Unusual addition of amines to C-2 of vinyl sulfone-modified-β-d-pent-2-enofuranosyl carbohydrates: synthesis of a new class of β-anomeric 2-amino-2,3-dideoxy-d-threo-pentofuranosides

Article abstract of DOI:10.1016/j.carres.2008.03.022

When 3-C-sulfonyl-pent-2-enofuranosides and 3-C-sulfonyl-hex-2-enofuranosides were reacted with primary and secondary amines, only the β-anomeric methoxy group of the pent-2-enofuranoside did not cause any hindrance to incoming nitrogen nucleophiles. This resulted in the 'unusual' addition of amines, in which the diastereoselectivity of the reaction was overwhelmingly in favor of amino sugars of the d-arabino configuration. Selected products were desulfonylated to obtain a new class of β-anomeric 2-amino-2,3-dideoxy-d-threo-pentofuranosides.

Full text of DOI:10.1016/j.carres.2008.03.022

Available online at www.sciencedirect.com
Carbohydrate Research 343 (2008) 1287–1296
Unusual addition of amines to C-2 of vinyl sulfone-modified-
b-D-pent-2-enofuranosyl carbohydrates: synthesis of a new class
of b-anomeric 2-amino-2,3-dideoxy-D-threo-pentofuranosides
c
b
a,
Indrajit Das,a,b Cheravakkattu G. Suresh, Jean-Luc Decout and Tanmaya Pathak
*
´
aDepartment of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India
bDe´partement de Pharmacochimie Mole´culaire, UMR 5063 CNRS/Universite´ Joseph Fourier-Grenoble I,
ICMG FR CNRS 2607, F-38041 Grenoble, France
cDivision of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
Received 18 January 2008; received in revised form 6 March 2008; accepted 13 March 2008
Available online 18 March 2008
Abstract—When 3-C-sulfonyl-pent-2-enofuranosides and 3-C-sulfonyl-hex-2-enofuranosides were reacted with primary and
secondary amines, only the b-anomeric methoxy group of the pent-2-enofuranoside did not cause any hindrance to incoming
nitrogen nucleophiles. This resulted in the ‘unusual’ addition of amines, in which the diastereoselectivity of the reaction was over-
whelmingly in favor of amino sugars of the D-arabino configuration. Selected products were desulfonylated to obtain a new class of
b-anomeric 2-amino-2,3-dideoxy-D-threo-pentofuranosides.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Vinyl sulfone-modified carbohydrates; Amino sugars; Deoxyaminosugars; Diastereoselective Michael addition; Desulfonylation with
Mg–MeOH–NiBr2
1. Introduction
specific sites. In addition, an epimeric variation in the
stereochemistry of the C–N bond might also lead to
different types of responses by a biological system.4
Since we are interested in developing new methodolo-
gies for the synthesis of aminodeoxy sugars, we treated
vinyl sulfone-modified hex-2-enopyranosides 1 and 2
(Fig. 1) with a wide range of amines. The addition of
primary amines to C-2 of both 1 and 2 exclusively pro-
duced C-2 equatorial (gluco) products. Secondary
amines on reactions with 2 produced only gluco deriva-
tives but with 1 produced mixtures containing the gluco
derivative as the major component.4d The strategy has
been implemented in the synthesis of D-lividosamine
The amino groups present in the aminoglycoside anti-
biotics and polysaccharides play an important role in
their biological activities.1–3 The most important mech-
anism of resistance to aminoglycoside antibiotics among
resistant bacteria arises from enzymatic N-acetylation,
O-phosphorylation, and O-nucleotidylation of specific
sites in the antibiotics. To avoid such deactivation pro-
cesses, several semisynthetic aminoglycoside antibiotics
have been designed where either the hydroxyl groups
undergoing enzymatic phosphorylation have been
removed and/or the amino groups susceptible to acety-
lation have been masked by acylation or alkylation.3
We therefore considered it to be of interest to design
general methodologies for the synthesis of modified
new amino sugars having one or more deoxygenated
centers and mono- or dialkylated amino groups at
O
O
O
O
Ph
Ph
O
OMe
O
OMe
PhO2S
PhO2S
1
2
*
Figure 1. Vinyl sulfone-modified hex-2-enopyranosides.
Corresponding author. E-mail: tpathak@chem.iitkgp.ernet.in
0008-6215/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2008.03.022

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I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
X
BnO
(a) for 5a
(b) for 5b-e
3
O
BnO
O
OMe
OMe
Tol(p)O2S
OMe
SO2(p)Tol
triazole
3
or
carbon
nucleophiles
5a X = amino (91%)
5b X = benzylamino (94%)a
5c X = cyclohexylamino (89%)a
5d X = pyrrolidino (96%)
5e X = morpholino (86%)a
BnO
O
aref 7
Tol(p)O2S
Scheme 1. Reagents and conditions: (a) 30% aqueous ammonia; (b)
4
neat amines, rt, 5–13 h.
Figure 2. Attack of triazole4f or carbon nucleophiles6 to C-2 of vinyl
sulfone-modified pent-2-enofuranosides.
SO2(p)Tol
X
(a) for 6a
BnO
OMe
BnO
OMe
(b) for 6b-e/e'
O
O
(2-amino-2,3-dideoxy-D-ribo-hexopyranose or ‘2-amino-
2,3-dideoxy-D-glucose’), a constituent of aminoglyco-
sides lividomycin-A, lividomycin-B, etc. Diastereoselec-
tive equatorial addition of ammonia to 1, followed by
the desulfonylation of the product at the C-3 site, pro-
duced a known intermediate for accessing D-lividos-
amine. Several partially and fully protected analogues
of D-lividosamine could be synthesized using N-mono-
4
+
SO2(p)Tol
N
O
6a X = amino (77%)
6e'
6b X = benzylamino (81%)
6c X = cyclohexylamino (80%)
6d X = pyrrolidino (86%)
6e, 6e' X = morpholino (86%) (1:1)
alkylated and N-dialkylated amines in
a similar
Scheme 2. Reagents and conditions: (a) 30% aqueous ammonia; (b)
approach.4c,d Although most of the naturally occurring
amino sugars have their C-2–N bond equatorially con-
figured, there are some amino sugars, such as kasug-
amine where the C-2–N bond is axially oriented.5
Since all of our earlier efforts to deliver primary
amines effectively and exclusively from the b-face of
the pyranose ring failed, it was necessary to develop a
methodology for the delivery of amines from the b-face
of the sugar ring. Since triazole4f and carbon nucleo-
philes6 added to 3 and 4 from a direction opposite to
the disposition of the anomeric methoxy group
(Fig. 2), we presumed that the anomeric configurations
would also influence the diastereoselctivity of addition
of amines to C-2 of 3 and 4 in a similar fashion.7
neat amines, rt, 5–13 h.
