Reactivity switching and selective activation of C-1 or C-3 in 2,3-unsaturated thioglycosides

Article abstract of DOI:10.1016/j.carres.2011.04.039

Reactivity switching and selective activation of C-1 or C-3 in 2,3-unsaturated thioglycosides, namely, 2,3-dideoxy-1-thio-d-hex-2- enopyranosides are reported. The reactivity switching allowed activation of either C-1 or C-3, with the use of either N-iodosuccinimide (NIS)/triflic acid (TfOH) or TfOH alone. C-1 glycosylation with alcohol acceptors occurred in the presence of NIS/TfOH, without the acceptors reacting at C-3. On the other hand, reaction of 2,3-unsaturated thioglycosides with alcohols mediated by triflic acid led to transposition of C-1 ethylthio-moiety to C-3 intramolecularly, to form 3-ethylthio-glycals. Resulting glycals underwent glycosylation with alcohols to afford 3-ethylthio-2-deoxy glycosides. However, when thiol was used as an acceptor, only a stereoselective addition at C-3 resulted, so as to form C-1, C-3 dithio-substituted 2-deoxypyranosides.

Full text of DOI:10.1016/j.carres.2011.04.039

Carbohydrate Research 346 (2011) 1569–1575
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Reactivity switching and selective activation of C-1 or C-3 in 2,3-unsaturated
thioglycosides
⇑
Arunima Mukherjee, Narayanaswamy Jayaraman
Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactivity switching and selective activation of C-1 or C-3 in 2,3-unsaturated thioglycosides, namely, 2,3-
dideoxy-1-thio-D-hex-2-enopyranosides are reported. The reactivity switching allowed activation of
Received 3 December 2010
Received in revised form 17 April 2011
Accepted 27 April 2011
either C-1 or C-3, with the use of either N-iodosuccinimide (NIS)/triflic acid (TfOH) or TfOH alone. C-1 gly-
cosylation with alcohol acceptors occurred in the presence of NIS/TfOH, without the acceptors reacting at
C-3. On the other hand, reaction of 2,3-unsaturated thioglycosides with alcohols mediated by triflic acid
led to transposition of C-1 ethylthio-moiety to C-3 intramolecularly, to form 3-ethylthio-glycals. Result-
ing glycals underwent glycosylation with alcohols to afford 3-ethylthio-2-deoxy glycosides. However,
when thiol was used as an acceptor, only a stereoselective addition at C-3 resulted, so as to form C-1,
C-3 dithio-substituted 2-deoxypyranosides.
Available online 3 May 2011
Dedicated to Professor Dr. András Lipták on
the occasion of his 75th birthday
Keywords:
2-Deoxy sugars
Glycals
Ó 2011 Elsevier Ltd. All rights reserved.
Glycosylation
Thioglycosides
1. Introduction
PO
O
Nu
PO
Thioglycosides are common activated glycosyl donors, on account
of their ease of preparation, stabilities, orthogonal reactivities in the
presence of other functionalities, and facile activation methods.1 On
the other hand, 2,3-dideoxy-hex-2-enopyranosides, referred to as
Ferrier products, serve as excellent intermediates in derivatizations
of monosaccharides with varied functionalities.2 Such products are
formed, in turn, from 1,2-unsaturated sugars, namely, glycals, having
a 3-O-acyl/alkyl group, through acid catalysis. In our efforts to utilize
glycals, the method of treating glycals with ethanethiol, in the pres-
ence of cerium(IV) salt, was identified, in order to prepare activated
2-deoxy glycosyl donors.3 In addition to the formation of 2-deoxy-
1-thioglycosides, the method also led to the formation of the Ferrier
Nu
1
PO
PO
PO
PO
O
O
+
SEt
3
PO
PO
O
I
Nu
P = Protecting group
Nu
Scheme 1.
tion of a nucleophile with dihydropyrylium ion I may lead to two re-
gio-isomers. Studies of the reaction of 1,5-anhydro-2-deoxy-hex-1-
enitol, namely, glycals and 2,3-dideoxy-2-enopyranosides with thiols
were studied previously by Zamojski6 and Fraser-Reid7 groups,
respectively. 2,3-Unsaturated thioglycosides undergo equilibration
to afford 3-S-alkyl-3-thio glycals6 in an acid-catalyzed condition
(HCl or SnCl4). Onthe other hand, glycals reactwiththiols, in the pres-
ence of BF3ꢀEt2O, to afford 2,3-unsaturated 1-thioglycosides, along
with allylic rearrangement isomer 3-S-aryl-3-thio glycals and aryl
1,3-dithio-2-deoxy glycosides.8–11 Further, Blattner and Ferrier
showed that glycals reacted with thiophenol, in the presence of
BF3ꢀEt2O along with catalytic amount of water, to afford S-phenyl 2-
deoxy-3-phenylthio-1-thioglycosides.12 With the knowledge that
thioglycosides are activated by N-iodosuccinimide (NIS)/triflic acid
(TfOH), a commonly used promoter system of thioglycosides, we
undertook to study the glycosylation of 2,3-unsaturated thioglyco-
product, namely, 2,3-dideoxy-1-thio-D-hex-2-enopyranosides. Gly-
cosylations involving activated 2-deoxy-1-thioglycosides afforded a
variety of 2-deoxy sugars, linear, and cyclic-oligosaccharides.4
Continuing to explore the synthetic potential of thioglycosides
formed from glycals, glycosylations of 2,3-unsaturated thioglyco-
sides, namely, 2,3-dideoxy-1-thio-D-hex-2-enopyranosides, ap-
peared attractive. Oxocarbenium ion5 is the reactive intermediate
during activation of a glycosyl donor, and in the case of a 2,3-unsatu-
rated thioglycoside, the oxocarbenium ion may stabilize further by
the presence of a C-2–C-3 unsaturation, as shown in Scheme 1. Reac-
⇑
Corresponding author.
E-mail address: jayaraman@orgchem.iisc.ernet.in (N. Jayaraman).
0008-6215/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2011.04.039

1570
A. Mukherjee, N. Jayaraman / Carbohydrate Research 346 (2011) 1569–1575
sides. The studies showed that it was possible to activate either C-1 or
C-3 selectively, depending on the choice of the activation agent.
Details of this reactivity switching potential of 2,3-unsaturated thio-
glycosides are presented herein.
BnOH, AgOTf, CH2Cl2,
0 oC rt, 15 min.
3
R1
1
OAc
O
R2
NIS, CH2Cl2, MS 4Å
0 oC rt, 15 min.
