Preparation of glycosyl disulfides and sulphides via the formation of glycosyl Bunte salts as thiol surrogates

Article abstract of DOI:10.1016/j.tet.2021.132242

A convenient odourless reaction condition has been developed for the preparation of symmetrical glycosyl disulfide derivatives and aryl glycosyl disulfide derivatives from corresponding glycosyl iodides via in situ formation of glycosyl Bunte salts as thiol surrogates. The reaction has been further extended towards the preparation of glycosyl sulphide derivatives from corresponding Bunte salt in the presence of sodium sulphide. Most of the reactions were high yielding and suitable for scaling up.

Full text of DOI:10.1016/j.tet.2021.132242

Tetrahedron xxx (xxxx) xxx
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Preparation of glycosyl disulfides and sulfides via the formation of
glycosyl Bunte salts as thiol surrogates
Monalisa Kundu, Anup Kumar Misra*
Bose Institute, Molecular Medicine Division, P-1/12, C.I.T. Scheme VII M, Kolkata, 700054, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A convenient odourless reaction condition has been developed for the preparation of symmetrical
glycosyl disulfide derivatives and aryl glycosyl disulfide derivatives from corresponding glycosyl iodides
via in situ formation of glycosyl Bunte salts as thiol surrogates. The reaction has been further extended
towards the preparation of glycosyl sulfides derivatives from corresponding Bunte salt in the presence of
sodium sulphide. Most of the reactions were high yielding and suitable for scaling up.
© 2021 Elsevier Ltd. All rights reserved.
Received 30 March 2021
Received in revised form
11 May 2021
Accepted 14 May 2021
Available online xxx
Keywords:
Disulfide
Bunte salt
Sulfide
Thiol
Glycosyl
1. Introduction
expensive reagents, prerequisite preparation of special reagents,
handling of moisture sensitive reaction condition etc. Therefore, it
Organic disulfides are important class of compounds having
wide application in the industrial production of pharmaceuticals
[1] and agrochemicals [2]. Moreover, they have been used in the
materials science [3] and synthetic chemistry for the construction
of sulphur containing compounds by CeS bond formation [4].
Glycosyl disulfides have been used as the O-glycoside mimics in the
glycobiology research such as lectin binding, [5] enzyme inhibition,
[6] protein-carbohydrate interactions, [7] development of anti-
cancer agents [8] and studies on the structural aspects of glycans
[9]. Since natural glycosyl disulfides are rare they have been syn-
thesized using a number of reaction methodologies which include,
oxidation of glycosyl sulfides; [10] nucleophilic attack of glycosyl
thiol onto a sulfenyl derivative (sulfonate esters); [11] use of sul-
fenyl halides; [12] sulfenic acids; [13] reaction of glycosyl halides
with selenyl sulfides; [14] benzyltriethylammonium tetrathiomo-
lybdate; [15] coupling of glycosyl thiols under mitsunobu reaction;
[16] 1-chlorobenzotriazole-mediated reaction, [17] DDQ mediated
reaction [18] and many more. Despite their synthetic utility, most of
the reaction conditions suffer from several shortcomings such as,
handling of malodorous thiol reagents, reactive intermediates,
is quite pertinent to develop a reaction condition for the prepara-
tion of glycosyl disulfides avoiding afore-mentioned drawbacks.
Bunte salts [19] can be considered as sulphur surrogates for the
incorporation of sulphur in organic compounds under a non-
malodorous reaction conditions [20]. In general, Bunte salts are
stable, easy-to-handle, non-malodorous and can be considered as
masked thiols. They can be prepared from alkyl halides by the
treatment of sodium thiosulfate (Na2S2O3,5H2O) under convenient
reaction conditions [20]. Bunte salts have versatile applications in
the synthetic chemistry such as they can react with samarium
metal in the presence of InCl3 or I2 to give symmetrical sulfides, [21]
can be hydrolyzed to thiols, [20] can react with Grignard reagent to
give sulfides, [22] can act effective thiol precursor in thia-Michael
reactions, [20,23] to name a few. Recently, Abbasi et al. [24] re-
ported the one-step synthesis of symmetrical disulfides by the re-
action of alkyl halides with Na2S2O3,5H2O in DMSO-H2O.