tions produced an inseparable mixture of compounds
6e/6e0 in a ratio of 1:1 (Scheme 2). It is well documented8
that the coupling constant (J1,2) values of authentic
methyl b-D-ribofuranosides and b-D-xylofuranosides
range between 0.0 and 2.0 Hz, which indicate a trans
relationship between H-1 and H-2. The coupling
constant (J1,2) values for authentic methyl b-D-arabino-
furanosides and b-D-lyxofuranosides range between 3.0
and 5.0 Hz, indicating a cis arrangement of H-1 and
H-2. Excluding the possibility of any lyxo derivative
formation for steric reasons, the coupling constant
(J1,2) values of compounds 6a–d, which range between
4.1 and 4.4 Hz, indicate the presence of the D-arabino
configuration in these compounds. Furthermore, single-
crystal X-ray diffraction studies of compounds 6c and 6d
confirm the arabino configuration, in line with the NMR
data (Figs. 3 and 4, respectively). Following the trend of
structures in the series 6a–d, the inseparable morpholino
derivatives 6e and 6e0 were assigned D-arabino and
D-xylo configurations, respectively.
2. Results and discussion
The addition of amines to the a-anomeric vinyl sulfone-
modified carbohydrate 3 afforded single diastereomeric
products 5a–e with the expected D-arabino configura-
tions (Scheme 1).7 Formation of the expected products
may be explained on the basis of the stereoelectronic
repulsion of amines by the anomeric configuration of 3.
Interestingly, vinyl sulfone 4 on reactions with 30%
aqueous ammonia, neat benzylamine, cyclohexylamine,
and pyrrolidine at ambient temperature produced single
isomers 6a–d in high yields (Scheme 2). In all these cases,
the arabino derivatives were the sole products, which
were isolated and identified unambiguously (see later).
Morpholine, on the other hand, under similar condi-
Although the a-anomeric vinyl sulfone-modified
carbohydrate 3 afforded the expected D-arabino deriva-
tive,7 in contrary to our expectations, the b-anomeric
vinyl sulfone-modified carbohydrate 4 on reactions with
amines produced amino sugars 6a–e with the D-arabino
configuration as well. In order to establish the fact
that the formation of 6a–e was indeed the result of an
‘unusual’ addition reaction, we intended to examine

I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
1289
O
O
O
X
Y
OTs
O
O
e)
c)
O
OMe
O
OH
O
7
8 X = OTs; Y = H
9 X = H; Y = p-TolS
d)
O
O
O
OMe
O
O
O
+
OMe
OH
OH
SO2Ar
11
SO2Ar
α:β = 1 : 4
10
Figure 3. ORTEP diagram of compound 6c.
f), g)
84%
f), g)
82%
O
O
O
OMe
O
O
O
OMe
ArO2S
ArO2S
13
12
Ar = p-Tol
Scheme 3. Reagents and conditions: (c) cyclohexanone, MeOH,
H2SO4, 80 °C, 2.5 h, 65%; (d) p-thiocresol, NaOMe, DMF,
110–120 °C, 4 h, 89%; (e) MMPP, MeOH, rt, 6 h, 91%; (f) MsCl, py,
0–4 °C, 24 h; (g) DBU, DCM, rt, 30 min.
known benzoyl derivative 14 was deprotected and glyc-
osylated in the presence of cyclohexanone, MeOH,
and concd H2SO4 to produce an anomeric mixture 15
of two diastereomers in a ratio of 1:1.5 (a:b) in 69% yield
(Scheme 4). These compounds were treated with p-tolu-
enesulfonyl chloride in pyridine at room temperature to
afford a mixture of two anomers 16 in 94% yield. The
mixture of tosylated derivatives 16 was then treated with
NaOMe in MeOH to afford a mixture of epoxides 17
and 18 in 89% yield. Compounds 17 and 18 were sepa-
rated at this stage. Compound 17 was reacted with the
sodium salt of p-thiocresol in DMF at 110 °C to afford
19 in 90% yield, which was then subjected to oxidation
with MMPP in MeOH to afford 20. Sulfone derivative
20 was mesylated, and the mesylated derivative was trea-
ted with DBU to afford 12 in good overall yield. On the
other hand, compound 18 under similar reaction condi-
tions produced a complex mixture of products. It was
probable that the ring opening of epoxide 18 was non-
regioselective and therefore produced a mixture.
Figure 4. ORTEP diagram of compound 6d.
the similar addition reaction patterns of related vinyl
sulfone-modified hex-2-enofuranosides 12 and 13. To
start with it was necessary to develop strategies for the
synthesis of these compounds. Thus, compound 7 on
treatment with cyclohexanone, methanol, and concd
H2SO4 generated a mixture of two anomers 8 in 65%
yield. These cyclohexanone derivatives were reacted
with the sodium salt of p-thiocresol in DMF at 110–
120 °C to afford a mixture of two anomers 9 in 89%
yield (Scheme 3). The mixture 9 was subjected to the
magnesium monoperoxyphthalate (MMPP) mediated
oxidation in MeOH for 6 h to produce 10 and 11 (1:4
from the 1H NMR spectrum) in 91% yield. The anomers
10 and 11 were separated at this stage, and methanesulf-
onated (mesylated). The mesyl derivatives were then
treated with DBU to afford vinyl sulfones 12 and 13,
respectively, in good yields.
Vinyl sulfone 12 on reactions with 30% aqueous
ammonia, neat benzylamine, cyclohexylamine, pyrrol-
idine, and morpholine at ambient temperature generated
single isomers 21a–e in high yields (Scheme 5).7
Similarly, vinyl sulfone 13 on reaction with 30% aque-
ous ammonia, neat benzylamine, cyclohexylamine,
Since the a-anomer 10 was the minor component in
the mixture of 10 and 11, we studied another sequence
of reactions to obtain 12 in large amount. Thus, the

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I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
O
O
O
O
O
O
O
O
SO2(p)Tol
X
OBz
O
(a) for 22a
(b) for 22b-e
OBz
O
OMe
OMe
O
O
a)
b)
13
+
OMe
O
X
SO2(p)Tol
OH
O
15
22a X = amino (71%)
14
22b X = benzylamino (80%)a
O
22c X = cyclohexylamino (81%)a
22d, 22d' X = pyrrolidino (89%) (1:1)
22e X = morpholino (76%)a
O
O
OBz
aref 7
X
O
O
O
c)
O
Y
OMe
Scheme 6. Reagents and conditions: (a) 30% aqueous ammonia; (b)
neat amines, rt, 5–13 h.
OTs
17 X = H; Y = OMe
18 X = OMe; Y = H
16
nucleophile showed the tendency of attacking C-2 in
the unusual way.