2. Results and discussion
12
O
N
Precursors of 2,3-unsaturated thioglycoside, namely, ethyl 4,6-
O
di-O-acetyl-2,3-dideoxy-1-thio-D-erythro-hex-2-enopyranoside
(1), and the threo-analog (2), were obtained by reaction of 3,4,6-tri-
O-acetyl glucal with EtSH, in the presence of (NH4)2Ce(NO3)6.3 Gly-
cosylation of thioglycoside 1 was undertaken with few aglycosyl
and glycosyl acceptors, in the presence of NIS/TfOH (cat.), in CH2Cl2
(Scheme 2). Product formed in the reaction was found to be O-gly-
cosides 3–11, with both aglycosyl and glycosyl acceptors. O-Glyco-
Scheme 3.
was prepared (Scheme 4) and subjected to NIS/TfOH promoted gly-
cosylation, as in Scheme 2. Analysis of the product showed that
glycosyl carbonate at C-4, formed under the reaction condition, re-
acted at C-3 to afford 6-O-benzoyl-3,4-di-O-carbonyl glucal 14. We
presume that an altered reactivity profile of carbonate may have
caused nucleophile entry at C-3 of dihydropyrylium ion I. Zamojski
and co-workers put-forth the possibility of hard–soft acid–base
principle13 to account for the reactivity preferences at C-1 and
C-3 of allyl thioglycosides under acidic conditions.6 It is likely that
both carbonate and succinimide nucleophiles exhibit borderline
hard–soft nucleophilicities, leading to entry at C-1 or C-3 which
is somewhat unpredictable. Alternatively, it might be that the
proximity effect led to reaction at C-3, than at C-1 in 13 in the
above reaction.
Reactivities of 2,3-unsaturated thioglycosides were assessed
further with TfOH, in the absence of NIS, with the anticipation that
the double bond might be activated selectively. Thus, reactions
were performed with 1, in the presence of TfOH (0.7 molar equiv)
and an alcohol acceptor (Scheme 5). Analysis of the product
showed that 2-deoxy glycosides 16–18 formed, with transposition
of C-1 ethylthio-moiety to C-3. The transformation appeared to oc-
cur through (i) shift of C-1 ethylthio-moiety to C-3 to afford 3-S-al-
kyl-3-thioglycal II and (ii) subsequent glycosylation of II under the
reaction conditions, leading to 2-deoxy glycoside 16–18. The reac-
tion did not occur when catalytic amount of TfOH was used. Fur-
ther, this transformation also occurred when TMSOTf was used in
place of TfOH. Important observations of the reaction were (i) C-1
ethylthio-moiety transposition led to an equatorial configuration
at C-3, even when anomeric mixture of 1 was used and (ii) product
sides with
a-anomeric configuration were predominant in the
above reactions. The observation that only O-glycosides 3–11
formed in the reaction illustrated that C-1 was the preferred reac-
tive center under NIS/TfOH reaction condition. It was also observed
that O-glycosylation at C-1 occurred in the presence of NIS, with-
out TfOH. Thus, products 4 and 6 were obtained without TfOH in
Scheme 2. Illustrative studies on glycosylations involving allyl
phenylthio-glycosides were demonstrated previously by Fraser-
Reid and co-workers, under iodonium-ion promoted condition, in
the absence of a Lewis acid.7 Our results are in agreement with this
report. Further, reaction of 2,3-unsaturated thioglycosides with
benzyl alcohol in the presence of AgOTf, without TfOH, also affor-
ded O-glycoside product 3, as an a-anomer (Scheme 3). In the ab-
sence of an acceptor, succinimide, generated during the reaction
with NIS, reacted at C-1, and glycosyl derivative 12 was isolated
(Scheme 3).
Constitutions of 2,3-unsaturated O-glycosides 3–13 were con-
firmed by NMR spectroscopies and mass spectrometry. Unsatura-
tions at CH-2–CH-3 were confirmed by the presence of
resonances at ꢁ6 and 5.8 ppm in 1H NMR spectra. Anomeric carbon
in 3–11 showed resonance at ꢁ96–102 and ꢁ92–94 ppm for b- and
a
-anomeric configurations, respectively, in 13C NMR spectra. Thio-
glycoside 1 showed resonance at ꢁ78–80 ppm, for
a- and b-config-
urations of C-1.
With the inability to identify a product with alcohol reacting at
C-3 in intermolecular reactions, an intramolecular reaction of I
with an acceptor was undertaken. For this purpose, C-4-O-tert-
butyloxycarbonyl (O-Boc)-protected thioglycoside derivative 13
with
a-anomeric configuration formed predominantly. When the
reaction was conducted in the absence of a glycosyl acceptor,
R1
OAc
R1
OAc
O
R'OH, NIS, TfOH,CH2Cl2,
MS 4Å, 0 oC, 15 min.
R2
O
R2
OR'
SEt
1
:
R1 = H, R2 = OAc
3: R' = Bn: R1 = H, R2 = OAc; α/β = 2.2:1
R' = Bn: R1 = OAc, R2 = H; only α
2
: R1 = OAc, R2 = H
4
:
5: R' = cyclohexyl: R 1 = H, R2 = OAc; only α
6: R' = cyclohexyl: R1 = OAc, R2 = H; α/β = 4.7:1
O
OMe
=
R'
7: R1 = H, R2 = OAc, R3 = Bz; only α
8: R1 = OAc, R2 = H, R3 = Bz; α/β = 1.75:1
9: R1 = H, R2 = OAc, R3 = Bn; only α
R3O
O
OR3
OMe
OR3
=
R'
10: R1 = H, R2 = OAc, R3 = Bz; only α
11: R1 = H, R2 = OAc, R3 = Bn; α/β = 3.6:1
R3O
OR3
Scheme 2.

A. Mukherjee, N. Jayaraman / Carbohydrate Research 346 (2011) 1569–1575
1571
(i) NaOMe/MeOH, rt, 3 h
BzO
BzO
O
NIS, TfOH, CH2Cl2
0 oC, 15 min.
(ii) BzCl/Py, 0 oC- rt, 1h
O
O
O
O
O
1
O
(iii) Boc2O, DMAP,
CH3CN 4 h, rt
O
SEt
13
14
Scheme 4.
OAc
OAc
O
O
AcO
AcO
1: R= Et
RS
SR
15:
R= 4-Methyl phenyl
II
ROH, TfOH, CH2Cl2
0 oC, 30 min.
(74-78%)
p-Thiocresol,TfOH,
CH2Cl2
TfOH, CH2Cl2,
0 oC, 30 min.
Me3COCOOCH2Ph
0 oC, 30 min.
TfOH, CH2Cl2,
0 oC, 30 min.
AcO
AcO
AcO
16
(only α)
O
O
AcO
AcO
AcO
20
SEt (18%)
RS
EtS
S
O
OR
OAc
OAc
O
16: R= Bn (α/β = 2.8:1)
19 (76%)
(α/β = 3.8:1)
20: R= Et (72%)
SR
17:
18:
21
R= cyclohexyl (α/β = 1.4:1)
R= n-butyl (α/β = 1.6:1)
: R= 4-methyl phenyl
(73%)
Scheme 5.
2,20-dideoxy trehalose derivative (20) formed, with C-1 ethylthio-
moiety transposed to C-3, which might have occurred as a result
of hydrolysis and subsequent glycosylation involving lactol. Reac-
tion of 2,3-unsaturated p-cresylthioglycoside 15 led similarly to
trehalose derivative 20, with transposed 4-methylphenylthio-
moiety.
