (Scheme 1).
Reaction of compounds 3a–c with methyl chloroformate in
the presence of pyridine afforded the corresponding
unsaturated carbonates 4a–c. The threo derivative 6 was
obtained from the erythro derivative 3a in a two-step
sequence, involving an inversion of configuration at C-4 via
a Mitsunobu reaction using chloroacetic acid in presence of
triphenylphosphine and diethyl azodicarboxylate, followed
by saponification with sodium methoxide in methyl alcohol,
and subsequent treatment with methylchloroformate in the
presence of pyridine.
The azidation of unsaturated carbohydrates 1a–c was first
examined in detail using Pd(PPh3)4 as the catalyst and sodium
azide as the nucleophile as a typical example (Scheme 2), the
reaction being performed in a THF/H2O mixture at 50 8C. The
The formation of these three isomers could be rationalized
Scheme 2.

R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
8273
Table 1. Palladium-catalyzed azidation of carbohydrates 1a–c using NaN3 as the nucleophile
Entry
Carbohydrate
Catalyst
Time (h)
Yield (%)a
Ratio 7:8:9b
1
2
3
4
5
6
7
8
9
10
1a
1b
1c
1a
1b
1a
1b
1c
1c
1a
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4C5 PPh3
Pd(PPh3)4C5 PPh3
Pd(PPh3)4C2 dppb
Pd(PPh3)4C2 dppb
Pd(PPh3)4C2 dppb
Pd(PPh3)4C4 dppb
Pd2(dba)3C4 dppb
1
1
1
2
2
1
1
1
1
2
76
72
78
69
68
70
69
72
46
45
14:32:54
15:32:53
14:36:50
14:30:56
19:29:52
91:2:7
92:4:4
86:8:6
76:13:11
84:11:5
a Calculated on the mixture of compounds 7–9 after column chromatography.
1
b Determined by H NMR on the mixture.
according to Scheme 2. The first step is the oxidative
addition of the unsaturated carbohydrate 1 to Pd(0) species
giving the (p-allyl)palladium intermediate A with inversion
of configuration at the allylic carbon. The attack of N3K
occurs trans to the palladium on the p-allyl complex A at
C-4 only, the C-2 position being crowded by the aglycon
moiety, affording allylic azide 7. However, this p-allyl
palladium complex A could be in equilibrium with the
p-allyl palladium complex B formed by the attack of the
palladium species on complex A. The attack of the azide ion
on complex B afforded the two unsaturated azides 8 and 9
with inversion of configuration; the formation of azide 9 as
the major product is probably due also to steric hindrance at
C-4, the position at C-2 being less crowded. Another
possibility is the isomerization of the allylic azides in the
presence of Pd(PPh3)4. In order to underline this isomeriza-
tion, the three allylic azides 7a, 8a, and 9a were treated
separately under similar reaction conditions (THF/H2O) in
the presence of Pd(PPh3)4 at 50 8C for 1 h. Compound 7a
gave a 94:3:3 mixture of 7a, 8a, and 9a, compound 8a a
11:67:22 mixture of 7a, 8a, and 9a, and compound 9a a
18:30:52 mixture of 7a, 8a, and 9a. Isomerization
effectively occurred, but it seems that this reaction is
slow. It is to be noticed that the thermal isomerization of
allylic azide 9a under the same conditions but without added
Pd(PPh3)4 does not occur, only 3% of compound 8a being
formed; however, heating the mixture at 70 8C for 14 h
increased the amount of 8a to 26%. The difference observed
using PPh3 or dppb as the ligand, quite similar to the results
of Murahashi and coll.58 could be related to the bulkiness of
the palladium catalyst, which prevents the attack of the free
palladium complex on the p-allyl palladium intermediate A.
We then examined the azidation of alkyl 6-O-(tert-
butyldimethylsilyl)-4-O-methoxycarbonyl-2,3-dideoxy-a-
D-hex-2-enopyranosides (4a–c) using Me3SiN3 as the
nucleophile in the presence of Pd2dba3 or tris(dibenzyl-
ideneacetone)dipalladium and PPh3 in THF at 50 8C
(Scheme 3). Starting from unsaturated carbohydrate 4a,
the highest conversion and chemical yield were obtained
using 10% Pd and a ratio [PPh3]/[Pd]Z4, with a chemical
yield up to 73% for 10a after column chromatography
(Table 2, entries 1–3). Using these optimised conditions, the
unsaturated carbohydrates 4b and 4c gave the corresponding
unsaturated azides 10b and 10c in 69 and 71% chemical
yields, respectively. It is to be noticed that the sole for-
mation of the azide 10 was observed under these conditions;
this could be due probably to the use of the more reactive
allylic carbonate instead of the acetate, avoiding the
presence of any palladium(0) complex in solution.66 The
retention of configuration resulted from an exo attack of
the nucleophile at the C-4 of the p-allyl palladium
complex C.
The structures of compounds 7–10 were assigned on the
basis of their 1H and 13C NMR spectral analysis. The vicinal
coupling constants J4,5Z9.4–10.0 Hz observed for the
hydrogen atom H-4 for compounds 7a–c and 10a–c
Scheme 3.

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R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
Table 2. Palladium-catalyzed azidation of carbohydrates 4a–c using Me3SiN3 as the nucleophile
Entry
Carbohydrate
% Pd
[PPh3]/[Pd]
Time (h)
Conversion of 4 (%)a
Yield of 10 (%)b
1
2
3
4
5
4a
4a
4a
4b
4c
5
5
10
10
10
2/1
4/1
4/1
4/1
4/1
24
5
2
2
2
40
80
100
100
100
15
54
73
69
71
a Determined by 1H NMR on the crude product.
b Chemical yield of pure product 10 after column chromatography.
indicated a trans diaxial relationship between H-4 and H-5,
proving the erythro configuration. Conversely, the signal
for the same proton H-4 in compounds 8a–c appeared at
dZ3.35–3.36 ppm, with a coupling constant J4,5Z1.5–
2.3 Hz, characteristic for a cis relationship between H-4 and
H-5, and therefore, a threo configuration for 8. We noticed
also that the H-4 signal for erythro compounds 7a–c and
10a–c appeared at higher d values than that of the analogous
hydrogen atom for threo compounds 8a–b (DdZ0.53 ppm),
owing to the respective axial and equatorial orientation of
H-4. The 13C NMR spectra, and particularly the chemical
shift of the anomeric carbon, also gave some informations.
These signals appeared at d 99.2, 99.3 and 97.3 ppm for
compounds 9a, 9b, 9c, respectively, compared to 94.2, 94.4
and 92.8 ppm for compounds 8a, 8b, and 8c; this is
characteristic for a 3,4-insaturation versus a 2,3-insaturation
in enopyranose chemistry.56 In addition, a very weak J1,2
coupling constant observed for compounds 8a–c is also in
agreement with 2,3-enopyranosides having the a-D-threo
configuration.56 Further, spectral data for compounds 8 and
9 are in agreement with those published for quite similar
structures.42
observed.67 The 1H an 13C NMR spectra are in good
agreement with the proposed structures. Coupling constants
J5,4Z9.8 and 1.4 Hz are observed for compounds 13 and 14,
respectively, characteristic of a trans and a cis relationship
for H-4 and H-5. The IR spectra showed two amide bands
(1640, 1570 cmK1) next to C]O vibration (1730 cmK1), as
well as a OH band (3300 cmK1). Furthermore, the 1H NMR
spectra showed only one proton for the NHAc signal as a
doublet (d 5.48 and 6.27 ppm for 13 and 14, respectively).
Reduction of unsaturated 2-azido-3,4-dideoxy-a-D-threo-
pyranoside 9b gave quantitatively the 2-amino-2,3,4-a-D-
threo-pyranoside 15 that was transformed into the acet-
amido and toluenesulfonamido derivatives 16 and 17
(Scheme 3). The configuration of toluenesulfonamido
derivative 17 was confirmed by NMR. The H-2 signal
appeared as a dd with coupling constants J2,3eqZJ2,3ax
Z
3.0 Hz, and J2,1Z0 Hz, suggesting that H-2 is equatorial.
Moreover, the relation between H-2 and NH was clearly
showed using a H,H COSY spectrum, when a H,H NOESY
experiment showed a NOE contact due to a syn relationship,
between NH and H-1, H-3eq and H-4ax.