17:18 = 1:1.5
O
O
Successful synthesis of deoxyamino sugars using
carbohydrate vinyl sulfones would depend on the critical
desulfonylation step.9 We experimented with a large
variety of desulfonylating agents available in the litera-
ture. However, none of these reagents were able to effi-
ciently desulfonylate the amine Michael addition
products of vinyl sulfone-modified carbohydrates. Since
most of the conventional reagents or combination of
reagents failed to deliver our desired products, we initi-
ated a search for an alternative methodology for the des-
ulfonylation. Reaction systems generating Ni(0) in situ10
or making direct use of Raney nickel11 for the reduction
of sulfones to the corresponding carbon–hydrogen
bonds have been reported. Although our compounds
were either inert to Raney Ni or produced several prod-
ucts under the reaction conditions, our attention was
drawn to a reported observation that the reduction of
nickel halides with low-oxidation-potential metals such
as magnesium produced finely divided Ni(0), which
exhibited general, catalytic activity greater than
commercial Raney nickel.12 Compounds 6a–e0 were
subjected to desulfonylation by the Mg–MeOH–NiX2
system to produce the aminodideoxy sugars 23a, 23b,
23c, and an inseparable mixture 23e/23e0 by the
Mg–MeOH–NiX2 system (Table 1).7 Compound 6d
underwent extensive degradation. It is clear from Table
1 that NiBr2 is a more efficient catalyst for the desulf-
onylation reaction.
OH
f)
O
d)
from 17
12
g)
OMe
R
19 R = p-TolS
e)
20 R = p-TolSO2
Scheme 4. Reagents and conditions: (a) cyclohexanone, MeOH,
H2SO4, 80 °C, 2.5 h, 69%; (b) TsCl, py, DMAP, rt, 48 h, 94%; (c)
NaOMe, MeOH, rt, 2.5 h, 89%; (d) p-thiocresol, NaOMe, DMF,
110 °C, 3.5 h, 90%; (e) MMPP, MeOH, rt, 6 h; (f) MsCl, py, 0–4 °C,
24 h; (g) DBU, DCM, rt, 30 min, 86% (yield in three steps).
O
(a) for 21a
(b) for 21b-e
X
O
O
12
OMe
SO2(p)Tol
21a X = amino (81%)
21b X = benzylamino (96%)a
21c X = cyclohexylamino (89%)a
21d X = pyrrolidino (94%)
21e X = morpholino (86%)a
aref 7
Scheme 5. Reagents and conditions: (a) 30% aqueous ammonia; (b)
neat amines, rt, 5–13 h.
morpholine, and pyrrolidine at ambient temperature
generated single isomers 22a–c and 22e in high yields.7
Only pyrrolidine under similar conditions afforded an
inseparable mixture of compounds 22d/22d0 in a ratio
of 1:1 (Scheme 6).
It was therefore clear from these experiments that
except for the formation of 22d0, amino nucleophiles
were always delivered to C-2 of 3, 12, and 13 from a
direction opposite to that of the disposition of the ano-
meric methoxy group. It may therefore be emphasized
that the addition pattern of amines to 4 was unusual
in nature. Interestingly, in the case of another b-anomer-
ic vinyl sulfone-modified carbohydrate 13, at least one
In conclusion, we have established an efficient and
new methodology for the synthesis of new amino sugars
through the Michael addition of nitrogen nucleophiles
to 3-C-sulfonyl-pent-2-enofuranosides 3 and 4 and
3-C-sulfonyl-pent-2-enofuranosides 12 and 13. Amines
added to C-2 of vinyl sulfones 3 (Scheme 1), 12 (Scheme
5), and 13 (Scheme 6) from a direction opposite to the
dispositions of the anomeric methoxy groups. From
the stereoelectronic consideration alone (Fig. 2),
compound 4, on reactions with amines, should have
produced D-ribo- or D-xylo-derivatives. On the contrary,
amines reacted with 4 to generate mostly ara-derivatives
(Scheme 2) in an unusual fashion. A new and efficient

I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
1291
a
Table 1. Desulfonylation of amino sugars 6a–e0
60, F254), and the spots were visualized with UV light
or by charring the plates dipped in 5% H2SO4–MeOH
solution or 5% H2SO4–vanillin–EtOH solution. Column
chromatography was performed on silica gel (60–120 or
Starting material
Productb
NiX2 (Yield, %)
O
NH2
BnO
OMe
NH
230–400 mesh). H and 13C NMR spectra for most of
O
1
NiCl2 (24)
NiBr2(37)
BnO
OMe
the compounds were recorded at 200 and 50.3 MHz,
respectively, in CDCl3 unless stated otherwise. Optical
rotations were recorded at 589 nm. Synthesis and spec-
troscopic data of compounds 5b, 5c, 5e, 21b, 21c, 21e,
22b, 22c, and 22e were reported earlier.7
O
SO2Ar
6a
23a
H
N
H
N
BnO
OMe
3.2. General procedure for the synthesis of sulfides 9 and
19
O
BnO
OMe
O
NiCl2 (60)
NiBr2(73)
SO2Ar
To a well-stirred solution of 8 or 17 in DMF (4 mL/
mmol) were added p-thiocresol (5 equiv/mmol) and
NaOMe (2.5 equiv/mmol). The mixture was heated at
100–120 °C with stirring for 4–5 h under N2. After the
completion of the reaction (TLC), the reaction mixture
was poured into a saturated solution of NaHCO3, and
the product was extracted with EtOAc (3 ꢀ 10 mL).
The combined organic layers were dried over anhyd
Na2SO4 and filtered, and the filtrate was concentrated
under reduced pressure to get a gummy residue. The
residue was purified over a silica gel column to afford
sulfides 9 and 19. Compounds 9 and 19 were taken
directly for the oxidation reaction.
23b
6b
NH
NH
OMe
BnO
BnO
OMe
O
BnO
BnO
NiCl2 (59)
NiBr2(67)
O
SO2Ar
23c
O
6c
OMe
OMe
O
ArO2S
N
NiCl2 (22)
NiBr2(48)
N
O
3.3. General procedure for the synthesis of sulfones 10, 11,
and 20
O
6e, 6e'
Ar = p-Tol.
23e, 23e'
To a well-stirred solution of sulfides 9 or 19 in dry
MeOH (10 mL/mmol) was added magnesium mono-
peroxyphthalate hexahydrate (2.5 equiv/mmol), and
the mixture was stirred for 6 h under N2. After comple-
tion of the reaction (TLC), MeOH was evaporated to
dryness under reduced pressure, and the residue was dis-
solved in satd NaHCO3. The aqueous part was washed
with EtOAc (3 ꢀ 10 mL). The combined organic layers
were dried over anhyd Na2SO4 and filtered, and the
filtrate was concentrated under reduced pressure to get
a residue. The residue was purified over silica gel column
to obtain sulfones 10, 11, and 20.
a All reactions were carried out at room temperature using Mg–
MeOH–NiX2 in 6 h.
b Desulfonylated product of 6a was isolated as the acetyl derivative
23a.
reagent system Mg–MeOH–NiBr2 desulfonylated 6a–c
and 6e,e0 to yield a wide range of 2-amino-2,3-di-
deoxy-b-D-threo-pentofuranosides 23a–c and 23e,e0 for
the first time. Research is in progress to identify the
interactions responsible for the delivery of amines from
the b-face of the vinyl sulfone-modified furanoside 4.