When p-thiocresol was used as an acceptor, in the reaction with
1, addition across C-2–C-3 double bond occurred and the major
product was ethyl 3-(4-methylphenyl)thio-2-deoxy-1-thioglyco-
side 19 (76%). The transposition and subsequent glycosylation at
C-1 led to 20 (18%) as a minor product. As observed previously,
20 would result by the formation of lactol and subsequent glyco-
sylation. Reaction of benzyl tert-butylcarbonate with ethyl thiogly-
coside 1 in the presence of TfOH provided 16, with transposed
ethylthio-moiety at C-3 and benzyl group at C-1. An anchimeric
assistance arising from C-4 acetoxy group is likely,2a,14 which, in
turn would permit facial selectivity of ethylthio-moiety at C-3. In
order to verify this possibility, 2,3-unsaturated thioglycosides 22
and 2315 were treated with BnOH in the presence of TfOH (Scheme
6).
Whereas 22 afforded O-glycosides 24 and 25 as an epimeric
mixture, galactosyl derivative 23 led to the formation of 3-(4-
methylphenylthio)-O-glycosides 26 and 27, as an anomeric mix-
ture, with axial orientation of the substituent at C-3. These reac-
tions reiterate the role of the C-4 substituent on carbocation at
C-3, through the presence or absence of anchimeric assistance.
In the absence of an ability of TfOH or TMSOTf alone to activate
thioglycoside moiety, preferred activation would occur at the dou-
ble bond. Upon activation, a facile 1?3 shift would lead to transpo-
sition of C-1 ethylthio-moiety to C-3, with concomitant glycal II
(Scheme 5) formation. A glycosylation, under acidic condition,
led to the formation of 2-deoxy glycoside. Glycals providing 2-
deoxy glycosides under acidic conditions are known previ-
ously.16–21
Such a type of 1?3 shift in allyl thioglycosides is known so far
in the presence of BF3ꢀEt2O7–12 and SnCl4.6 A sigmatropic shift
occurring with 3-azido glycals to 2,3-dideoxy-hex-2-enopyranosyl
azides under catalysis by BF3ꢀEt2O,22 as also shifts in 3,4,6-tri-O-
benzyl-D-glycals to 2,3-unsaturated a/b-benzyl glycosides by
BF3ꢀEt2O23 and InCl3 are known. The observed transposition in
24
BnO
BnO
BnO
BnO
BnO
O
BnOH, TfOH,
O
O
BnO
OBn
OBn
CrS
25 (32%)
OAc
+
CH2Cl2, 0 oC-rt
22
SCr
SCr
24 (62%)
Cr
=
Me
AcO
AcO
AcO
OAc
OAc
BnOH, TfOH,
O
O
O
OBn
27 (34%)
+
CH2Cl2, 0 oC-rt,
SCr
23
SCr
OBn
SCr
26 (62%)
Scheme 6.

1572
A. Mukherjee, N. Jayaraman / Carbohydrate Research 346 (2011) 1569–1575
this study thus appeared general, although hard–soft nature of car-
bon centers and those of acceptors seemed to be important. This
view is supported when comparing the reactions of 1 with alcohols
and thiocresol, in the presence of TfOH. Whereas 2-deoxy glyco-
sides 16–18 formed with alcohols, derivative 19 formed as the ma-
jor product, when thiocresol was used (Scheme 5). TfOH-mediated
activation of the double bond is probably prone to attack by a soft
nucleophile, arising either intra- or intermolecularly, thereby lead-
ing to either C-1?C-3 transposition or incorporation of externally
added of thio-functionality, respectively. This observation also
confirms that addition across C-2–C-3 double bond predominates
in the presence of TfOH or TMSOTf, without affecting C-1 thioeth-
yl-moiety. Hard–soft acid–base principle, put-forth by Zamojski
and co-workers for reactivities arising from glycals,6 appears to
be reasonable in order to rationalize the observed addition pattern
upon allylic bond activation.
Structures of 16–21 were confirmed by NMR spectroscopies and
mass spectrometry. In addition, heteronuclear multiple quantum
coherence, correlated spectroscopy, and proton decoupling NMR
techniques were utilized to identify the resonances of individual
nuclei and configurations in few cases. Absence of olefinic protons
in 1H NMR spectra and appearance of resonance at ꢁ91–98 ppm in
13C NMR spectra confirmed 2-deoxy glycoside formation in 16–18,
20, and 21. trans-diequatorial configuration of substituents at C-3–
C-4 was confirmed through proton decoupling experiments,
through which a J value of ꢁ10.5 Hz was observed. Presence of res-
onances at ꢁ1.9 and ꢁ2.1 ppm corresponded to C-2 methylene
protons in 1H NMR spectra, as also a resonance at ꢁ36 ppm, in
the 13C NMR spectra. In the case of C-3 with ethylthio-moiety, sig-
nal at ꢁ39–41 ppm appeared, whereas, that with (4-methyl-
phenyl)thio-moiety, C-3 appeared at ꢁ45–47 ppm. In the case of
24 and 25, the epimeric nature was identified through C-3 reso-
nances that appeared at 45.5 and 46.9 ppm, respectively. The ano-
mers 26 and 27 were adjudged through 13C NMR values of C-1,
in vacuo, and purified by column chromatography (SiO2) to afford
the desired 2,3-unsaturated O-glycosides.
4.2. Benzyl 4,6-di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-
enopyranoside (3)
Yield: 62%. Rf = 0.3 (12% EtOAc/pet. ether). [a] +0.75 (c 0.44,
D
CHCl3). 1H NMR (CDCl3): d 7.36–7.26 (m, 5H), 5.97–5.86 (m, 2H),
5.33 (app. d, J = 12 Hz, 1H), 5.23 (app. s, 1H), 4.80 (d, J = 12 Hz,
1H), 4.59 (d, J = 12 Hz, 1H), 4.31–4.20 (m, 2H), 4.17–4.06 (m, 1H),
2.03 (s, 3H), 2.02 (s, 3H); 13C NMR (CDCl3): d 170.7, 170.2, 137.5,
130.4, 128.0, 127.9, 125.9, 93.6, 72.7, 70.2, 67.0, 65.2 62.8, 20.9,
20.7. HR-MS: m/z calcd for C17H20O6: 343.1158 [M+Na]+. Found:
343.1108.
Alternatively, benzyl alcohol (0.1 mL, 1.2 mmol) and AgOTf
(0.25 g, 0.98 mmol) were added to a solution of 1 (0.3 g, 1.09
mmol) in CH2Cl2 at 0 °C and stirred at room temperature for
ꢁ15 min. The reaction mixture was then concentrated in vacuo
and purified by column chromatography (SiO2) to afford 3. Yield:
0.32 g (91%).