In order to confirm unambiguously the assigned configura-
tions, azidocarbohydrates 7a, 8b, and 9b, were transformed
to the corresponding saturated amines 13, 14, and 15
(Scheme 4). Reduction of 4-azido-a-D-hex-2-enopyrano-
sides 7a and 8b, having, respectively, the erythro and threo
configuration, with hydrogen in the presence of palladium
on charcoal gave the corresponding saturated compounds 13
and 14 bearing a 4-acetamido group in quite good chemical
yields. Such O/N migration of an acetate during
hydrogenation in carbohydrate chemistry has already been
We finally, turned our attention to the palladium-catalyzed
reaction of ethyl 6-O-(tert-butyldimethylsilyl)-4-O-
methoxycarbonyl-2,3-dideoxy-a-D-threo-hex-2-enopyrano-
side (6) with Me3SiN3 under the above optimized conditions
(Scheme 3). A 40:60 mixture of 4-azido-2,3,4-trideoxy-a-D-
threo-hex-2-enopyranoside 11 and 2-azido-2,3,4-trideoxy-
a-D-threo-hex-2-enopyranoside 12 was obtained in 76%
chemical yield. The structures of compounds 11 and 12
1
were assigned from the H and 13C NMR spectra of the
mixture, which showed some similarities with the spectra of
Scheme 4. Reagents and conditions: i: H2 (1 bar), Pd/C, CH3OH; ii: Ac2O, pyridine, 0 8C; iii: TsCl, pyridine, CH2Cl2, 0 8C.

R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
8275
Scheme 5. Reagents and conditions: i: cat. OsO4, NMO, acetone/water, rt; ii: Ac2O, pyridine; iii: H2, Pd/C, CH3CO2Et.
compounds 8a and 9a, respectively. However, since these
two compounds 11 and 12 could not be separated, the
mixture was desilylated using n-Bu4NF$3H20 in THF, and
the resulting mixture was acetylated using (CH3CO)2O in
C5H5N to give in 77% global yield a mixture of two
compounds, whose characteristics, after separation, are
similar to those of compounds 8a and 9a. The formation of
these two regioisomers having the threo configuration
resulted from the attack of the nucleophile at the two
termini C-4 and C-2 of the p-allyl complex D; such
behaviour has already been observed in palladium-catalyzed
alkylation starting from the threo derivative.49
H-5 and H-3, which should be expected if the bis-
hydroxylation occurred on the other side of the double bond.
3. Conclusion
In conclusion, the palladium-catalyzed substitution of allylic
acetate or carbonate derivatives of alkyl a-D-erythro-hex-2-
enopyranosides is a useful methodology for the preparation
of unsaturated 4-azido or 2-azidopyranosides. The selectiv-
ity of the palladium-catalyzed substitution is dependent on
the nature of the catalyst used and the leaving group at C-4
of the carbohydrate. Alkyl 4,6-di-O-acetyl-a-D-erythro-hex-
2-eno-pyranosides gave predominantly alkyl 2-azido-2,3,4-
trideoxy-a-Dthreo-hex-2-enopyranosides in the presence of
Pd(PPh3)4, when alkyl 6-O-acetyl-4-azido-2,3,4-trideoxy-
a-D-erythro-hex-2-enopyranosides were obtained as the
major products in the presence of dppb as the added ligand.
Conversely, alkyl 6-O-(tert-butyldimethylsilyl)-4-O-
methoxycarbonyl-2,3-dideoxy-a-D-hex-2-enopyranosides
gave exclusively alkyl 4-azido-6-O-(tert-butyldimethyl-
silyl)-2,3,4-trideoxy-a-D-erythro-hex-2-enopyranosides in
the presence of Pd(0)/PPh3 as the catalyst. These readily
accessible 2- or 4-azido unsaturated carbohydrates are key
intermediates for the preparation of aminocarbohydrates.
For example, the bishydroxylation of ethyl 4-azido-2,3,4-
trideoxy-a-D-erythro-hex-2-enopyranoside 10a afforded
4-amino-a-D-mannopyranoside 19, when propyl 2-azido-
2,3,4-trideoxy-a-D-threo-hex-3-enopyranoside 9b gave the
corresponding 2-amino-a-D-altropyranoside 21 under the
same conditions.
Ethyl 4-azido-a-D-erythro-hex-2-enopyranosides 7a and
10a were subjected to the bis-hydroxylation reaction in
the presence of a catalytic amount of OsO4, followed by
acetylation of the obtained mixture (Scheme 5). As expected
ethyl 4-azido-4-deoxy-a-D-mannopyranosides 18a and 18b
were obtained in 91 and 85% chemical yield, respectively,
as the unique products. These compounds resulted from the
bishydroxylation on the less hindered side of the double
bond, as expected from preceding results in this field.68,69
The assigned configurations are mainly based on the
coupling constant J4,5Z10.3, 10.6 Hz, and J3,4Z9.9,
10.6 Hz (d 3.82 and 3.88 ppm, respectively, for H-4) for
18a and 18b, characteristics of an axial–axial disposition for
H-3, H-4 and H-5. Moreover reduction of the azido
derivative 18b with molecular hydrogen in the presence of
Pd/C afforded ethyl 4-amino-4-deoxy-a-D-mannopyrano-
side 19 in 87% yield, characterized again by the axial–axial
couplings J4,5ZJ3,4Z10.5 Hz.
Bis-hydroxylation of propyl 2-azido-2,3,4-trideoxy-a-D-
threo-hex-3-enopyranoside 9b under the same conditions
gave, after acetylation, the unique propyl 3,4,6-tri-O-acetyl-
2-azido-2-deoxy-a-D-altropyranoside (20) in 77% yield,
which was reduced in 80% yield to the corresponding
triacetylated 2-aminoaltropyranoside 21 (Scheme 5). The
bis-hydroxylation occurred again on the less hindered side
of the double bond of the azido carbohydrate 9b. The altrose
configuration is consistent with the NMR data. The coupling
constant J4,5Z8.1 Hz for H-4 at d 5.24 ppm is in agreement
with an axial–axial disposition of H-4 and H-5. Moreover, a
H,H NOESY experiment showed no NOE contact between
4. Experimental
Melting points were determined on a Buchi melting point
apparatus and are uncorrected. Optical rotations were
measured on a Perkin Elmer Model 241 polarimeter. The
IR spectra were obtained on a Perkin Elmer Model 681. 1H
(300 MHz) and 13C NMR (75.5 MHz) spectra were
recorded on a Brucker AM 300 spectrometer; chemical
shifts are reported with reference to SiMe4 or CDCl3 as an
internal standard. Exact mass spectra were recorded on a
Finnigan Mat 95 XL spectrometer. Thin layer chromato-
graphy (TLC) was carried out on plates coated with silica

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R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
gel (60 F-254), and column chromatography on Silica gel 60
or Silica Florisil Merck, the ratio of solvents being measured
in volume.
4.2. General procedure for the preparation of alkyl 6-O-
(tert-butyldimethylsilyl)-4-O-methoxycarbonyl-2,3-
dideoxy-a-D-hex-2-enopyranoside (4a–c)
Alkyl 4,6-di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-eno-
pyranosides (1a–c) and alkyl 2,3-dideoxy-a-D-erythro-hex-
2-enopyranosides (2a–c) have been prepared according to
literature procedures.53,64,70,71
To a solution of unsaturated carbohydrate 3 (1.2 mmol) in
CH2Cl2 (10 mL) maintained at 0 8C was added pyridine,
(200 mg, 2.4 mmol), DMAP (50 mg), and methyl chloro-
formate (227 mg, 2.4 mmol). After being stirred at rt for
24 h, the solution was diluted with water (5 mL) and
extracted with CH2Cl2 (3!15 mL). Evaporation of the
solvent followed by column chromatography gave the
corresponding carbonate 4 as an oil.
4.1. General procedure for the preparation of alkyl 6-O-
(tert-butyldimethylsilyl)-2,3-dideoxy-a-D-erythro-hex-2-
enopyranosides (3a–c)
4.2.1. Ethyl 6-O-(tert-butyldimethylsilyl)-4-O-methoxy-
carbonyl-2,3-dideoxy-a-D-erythro-hex-2-enopyranoside
(4a). Yield 74%; oil; RfZ0.8 (CHCl3); [a]2D0 C91 (c 1.1,
To a solution of unsaturated carbohydrate 2 (1 mmol)
and imidazole (75 mg, 1.1 mmol) in DMF (4 mL) main-
tained at 0 8C was slowly added tert-butyldimethylsilyl
chloride (166 mg, 1.1 mmol). The solution was stirred at
rt until TLC showed no more starting material. After
addition of water (15 mL), and extraction with ether (3!