3.4. General procedure for the synthesis of vinyl sulfone-
modified carbohydrates 12 and 13
3. Experimental
To a well-stirred solution of sulfones 10, 11, or 20 in
pyridine (5 mL/mmol) was added methanesulfonyl chlo-
ride (4 equiv/mmol) in pyridine (1 mL/mmol of MsCl)
dropwise at 0 °C under N2. After completion of the
addition, the reaction mixture was kept at +4 °C. After
24 h (TLC), the reaction mixture was poured into satd
aq NaHCO3, and the product was extracted with EtOAc
(3 ꢀ 10 mL). The combined organic layers were dried
over anhyd Na2SO4 and filtered, and the filtrate was
3.1. General methods
Melting points were determined in open-end capillary
tubes and are uncorrected. Carbohydrates and other fine
chemicals were obtained from commercial suppliers and
are used without purification. Solvents were dried and
distilled following standard procedures. TLC was
carried out on precoated plates (E. Merck Silica Gel

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I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
concentrated under reduced pressure to get a residue.
The residue in CH2Cl2 (10 mL) was treated with DBU
at ambient temperature for 30 min. The solvent was
evaporated under reduced pressure, and the resulting
residue was purified over a silica gel column to afford
12 and 13.
3.8. Methyl 5-O-benzyl-2,3-dideoxy-2-pyrrolidino-(3-C-
p-tolylsulfonyl)-a-D-arabinofuranoside (5d)
Compound 3 (0.25 g, 0.67 mmol) was converted to 5d
following the general procedure (0.29 g, 96%). Eluent:
29
1:3 EtOAc–petroleum ether. Yellow gum. ½aꢁD +55.4
1
(c 0.26, CHCl3). H NMR (CDCl3): d 1.67 (br m, 4H),
3.5. General procedure for the synthesis of 5a–e, 6a–e0,
21a–e, and 22a–e
2.44 (s, 3H), 2.68 (br m, 4H), 3.19 (s, 3H), 3.43 (m,
1H), 3.70 (dd, J = 1.9, 11.1 Hz, 1H), 3.79–3.88 (m,
2H), 4.38–4.56 (m, 3H), 5.08 (s, 1H), 7.23–7.35 (m,
7H), 7.73 (d, J = 8.3 Hz, 2H). 13C NMR (CDCl3): d
21.6, 23.2, 49.6, 54.5, 64.6, 69.7, 69.8, 73.5, 77.7, 106.4,
127.6, 128.3, 128.9, 129.7, 135.3, 137.9, 144.9. Anal.
Calcd for C24H31NO5S: C, 64.69; H, 7.01; N, 3.14.
Found: C, 64.71; H, 6.84; N, 3.26.
A mixture of 3, 4, 12, or 13 and the appropriate amine
(30% aqueous ammonia or neat; 5 equiv/mmol) was stir-
red at ambient temperature. After completion of the
reaction (TLC), satd NH4Cl solution was added, and
the mixture was extracted with EtOAc (3 ꢀ 10 mL).
The combined organic layers were dried over anhyd
Na2SO4 and filtered, and the filtrate was concentrated
under reduced pressure to get a residue. The residue
was purified over a silica gel column to afford 5a–e,
6a–e0, 21a–e, and 22a–e.
3.9. Methyl 2-amino-5-O-benzyl-2,3-dideoxy-(3-C-p-
tolylsulfonyl)-b-D-arabinofuranoside (6a)
Compound 4 (0.22 g, 0.59 mmol) was converted to 6a
following the general procedure (0.18 g, 77%). Eluent:
1:1 EtOAc–petroleum ether. Amorphous solid. Mp
3.6. General procedure for desulfonylation
29
1
90 °C. ½aꢁD ꢃ110.9 (c 0.1, CHCl3). H NMR (CDCl3):
d 2.43 (s, 3H), 3.22–3.29 (m, 3H), 3.32 (s, 3H), 3.86
(m, 1H), 4.41–4.49 (m, 3H), 4.81 (d, J = 4.4 Hz, 1H),
7.22–7.34 (m, 7H), 7.74 (d, J = 8.2 Hz, 2H). 13C NMR
(CDCl3): d 21.6, 54.7, 57.4, 70.3, 72.6, 73.12, 77.6,
103.6, 127.6, 128.2, 128.6, 129.9, 134.8, 137.7, 145.3.
Anal. Calcd for C20H25NO5S: C, 61.36; H, 6.44; N,
3.58. Found: C, 61.52; H, 6.41; N, 3.61.
To a well-stirred solution of 6a, 6b, 6c, or 6e/6e0 in dry
MeOH (10 mL) was added Mg turnings (15 mmol)
and the appropriate nickel halide (10 mol % for primary
amines and 20 mol % for secondary amines) at 0 °C
under Ar. The mixture was stirred at ambient tempera-
ture. After 2–3 h another portion of Mg turnings
(15 mmol) and dry MeOH (5 mL) were added. The
mixture was stirred for an additional 2–3 h. The reaction
mixture was filtered through Celite. The residue was
washed thoroughly with MeOH. The filtrates were
pooled together, and the liquid was concentrated under
reduced pressure. The resulting residue was dissolved in
EtOAc, and the solution was washed with satd aq
NH4Cl, dried over anhyd Na2SO4, and filtered. The
filtrate was concentrated under reduced pressure to get
a residue that was purified over a silica gel column to
afford 23a, 23b, 23c, or 23e–e0.
3.10. Methyl 5-O-benzyl-2-benzylamino-2,3-dideoxy-
(3-C-p-tolylsulfonyl)-b-D-arabino-furanoside (6b)
Compound 4 (0.48 g, 1.28 mmol) was converted to 6b
following the general procedure (0.5 g, 81%). Eluent:
1:3 EtOAc–petroleum ether. White crystalline solid.
29
Mp 103 °C. ½aꢁD ꢃ119.1 (c 0.22, CHCl3). 1H NMR
(CDCl3): d 2.41 (s, 3H), 3.25 (s, 3H), 3.42–3.49 (m,
3H), 3.59 (d, J = 4.2 Hz, 1H), 3.63–3.68 (m, 2H), 4.48
(s, 2H), 4.57 (m, 1H), 4.68 (d, J = 4.3 Hz, 1H), 7.11–
7.36 (m, 12H), 7.69 (d, J = 8.2 Hz, 2H). 13C NMR
(CDCl3): d 21.6, 52.4, 54.7, 62.9, 68.5, 73.1, 76.4,
102.1, 127.0, 127.6, 127.6, 128.0, 128.2, 128.7, 129.7,
135.2, 137.8, 139.6, 144.9. Anal. Calcd for C27H31NO5S:
C, 67.34; H, 6.49; N, 2.91. Found: C, 67.65; H, 6.09; N,
2.76.