4.3. Benzyl 4,6-di-O-acetyl-2,3-dideoxy-a-D-threo-hex-2-
enopyranoside (4)
Yield: 91%. Rf = 0.2 (12% EtOAc/pet. ether). [
a
]
ꢂ0.83 (c 0.27,
D
CHCl3). 1H NMR (CDCl3): d 7.44–7.26 (m, 5H), 6.12 (dd, J = 5.2,
10 Hz, 1H), 6.04 (dd, J = 2.6, 10 Hz, 1H), 5.17 (d, J = 2.6 Hz, 1H),
5.04 (dd, J = 5.2, 2.6 Hz, 1H), 4.79 (d, J = 8 Hz, 1H), 4.53 (d,
J = 8 Hz, 1H), 4.44–4.41 (m, 1H), 4.31–4.11 (m, 2H), 2.09 (s, 3H),
2.08 (s, 3H); 13C NMR (CDCl3): d 170.6, 170.3, 137.3, 130.5, 128.5,
128.1, 127.9, 125.3, 92.8, 69.8, 66.9, 62.8, 20.8, 20.7. HR-MS: m/z
calcd for C17H20O6: 343.1158 [M+Na]+. Found: 343.1154.
4.4. Cyclohexyl 4,6-di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-
appearing at 95.1 and 97.2 ppm, for
a- and b-anomers, respec-
enopyranoside (5)
tively. b-Anomers showed generally resonances in the range of
96–98 ppm, whereas, those in
range of 92–95 ppm.
a
-anomers were observed in the
Yield: 87%. Rf = 0.35 (12% EtOAc/pet. ether). [a] +86 (c 0.67,
D
CHCl3). 1H NMR (CDCl3): d 5.85–5.82 (m, 2H), 5.29 (app. d,
J = 9.2 Hz, 1H), 5.17 (app. s, 1H), 4.25–4.15 (m, 2H), 3.67–3.62 (m,
1H), 2.09 (s, 3H), 2.06 (s, 3H), 1.93–1.89 (m, 1H), 1.74 (d,
J = 5.2 Hz, 2H), 1.67 (s, 1H), 1.56–1.53 (m, 1H), 1.41–1.17 (m,
6H); 13C NMR (CDCl3): d 170.7, 170.3, 128.7, 128.5, 92.8, 72.6,
66.7, 63.5, 33.7, 32.1, 25.5, 24.3, 20.9, 20.7. HR-MS: m/z calcd for
3. Conclusion
From the series of studies, the possibility of selective activation
of either thioglycoside moiety or allylic bond in 2,3-unsaturated
thioglycoside is established. A reactivity switching between these
two functionalities was possible by a choice of activation reagent.
Thus, whereas NIS or AgOTf activated thioglycoside moiety, double
bond activation occurred in the presence of TfOH or TMSOTf. This
activation led to the formation of a glycal with C-1 thioglycoside
moiety transposed to C-3. The newly formed glycal underwent a
glycosylation at C-1 with available acceptor under the reaction
conditions. Soft thiol nucleophile afforded allylic bond addition
as the major product, with stereoselective substitution at C-3,
thereby leading to the formation of C-1, C-3 dithio-substituted 2-
deoxy pyranosides.
C
16H24O6: 335.1471 [M+Na]+. Found: 335.1473.
4.5. Cyclohexyl 4,6-di-O-acetyl-2,3-dideoxy a-D-threo-hex-2-
enopyranoside (6)
Yield: 89%. Rf = 0.3 (12% EtOAc/pet. ether). [
a
]
ꢂ0.79 (c 0.38,
D
CHCl3). 1H NMR (CDCl3): d 6.09 (dd, J = 5.2, 10.0 Hz, 1H), 6.02 (dd,
J = 2.8, 10.0 Hz, 1H), 5.28 (d, J = 2.8 Hz, 1H), 5.02 (dd, J = 2.3,
5.2 Hz, 1H), 4.50- 4.31 (m, 1H), 4.28–4.19 (m, 1H), 3.68–3.65 (m,
1H), 2.08 (s, 3H), 2.06 (s, 3H), 2.00–1.95 (m, 2H), 1.78–1.65 (m,
2H), 1.56–1.54 (band, 1H), 1.46–1.17 (m, 6H); 13C NMR (CDCl3): d
170.6, 170.3, 131.2, 124.2, 92.3, 70.9, 66.5, 62.9, 33.7, 32.0, 25.5,
24.4, 20.8, 20.7. HR-MS: m/z calcd for
C16H24O6: 335.1471
[M+Na]+. Found: 335.1479.
4. Experimental
4.1. General procedure for the synthesis of 2,3-unsaturated-O-
glycosides
4.6. Methyl-5-O-(4,6-di-O-acetyl-2,3-dideoxy-
a-D-erythro-hex-
2-enopyranosyl)-2,3-di-O-benzoyl- -arabinofuranoside (7)
a-D
Alcohol (1.2 mmol), NIS (1.2 mmol), and molecular sieves (MS)
4 Å were added to a stirred solution of 1 (1 mmol) in CH2Cl2. A
solution of TfOH (10 mol % in CH2Cl2) was added subsequently,
the reaction mixture stirred for ꢁ15 min at 0 °C, diluted with
CH2Cl2, washed with aq Na2S2O3 (5%) solution, brine, concentrated
Yield: 78%. Rf = 0.3 (30% EtOAc/pet. ether). [
a
]
ꢂ19.2 (c 0.67,
D
CHCl3). 1H NMR (CDCl3): d 8.08–8.03 (m, 5H), 7.61–7.54 (m, 1H),
7.46–7.37 (m, 4H), 5.98–5.82 (m, 2H), 5.55 (d, J = 4.8 Hz, 1H),
5.47 (d, J = 2.5 Hz, 1H), 5.45–5.42 (m, 1H), 5.34–5.31 (m, 1H),
5.18–5.15 (m, 1H), 4.41–4.38 (m, 1H), 4.32–4.16 (m, 2H), 4.07–

A. Mukherjee, N. Jayaraman / Carbohydrate Research 346 (2011) 1569–1575
1573
4.03 (m, 1H), 3.94 (d, J = 2.2 Hz, 1H), 3.95–3.89 (m, 1H), 3.47 (s,
4.11. 4,6-Di-O-acetyl-2,3-dideoxy-1-succinimido-
hex-2-enopyranoside (12)
a-D-erythro-
3H), 2.07 (s, 3H), 2.03 (s, 3H); 13C NMR (CDCl3): d 170.8, 170.2,
165.7, 165.4 133.4, 129.9, 129.7, 128.4, 127.5, 106.8, 94.6, 82.1,
70.2, 67.1, 65.0, 62.7, 55.4, 54.9, 20.9,20.7. HR-MS: m/z calcd for
N-Iodosuccinamide (1.2 mmol) and molecular sieves 4 Å were
added to a stirred solution of 1 (1 mmol) in CH2Cl2, stirred for
25 min at 0 °C, diluted with CH2Cl2, washed with aq Na2S2O3 (5%)
solution, brine, concentrated in vacuo and purified by column
chromatography (SiO2).
C
30H32O12: 607.1791 [M+Na]+. Found: 607.1782.