15 mL), the organic layer was dried. After evaporation of
the solvent under reduced pressure, the residue was puri-
fied by column chromatography using petroleum ether/
EtOAc (9:1) as the eluent to give the corresponding alkyl 6-
O-(tert-butyldimethylsilyl)-2,3-dideoxy-a-D-erythro-hex-2-
enopyranoside 3.
CH2Cl2); IR: 1750, 1270 cmK1 1H NMR (300 MHz,
;
CDCl3): d 0.01 (s, 6H, SiMe2), 0.8 (s, 9H, CMe3), 1.12 (t,
3H, CH3CH2, JZ7.2 Hz), 3.49 (dq, 1H, OCH2CH3, JZ9.7,
7.0 Hz), 3.73 (s, 3H, CH3O), 3.68–3.75 (m, 2H, H-6, H-60),
3.79 (dq, 1H, OCH2CH3, JZ9.4, 7.1 Hz), 3.89 (ddd, 1H,
H-5, JZ9.7, 4.3, 3.0 Hz), 4.96 (br s, 1H, H-1), 5.10 (br dd,
1H, H-4, JZ9.4, 1.4 Hz), 5.77 (ddd, 1H, H-2, JZ10.2, 2.6,
2.6 Hz), 5.89 (br d, 1H, H-3, JZ10.2 Hz); 13C NMR
(75.5 MHz, CDCl3): d K5.1, 15.6, 18.8, 26.3, 55.3, 63.0,
64.4, 69.5, 94.4, 128.7, 129.1, 155.6. Anal. Calcd for
C16H30O6Si: C, 55.46; H, 8.73. Found: C, 55.68; H, 8.56.
4.1.1. Ethyl 6-O-(tert-butyldimethylsilyl)-2,3-dideoxy-a-
D-erythro-hex-2-enopyranoside (3a). Yield 83%; oil; RfZ
0.4 (CHCl3); [a]D20 C23 (c 1.0, CH2Cl2) [lit.72C22.1 (c 1.0,
CH2Cl2)]; the 1H and 13C NMR data are in agreement with
the literature.72
4.2.2. Propyl 6-O-(tert-butyldimethylsilyl)-4-O-methoxy-
carbonyl-2,3-dideoxy-a-D-erythro-hex-2-enopyranoside
(4b). Yield 79%; oil; RfZ0.7 (CHCl3); [a]2D0 C92 (c 1.0,
CH2Cl2); IR: 1750, 1270 cmK1 1H NMR (300 MHz,
;
CDCl3): d K0.01 (s, 6H, SiMe2), 0.84 (s, 9H, CMe3),
1.16 (t, 3H, CH2CH3, JZ7.1 Hz), 1.55 (m, 2H, CH2CH3),
3.38 (dt, 1H, OCH2CH2, JZ13.1, 6.6 Hz), 3.48 (dt, 1H,
OCH2CH2, JZ13.1, 7.0 Hz), 3.71 (s, 3H, OCH3), 3.62–3.82
(m, 2H, H-6, H-60), 3.88 (m, 1H, H-5), 4.94 (br s, 1H, H-1),
5.08 (br d, 1H, H-4, JZ9.4 Hz), 5.75 (ddd, 1H, H-2, JZ
10.2, 2.6, 2.3 Hz), 5.87 (br d, 1H, H-3, JZ10.2 Hz); 13C
NMR (75.5 MHz, CDCl3): d K5.2, 10.9, 18.6, 23.2, 26.2,
55.0, 62.9, 64.1, 69.3, 69.4, 94.2, 128.6, 128.9, 155.4. Anal.
Calcd for C17H32O6Si: C, 56.64; H, 8.95. Found: C, 57.00;
H, 9.28.
4.1.2. Propyl 6-O-(tert-butyldimethylsilyl)-2,3-dideoxy-
a-D-erythro-hex-2-enopyranoside (3b). Yield 84%; oil;
RfZ0.4 (CHCl3); [a]2D0 C25 (c 1.5 CH2Cl2). IR: 3500,
1080 cmK1 1H NMR (300 MHz, CDCl3):d K0.01 (s,
;
6H, SiMe2), 0.80 (s, 9H, CMe3), 1.51 (m, 2H,
CH2CH3), 2.80 (d, 1H, OH, JZ4.3 Hz), 3.33 (dt, 1H,
OCH2CH2, JZ9.4, 6.6 Hz), 3.55–3.72 0(m, 3H,
OCH2CH2, H-5, H-6), 3.79 (dd, 1H, H-6 , JZ9.8,
5.1 Hz), 4.04 (ddd, 1H, H-4, JZ6.3, 4.3, 2.0 Hz), 4.82
(br s, 1H, H-1), 5.59 (ddd, 1H, H-2, JZ10.2, 2.5,
2.0 Hz), 5.80 (br d, 1H, H-3, JZ10.2 Hz); 13C NMR
(75.5 MHz, CDCl3): d K5.1, 10.9, 18.5, 23.2, 26.2,
64.5, 65.6, 70.4, 71.6, 94.3, 126.2, 133.5. Anal. Calcd
for C15H30O4Si: C, 59.56; H, 10.0. Found: C, 59.15; H,
10.39.
4.2.3. Cyclohexyl 6-O-(tert-butyldimethylsilyl)-4-O-
methoxycarbonyl-2,3-dideoxy-a-D-erythro-hex-2-eno-
pyranoside (4c). Yield 69%; oil; RfZ0.7 (CHCl3); [a]D20
C88 (c 1.0, CH2Cl2); IR: 1750, 1270 cmK1 1H NMR
;
(300 MHz, CDCl3): d K0.1 (s, 6H, SiMe2), 0.91 (s, 9H,
CMe3), 1.20–1.90 (m, 10H, 5!CH2), 3.80 (s, 3H, OCH3),
3.60–3.90 (m, 3H, C5H10CHO, H-6, H-60), 4.02 (ddd, 1H,
H-5, JZ9.4, 4.3, 3.2 Hz), 5.16 (dd, 1H, H-4, JZ9.4,
1.7 Hz), 5.19 (br s, 1H, H-1), 5.82 (ddd, 1H, H-2, JZ10.1,
2.5, 1.7 Hz), 5.95 (br d, 1H, H-3, JZ10.1 Hz); 13C NMR
(75.5 MHz, CDCl3): d K5.1, 18.8, 24.6, 24.8, 26.0, 26.3,
32.3, 34.1, 55.3, 63.2, 69.4, 69.6, 76.3, 92.6, 128.8, 129.3,
155.6. Anal. Calcd for C20H36O6Si: C, 59.97; H, 9.06.
Found: C, 60.31; H, 9.49.
4.1.3. Cyclohexyl 6-O-(tert-butyldimethylsilyl)-2,3-
dideoxy-a-D-erythro-hex-2-enopyranoside (3c). Yield
80%; oil; RfZ0.5 (CHCl3); [a]2D0 C31 (c 1.0, CHCl3); IR:
3450, 1060 cmK1; 1H NMR (300 MHz, CDCl3): d K0.1 (s,
6H, SiMe2), 0.81 (s, 9H, CMe3), 1.27–1.80 (m, 10H, 5!
CH2), 2.70 (d, 1H, OH, JZ4.3 Hz), 3.50 (m, 1H,
C5H10CHO), 3.65–3.78 (m, 3H, H-5, H-6, H-60), 4.01 (m,
1H, H-5), 4.98 (br s, 1H, H-1), 5.60 (ddd, 1H, H-2, JZ10.2,
2.6, 2.2 Hz), 5.80 (br d, 1H, H-3, JZ10.2 Hz); 13C NMR
(75.5 MHz, CDCl3): d K5.1, 18.6, 24.0, 24.6, 26.0, 26.2,
34.1, 34.3, 65.7, 67.4, 70.5, 76.5, 92.8, 127.0, 132.8. Anal.
Calcd for C18H34O4Si: C, 63.11; H, 10.00. Found: C, 62.93;
H, 10.02.
4.2.4. Ethyl 6-O-(tert-butyldimethylsilyl)-4-O-methoxy-
carbonyl-2,3-dideoxy-a-D-threo-hex-2-enopyranoside (6).