3.7. Methyl 2-amino-5-O-benzyl-2,3-dideoxy-(3-C-p-
tolylsulfonyl)-a-D-arabinofuranoside (5a)
Compound 3 (0.32 g, 0.85 mmol) was converted to 5a
following the general procedure (0.3 g, 91%). Eluent:
1:1 EtOAc–petroleum ether. White crystalline solid.
29
Mp 99 °C. ½aꢁD +119.7 (c 0.11, CHCl3). 1H NMR
(CDCl3): d 2.44 (s, 3H), 3.29 (s, 3H), 3.36 (m, 1H),
3.63–3.75 (m, 3H), 4.45–4.52 (m, 3H), 4.73 (d, J =
2.1 Hz, 1H), 7.26–7.34 (m, 7H), 7.74 (d, J = 8.3 Hz,
2H). 13C NMR (CDCl3): d 21.5, 55.2, 60.0, 69.3, 71.4,
73.4, 77.0, 110.4, 127.5, 128.27, 128.5, 129.8, 134.9,
137.5, 145.0. Anal. Calcd for C20H25NO5Sꢂ0.25H2O:
C, 60.67; H, 6.49; N, 3.54. Found: C, 60.66; H, 6.54;
N, 3.06.
3.11. Methyl 5-O-benzyl-2-cyclohexylamino-2,3-dideoxy-
(3-C-p-tolylsulfonyl)-b-D-arabinofuranoside (6c)
Compound 4 (0.33 g, 0.88 mmol) was converted to 6c
following the general procedure (0.34 g, 80%). Eluent:
1:3 EtOAc–petroleum ether. White crystalline solid.
29
Mp 133 °C. ½aꢁD ꢃ99.4 (c 0.11, CHCl3). 1H NMR
(CDCl3): d 0.87–1.60 (m, 10H), 2.26 (m, 1H), 2.42 (s,

I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
1293
3H), 3.32 (s, 3H), 3.35–3.43 (m, 3H), 3.72 (m, 1H), 4.47
(d, J = 1.3 Hz, 2H), 4.60 (m, 1H), 4.83 (d, J = 4.4 Hz,
1H), 7.26–7.30 (m, 7H), 7.76 (d, J = 8.3 Hz, 2H). 13C
NMR (CDCl3): d 21.6, 24.8, 24.9, 25.8, 33.2, 34.3,
54.7, 55.7, 61.4, 68.9, 73.1, 76.1, 102.9, 127.6, 127.7,
128.2, 128.7, 129.5, 135.6, 137.8, 144.8. Anal. Calcd
for C26H35NO5S: C, 65.93; H, 7.45; N, 2.96. Found:
C, 66.24; H, 7.78; N, 3.04.
inseparable mixture of two anomers 9 (2.7 g, 89%)
following the general procedure. Eluent: 1:5 EtOAc–
petroleum ether. Yellow gum. Compound 9 (2.0 g,
5.26 mmol) was converted to 10 and 11 (2.0 g, 91%)
following the general procedure. The anomeric mixture
can be separated at this stage (10:11 = 1:4). Compound
10: (0.33 g, 15%). Eluent: 1:3 EtOAc–petroleum ether.
29
White crystalline solid. Mp 116 °C. ½aꢁD +131.4 (c 0.1,
CHCl3). 1H NMR (CDCl3): d 1.41–1.57 (m, 10H),
2.44 (s, 3H), 3.47 (s, 3H), 3.87 (dd, J = 5.1, 18.9 Hz,
1H), 4.05–4.13 (m, 2H), 4.29–4.37 (m, 2H), 4.79 (m,
1H), 4.92 (d, J = 4.5 Hz, 1H), 7.34 (d, J = 8.0 Hz, 2H),
7.83 (d, J = 8.3 Hz, 2H). 13C NMR (CDCl3): d 21.4,
23.3, 23.7, 24.9, 33.6, 35.6, 55.0, 63.4, 64.3, 72.4, 77.4,
77.5, 101.6, 110.1, 128.22, 129.4, 137.6, 144.5. Anal.
Calcd for C20H28O7S: C, 58.24; H, 6.84. Found: C,
57.93; H, 7.06. Compound 11: (1.5 g, 69%). Eluent: 1:3
EtOAc–petroleum ether. White crystalline solid. Mp
3.12. Methyl 5-O-benzyl-2,3-dideoxy-2-pyrrolidino-(3-C-
p-tolylsulfonyl)-b-D-arabinofuranoside (6d)
Compound 4 (0.19 g, 0.51 mmol) was converted to 6d
following the general procedure (0.2 g, 86%). Eluent:
1:3 EtOAc–petroleum ether. White crystalline solid.
29
Mp 149 °C. ½aꢁD ꢃ84.9 (c 0.22, CHCl3). 1H NMR
(CDCl3): d 1.68 (br m, 4H), 2.41 (s, 3H), 2.65 (br m,
2H), 2.81 (br m, 2H), 3.32 (s, 3H), 3.34–3.46 (m, 2H),
3.79–3.81 (m, 2H), 4.37 (d, J = 4.6 Hz, 2H), 4.52 (m,
1H), 4.95 (d, J = 4.1 Hz, 1H), 7.17–7.32 (m, 7H), 7.74
(d, J = 8.2 Hz, 2H). 13C NMR (CDCl3): d 21.5, 23.3,
50.5, 54.9, 64.8, 65.4, 72.6, 72.9, 77.4, 105.1, 127.5,
128.1, 128.7, 129.5, 135.2, 137.7, 144.7. Anal. Calcd
for C24H31NO5S: C, 64.69; H, 7.01; N, 3.14. Found:
C, 65.03; H, 6.73; N, 3.20.
29
1
74 °C. ½aꢁD ꢃ67.5 (c 0.26, CHCl3). H NMR (CDCl3):
d 1.38–1.56 (m, 10H), 2.46 (s, 3H), 3.31 (s, 3H), 3.77
(dd, J = 4.9, 15.5 Hz, 1H), 3.89–4.19 (m, 3H), 4.26 (d,
J = 5.1 Hz, 1H), 4.72 (dd, J = 6.1, 14.5 Hz, 1H), 4.84
(d, J = 0.6 Hz, 1H), 7.36 (d, J = 7.9 Hz, 2H), 7.85 (d,
J = 8.3 Hz, 2H). 13C NMR (CDCl3): d 21.4, 23.5, 23.7,
24.9, 34.4, 35.7, 54.9, 65.5, 67.5, 75.9, 76.8, 78.4, 108.4,
110.3, 128.3, 129.6, 136.1, 145.1. Anal. Calcd for
C20H28O7S: C, 58.24; H, 6.84. Found: C, 58.10; H, 6.94.