4.7. Methyl-5-O-(4,6-di-O-acetyl-2,3-dideoxy-
a/b-D-threo-hex-2-
enopyranosyl)-2,3-di-O-benzoyl- -arabinofuranoside (8)
a
-D
Yield: 84%. Rf = 0.5 (35% EtOAc/pet. ether). 1H NMR (CDCl3,
400 MHz) d 6.11 (d, J = 10.2 Hz, 1H), 5.78 (d, J = 10.2 Hz, 1H), 5.73
(m, 1H), 5.46 (s, 1H) 4.33 (m, 1H), 4.25–4.15 (m, 2H), 2.15 (s,
3H), 2.08 (s, 3H), 2.77–2.73 (band, 4H); 13C NMR (CDCl3,
100 MHz) d 176.9, 175.4, 170.2, 129.3, 128.8, 126.7, 125.9, 89.8,
74.7, 70.8, 62.5, 29.5, 28.0, 20.9, 20.8. HR-MS: m/z calcd for
Yield: 67%. a
b = 1.75:1. Rf = 0.5 (30% EtOAc/pet. ether). 1H NMR
(CDCl3): d 8.05 (t, J = 8.4 Hz, 12.3H), 7.62–7.51 (m, 4.17H), 7.42 (q,
J = 7.2, 10.5 Hz, 16.3H), 7.39–7.37 (m, 3.52H), 6.09–6.03 (m, 4.50H),
5.52 (d, J = 4.6 Hz, 2.63H), 5.48 (br s, 1.75H), 5.19 (s, 1.50H), 5.13 (s,
1.57H), 4.92 (d, J = 1.2 Hz, 1.27H), 4.41–4.32 (m, 3.62H), 4.03 (d,
J = 6.8 Hz, 6.02H), 3.96 (d, J = 2.8 Hz, 1H), 3.93 (d, J = 4.6 Hz,
1.75H), 3.48 (s, 4.11H), 3.43 (s, 1.05H) 2.13–2.04 (m, 12.7H), 1.98
(s, 8.78H); 13C NMR (CDCl3): d 170.6, 170.3, 167.0, 165.7, 165.3,
133.5, 133.3, 130.3, 129.9, 129.5, 128.5, 125.2, 125.1, 106.8,
101.3, 94.1, 82.1, 79.3, 69.9, 67.0 62.7, 55.5, 54.9, 52.0, 20.8, 20.6.
C
14H17O7N 334.0903 [M+Na]+. Found: 334.0911.
4.12. Ethyl 6-O-benzoyl-4-tert-butyl-O-carbonate-2,3-dideoxy-
1-thio- -erythro-hex-2-enopyranoside (13)
a
-D
C30H32O12:
607.1791 [M+Na]+. Found:
Di-tert-butyldicarbonate(1.2 mmol) andN,N-dimethylaminopyr-
idine (cat.) were added to a solution of ethyl 6-O-benzoyl 2,3-dide-
oxy-1-thio-a-D-erythro-hex-2-enopyranoside (1 mmol) in CH3CN
HR-MS: m/z calcd for
607.1747.
(5 mL). Afterstirringatrtfor 4 h, thereactionmixture wasevaporated
in vacuo, and purified by column chromatography (SiO2).
4.8. Methyl-5-O-(4,6-di-O-acetyl-2,3-dideoxy-
a-D-erythro-hex-
2-enopyranosyl)-2,3-di-O-benzyl- -arabinofuranoside (9)
a-D
Yield: 74%. Rf = 0.2 (40% EtOAc/pet. ether). 1H NMR (CDCl3): d
8.07–8.05 (m, 2H), 7.58–7.54 (m, 1H), 7.45–7.42 (m, 2H), 5.96
(app. d, J = 10.2 Hz, 1H), 5.88 (app. d, J = 10.2 Hz, 1H), 5.57 (app.
s, 1H), 5.25 (app. d, J = 7.1 Hz, 1H), 4.54–4.48 (band, 3H), 2.66 (dt,
J = 7.2, 14.4 Hz, 2H), 1.47 (s, 9H), 1.25 (t, J = 7.2 Hz, 3H); 13C NMR
(CDCl3): d 166.3, 152.7, 133.0, 129.8, 129.6, 129.2, 128.3, 126.6,
83.0, 79.9, 68.0, 66.8, 63.7, 27.6, 25.9, 15.1. HR-MS: m/z calcd for
Yield: 75%. Rf = 0.4 (30% EtOAc/pet. ether). [a] +0.82 (c 0.45,
D
CHCl3). 1H NMR (CDCl3): d 7.29–7.18 (band, 10H), 5.74 (app. q,
J = 7.4, 10.0 Hz, 2H), 5.23 (app. d, J = 10.0 Hz, 1H), 5.02 (app. s,
1H), 4.85 (s, 1H) 4.53–4.38 (m, 6H), 4.16–4.03 (m, 2H), 3.92–3.79
(m, 2H), 3.66 (dd, J = 3.8, 11.2 Hz, 2H), 3.30 (s, 3H), 2.00 (s, 3H),
1.97 (s, 3H); 13C NMR (CDCl3): d 170.8, 170.2, 137.7, 137.3, 129.0,
128.4, 127.9, 127.6, 107.3, 94.6, 87.6, 83.4, 82.5, 80.6, 72.3, 72.1,
67.7, 66.8, 65.1, 62.7, 62.2, 54.9, 54.8, 20.9, 20.4. HR-MS: m/z calcd
for C30H36O10: 579.2206. Found: 579.2206.
C
20H26O6S: 417.1348 [M+Na]+. Found: 417.1345.
4.13. 1, 5 Anhydro-6-O-benzoyl-3,4-O-carbonate-2-deoxy-D-
arabino-hex-1-enitol (14)
Yield:71%. Rf = 0.2 (40%EtOAc/pet. ether). 1H NMR (CDCl3):d8.10–
8.04 (m, 2H), 7.61–7.58 (m, 1H), 7.46 (t, J = 7.6 Hz, 2H), 6.78 (d,
J = 6 Hz, 1H), 5.21 (dd, J = 4.8, 6 Hz, 1H), 5.10–5.07 (m, 1H), 4.86–
4.82 (m, 1H), 4.74 (dd, J = 2.8, 12.4 Hz, 1H), 4.60 (dd, J = 4.8, 12.4 Hz,
1H), 4.08–4.04 (m, 1H). 13C NMR (CDCl3): d 165.9, 153.5, 150.0,
133.4, 129.7, 128.5, 127.6, 96.9, 72.0, 71.2, 69.0, 64.0, 62.0. HR-MS:
m/z calcd for C14H12O6: 299.0532 [M+Na]+. Found: 299.0531.