Toasolutionofunsaturatedcarbohydrate3a(1.3 g,4.8 mmol)
in toluene (2.5 mL) was added triphenylphosphine (2.5 g,

R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
8277
9.6 mmol) and chloroacetic acid (0.9 g, 9.6 mmol). After
being stirred for 30 min at rt, diethyl azodicarboxylate
(1.7 g, 9.6 mmol) was added and the solution was stirred for
24 h. The solution was filtered, then washed with hexane
(10!5 mL) and concentrated. The resulting oil was
dissolved in methanol (30 mL) and treated with a catalytic
amount of sodium methanolate. After 2 h, the solution was
concentrated, the oil was dissolved in CH2Cl2 (30 mL) and
the solution washed with a 0.1 N aqueous solution of
ammonium chloride (10 mL). Evaporation of the solvent
under reduced pressure gave the threo derivative 5 (950 mg,
73% yield) as an oil, whose characteristics were in
agreement with the literature.13 Following the procedure
described for 4, the carbonate 6 was obtained (750 mg, 48%
from 3a) as an oil. RfZ0.6 (eluent hexane/ethyl acetate 9:1);
[a]D20 K148 (c 1, CH2Cl2); IR: 1750, 1270 cmK1; 1H NMR
(300 MHz, CDCl3): d K0.06 (s, 3H, SiMe), K0.01 (s, 3H,
SiMe), 0.82 (s, 9H, CMe3), 1.17 (t, 3H, CH3CH2, JZ
7.2 Hz), 3.48 (dq,1H, OCH2CH3, JZ9.6, 7.2 Hz), 3.65–3.75
(m, 2H, H-6, H-60), 3.71 (s, 3H, OCH3), 3.79 (dq,1H,
OCH2CH3, JZ9.6, 7.2 Hz), 4.13 (ddd, 1H, H-5, JZ6.9, 6.6,
2.3 Hz), 4.82 (dd, 1H, H-4, JZ5.5, 2.3 Hz), 4.98 (d, 1H,
H-1, JZ3.0 Hz), 5.97 (dd, 1H, H-2, JZ10.0, 3.0 Hz), 6.13
(dd, 1H, H-3, JZ10.0, 5.5 Hz); 13C NMR (75.5 MHz,
CDCl3): d K5.3, d K5.1, 15.6, 18.5, 26.1, 55.1, 61.9, 64.2,
66.6, 69.5, 94.0, 125.3, 131.8, 155.8. Anal. Calcd for
C16H30O6Si: C, 55.46; H, 8.73. Found: C, 55.23; H, 8.75.
hex-2-enopyranoside (8a). Oil; RfZ0.6 (petroleum ether/
EtOAc 4:2); [a]D20 K255 (c 2.0, CH2Cl2); IR: 2100,
1
1745 cmK1; H NMR (300 MHz, CDCl3): d 1.25 (t, 3H,
CH3CH2, JZ7.0 Hz), 2.09 (s, 3H, CH3CO), 3.36 (dd, 1H,
H-4, JZ5.2, 1.5 Hz), 3.59 (dq, 1H, OCH2CH3, JZ9.8,
7.0 Hz), 3.84 (dq, 1H, OCH2CH3, JZ9.8, 7.0 Hz), 4.25–
4.34 (m, 3H, H-5, H-6, H-60), 5.07 (d, 1H, H-1, JZ2.8 Hz),
6.09 (dd, 1H, H-3, JZ10.1, 5.2 Hz), 6.16 (dd, 1H, H-2, JZ
10.1, 2.8 Hz); 13C NMR (75.5 MHz, CDCl3): d 15.6, 21.1,
52.8, 64.2, 64.4, 68.4, 94.2, 124.4, 131.4, 171.0. HRMS:
Calcd for C10H16O4N3 [MCH–N2]C: 214.1079. Found:
214.1080.
4.3.3. Ethyl 6-O-acetyl-2-azido-2,3,4-trideoxy-a-D-threo-
hex-3-enopyranoside (9a). Oil; RfZ0.7 (petroleum ether/
EtOAc 4:1); [a]2D0 C370 (c 0.7, CHCl3); IR: 2100,
1
1740 cmK1; H NMR (300 MHz, CDCl3): d 1.24 (t, 3H,
CH3CH2, JZ7.2 Hz), 2.09 (s, 3H, CH3CO), 3.35 (br d, 1H,
H-2, JZ4.0 Hz), 3.62 (dq, 1H, OCH2CH3, JZ9.8, 7.2 Hz),
3.82 (dq, 1H, OCH2CH3, JZ9.8, 7.0 Hz), 4.2 (d, 2H, H-6,
H-60, JZ5.1 Hz), 4.42 (m, 1H, H-5), 5.00 (br s, 1H, H-1),
5.90 (dddd, 1H, H-3, JZ10.5, 5.1, 2.1, 1.1 Hz), 6.1 (br d,
1H, H-4, JZ10.5 Hz); 13C NMR (75.5 MHz, CDCl3): d
15.0, 21.2, 55.0, 64.7, 65.6, 66.9, 99.2, 121.1, 131.3, 171.0.
HRMS: Calcd for C10H16O4N3 [MCH]C: 242.1141.
Found: 242.1142.
4.3.4. Propyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-
erythro-hex-2-enopyranoside (7b). Oil; RfZ0.7 (petro-
leum ether/EtOAc 4:1); [a]2D0 C145 (c 1.0, CH2Cl2); IR:
4.3. Palladium-catalyzed azidation using sodium azide.
General procedure
2100, 1740 cmK1 1H NMR (300 MHz, CDCl3): d 0.94
;
The catalytic system was prepared by stirring for 1 h in a
Schlenk tube under argon the palladium complex (3%) and
the corresponding ligand in tetrahydrofuran (3 mL). This
solution was added under argon to a Schlenk tube
containing the unsaturated carbohydrate 1 (1 mmol) and
sodium azide (72 mg, 1.1 mmol) in a mixture THF/water
(3 mL/2 mL). The mixture was stirred at 50 8C for 1 h, and
then extracted with ether (3!10 mL), and the combined
extracts were washed successively with 1 M HCl (30 mL),
saturated NaHCO3 (30 mL) and brine (30 mL). The organic
layer was dried over Na2SO4. Removal of the solvent under
reduced pressure gave a residue that was submitted to
column chromatography on silica gel using petroleum ether/
EtOAc as the eluent to afford the pure corresponding allyl
azide 7, 8 and 9.
(t, 3H, CH3CH2, JZ7.4 Hz), 1.62 (m, 2H, CH2CH3), 2.11
(s, 3H, CH3CO), 3.48 (dt, 1H, OCH2CH2, JZ9.4, 6.4 Hz),
3.71 (dt, 1H, OCH2CH2, JZ9.4, 6.8 Hz), 3.88 (br d, 1H,
H-4, JZ9.9 Hz), 03.94 (ddd, 1H, H-5, JZ9.9, 4.7, 2.3 Hz),
4.28 (dd, 1H, H-6 , JZ12.1, 4.7 Hz), 4.35 (dd, 1H, H-6, JZ
12.1, 2.3 Hz), 5.01 (br d, 1H, H-1, JZ1.5 Hz), 5.9 (ddd, 1H,
H-2, JZ10.3, 1.8, 1.8 Hz), 6.00 (br d, 1H, H-3, JZ
10.3 Hz); 13C NMR (75.5 MHz, CDCl3): d 11.1, 21.2, 23.3,
54.8, 63.9, 71.0, 68.1, 94.5, 128.0, 129.3, 171.1. HRMS:
Calcd for C11H18O4N3 [MCH]C: 256.1297. Found:
256.1299.
4.3.5. Propyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-
threo-hex-2-enopyranoside (8b). Oil; RfZ0.6 (petroleum
ether/EtOAc 8:2); [a]2D0 K273 (c 0.6, CH2Cl2); IR: 2100,
1
1735 cmK1; H NMR (300 MHz, CDCl3): d 0.94 (t, 3H,
4.3.1. Ethyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-erythro-
hex-2-enopyranoside (7a). Oil; RfZ0.6 (petroleum ether/
EtOAc 4:1); [a]D20 C219 (c 1.0, CH2Cl2); IR: 2100,
CH3CH2, JZ7.4 Hz), 1.64 (m, 2H, CH2CH3), 2.09 (s, 3H,
CH3CO), 3.35 (dd, 1H, H-4, JZ5.4, 1.7 Hz), 3.50 (dt, 1H,
OCH2CH2, JZ9.1, 6.4 Hz), 3.73 (dt, 1H, OCH2CH2, JZ
9.1, 6.7 Hz), 4.25–4.35 (m, 3H, H-5, H-6, H-60), 5.06 (d, 1H,
H-1, JZ2.7 Hz), 6.07 (dd, 1H, H-3, JZ10.2, 5.4 Hz), 6.17
(dd, 1H, H-2, JZ10.2, 2.7 Hz); 13C NMR (75.5 MHz,
CDCl3): d 11.0, 21.1, 23.3, 52.8, 64.2, 70.6, 68.5, 94.4,
124.3, 131.4, 170.9. HRMS: Calcd for C11H18O4N3
[MCH]C: 256.1297. Found: 256.1291.