3.13. Methyl 5-O-benzyl-2,3-dideoxy-2-morpholino-(3-
C-p-tolylsulfonyl)-b-D-arabino- and xylofuranoside (6e
and 6e0)
3.15. Methyl 5,6-O-cyclohexylidene-2,3-dideoxy-(3-C-p-
tolylsulfonyl)-a-D-erythro-hex-2-enopyranoside (12)
Compound 4 (0.27 g, 0.72 mmol) was converted to 6d
and 6d0, an inseparable mixture of two diastereomers
following the general procedure (0.25 g, 76%). Eluent:
1:2 EtOAc–petroleum ether. Amorphous solid.
Compound 10 (1.2 g, 2.91 mmol) was converted to 12
following the general procedure (0.97 g, 84%). Eluent:
29
1:5 EtOAc–petroleum ether. Yellow gum. ½aꢁD ꢃ5.8 (c
0.64, CHCl3). 1H NMR (CDCl3): d 1.40–1.66 (m,
10H), 2.46 (s, 3H), 3.35 (s, 3H), 3.64 (m, 1H), 3.86 (m,
1H), 4.49 (m, 1H), 5.12 (m, 1H), 5.81 (d, J = 4.5 Hz,
1H), 6.52 (m, 1H), 7.37 (d, J = 8.1 Hz, 2H), 7.81 (d,
J = 8.1 Hz, 2H). 13C NMR (CDCl3): d 21.6, 23.7, 23.8,
25.0, 34.6, 35.4, 54.7, 63.6, 75.4, 83.0, 106.9, 110.6,
128.2, 130.1, 135.6, 136.6, 145.5, 147.8. Anal. Calcd for
C20H26O6S: C, 60.89; H, 6.64. Found: C, 60.85; H, 6.48.
3.14. Methyl 5,6-O-cyclohexylidene-3-deoxy-(3-C-p-
tolylsulfonyl)-a-D-allopyranoside (10) and methyl 5,6-
O-cyclohexylidene-3-deoxy-(3-C-p-tolylsulfonyl)-b-D-
allopyranoside (11)
Compound 7 (5.0 g, 12.06 mmol) was gently heated un-
der reflux at 80 °C with cyclohexanone (1.2 mL/mmol),
MeOH (60 mL), and concd H2SO4 (0.1 mL) for
2.5 h.13 After completion of the reaction (TLC), toluene
(30 mL) was added, and the mixture was cooled to room
temperature. MeOH was evaporated to dryness under
reduced pressure to get a residue. The residue was neu-
tralized with Et3N, and the mixture was diluted with
EtOAc (40 mL), washed with satd aq NaHCO3, and
then with H2O. The combined organic layers were dried
over anhyd Na2SO4 and filtered, and the filtrate was
concentrated under reduced pressure to get a gummy
residue. The residue was purified over a silica gel column
(eluent: 1:1 EtOAc–petroleum ether) to obtain an insep-
arable mixture of two anomers 8 (3.4 g, 65%). The ano-
meric mixture 8 (3.4 g, 7.93 mmol) was converted to an
3.16. Methyl 5,6-O-cyclohexylidene-2,3-dideoxy-(3-C-p-
tolylsulfonyl)-b-D-erythro-hex-2-enopyranoside (13)
Compound 11 (1.8 g, 4.36 mmol) was converted to 13
following the general procedure (1.4 g, 82%). Eluent:
1:5 EtOAc–petroleum ether. White crystalline solid.
29
Mp 84 °C. ½aꢁD ꢃ172.0 (c 0.04, CHCl3). 1H NMR
(CDCl3): d 1.40–1.64 (m, 10H), 2.46 (s, 3H), 3.45 (s,
3H), 3.70 (dd, J = 6.9, 16.6 Hz, 1H), 3.92 (dd, J = 5.9,
16.8 Hz, 1H), 4.39 (m, 1H), 5.02 (m, 1H), 5.66 (m,
1H), 6.52 (m, 1H), 7.36 (d, J = 7.9 Hz, 2H), 7.79 (d,
J = 8.4 Hz, 2H). 13C NMR (CDCl3): d 21.6, 23.7,
23.9, 25.1, 34.7, 35.7, 56.2, 63.7, 75.4, 83.6, 107.1,

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I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
110.2, 128.2, 130.0, 135.7, 136.3, 145.5, 147.5. Anal.
Calcd for C20H26O6S: C, 60.89; H, 6.64. Found: C,
60.51; H, 6.24.
(m, 10H), 3.48 (s, 3H), 3.71–3.81 (m, 3H), 3.93 (m,
1H), 4.09 (m, 1H), 4.24 (m, 1H), 4.99 (s, 1H). 13C
NMR (CDCl3): d 23.3, 23.6, 24.7, 34.3, 36.2, 54.7, 55.5,
56.1, 66.3, 72.9, 76.8, 102.1, 109.3. Anal. Calcd for
C13H20O5: C, 60.92; H, 7.87. Found: C, 60.52; H, 8.02.
3.17. Methyl 2,3-anhydro-5,6-O-cyclohexylidene-a-D-
mannofuranoside (17) and methyl 2,3-anhydro-5,6-O-
cyclohexylidene-b-D-mannofuranoside (18)
3.18. Methyl 5,6-O-cyclohexylidene-3-deoxy-(3-C-p-
tolylsulfonyl)-a-D-mannopyranoside (19)
Compound 14 (6.0 g, 16.46 mmol) was gently refluxed at
80 °C with cyclohexanone (1.2 mL/mmol), MeOH
(65 mL), and concd H2SO4 (0.1 mL) for 2.5 h.13 After
completion of the reaction (TLC), toluene (35 mL) was
added, and the mixture was cooled to room temperature.
MeOH was evaporated to dryness under reduced pres-
sure to get a residue. The residue was neutralized with
Et3N, and the mixture was diluted with EtOAc
(40 mL), washed with satd aq NaHCO3, and then with
H2O. The combined organic layers were dried over
anhyd Na2SO4 and filtered, and the filtrate was concen-
trated under reduced pressure to get a gummy residue.