4.9. Methyl-6-O-(4,6-di-O-acetyl-2,3-dideoxy-
a-erythro-hex-2-
enopyranosyl)-2,3,4-tri-O-benzoyl- - glucopyranoside (10)
a-D
Yield: 62%. Rf = 0.2 (30% EtOAc/pet. ether). [
a
]
D
+23 (c 0.2,
CHCl3). 1H NMR (CDCl3): d 7.94 (m, 4H), 7.81 (d, J = 7.2 Hz, 2H),
7.51 (m, 2H), 7.44–7.36 (m, 4H), 7.29–7.25 (m, 3H), 5.94 (app. d,
J = 5.2 Hz, 2H), 5.76 (m, 1H), 5.63 (app. t, J = 9.6 Hz, 1H), 5.53–
5.45 (m, 2H), 5.28 (d, J = 8.4 Hz, 1H), 5.05 (br s, 1H), 4.73 (d,
J = 7.9 Hz, 1H), 4.12–4.05 (m, 1H), 4.02–3.86 (m, 3H), 3.81–3.76
(m, 1H), 3.55 (s, 3H), 2.10 (s, 3H), 2.08 (s, 3H); 13C NMR (CDCl3):
d 170.7, 170.2, 165.8, 165.1, 133.4, 133.2, 129.9, 129.2, 128.9,
128.5, 128.2, 127.2, 102.0, 94.5, 76.6, 74.5, 73.1, 71.7, 69.5, 65.0,
62.6, 57.2, 20.9, 20.6. HR-MS: m/z calcd for C38H38O14: 741.2159
[M+Na]+. Found: 741.2151.
4.14. 4-Methylphenyl 4,6-di-O-acetyl-2,3-dideoxy-1-thio-
a-D-
erythro-hex-2-enopyrano-side (15)
A mixture of tri-O-acetyl glycal (1 mmol), (NH4)6Ce(NO3)4
(10 mol %) in MeCN was stirred at 0 °C for 15 min. A solution of
p-cresol (5 mmol) in MeCN was added drop-wise to the reaction
mixture and stirring was continued for 15 h at room temperature,
the reaction mixture extracted with Et2O, dried, concentrated in
vacuo, and purified by column chromatography to afford 15.
4.10. Methyl-6-O-(4,6-di-O-acetyl-2,3-dideoxy-
hex-2-enopyranosyl)-2,3,4-tri-O-benzyl-a-D-glucopyranoside
(11)
a
/b-D-erythro-
Yield: 76%. Rf = 0.5 (15% EtOAc/pet. ether). [a] +0.128 (c 0.67,
D
CHCl3). 1H NMR (CDCl3): d 7.45–7.34 (m, 2H), 7.13–7.01 (m, 2H),
6.05 (d, J = 10.2 Hz, 1H), 5.84 (d, J = 10.2 Hz, 1H), 5.68 (s, 1H),
5.37 (d, J = 9.6 Hz, 1H), 4.51–4.46 (m, 1H), 4.29–4.20 (m, 2H),
2.34 (s, 3H), 2.11–2.01 (band, 6H); 13C NMR (CDCl3) d 170.7,
170.3, 138.2, 133.3, 132.4, 130.9, 129.9, 128.6, 127.4, 84.0, 74.7,
67.1, 65.1, 63.2, 20.9, 20.8. HR-MS: m/z calcd for C17H20O5S:
359.0929 [M+Na]+. Found 359.0933.
Yield: 68%. Rf = 0.3 (30% EtOAc/pet. ether).
a
b = 3.6:1. 1H NMR
(CDCl3): d 7.25–7.26 (band, 68.8H), 5.85 (br s, 3.58H), 5.29 (d,
J = 5.2 Hz, 6.89H), 5.10 (br s, 2.98H), 4.97 (d, J = 10.6 Hz, 9.32H),
4.78 (dd, J = 2.8, 11.6 Hz, 10.76H), 4.64 (m, J = 11.6 Hz, 10.79H),
4.62–4.60 (m, 3.65H), 4.58–4.56 (m, 1H), 4.40 (m, 3.08H), 4.16
(dd, J = 4.4, 11.6 Hz, 10.3H), 4.04–3.97 (m, 9.5H), 3.77–3.60 (m,
9.56H), 3.57 (s, 15.92H), 3.37 (s, 13.9H), 2.07 (s, 13.9H), 2.01 (s,
8.76H); 13C NMR (CDCl3): d 170.7, 170.2, 138.6, 138.3, 128.9,
128.4, 128.1, 127.9, 127.7, 98.0, 94.7, 82.1, 79.9, 75.7, 74.8, 73.3,
69.9, 67.0, 66.9, 65.1, 62.7, 55.1, 50.8, 20.9, 20.6. HR-MS: m/z calcd
for C38H44O11: 699.2781, [M+Na]+. Found: 699.2772.
4.15. General procedure for the synthesis of 2,3-dideoxy-3-
thioethyl-O-glycosides
TfOH/TMSOTf (70 mol % in CH2Cl2) was added to a stirred
solution of 2,3-dideoxy-1-thioglycoside (1 mmol), alcohol/thiol

1574
A. Mukherjee, N. Jayaraman / Carbohydrate Research 346 (2011) 1569–1575
(1.2 mmol), CH2Cl2 (6 mL), and stirred at 0 °C for ꢁ30 min. The
reaction mixture was concentrated in vacuo and purified by col-
umn chromatography (SiO2).
4.20. General procedure for the synthesis of 2,3-dideoxy-(1?1)-
disaccharide
TfOH/TMSOTf (70 mol % in CH2Cl2) was added to a stirred solu-
tion of 2,3-dideoxy-1-thioglycoside (1 mmol) in CH2Cl2 (6 mL),
stirred at 0 °C for 30 min, the reaction mixture concentrated in va-
cuo, and purified by column chromatography to afford the
disaccharide.
4.16. Benzyl 4,6-di-O-acetyl-2,3-dideoxy-3-ethylthio-
arabino-hexopyranoside (16)
a-D-
Yield: 78%. Rf = 0.2 (15% EtOAc/pet. ether). [
a
]
ꢂ0.76 (c 0.27,
D
CHCl3). 1H NMR (CDCl3): d 7.39–7.30 (m, 5H), 4.97 (app. d,
J = 2.4 Hz, 1H), 4.90 (app. t, J = 10.2 Hz, 1H), 4.68 (d, J = 12 Hz,
1H), 4.55 (d, J = 12 Hz, 1H), 4.25 (dd, J = 4.8, 12 Hz, 1H), 3.98–3.93
(m, 2H), 3.18–3.11 (m, 1H), 2.58–2.52 (m, 2H), 2.24 (dd, J = 4.4,
13.4 Hz, 1H), 2.09 (s, 6H), 1.94 (ddd, J = 3.2, 13.4, 13.6 Hz, 1H),
1.25–1.19 (t, J = 7.4 Hz, 3H); 13C NMR (CDCl3): d 170.8, 169.7,
137.2, 128.4, 127.9, 127.7, 95.8, 69.6, 69.4, 69.0, 62.9, 41.4, 37.0,
4.21. 4,6-Di-O-acetyl-2,3-dideoxy-3-ethylthio-
a-
D-arabino-pyra
nosyl-(1?1)-4,6-di-O-acetyl-2,3-dideoxy-3-ethylthio-
a-D
-arabi
no-pyranose (20)
Yield: 72%. Rf = 0.4 (40% EtOAc/pet. ether). [a]D 61.73 (c0.18, CHCl3).