1
1740 cmK1; H NMR (300 MHz, CDCl3): d 1.25 (t, 3H,
CH3CH2, JZ7.2 Hz), 2.11 (s, 3H, CH3CO), 3.58 (dq, 1H,
OCH2CH3, JZ9.6, 7.0 Hz), 3.80 (dq, 1H, OCH2CH3, JZ
9.6, 7.2 Hz), 3.89 (br d, 1H, H-4, JZ10.0 Hz), 3.94 (ddd,
1H, H-5, JZ10.0, 4.4, 2.4 Hz), 4.28 (dd, 1H, H-60, JZ11.9,
4.4 Hz), 4.35 (dd, 1H, H-6, JZ11.9, 2.4 Hz), 5.03 (d, 1H,
H-1, JZ2.3 Hz), 5.94 (ddd, 1H, H-2, JZ10.3, 2.3, 1.7 Hz),
6.00 (br d, 1H, H-3, JZ10.3 Hz); 13C NMR (75.5 MHz,
CDCl3): d 15.6, 21.1, 54.8, 63.8, 64.6, 68.0, 94.4, 128.0,
129.3, 171.0. Anal. Calcd for C10H15O4N3: C, 49.79; H,
6.27. Found: C, 49.99; H, 6.37.
4.3.6. Propyl 6-O-acetyl-2-azido-2,3,4-trideoxy-a-D-
threo-hex-3-enopyranoside (9b). Oil; RfZ0.7 (petroleum
ether/EtOAc 4:1); [a]2D0 C421 (c 1.0, CH2Cl2); IR: 2100,
1
1740 cmK1; H NMR (300 MHz, CDCl3): d 0.92 (t, 3H,
CH3CH2), JZ7.2 Hz), 1.60 (m, 2H, CH2CH3), 2.09 (s, 3H,
CH3CO), 3.35 (br d, 1H, H-2, JZ4.0 Hz), 3.50 (dt, 1H,
4.3.2. Ethyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-threo-

8278
R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
OCH2CH2, JZ9.6, 6.6 Hz), 3.70 (dt, 1H, OCH2CH2, JZ
9.6, 6.8 Hz), 4.24 (m, 2H, H-6, H-60), 4.42 (m, 1H, H-5),
4.98 (br s, 1H, H-1), 5.91 (dddd, 1H, H-3, JZ10.4, 4.5, 2.1,
1.1 Hz), 6.11 (br d, 1H, H-4, JZ10.4 Hz); 13C NMR
(75.5 MHz, CDCl3): d 10.9, 21.2, 23.1, 55.0, 65.6, 69.9,
70.8, 99.3, 121.1, 131.3, 171.3. Anal. Calcd for
C11H17O4N3: C, 51.76; H, 6.71. Found: C, 51.70; H, 6.85.
73%; oil; RfZ0.6 (petroleum ether/EtOAc 49:1); [a]D20
C129 (c 1.1, CH2Cl2); IR: 2100 cmK1 1H NMR
;
(300 MHz, CDCl3): d 0.00 (s, 6H, SiMe2), 0.81 (s, 9H,
CMe3), 1.13 (t, 3H, CH3CH2), JZ7.2 Hz), 3.45 (dq, 1H,
OCH2CH3, JZ9.6, 7.0 Hz), 3.64 (dq, 1H, OCH2CH3,, JZ
9.6, 3.4 Hz), 3.72–3.78 (m, 3H, H-5, H-6, H-60), 3.86 (br d,
1H, H-4, JZ9.6 Hz), 4.91 (br s, 1H, H-1), 5.80 (ddd, 1H,
H-2, JZ10.3, 2.4, 2.3 Hz), 5.88 (br d, 1H, H-3, JZ
10.3 Hz); 13C NMR (75.5 MHz, CDCl3): d K5.0, 15.6,
18.8, 26.3, 54.4, 63.3, 64.3, 70.7, 94.2, 128.7, 129.1. Anal.
Calcd for C14H27O3N3Si: C, 53.64; H, 8.68. Found: C,
53.49; H, 8.58.
4.3.7. Cyclohexyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-
erythro-hex-2-enopyranoside (7c). Oil; RfZ0.7 (pet-
roleum ether/EtOAc 4:1); [a]2D0 C139 (c 1.5, CH2Cl2);
IR: 2100, 1740 cmK1; 1H NMR (300 MHz, CDCl3): d 1.10–
1.90 (m, 10H, 5!CH2), 2.11 (s, 3H, CH3CO), 3.63 (m, 1H,
C5H10CHO), 3.87 (dd, 1H, H-4, JZ9.9, 1.4 Hz), 3.98 (ddd,
1H, H-5, JZ9.9, 5.3, 2.6 Hz), 4.29 (dd, 1H, H-60, JZ12.1,
5.3 Hz), 4.32 (dd, 1H, H-6, J6,5Z12.1, 2.6 Hz), 5.15 (br s,
1H, H-1), 5.90 (ddd, 1H, H-2, JZ10.2, 2.4, 2.0 Hz), 5.98 (br
d, 1H, H-3, JZ10.2 Hz); 13C NMR (75.5 MHz, CDCl3): d
21.2, 24.6, 24.8, 25.9, 32.5, 34.1, 54.9, 64.0, 68.0, 77.0,
93.0, 127.8, 129.9, 171.1. Anal. Calcd for C14H21O4N3: C,
56.94; H, 7.17. Found: C, 57.41; H, 7.61.
4.4.2. Propyl 4-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-
trideoxy-a-D-erythro-hex-2-enopyranoside (10b). Yield
69%; oil; RfZ0.7 (petroleum ether/EtOAc 49:1); [a]D20
C117 (c 1.5, CH2Cl2); IR: 2100 cmK1
;
1H NMR
(300 MHz, CDCl3): d 0.00 (s, 6H, Me2Si), 0.80 (t, 3H,
CH3CH2, JZ7.2 Hz), 0.82 (s, 9H, CMe3), 1.52 (m, 2H,
CH3CH2), 3.34 (dt, 1H, OCH2CH2, JZ9.4, 6.6 Hz), 3.57–
3.71 (m, 2H, OCH2CH2, H-5), 3.75 (d, 2H, H-6, H-60, JZ
4.0 Hz), 3.85 (br d, 1H, H-4, JZ9.7 Hz), 4.89 (br s, 1H, H-
1), 5.80 (ddd, 1H, H-2, JZ10.2, 2.3, 2.3 Hz), 5.87 (br d, 1H,
H-3, JZ10.2 Hz); 13C NMR (75.5 MHz, CDCl3): d K5.0,
11.0, 18.8, 23.3, 26.3, 54.5, 63.3, 70.6, 70.7, 94.4, 128.6,
129.1. Anal. Calcd for C15H29O3N3Si: C, 55.01; H, 8.93.
Found: C, 55.28; H, 9.14.
4.3.8. Cyclohexyl 6-O-acetyl-4-azido-2,3,4-trideoxy-a-D-
theo-hex-2-enopyranoside (8c). Oil; RfZ0.6 (petroleum
ether/EtOAc 4:1); [a]2D0 K207 (c 2.4, CH2Cl2); IR: 2100,
1
1740 cmK1; H NMR (300 MHz, CDCl3): d 1.3–1.9 (m,
10H, 5!CH2), 2.08 (s, 3H, CH3CO), 3.35 (dd, 1H, H-4, JZ
5.3, 2.3 Hz), 3.67 (m, 1H, C5H10CHO), 4.29 (d, 2H, H-6,
H-60, JZ5.8 Hz), 4.38 (dt, 1H, H-5, JZ5.8, 2.3 Hz), 5.21
(d, 1H, H-1, JZ2.7 Hz), 6.06 (dd, 1H, H-3, JZ10.0,
5.3 Hz), 6.15 (dd, 1H, H-2, JZ10.0, 2.7 Hz); 13C NMR
(75.5 MHz, CDCl3): d 21.1, 24.5, 24.8, 25.9, 32.5, 34.1,
52.9, 64.3, 68.4, 76.8, 92.8, 124.1, 131.9, 170.9. HRMS:
Calcd for C14H22O4N3 [MCH]C: 296.1610. Found:
296.1608.