One of the easily accessible precursor of glycosyl thiols and
disulfides would be glycosyl Bunte salts namely S-glycosylth-
iosulfates, which can be prepared by the reaction of glycosyl halides
with sodium thiosulfate. Recently, Shoda and co-workers reported
the synthesis of anomeric glycosyl Bunte salt by the reaction of
unprotected sugars with Na2S2O3,5H2O in the presence of 2-
chloro-1,3-dimethylimidazolinium chloride (DMC) [25] and their
application in the preparation of S-glycosides, glycosyl disulfides
* Corresponding author.
E-mail address: akmisra69@gmail.com (A.K. Misra).
https://doi.org/10.1016/j.tet.2021.132242
0040-4020/© 2021 Elsevier Ltd. All rights reserved.
Please cite this article as: M. Kundu and A.K. Misra, Preparation of glycosyl disulfides and sulfides via the formation of glycosyl Bunte salts as
thiol surrogates, Tetrahedron, https://doi.org/10.1016/j.tet.2021.132242

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
and thio-Michael adducts [26]. Based on their easy accessibility, it
was decided to explore the possibility of preparing non-anomeric
glycosyl Bunte salts and their use in the preparation of non-
anomerically linked symmetrical as well as unsymmetrical
glycosyl disulfide derivatives. Detailed experimental findings on
the preparation of non-anomerically linked symmetrical as well as
unsymmetrical glycosyl disulfide derivatives using glycosyl Bunte
salts is presented herein (Scheme 1).
non-anomeric glycosyl Bunte salt as odourless thiol surrogate. In
order to optimize the reaction condition, compound 1 was treated
with Na2S2O3,5H2O (1.5 equiv.) in DMSO-H2O (9:1) for 8 h till
complete consumption of the starting material into a polar inter-
mediate (Bunte salt). Treatment of the in situ generated Bunte salt
with 2,6-dimethylthiophenol (1.1 equiv.) in the presence of triethyl
amine (2.0 equiv.) at room temperature led to the formation of
asymmetric disulfide derivative 13 in 82% yield in 45 min. Reduc-
tion in the amount of thiol and base resulted some unreacted Bunte
salt, which on work up furnished symmetric disulfide (7). Since the
reaction mixture of the Bunte salt was acidic in nature, addition of
the triethyl amine is essential for the activation of thiol as well as
cleavage of SeSO3Na bond in Bunte salt. Following similar reaction
conditions, a variety of glycosyl aryl disulfide derivatives (13e28)
were prepared in excellent yield (Table 3). A number of glycosyl
anomeric thiols were allowed to react with Bunte salts in place of
aryl thiols under the reported reaction conditions. Unfortunately,
no desired products were obtained after a long reaction time except
degradation of the anomeric thiols, probably due to the poor
nucleophilicity of the glycosyl anomeric thiols in comparison to the
aromatic thiols. Spectroscopic analysis of synthesized compounds
confirmed their formation.
After successful achievements on the synthesis of glycosyl aryl
disulfide derivatives (13e28), attention was given towards the
preparation of glycosyl alkyl sulfide derivatives using glycosyl
Bunte salt as thiol precursor. Taking clue from the Shoda et al. [26] it
was envisioned that use of a sulfide source may substitute the
thiosulfonate functionality resulting in the formation of a thiolate
anion, which on treatment with alkyl halide could furnish alkyl
sulfides derivative. With this thought, compound 1 was trans-
formed into Bunte salt intermediate by the treatment with
Na2S2O3,5H2O (1.5 equiv.) in DMSO-H2O (9:1). The reaction
mixture was diluted with CH3OH and treated with benzyl bromide
(1.5 equiv.) in the presence of sodium sulfides nonahydrate
(Na2S,9H2O) (3.0 equiv.) at room temperature. Gratifyingly for-
2. Results and discussion
In order to optimize the preparation of glycosyl disulfide de-
rivative via the formation of Bunte salt, 1,2:3,4-di-O-iso-
propylidene-6-iodo-
varied quantities
a
-D-galactopyranose (1) was treated with
of sodium thiosulfate pentahydrate
(Na2S2O3,5H2O) in a variety of solvents and temperature. The re-
action proceeded with the formation of a highly polar compound,
which appeared at the base line of the TLC experiment. After a
series of experimentation, it was observed that use of 1.5 equiv. of
Na2S2O3,5H2O in DMSO-H2O (9:1) at 80 ꢀC could convert com-
pound 1 into corresponding Bunte salt quantitatively in 8 h
(Table 1). Reduction of the quantity of Na2S2O3,5H2O and lowering
the temperature either delayed the formation of the Bunte salt or
resulted incomplete consumption of the starting material. Use of
pure DMSO did not give satisfactory conversion may be due to the
poor solubility of Na2S2O3,5H2O. The advantages of using DMSO-
H2O (9:1) has already been discussed earlier by Abbasi et al. [24]
Due to the instability of the Bunte salt, it was not isolated and
allowed to proceed for next transformation. After complete con-
sumption of the starting material and formation of a highly polar
intermediate (TLC), dilution of the reaction mixture with satd. aq.