The residue was purified over a silica gel column (eluent:
1:1 EtOAc–petroleum ether) to obtain an inseparable
mixture of two anomers 15 (4.3 g, 69%). The anomeric
mixture 15 (4.3 g, 11.36 mmol) was then tosylated with
TsCl (1.5 equiv/mmol), pyridine (10 mL/mmol), and
DMAP (catalytic). After completion of the reaction
(TLC), the reaction mixture was poured into an ice-cold
solution of satd aq NaHCO3, and the mixture was
extracted with EtOAc (3 ꢀ 10 mL). The combined
organic layers were dried over anhyd Na2SO4 and
filtered, and the filtrate was concentrated under reduced
pressure to get a residue. The residue was purified over a
silica gel column (eluent: 1:3 EtOAc–petroleum ether) to
afford 16 (5.7 g, 94%). Then compound 16 (5.7 g,
10.7 mmol) was stirred at ambient temperature with
NaOMe (1.2 equiv/mmol) and MeOH (50 mL) for
2.5 h. After completion of the reaction (TLC), MeOH
was evaporated to dryness under reduced pressure. The
reaction mixture was then poured into satd aq NH4Cl,
and the mixture was extracted with EtOAc (3 ꢀ 10
mL). The combined organic layers were dried over anhyd
Na2SO4 and filtered, and the filtrate was concentrated
under reduced pressure to get a residue. The residue
was purified over a silica gel column to afford 17 and
18 (2.4 g, 89%). The anomeric mixture was separated at
this stage (17:18 = 1:1.5). Compound 17: 0.96 g, 35%.
Compound 17 (1.2 g, 4.68 mmol) was converted to 19
(1.6 g, 90%) following the general procedure. Eluent:
1:4 EtOAc–petroleum ether. Yellow gum. 1H NMR
(CDCl3): d 1.41–1.64 (m, 10H), 2.32 (s, 3H), 3.40 (s,
3H), 3.45–3.52 (m, 2H), 4.00 (m, 1H), 4.17–4.22 (m,
2H), 4.42 (m, 1H), 4.93 (s, 1H), 7.13 (d, J = 8.1 Hz,
2H), 7.34 (d, J = 8.1 Hz, 2H). 13C NMR (CDCl3): d
20.7, 23.3, 23.6, 24.8, 33.8, 35.4, 52.1, 54.6, 64.9, 75.3,
80.5, 84.8, 109.6, 110.4, 129.7, 130.9, 131.6, 136.8. Anal.
Calcd for C20H28O5Sꢂ2H2O: C, 57.67; H, 7.74. Found:
C, 57.54; H, 7.63.
3.19. Methyl 5,6-O-cyclohexylidene-2,3-dideoxy-(3-C-p-
tolylsulfonyl)-a-D-erythro-hex-2-enopyranoside (12)
Compound 19 (0.8 g, 2.1 mmol) was converted to
sulfone derivative 20 following the general procedure.
Then the sulfone derivative 20 was converted to vinyl
sulfone-modified carbohydrate 12 (0.71 g, 86%) follow-
ing the general procedure. Eluent: 1:5 EtOAc–petroleum
ether. Yellow gum.
3.20. Methyl 2-amino-5,6-O-cyclohexylidene-2,3-di-
deoxy-(3-C-p-tolylsulfonyl)-a-D-mannopyranoside (21a)
Compound 12 (0.5 g, 1.27 mmol) was converted to 21a
following the general procedure (0.42 g, 81%). Eluent:
1:1 EtOAc–petroleum ether. Yellow crystalline solid.
29
Mp 90 °C. ½aꢁD ꢃ12.7 (c 0.06, CHCl3). 1H NMR
(CDCl3): d 1.40–1.94 (m, 10H), 2.45 (s, 3H), 3.25 (s,
3H), 3.50 (m, 1H), 3.76 (m, 1H), 3.88–4.08 (m, 2H),
4.39 (m, 1H), 4.56 (m, 1H), 4.79 (s, 1H), 7.37 (d,
J = 8.1 Hz, 2H), 7.82 (d, J = 8.1 Hz, 2H). 13C NMR
(CDCl3): d 21.5, 23.5, 23.8, 24.9, 33.9, 35.6, 55.1, 60.1,
64.4, 72.4, 75.8, 77.9, 110.3, 110.5, 128.8, 129.8, 135.2,
144.9. Anal. Calcd for C20H29NO6S: C, 58.37; H, 7.10;
N, 3.40. Found: C, 58.20; H, 7.19; N, 3.51.
26
Eluent: 1:5 EtOAc–petroleum ether. Yellow oil. ½aꢁD
1
+40.8 (c 10.0, CHCl3). H NMR (CDCl3): d 1.40–1.67
3.21. Methyl 5,6-O-cyclohexylidene-2,3-dideoxy-2-pyrr-
olidino-(3-C-p-tolylsulfonyl)-a-D-mannopyranoside (21d)
(m, 10H), 3.39 (s, 3H), 3.66 (d, J = 2.6 Hz, 1H), 3.83
(d, J = 3.1 Hz, 1H), 3.88–3.97 (m, 2H), 4.05–4.13 (m,
2H), 4.90 (s, 1H). 13C NMR (CDCl3): d 23.3, 23.6,
24.7, 34.3, 36.2, 53.8, 54.7, 56.0, 66.5, 73.0, 76.8, 101.9,
109.3. Anal. Calcd for C13H20O5: C, 60.92; H, 7.87.
Found: C, 61.01; H, 7.63. Compound 18: 1.4 g, 51%.
Compound 12 (0.4 g, 1.01 mmol) was converted to 21d
following the general procedure (0.44 g, 94%). Eluent:
29
1:3 EtOAc–petroleum ether. Yellow gum. ½aꢁD +33.0
(c 0.4, CHCl3). 1H NMR (CDCl3): d 1.40–1.72 (m,
14H), 2.44 (s, 3H), 2.53 (br m, 4H), 3.22 (s, 3H), 3.66
(m, 1H), 3.74 (m, 1H), 4.02 (d, J = 6.0 Hz, 2H), 4.24
26
Eluent: EtOAc/petroleum ether (1:5). Yellow oil. ½aꢁD
1
ꢃ59.4 (c 9.8, CHCl3). H NMR (CDCl3): d 1.40–1.66

I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
1295
(m, 1H), 4.41 (m, 1H), 4.99 (s, 1H), 7.34 (d, J = 8.2 Hz,
2H), 7.80 (d, J = 8.2 Hz, 2H). 13C NMR (CDCl3): d
21.5, 23.1, 23.6, 23.9, 25.0, 34.4, 35.7, 50.8, 54.8, 65.4,
67.4, 70.8, 75.6, 78.8, 106.8, 110.3, 129.3, 129.5, 135.3,
144.8. Anal. Calcd for C24H35NO6S: C, 61.91; H, 7.58;
N, 3.01. Found: C, 61.84; H, 7.86; N, 3.01.
NMR (CDCl3): d 1.43 (m, 1H), 2.28 (m, 1H), 3.25 (m,
1H), 3.32 (s, 3H), 3.38–3.53 (m, 2H), 3.79 (s, 2H), 4.22
(m, 1H), 4.58 (s, 2H), 4.74 (d, J = 4.2 Hz, 1H), 7.18–
7.50 (m, 10H). 13C NMR (CDCl3): d 32.7, 52.4, 54.4,
61.1, 73.3, 74.7, 76.8, 101.9, 127.0, 127.6, 127.7, 128.2,
128.3, 128.4, 138.2, 140.1. Anal. Calcd for C20H25NO3ꢂ
0.5H2O: C, 71.40; H, 7.78; N, 4.16. Found: C, 71.45;
H, 7.80; N, 4.10.