4.4.3. Cyclohexyl 4-azido-6-O-(tert-butyldimethylsilyl)-2,
3,4-trideoxy-a-D-erythro-hex-2-enopyranoside (10c).
Yield 71%; oil; RfZ0.8 (petroleum ether/EtOAc 49:1);
[a]2D0 C105 (c 1.0, CH2Cl2); IR: 2100 cmK1 1H NMR
;
(300 MHz, CDCl3): d 0.01 (s, 6H, SiMe2), 0.82 (s, 9H,
CMe3), 1.10–1.80 (m, 10H, 5!CH2), 3.30–3.75 (m, 4H,
C5H10CHO, H-5, H-6, H-60), 3.82 (br d, 1H, H-4, JZ
9.4 Hz), 5.04 (br s, 1H, H-1), 5.77 (ddd, 1H, H-2, JZ10.0,
2.6, 2.1 Hz), 5.86 (br d, 1H, H-3, JZ10.0 Hz); 13C NMR
(75.5 MHz, CDCl3): d K5.0, 18.9, 24.6, 24.8, 26.0, 32.4,
34.2, 26.3, 54.5, 63.5, 70.6, 76.5, 92.5, 128.3, 129.7. Anal.
Calcd for C18H33O3N3Si: C, 58.82; H, 9.05. Found: C,
58.39; H, 9.32.
4.3.9. Cyclohexyl 6-O-acetyl-2-azido-2,3,4-trideoxy-a-D-
threo-hex-3-enopyranoside (9c). Oil; RfZ0.7 (petroleum
ether/EtOAc 4:1); [a]2D0 C231 (c 2.3, CH2Cl2); IR: 2100,
1
1740 cmK1; H NMR (300 MHz, CDCl3): d 1.11–1.91 (m,
10H, 5!CH2), 2.09 (s, 3H, CH3CO), 3.32 (d, 1H, H-2, JZ
5.1 Hz), 3.64 (m, 1H, C5H10CHO), 4.24 (d, 2H, H-6, H-60,
JZ4.9 Hz), 4.46 (m, 1H, H-5), 5.12 (br s, 1H, H-1), 5.89
(dddd, 1H, H-3, JZ10.3, 5.1, 2.3, 1.0 Hz), 6.10 (br d, 1H,
H-4, JZ10.3 Hz); 13C NMR (75.5 MHz, CDCl3): d 21.2,
24.3, 24.6, 25.9, 32.0, 33.7, 55.5, 65.7, 67.1, 76.5, 97.3,
121.3, 131.3, 171.3. HRMS: Calcd for C140H22O4N3
[MCH]C: 296.1610. Found: 296.1611.
4.4.4. Ethyl 4-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-
trideoxy-a-D-threo-hex-2-enopyranoside (11) and ethyl
2-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-trideoxy-a-D-
threo-hex-3-enopyranoside (12). The title compounds
were obtained as described before using Me3SiN3 as the
azido nucleophile starting from carbonate 6 (500 mg
1.4 mmol). Purification by silica gel chromatography
using petroleum ether/ethyl acetate (95:5) as the eluent
gave the regioisomeric azides 11 and 12 as a 40:60
inseparable mixture (340 mg, 76% yield), which gave,
4.4. Palladium-catalyzed azidation using trimethylsilyl
azide. General procedure
1
To a mixture of Pd2(dba)3 (45 mg, 0.05 mmol), PPh3 5%
(104 mg, 0.4 mmol), and the unsaturated carbohydrate 4
(0.1 mmol) in THF (2.5 mL) was added TMSN3 (172 mg,
1.5 mmol). The solution was stirred at 50 8C for 2 h.
Evaporation of the solvent under reduced pressure gave a
residue that was purified by column chromatography on
silica using petroleum ether/EtOAc (95:5) as the eluent to
give the corresponding allylic azides 10a–c.
however, distinct signals patterns in the H and 13C NMR
spectra. Colourless oil; RfZ0.8 (petroleum ether/EtOAc
9:1). Anal. Calcd for C14H27O3N3Si: C, 53.64; H, 8.68.
Found: C, 53.96; H, 8.89.
4.4.5. Ethyl 4-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-
trideoxy-a-D-threo-hex-2-enopyranoside (11). 1H NMR
(300 MHz, CDCl3): d K0.01 (s, 3H, SiMe), 0.01 (s, 3H,
SiMe), 0.82 (s, 9H, CMe3), 1.15 (t, 3H, CH3CH2, JZ
7.2 Hz), 3.33 (dd, 1H, H-4, JZ4.8, 2.1 Hz), 3.50–3.65 (m,
1H, OCH2CH3), 3.76–3.88 (m, 3H, OCH2CH3, H-6, H-60),
4.4.1. Ethyl 4-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-
trideoxy-a-D-erythro-hex-2-enopyranoside (10a). Yield

R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
8279
4.16 (ddd, 1H, JZ9.0, 6.8, 2.4 Hz, H-5), 4.96 (br s, 1H,
H-1), 6.08 (dm, 1H, H-3, JZ10.0 Hz), 6.13 (dd, 1H, H-2,
JZ10.0, 2.4 Hz); 13C NMR (75.5 MHz, CDCl3): d K5.0,
15.6, 18.7, 26.2, 52.7, 63.0, 64.4, 70.9, 94.2, 125.0, 131.2.
11.1, 21.3, 21.5, 23.2, 25.8, 47.9, 67.1, 67.2, 69.4, 102.0,
171.3. HRMS: Calcd for C11H22O4N [MCH]C: 232.1548.
Found: 232.1548.
4.4.10. Propyl 2-acetylamino-6-O-acetyl-2,3,4-trideoxy-
a-D-threo-hexopyranoside (16). To a solution of amino
carbohydrate 15 (75 mg, 0.32 mmol) in pyridine (1.5 mL) at
0 8C was added acetic anhydride (1 mL), and the mixture
was stirred for 13 h at rt. The solution was concentrated
under reduced pressure and the residue was purified by
chromatography on Silica Fluorisil using petroleum ether/
EtOAc (4:6) as the eluent to give 16 (78 mg, 88% yield) as a
solid; mpZ60–63 8C; RfZ0.4 (petroleum ether/EtOAc/
methanol 6:3:1); [a]2D0 C77 (c 1.0, CH2Cl2); IR: 3300,
4.4.6. Ethyl 2-azido-6-O-(tert-butyldimethylsilyl)-2,3,4-
trideoxy-a-D-threo-hex-3-enopyranoside (12). 1H NMR
(300 MHz, CDCl3): d K0.01 (s, 3H, SiMe), 0.01 (s, 3H,
SiMe), 0.82 (s, 9H, CMe3), 1.15 (t, 3H, CH3CH2, JZ
7.2 Hz), 3.27 (br d, 1H, H-2, JZ4.3 Hz), 3.50–3.65 (m, 2H,
OCH2CH3), 3.76–3.88 (m, 2H, H-6, H-60), 4.22 (m, 1H,
H-5), 4.87 (br s, 1H, H-1), 5.74 (br dd, 1H, H-3, JZ10.4,
4.3 Hz), 6.17 (br d, 1H, H-4, JZ10.4 Hz); 13C NMR
(75.5 MHz, CDCl3): d K5.0, 15.6, 18.7, 26.2, 0.82, 15.0,
21.2, 55.6, 64.1, 66.1, 69.3, 98.9, 119.3, 133.1.
1
1740, 1650, 1540 cmK1; H NMR (300 MHz, CDCl3): d
0.94 (t, 3H, CH3CH2, JZ7.4 Hz), 1.42–1.72 (m, 6H, CH2),
2.01 (s, 3H, CH3CO), 2.09 (s, 6H, CH3CO), 3.39 (dt, 1H,
OCH2CH2, JZ9.4, 6.4 Hz), 3.62 (dt, 1H, OCH2CH2, JZ
9.4, 6.6 Hz), 3.97–4.10 (m, 4H, H-6, H-60, H-5, H-2), 4.61
(br s, 1H, H-1), 6.09 (br d, 1H, NH, JZ8.5 Hz); 13C NMR
(75.5 MHz, CDCl3): d 11.0, 21.1, 23.0, 22.3, 22.7, 23.6,
46.0, 66.7, 67.0, 69.5, 98.9, 170.1, 171.2. Anal. Calcd for
C13H23O5N: C, 57.13; H, 8.48. Found: C, 57.11; H, 8.53.