NaHCO3 followed by extraction with ethyl acetate furnished sym-
metric disulfide derivative (7) in almost quantitative yield (96%).
Following similar reaction conditions,
a series of symmetric
glycosyl disulfide derivatives (7e12) have been prepared in excel-
lent yield (Table 2). It is noteworthy that compounds 7e12 could be
considered as non-glycosidically disulfide linked pseudo-
disaccharide derivatives, which are important class of glycomi-
metics [5,8]. In order to get secondary glycosyl disulfides, a number
of secondary glycosyl iodide derivatives were also treated with
Na2S2O3,5H2O in DMSO-H2O (9:1) under similar reaction condi-
tions. Unfortunately the reaction did not occur after a long reaction
time (48 h) to give corresponding Bunte salts. All synthesized
compounds were unambiguously characterized by NMR and mass
spectroscopic analysis.
mation of 6-S-benzyl-1,2:3,4-di-O-isopropylidene-6-thio-a-D-gal-
actopyranose (29) was observed in 85% yield in 1 h. Reduction of
the quantity of Na2S,9H2O led to an incomplete reaction mixture,
which on work-up furnished desired compound 29 (46%) together
with a symmetric disulfide derivative 7 (40%) generated from the
unreacted Bunte salt. Therefore, treatment glycosyl Bunte salts
derived from corresponding halides (1e3) were treated with
(Na2S,9H2O) (3.0 equiv.) and alkyl halide (1.5 equiv.) in CH3OH
furnished satisfactory yield of the glycosyl alkyl sulfides derivatives
(29e36) (Table 4). All synthesized compounds were characterized
by their NMR spectral analysis.
After achieving symmetric disulfide derivatives in excellent
yield, it was decided to extend the reaction condition for the
preparation of asymmetric glycosyl aryl disulfide derivatives using
3. Conclusions
In summary, a series of non-anomerically linked symmetrical
glycosyl disulfide derivatives, unsymmetrical glycosyl aryl disulfide
derivatives and glycosyl alkyl sulfide derivatives have been syn-
thesized in excellent yield from glycosyl Bunte salts, generated in
situ by the treatment of glycosyl halides with sodium thiosulfate in
DMSO-H2O (9:1). Synthesized compounds may be considered as
useful glycomimetics for their use in glycobiology research. Since
the reaction condition is simple, reasonably fast, odourless and easy
to scale up, it may be considered as better alternative in comparison
to the methods available in the literature.
8-12
13-28
1-6
4. Experimental
29-36
General methods: All reactions were monitored by thin layer
chromatography over silica gel coated TLC plates. The spots on TLC
were visualized by warming ceric sulphate (2% Ce(SO4)2 in 2 N
Scheme 1. Preparation of non-anomerically linked symmetric and asymmetric
glycosyl aryl disulfides and glycosyl alkyl sulfides derivatives from glycosyl halides
through in situ generation of glycosyl Bunte salt.
2

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
Table 1
Optimization of the reaction condition for the formation of Bunte salt.
1
1a
Sl. No.
Na2S2O3,5H2O (Equiv.)
Solvent
Temp. (ꢀC)
Time (h)
Bunte salt of compd. 1a
1
2
3
4
5
6
7
1.0
1.1
1.5
1.5
1.2
1.5
1.5
CH3OH
CH3OHeH2O (3:1)
DMSO
DMSO-H2O (9:1)
DMSO-H2O (9:1)
DMSO-H2O (9:1)
DMF
70
70
80
80
80
60
80
6
6
8
8
8
8
8
20
20
50
98
90
60
30
a
Not isolated. Yield based on the formation of the spot of polar compound and consumption of starting material in TLC.