1H NMR (CDCl3): d 5.18 (d, J = 2.6 Hz, 2H), 4.90 (d, J = 10.2 Hz, 2H), 4.23
(dd, J = 5.2, 12.4 Hz, 2H), 4.01 (dd, J = 2.6, 12.4 Hz, 2H), 3.88–3.84 (m,
2H), 3.12–3.05 (m, 2H), 2.62–2.58 (m, 4H), 2.16 (dd, J = 4.4, 13.6 Hz,
2H), 2.12 (s, 6H), 2.08 (s, 6H), 1.98 (dd, J = 3.6, 13.6 Hz, 2H), 1.23 (t,
J = 7.2, Hz 6H); 13C NMR (CDCl3): d 170.7, 169.6, 91.7, 69.8, 69.4, 62.9,
41.0, 36.4, 23.6, 20.8, 20.7, 14.6. HR-MS: m/z calcd for C24H38O11S2
589.1753 [M+Na]+. Found: 589.1755.
23.9, 20.9, 14.7. HR-MS: m/z calcd for
C19H26O6S: 405.1348
[M+Na]+. Found: 405.1351.
4.17. Cyclohexyl 4,6-di-O-acetyl-2,3-dideoxy-3-ethylthio-
arabino-hexopyranoside (17)
a/b-D-
Yield: 75%. Rf = 0.3 (15% EtOAc/pet. ether).
a
b = 1.4:1. 1H NMR
(CDCl3): d 5.03–4.94 (m, 1.85H), 4.89 (app. t, J = 10.4 Hz, 1.43H),
4.40–4.18 (m, 3.10H), 4.15–4.11 (m, 0.59H), 4.07–3.97 (m,
3.10H), 3.65–3.50 (m, 3.16H), 3.31–3.29 (m, 0.75H), 3.16–3.09
(m, 1H), 2.72–2.60 (m, 1.53H), 2.59–2.52 (m, 5.16H), 2.25–2.16
(m, 1H), 2.14 (dd, J = 3.6, 13.4 Hz, 1.4H), 2.09–2.04 (m, 20.3H),
1.94 (dd, J = 3.6, 13.4 Hz, 1H), 1.91–1.88 (m, 4.83H), 1.86–1.67
(m, 3.58H), 1.53 (d, J = 8.4 Hz, 2.45H), 1.39–1.18 (m, 16.9H);
13C NMR (CDCl3): d 170.8, 170.1, 169.8, 97.6, 95.7, 75.6, 71.4,
70.6, 66.2, 41.4, 40.8, 36.6, 33.3, 31.5, 26.4, 24.2, 23.9, 20.9,
14.7. HR-MS: m/z calcd for C18H30O6S: 397.1661 [M+Na]+. Found:
397.1666.
4.22. 4,6-Di-O-acetyl-2,3-dideoxy-3-(4-methylphenylthio)-
arabino-pyranosyl-(1?1)-4,6-di-O-acetyl-2,3-dideoxy-3-(4-
methylphenylthio)- -arabino-pyranose (21)
a-D-
a
-D
Yield: 73%. Rf = 0.5 (35% EtOAc/pet. ether). [
a
]
ꢂ39.8 (c 0.44,
D
CHCl3). 1H NMR (CDCl3): d 7.41–7.26 (m, 4H), 7.15–7.04 (m, 4H),
5.15 (d, J = 2.4 Hz, 2H), 4.97 (app. t, J = 9.6 Hz, 2H), 4.92 (dd,
J = 4.0, 9.6 Hz, 2H), 4.31–4.23 (m, 2H), 4.22–4.08 (m, 2H), 4.05–
3.76 (m, 2H), 2.33 (s, 6H), 2.12 (dd, J = 3.4, 16.4 Hz, 2H), 2.07–
2.04 (band, 12H), 1.96 (dd, J = 3.4, 8.8 Hz, 2H); 13C NMR (CDCl3):
d 170.7, 169.9, 137.6, 134.8, 131.7, 129.8, 129.6, 92.5, 75.2, 69.3,
65.4, 62.7, 45.0, 36.6, 20.9, 20.6. HR-MS: m/z calcd for
4.18. Butyl 4,6-di-O-acetyl-2,3-dideoxy-3-ethylthio-
a/b-
D
-
C
34H42O11S2: 713.2066 [M+Na]+. Found: 713.2064.
arabino-hexopyranoside (18)
4.23. Benzyl 4,6-di-O-benzyl-2,3-dideoxy-3-(4-
methylphenylthio)-b- -ribo-hexopyrano side (24)
Yield: 74%. Rf = 0.4 (20% EtOAc/pet. ether).
a
b = 1.6:1. 1H NMR
D
(CDCl3): d 5.02–4.95 (m, 1.18H), 4.90–4.80 (m, 2.1H), 4.79 (dd,
J = 2.6, 6.8 Hz, 0.91H), 4.30–4.22 (m, 3.46H), 4.16–4.07 (m,
1.28H), 4.06–4.01 (m, 1.96H), 3.93–3.87 (m, 1.06H), 3.84–3.80
(m, 1.40H), 3.66–3.59 (m, 1.28H), 3.55–3.49 (m, 1.12H), 3.479–
3.38 (m, 2.48H), 3.14–3.06 (m, 1.05), 2.85–2.49 (band, 5.25H),
2.35–2.24 (band, 0.46H), 2.22–2.15 (dd, J = 3.8, 18 Hz, 1.02H),
2.12–2.05 (m, 16.6H), 2.01–1.96 (m, 1H), 1.95–1.90 (m, 1.6H),
1.62–1.52 (m, 5.04H), 1.55 ꢂ1.35 (m, 5.25H), 1.33–1.18 (m,
9.7H), 0.97–0.87 (m, 8H); 13C NMR (CDCl3): d 170.8, 170.0, 169.8,
98.1, 96.4, 71.7, 69.7, 69.1, 68.9, 67.2, 63.0, 41.4, 40.1, 37.1, 35.2,
31.6 26.2, 23.8, 20.7, 19.4, 19.1, 14.7, 13.8. HR-MS: m/z calcd for
Yield: 62%. Rf = 0.5 (15% EtOAc/pet. ether). [
a
]
ꢂ63.45 (c 0.57,
D
CHCl3). 1H NMR (CDCl3): d 7.36–7.21 (m, 17H), 7.07–7.02 (m,
2H), 5.03 (app. d, J = 5.6 Hz, 1H), 4.86 (d, J = 12 Hz, 1H), 4.64 (d,
J = 12 Hz, 1H), 4.58–4.50 (m, 3H), 4.45 (d, J = 12 Hz, 1H), 4.13–
4.09 (m, 1H), 3.89–3.70 (m, 4H), 2.31 (s, 3H), 2.16–2.11 (m, 1H),
1.90–1.84 (m, 1H); 13C NMR (CDCl3) d 138.2, 137.7, 137.3, 132.8,
130.7, 129.8, 128.3, 128.2, 127.9, 127.7, 127.6, 127.5, 97.0, 74.2,
73.6, 73.3, 71.0, 70.1, 69.8, 45.5, 34.2, 21.0. HR-MS: m/z calcd for
C
34H36O4S: 563.2232 [M+Na]+. Found: 563.2231.