4.4.7. Ethyl 4-acetylamino-2,3,4-trideoxy-a-D-erythro-
hexopyranoside (13). A solution of azide 7a (100 mg,
0.4 mmol) in methanol (10 mL) was stirred under H2 (2 bar)
for 17 h in the presence of 10% Pd–C (20 mg). The catalyst
was removed by filtration and evaporation of the solvent
under reduced pressure afforded the amino sugar 13 (79 mg,
90% yield) as a solid; mpZ119–121 8C; RfZ0.3 (petroleum
ether/EtOAc/methanol 6:3:1); [a]2D0 C108 (c 0.5, CH2Cl2);
1
IR: 3400, 1730, 1640, 1540 cmK1; H NMR (300 MHz,
4.4.11. Propyl 6-O-acetyl-2-p-toluenesulfonylamino-2,3,
4-trideoxy-a-D-threo-hexopyranoside (17). To a solution
of amino carbohydrate 15 (50 mg, 0.21 mmol) in pyridine
(1 mL) and CH2Cl2 (2 mL) at 0 8C was added p-toluene-
sulfonyl chloride (42 mg, 0.22 mmol), and the mixture was
stirred for 16 h at rt. The reaction mixture was then diluted
with water (10 mL), and extracted with dichloromethane
(2!5 mL). Evaporation of the solvent under reduced
pressure gave a residue that was purified by chromatography
on Silica Fluorisil using petroleum ether/EtOAc (7:3) as the
eluent to give 17 (58 mg, 70% yield) as an oil. RfZ0.7
(petroleum ether/EtOAc/methanol 6:3:1); [a]2D0 C38 (c 2.0,
CDCl3): d 1.21 (t, 3H, CH3CH2, JZ7.0 Hz), 1.83 (br s, 4H,
2!CH2), 2.04 (s, 3H, CH3CO), 3.39 (br d, 1H, H-5, JZ
9.8 Hz), 3.48 (dq, 1H, OCH2CH3, JZ9.8, 6.8 Hz), 3.58 (dd,
1H, H-6, JZ13.0, 1.7 Hz), 3.67 (dd, 1H, H-60, JZ13.0,
2.7 Hz), 3.73 (m, 1H, OCH2CH3), 3.95 (m, 1H, H-4), 4.89
(br s, 1H, H-1), 5.48 (d, 1H, NH, JZ7.4 Hz); 13C NMR
(75.5 MHz, CDCl3): d 16.6, 24.6, 26.2, 30.9, 46.7, 63.5,
63.9, 70.4, 97.5, 172.9. Anal. Calcd for C10H19O4N: C,
55.28; H, 8.81. Found: C, 54.79; H, 8.74.
4.4.8. Propyl 4-acetylamino-2,3,4-trideoxy-a-D-threo-
hexopyranoside (14). Reduction of 8b following the
procedure already described for the preparation of 13 gave
compound 14 in 94% yield as a solid; mpZ45–47 8C; RfZ
0.2 (petroleum ether/EtOAc/methanol 6:3:1); [a]2D01 C36 (c
0.5, CH2Cl2); IR: 3400, 1700, 1570, 1480 cmK1; H NMR
(300 MHz, CDCl3): d 0.93 (t, 3H, CH3CH2, JZ7.4 Hz),
1.50–1.80 (m, 6H, 3!CH2), 2.07 (s, 3H, CH3CO), 3.05 (br
s, 1H, OH), 3.33 (dd, 1H, H-6, JZ11.7, 8.5 Hz), 3.35 (dt,
1H, OCH2CH2, JZ13.4, 6.6 Hz), 3.52 (dd, 1H, H-60, JZ
11.7, 5.7 Hz), 3.58 (dt, 1H, OCH2CH2, JZ13.4, 7.0 Hz),
4.01 (ddd, 1H, H-5, JZ8.2, 5.9, 1.4 Hz), 4.15 (dm, 1H, H-4,
JZ7.1 Hz), 4.81 (br s, 1H, H-1), 6.27 (d, 1H, NH, JZ
7.1 Hz); 13C NMR (75.5 MHz, CDCl3): d 11.0, 23.1, 23.2,
23.6, 25.2, 44.2, 62.0, 69.4, 69.4, 96.9, 171.9. HRMS: Calcd
for C11H22O4N [MCH]C: 232.1549. Found: 232.1543.
CH2Cl2); IR: 3300, 1740 cmK1 1H NMR (500 MHz,
;
CDCl3): d 0.79 (t, 3H, CH3CH2, JZ7.4 Hz), 1.41 (m, 1H,
H-4eq), 1.49 (m, 1H, H-4ax), 1.52 (m, 2H, CH2CH3), 1.57
(m, 1H, H-3eq), 1.98 (m, 1H, H-3ax), 2.00 (s, 3H, CH3CO),
2.35 (s, 3H, CH3Ar), 3.18 (dt, 1H, OCH2CH2, JZ9.6,
6.4 Hz), 3.34 (ddd, 1H, H-2, JZ9.6, 3.0, 3.0 Hz), 3.43 (dt,
1H, OCH2CH2, JZ9.6, 6.8 Hz), 3.93 (m, 1H, H-5), 4.00
(dd, 1H, H-6, JZ11.6, 6.5 Hz), 4.04 (dd, 1H, H-60, JZ11.6,
3.6 Hz), 4.27 (br s, 1H, H-1), 5.21 (d, 1H, NH, JZ9.6 Hz),
7.23 (d, 2H, Ar, JZ8.3 Hz), 7.69 (d, 2H, Ar, JZ8.3 Hz);
13C NMR (75.5 MHz, CDCl3): d 11.0, 21.2, 22.9, 21.8, 21.9,
23.7, 50.0, 66.6, 66.9, 69.4, 98.7, 127.3, 127.4, 130.2, 138.3,
143.9, 171.3. Anal. Calcd for C18H27O6NS: C, 56.08; H,
7.06. Found: C, 55.65; H, 7.39.
4.5. General procedure for bis-hydroxylation
4.4.9. Propyl 6-O-acetyl-2-amino-2,3,4-trideoxy-a-D-
threo-hexopyranoside (15). Reduction of 9b following
the procedure already described for the preparation of 13
gave compound 15 in 97% yield; RfZ0.1 (petroleum ether/
EtOAc/methanol 6:3:1); [a]2D0 C24 (c 0.3, CH2Cl2); IR:
The unsaturated azide 7a, 9b, or 10a (1 mmol) was
dissolved in a 4:1 mixture of acetone/water (5 mL) in the
presence of a catalytic amount of osmium tetroxide (2%)
and N-methylmorpholine-N-oxide (458 mg, 4 mmol). The
mixture was stirred overnight at rt, NaHSO3 (500 mg) was
then added, and the mixture was stirred for 30 min. A
saturated aqueous solution of NaCl (10 mL) was added, and
the mixture was extracted with EtOAc (2!10 mL). The
organic layer was dried over Na2SO4. After evaporation of
the solvent under reduced pressure, the crude mixture
3400, 1740 cmK1 1H NMR (300 MHz, CDCl3): d 0.94
;
(t, 3H, CH3CH2, JZ7.4 Hz), 1.45–1.70 (m, 8H, 3!CH2,
NH2), 2.09 (s, 3H, CH3CO), 2.84 (br s, 1H, H-2), 3.39
(dt, 1H, OCH2CH2, JZ9.6, 6.4 Hz), 3.64 (dt, 1H,
OCH2CH2, JZ9.6, 7.0 Hz), 3.94–4.12 (m, 3H, H-6, H-60,
H-5), 4.58 (br s, 1H, H-1); 13C NMR (75.5 MHz, CDCl3): d

8280
R. N. de Oliveira et al. / Tetrahedron 61 (2005) 8271–8281
obtained was acetylated using Ac2O/pyridine for 1 day.
After removing the solvent under reduced pressure, the
residue was purified by column chromatography on silica
gel using petroleum ether/EtOAc (8:2) as the eluent to
afford the corresponding pure saturated azido carbohydrate.
(10% w/w of azido sugar). The catalyst was then removed
by filtration and the solvent was evaporated under reduced
pressure. The obtained residue was purified by chromato-
graphy on Silica Florisil using 4% MeOH in CH2Cl2 as the
eluent affording the corresponding amino sugar 19 and 21,
respectively.