H2SO4) sprayed plates in hot plate. Silica gel 230e400 mesh was
used for column chromatography. NMR spectra were recorded on
Bruker Avance 500 MHz using CDCl3 as solvent and TMS as internal
reference unless stated otherwise. Chemical shift value is expressed
J ¼ 3.5 Hz, 1 H, H-1), 3.95 (t, J ¼ 9.5 Hz, 1 H, H-4), 3.84e3.79 (m, 1 H,
H-5), 3.47 (dd, J ¼ 10 Hz, 3.5 Hz,1 H, H-2), 3.35 (s, 3 H, OCH3), 3.28 (t,
J ¼ 9.5 Hz,1 H, H-3), 3.12 (dd, J ¼ 13.5 Hz, 8.5 Hz,1 H, H-6a), 2.73 (dd,
J ¼ 13.5 Hz, 2 Hz, 1 H, H-6b); 13C NMR (125 MHz, CDCl3):
in
d
ppm. The complete assignment of proton and carbon spectra
d 138.6e127.6 (AreC), 97.7 (C-1), 81.9 (C-2), 80.6 (C-4), 80.1 (C-3),
was carried out by using a standard set of NMR experiments, e.g. 1H
NMR, 13C NMR, 13C DEPT 135 etc. ESI-MS were recorded on a Water
Xevo G2-S Q-TOF LC-MS instrument. Optical rotations were recor-
ded in a Jasco P-2000 spectrometer. Commercially available grades
of organic solvents of adequate purity are used in all reactions.
Typical reaction condition for the preparation of symmetri-
cal glycosyl disulfide (7): To a solution of compound 1 (185 mg,
0.5 mmol) in DMSO-H2O (5 mL; 9:1 v/v) was added Na2S2O3,5H2O
(188 mg, 0.75 mmol) and the reaction mixture was stirred at 80 ꢀC
for 8 h (Table 2). After complete consumption of the starting ma-
terial (formation of a spot at the base line of TLC plate; hexane-
EtOAc 1:2), the reaction mixture was diluted with satd. aq.
NaHCO3 (10 mL) and extracted with EtOAc (10 mL). The organic
layer was dried (Na2SO4) and concentrated under reduced pressure.
The crude product was passed through a short pad of SiO2 using
hexane-EtOAc (6:1) as eluant to give pure symmetrical glycosyl
disulfide derivative (7) (265 mg, 96%). Following similar reaction
conditions, compound (8e12) were prepared (Table 2).
75.7 (PhCH2), 74.9 (PhCH2), 73.2 (PhCH2), 69.1 (C-5), 55.3 (OCH3),
42.2 (C-6); HRMS for C56H62O10S2 [MþH]þ: Calcd. 959.3862; found:
959.3846.
Bis-(methyl
disulfide (9): Yield: 460 mg, 96%; Colorless oil. [
CHCl3); 1H NMR (500 MHz, CDCl3):
7.23e7.17 (m,15 H, AreH), 4.91
2,3,4-tri-O-benzyl-
a
-D
-mannopyranosyl)-6,6′-
a
]
D
þ 67 (c 1.0,
d
(d, J ¼ 11.0 Hz, 1 H, PhCH), 4.69 (ABq, J ¼ 10.5 Hz, 2 H, 2 PhCH), 4.65
(d, J ¼ 1.5 Hz, 1 H, H-1), 4.57 (br s, 2 H, 2 PhCH), 4.54 (d, J ¼ 11.5 Hz,
1 H, PhCH), 3.84 (dd, J ¼ 9.5 Hz, 3.0 Hz, 1 H, H-3), 3.80e3.77 (m, 1 H,
H-5), 3.74 (br s, 1 H, H-2), 3.73 (t, J ¼ 9.5 Hz, 1 H, H-4), 3.29 (s, 3 H,
OCH3), 3.15 (dd, J ¼ 13.0 Hz, 2.0 Hz, 1 H, H-6a), 2.84 (dd, J ¼ 13.0 Hz,
1.2 Hz,1 H, H-6b); 13C NMR (125 MHz, CDCl3):
d 138.4e127.5 (AreC),
98.8 (C-1), 80.2 (C-5), 77.7 (C-4), 74.8 (C-3), 74.7 (PhCH2), 72.7
(PhCH2), 72.1 (PhCH2), 70.4 (C-2), 54.8 (OCH3), 41.5 (C-6); HRMS for
C
56H62O10S2 [MþH]þ: Calcd. 959.3862; found: 959.3846.