3.22. Methyl 2-amino-5,6-O-cyclohexylidene-2,3-di-
deoxy-(3-C-p-tolylsulfonyl)-b-D-gluco-pyranoside (22a)
3.26. Methyl 5-O-benzyl-2-cyclohexylamino-2,3-dideoxy-
b-D-threo-pentofuranoside (23c)
Compound 13 (0.25 g, 0.63 mmol) was converted to 22a
following the general procedure (0.18 g, 71%). Eluent:
1:1 EtOAc–petroleum ether. White crystalline solid.
Compound 6c (0.22 g, 0.46 mmol) was converted to 23c
following the general procedure (0.1 g, 67%, NiBr2),
(0.09 g, 59%, NiCl2). Eluent: 1:2 EtOAc–petroleum
29
Mp 115 °C. ½aꢁD ꢃ96.3 (c 0.13, CHCl3). 1H NMR
(CDCl3): d 1.14–1.76 (m, 10H), 2.44 (s, 3H), 3.36 (s,
3H), 3.76–3.86 (m, 3H), 3.89–3.97 (m, 2H), 4.38 (m,
1H), 4.85 (d, J = 2.8 Hz, 1H), 7.36 (d, J = 8.0 Hz, 2H),
7.81 (d, J = 8.2 Hz, 2H). 13C NMR (CDCl3): d 21.6,
23.5, 23.9, 25.0, 34.4, 35.7, 55.8, 59.9, 66.1, 68.2, 76.3,
79.2, 110.2, 110.3, 128.5, 129.7, 136.5, 144.9. Anal.
Calcd for C20H29NO6Sꢂ0.25 H2O: C, 57.75; H, 7.14; N,
3.37. Found: C, 57.69; H, 7.23; N, 3.48.
29
ether. Yellow oil. ½aꢁD ꢃ40.6 (c 0.22, CHCl3). 1H
NMR (CDCl3): d 1.02–1.84 (m, 11H), 2.25 (m, 1H),
2.44 (m, 1H), 3.33 (s, 3H), 3.35–3.52 (m, 3H), 4.20–
4.28 (m, 1H), 4.58 (s, 2H), 4.76 (d, J = 4.2 Hz, 1H),
7.25–7.40 (m, 5H). 13C NMR (CDCl3): d 24.9, 26.0,
33.0, 33.6, 33.8, 54.4, 55.0, 58.5, 73.3, 74.7, 76.9, 102.4,
127.5, 127.7, 128.3, 138.2. Anal. Calcd for C19H29NO3:
C, 71.44; H, 9.15; N, 4.38. Found: C, 71.04; H, 9.50;
N, 4.0.
3.23. Methyl 5,6-O-cyclohexylidene-2,3-dideoxy-2-pyr-
rolidino-(3-C-p-tolylsulfonyl)-b-D-gluco- and mannopyr-
anoside (22d and 22d0)
3.27. Methyl 5-O-benzyl-2,3-dideoxy-2-morpholino-b-D-
erythro- and threo-pentofuranoside (23e and 23e0)
Compound 13 (0.25 g, 0.63 mmol) was converted to 22d
and 22d0 an inseparable mixture of two diastereomers
following the general procedure (0.26 g, 89%). Eluent:
1:3 EtOAc–petroleum ether. Amorphous solid.
Compounds 6e and 6e0 (0.18 g, 0.39 mmol) were con-
verted to 23e and 23e0, an inseparable mixture of two
diastereomers following the general procedure (0.05 g,
48%, NiBr2), (0.03 g, 22%, NiCl2). Eluent: 1:1 EtOAc–
3.24. Methyl 2-acetylamino-5-O-benzyl-2,3-dideoxy-b-D-
threo-pentofuranoside (23a)
1
petroleum ether. Yellow oil. H NMR of the mixture
(CDCl3): d 1.63–2.24 (m, 4H), 2.47–2.51 (m, 8H),
2.59–2.65 (m, 2H), 3.30 (s, 6H), 3.31–3.59 (m, 4H),
3.67–3.78 (m, 8H), 4.36 (m, 2H), 4.56 (s, 4H), 4.83/
4.92 (each d, 2H), 7.28–7.34 (m, 10H).
Compound 6a (0.12 g, 0.31 mmol) was desulfonylated
following the general procedure. The residue obtained
was acetylated to afford 23a (0.03 g, 37%, NiBr2),
(0.02 g, 24%, NiCl2). Eluent: 1:3 EtOAc–petroleum
29
ether. White crystalline solid. Mp 112 °C. ½aꢁD +16.8 (c
1
Acknowledgment
0.06, CHCl3). H NMR (CDCl3): d 1.49 (m, 1H), 1.96
(s, 3H), 2.39 (m, 1H), 3.34 (s, 3H), 3.43 (d, J = 8.7 Hz,
2H), 4.33 (m, 1H), 4.44 (m, 1H), 4.54 (s, 2H), 4.76 (d,
J = 4.5 Hz, 1H), 5.92 (br d, J = 7.6 Hz, 1H), 7.25–7.42
(m, 5H). 13C NMR (CDCl3): d 23.2, 32.1, 51.9, 54.5,
73.3, 73.9, 77.3, 101.7, 127.6, 128.3, 138.1, 169.8. Anal.
Calcd for C15H21NO4.1H2O: C, 60.59; H, 7.79; N,
4.71. Found: C, 60.19; H, 7.70; N, 4.90.
The authors thank the Indo-French Centre for the Pro-
motion of Advanced Research, New Delhi for funding
(Project No. 3405-1).
Supplementary data
3.25. Methyl 5-O-benzyl-2-benzylamino-2,3-dideoxy-b-D-
threo-pentofuranoside (23b)
Complete crystallographic data for the structural analy-
sis have been deposited with the Cambridge Crystallo-
graphic Data Centre, CCDC Nos. 670145 and 670146.
Copies of this information may be obtained free of
charge from the Director, Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge, CB21EZ,
UK. (fax: +44-1223-336033, e-mail: deposit@ccdc.cam.
Compound 6b (0.1 g, 0.21 mmol) was converted to 23b
following the general procedure (0.07 g, 73%, NiBr2),
(0.06 g, 60%, NiCl2). Eluent: 1:2 EtOAc–petroleum
29
ether. Yellow oil. ½aꢁD ꢃ80.9 (c 0.36, CHCl3). 1H

1296
I. Das et al. / Carbohydrate Research 343 (2008) 1287–1296
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23e/23e0 all new compounds. Supplementary data
associated with this article can be found, in the online
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