4.5.1. Ethyl 2,3,6-tri-O-acetyl-4-azido-4-deoxy-a-D-manno-
pyranoside (18a). Yield 91%; oil; RfZ0.3 (petroleum
ether/EtOAc 4:1); [a]2D0 C101 (c 1.7, CH2Cl2); IR: 1750,
4.6.1. Ethyl 2,3-di-O-acetyl-4-amino-6-O-(tert-butyldi-
methylsilyl)-4-deoxy-a-D-mannopyranoside (19). Yield
87%; oil; RfZ0.6 (CH2Cl2/MeOH 19:1); [a]2D0 C96 (c 1,
1
2100 cmK1; H NMR (300 MHz, CDCl3): d 1.23 (t, 3H,
CH2Cl2); IR: 3400, 1740 cmK1 1H NMR (300 MHz,
;
CH3CH2), JZ7.0 Hz), 2.08 (s, 3H, CH3CO), 2.14 (s, 3H,
CH3CO), 2.15 (s, 3H, CH3CO), 3.52 (dq, 1H, OCH2CH3,
JZ9.8, 7.1 Hz), 3.72 (dq, 1H, OCH2CH3, JZ9.8, 7.1 Hz),
3.82 (dd, 1H, H-4, JZ10.3, 9.9 Hz), 3.70–3.80 (m, 1H,
H-5), 4.31 (dd, 1H, H-60, JZ12.1, 4.1 Hz), 4.37 (dd, 1H,
H-6, JZ12.1, 2.1 Hz), 4.81 (d, 1H, H-1, JZ1.7 Hz), 5.21
(dd, 1H, H-2, JZ3.2, 1.7 Hz), 5.30 (dd, 1H, H-3, JZ9.9,
3.2 Hz); 13C NMR (75.5 MHz, CDCl3): d 15.2, 21.1, 21.1,
21.2, 57.5, 63.7, 64.4, 69.0, 69.4, 70.9, 97.8, 169.9, 170.3,
171.0. Anal. Calcd for C14H21O8N3: C, 46.80; H, 5.89.
Found: C, 46.30; H, 5.92.
CDCl3): d K0.01 (s, 6H, SiMe2), 0.82 (s, 9H, CMe3),
1.11 (t, 3H, CH3CH2, JZ7.0 Hz), 1.28 (br s, 2H, NH2), 1.97
(s, 3H, CH3CO), 1.99 (s, 3H, CH3CO), 3.13 (dd, 1H, H-4,
JZ10.5, 10.5 Hz), 3.32–3.48 (m, 2H, OCH2CH3, H-5), 3.63
(dq, 1H, OCH2CH3, JZ9.6, 7.1 Hz), 3.77 (dd, 1H, H-6, JZ
11.3, 3.2 Hz), 3.83 (dd, 1H, H-60, JZ11.3, 4.3 Hz), 4.67
(d, 1H, H-1, JZ1.3 Hz), 4.98 (dd, 1H, H-3, JZ10.5,
3.2 Hz), 5.05 (dd, 1H, H-2, JZ3.2, 1.3 Hz); 13C NMR
(75.5 MHz, CDCl3): d K4.9, 15.3, 18.7, 21.2, 21.3, 26.3,
48.7, 63.6, 63.9, 69.7, 73.2, 74.4, 97.7, 170.6, 170.9. Anal.
Calcd for C18H35O7NSi: C, 53.31; H, 8.70. Found: C, 53.99;
H, 8.80.
4.5.2. Ethyl 2,3-di-O-acetyl-4-azido-6-O-(tert-butyldi-
methylsilyl)-4-deoxy-a-D-mannopyranoside (18b). Yield
85%; oil; RfZ0.6 (petroleum ether/EtOAc 9:1); [a]2D0 C108
(c 0.5, CH2Cl2); IR: 1750, 2100 cmK1; 1H NMR (300 MHz,
CDCl3): d 0.00 (s, 6H, SiMe2), 0.83 (s, 9H, CMe3), 1.09
(t, 3H, CH3CH2, JZ7.0 Hz), 1.98 (s, 3H, CH3CO), 2.01
(s, 3H, CH3CO), 3.38 (dq, 1H, OCH2CH3, JZ9.8, 7.0 Hz),
3.44 (ddd, 1H, H-5, JZ10.6, 3.4, 1.7 Hz), 3.6 (dq, 1H,
OCH2CH3, JZ9.8, 7.1 Hz), 3.71 (dd, 1H, H-60, JZ11.5,
1.7 Hz), 3.81 (dd, 1H, H-6, JZ11.5, 3.4 Hz), 3.88 (dd, 1H,
H-4, JZ10.6, 10.6 Hz), 4.68 (d, 1H, H-1, JZ1.7 Hz), 5.06
(dd, 1H, H-2, JZ3.3, 1.8 Hz), 5.17 (dd, 1H, H-3, JZ10.6,
3.4 Hz); 13C NMR (75.5 MHz, CDCl3): d K5.0, 15.2, 18.7,
21.2, 26.2, 57.0, 62.6, 63.9, 69.6, 70.9, 71.8, 97.6, 170.4,
170.1. Anal. Calcd for C18H33O7N3Si: C, 50.10; H, 7.71.
Found: C, 49.80; H, 7.69. HRMS: Calcd for C18H34O7N3Si
[MCH]C: 432.2166. Found: 432.2165.
4.6.2. Propyl 3,4,6-tri-O-acetyl-2-amino-2-deoxy-a-D-
altropyranoside (21). Yield 80%; oil; RfZ0.5 (CH2Cl2/
MeOH 19:1); [a]D20 C78 (c 1.5, CH2Cl2); IR: 3400,
1
1740 cmK1; H NMR (300 MHz, CDCl3): d 0.97 (t, 3H,
CH3CH2, JZ7.5 Hz), 1.55–1.68 (m, 4H, NH2, CH3CH2),
2.05 (s, 3H, CH3CO), 2.08 (s, 3H, CH3CO), 2.10 (s, 3H,
CH3CO), 3.24 (dd, 1H, H-2, JZ5.5, 2.8 Hz), 3.40 (dt, 1H,
OCH2CH2, JZ9.4, 6.2 Hz), 3.68 (dt, 1H, OCH2CH2, JZ
9.4, 6.8 Hz), 4.15 (dd, 1H, H-60, JZ11.3, 2.1 Hz), 4.27–4.40
(m, 2H, H-5, H-6), 4.66 (d, 1H, H-1, JZ2.8 Hz), 5.04 (1H,
H-3, JZ5.5, 3.6 Hz), 5.24 (dd, 1H, H-4, JZ8.1, 3.6 Hz);
13C NMR (75.5 MHz, CDCl3): d 11.1, 21.1, 21.2, 21.3, 23.2,
54.5, 63.1, 70.4, 66.0, 68.3, 68.8, 101.9, 170.2, 170.8, 171.1.
Anal. Calcd for C15H25O8N: C, 51.87; H, 7.25. Found: C,
52.05; H, 7.58.
4.5.3. Propyl 3,4,6-tri-O-acetyl-2-azido-2-deoxy-a-D-
altropyranoside (20). Yield 77%; oil; RfZ0.4 (petroleum
ether/EtOAc 4:1); [a]2D0 C148 (c 2.3, CH2Cl2); IR: 1740,
Acknowledgements
1
2100 cmK1; H NMR (300 MHz, CDCl3): d 0.97 (t, 3H,
We are indebted to the CAPES/COFECUB programme no.
334/01 for financial support and CNPq-Brazil for providing
a fellowship to one of us (R. N. de O.).
CH3CH2, JZ7.4 Hz), 1.64 (m, 2H, CH3CH2), 2.08 (s, 3H,
CH3CO), 2.09 (s, 3H, CH3CO), 2.11 (s, 3H, CH3CO), 3.45
(dt, 1H, OCH2CH2, JZ9.4, 6.3 Hz), 3.71 (dt, 1H,
OCH2CH2, JZ9.4, 6.7 Hz), 3.83 (dd, 1H, H-2, JZ6.6,
3.5 Hz), 4.15 (dd, 1H, H-60, JZ11.8, 2.9 Hz), 4.25 (ddd, 1H,
H-5, JZ7.0, 5.6, 2.9 Hz), 4.35 (dd, 1H, H-6, JZ11.8,
5.6 Hz), 4.76 (d, 1H, H-1, JZ3.5 Hz), 5.12 (dd, 1H, H-3,
JZ6.6, 3.6 Hz), 5.19 (dd, 1H, H-4, JZ7.0, 3.6 Hz); 13C
NMR (75.5 MHz, CDCl3): d 11.0, 21.1, 23.1, 60.6, 62.8,
70.8, 66.0, 68.3, 68.8, 99.1, 170.0, 170.3, 170.9. Anal. Calcd
for C15H23O8N3: C, 48.25; H, 6.21. Found: C, 48.41; H,
6.40.
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