C
16H28O6S: 371.1504 [M+Na]+. Found: 371.1503.
4.24. Benzyl 4,6-di-O-benzyl-2,3-dideoxy-3-(4-
methylphenylthio)- -arabino-hexopyrano side (25)
a
-D
4.19. Ethyl 4,6-di-O-acetyl-2,3-dideoxy-3-(4-methylphenylthio)-
1-thio- /b- -arabino-hexopyranoside (19)
a
D
Yield: 32%. Rf = 0.55 (15% EtOAc/pet. ether). [
a
]
D ꢂ82.27 (c 0.38,
CHCl3). 1H NMR (CDCl3): d 7.45–7.21 (m, 17H), 7.02–7.00 (m, 2H),
4.94 (br s, 1H), 4.81 (d, J = 12 Hz, 1H), 4.68–4.42 (m, 4H), 4.31–4.21
(m, 2H), 3.90–3.87 (m, 1H), 3.83–3.72 (m, 2H), 3.67–3.59 (m, 1H),
2.34 (s, 3H), 2.23–2.18 (m, 2H); 13C NMR (CDCl3) d 138.0, 137.8,
133.0, 129.4, 128.3, 128.2, 128.0, 127.8, 127.5, 127.4, 127.2, 96.1,
74.9, 73.4, 71.6, 69.2, 68.9, 68.5, 46.9, 34.4, 21.0. HR-MS: m/z calcd
for C34H36O4S: 563.2232 [M+Na]+. Found: 563.2240.
Yield: 76%. Rf = 0.5 (15% EtOAc/pet. ether).
a
b = 3.8:1. 1H NMR
(CDCl3): d 7.42–7.26 (m, 13.4H), 7.14–7.02 (m, 13.4H), 5.50 (d,
J = 5.6 Hz, 1.86H), 5.03 (app. t, J = 8 Hz, 1H) 4.94–4.86 (m, 3.82H),
4.33–4.23 (m, 6.16H), 4.21–3.99 (m, 4.4H), 3.18–3.14 (m, 1.99H),
2.77–2.70 (m, 3.30H), 2.60–2.52 (m, 7.23H), 2.33–2.30 (band,
17.9H), 2.10 (dd, J = 3.8, 6 Hz, 5.03H), 2.08–2.06 (band, 17.9H),
2.01 (dd, J = 3.8, 6 Hz, 4.89H), 2.03 (s, 5.15H), 1.38–1.30 (m,
0.48H), 1.29–1.18 (m, 17.6H); 13C NMR (CDCl3): d 170.7, 169.9,
138.0, 137.7, 133.8, 132.5, 130.2, 129.7, 80.5, 78.2, 72.9, 70.3,
69.5, 62.7, 47.7, 45.4, 36.8, 36.3, 25.0, 24.6, 21.0, 20.4, 15.0, 14.8.
HR-MS: m/z calcd for C19H26O5S2: 421.1119 [M+Na]+. Found:
421.1115.
4.25. Benzyl 4,6-di-O-acetyl-2,3-dideoxy-3-(4-methylphenyl
thio)-a-D-xylo-hexopyrano side (26)
Yield: 62%. Rf = 0.57 (15% EtOAc/pet. ether). [
a
]D ꢂ61.87 (c 0.46,
CHCl3). 1H NMR (CDCl3): d 7.45–7.43 (m, 1H), 7.40–7.25 (m, 7H),

A. Mukherjee, N. Jayaraman / Carbohydrate Research 346 (2011) 1569–1575
1575
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3851–3858.
7.14–7.08 (m, 1H), 5.00 (app. d, J = 2.8 Hz, 1H), 4.90 (app. d,
J = 2 Hz, 1H), 4.83 (d, J = 12 Hz, 1H), 4.71 (app. t, J = 6.2 Hz, 1H),
4.62–4.58 (m, 1H), 4.53 (d, J = 12 Hz, 1H), 4.13–4.10 (m, 1H),
3.45–3.42 (m, 1H), 2.44 (ddd, J = 4.2, 12, 15.4 Hz, 1H), 2.32 (s,
3H), 2.07 (s, 3H), 2.05 (s, 3H), 2.00–1.98 (m, 1H), 13C NMR (CDCl3)
d 170.6, 170.2, 137.5, 137.2, 131.9, 131.3, 129.8, 128.4, 127.9,
127.7, 127.6, 127.5, 95.1, 69.3, 68.9, 66.0, 63.5, 62.7, 42.8, 30.2,
21.0, 20.9, 20.7. HR-MS: m/z calcd for
C24H28O6S: 467.1504
[M+Na]+. Found: 467.1504.
8. Valverde, S.; Garcia-Ochoa, S.; Martin-Lomas, M. J. Chem. Soc., Chem. Commun.
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4.26. Benzyl 4,6-di-O-acetyl-2,3-dideoxy-3-(4-methyl
phenylthio)-b- -xylo-hexopyrano side (27)
D
10. De Raadt, A.; Ferrier, R. J. Carbohydr. Res. 1991, 216, 93–107.
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14. Bock, K.; Lundt, I.; Pedersen, C. Acta Chem. Scand. 1969, 2083–2089.
15. Derivatives 22 and 23 were obtained by reaction of 3,4,6-tri-O-acetyl glucal
with thiocresol, in the presence of (NH4)2Ce(NO3)6, as in the preparation of
derivatives 1 and 2.
Yield: 34%. Rf = 0.55 (15% EtOAc/pet. ether). [
a
]
D ꢂ78.31 (c 0.39,
CHCl3). 1H NMR (CDCl3): d 7.37–7.32 (m, 7H), 7.14–7.12 (m, 2H),
4.95 (dd, J = 2.8 Hz, 1H), 4.94 (d, J = 12 Hz, 1H), 4.77 (dd, J = 1.2,
2.4 Hz, 1H), 4.62 (d, J = 12 Hz, 1H), 4.43–4.40 (m, 1H), 4.26–4.21
(m, 1H), 4.17–4.13 (m, 1H), 3.65–3.62 (m, 1H), 2.32 (s, 3H), 2.19–
2.14 (m, 1H), 2.08 (s, 3H), 2.06 (s, 3H), 1.98–1.92 (m, 1H); 13C
NMR (CDCl3) d 170.5, 170.2, 138.0, 137.2, 130.0, 129.3, 128.1,
127.9, 127.6, 97.2, 70.4, 69.9, 67.9, 62.9, 44.9, 31.8, 21.1, 20.9,
20.7. HR-MS: m/z calcd for C24H28O6S: 467.1504 [M+Na]+. Found:
467.1504.
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5813.
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20. Barnes, N. J.; Probert, M. A.; Wightman, R. H. J. Chem. Soc., Perkin Trans. 1 1996,
431–438.
Acknowledgments
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We thank the Department of Biotechnology, New Delhi, for
financial support. Council of Scientific and Industrial Research,
New Delhi, is acknowledged for a research fellowship to A.M.
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