Bis-(2-benzyloxycarbonylamino 2,3,4-tri-O-benzyl-
a-D-glu-
copyranosyl)-6,6′-disulfide (10): Yield: 578 mg, 90%; Colorless oil.
[
a
]
D þ 33 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
d 7.22e7.17 (m,
Analytical data of symmetrical glycosyl disulfide derivative
(7e12):
Since compounds 7e12 are symmetrical in nature, the integra-
tion of each proton signal is two, although they appeared as one in
the NMR spectra.
20 H, AreH), 5.32 (br s, 1 H, NH), 5.01 (br s, 2 H, 2 PhCH (Cbz)), 4.87
(d, J ¼ 11.0 Hz, 1 H, PhCH), 4.78 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.69 (d,
J ¼ 10.5 Hz, 1 H, PhCH), 4.62 (d, J ¼ 11.5 Hz, 1 H, PhCH), 4.53 (d,
J ¼ 3.0 Hz, 1 H, H-1), 4.48e4.45 (m, 2 H, 2 PhCH), 3.85 (t, J ¼ 9.5 Hz,
1 H, H-3), 3.77e3.74 (m,1 H, H-5), 3.41 (dd, J ¼ 8.0 Hz, 4.5 Hz,1 H, H-
2), 3.37e3.26 (m, 3 H, 2 OCH, NCH), 3.21e3.17 (m, 1 H, H-6a),
3.03e3.00 (m, 1 H, H-6b), 2.60e2.55 (m, 1 H, NCH); 13C NMR
Bis-(1,2:3,4-di-O-isopropylidene-
disulfide (7): Yield: 265 mg, 96%; Colorless oil. [
CHCl3); 1H NMR (500 MHz, CDCl3):
a
-
D
-galactopyranosyl)-6,6′-
a
]
D
þ 43 (c 1.0,
d
5.44 (d, J ¼ 5.0 Hz, 1 H, H-1),
(125 MHz, CDCl3): d 156.3 (PhCO), 138.6e127.6 (AreC), 97.0 (C-1),
4.55 (dd, J ¼ 7.0 Hz, 1.0 Hz, 1 H, H-3), 4.29 (dd, J ¼ 8.0 Hz, 1.0 Hz, 1 H,
H-2), 4.23e4.22 (m, 1 H, H-4), 3.98e3.96 (m, 1 H, H-5), 2.86e2.85
(m, 2 H, H-6ab), 1.48 (s, 3 H, CH3), 1.36 (s, 3 H, CH3), 1.27 (s, 3 H, CH3),
81.8 (C-2), 80.5 (C-3), 80.3 (C-4), 75.6 (PhCH2), 75.0 (PhCH2), 73.3
(PhCH2), 69.3 (C-5), 67.6 [PhCH2(Cbz)], 66.7 (OCH2), 41.8 (NCH2),
40.7 (C-6); HRMS for C74H80N2O14S2 [MþH]þ: Calcd. 1285.5129;
found: 1285.5110.
1.26 (s, 3 H, CH3); 13C NMR (125 MHz, CDCl3):
d 138.1e126.9 (AreC),
109.2 [C(CH3)2], 108.7 [C(CH3)2], 96.6 (C-1), 71.5 (C-3), 70.9 (C-4),
70.5 (C-5), 66.5 (C-2), 43.4 (C-6), 26.1 (CH3), 26.0 (CH3), 25.0 (CH3),
24.5 (CH3); HRMS for C24H38O10S2 [MþH]þ: Calcd. 551.1984; found:
551.1968.
Bis-(methyl 2,3,4-tri-O-benzoyl-
sulfide (11): Yield: 500 mg, 96%; Colorless oil. [
CHCl3); 1H NMR (500 MHz, CDCl3):
7.83e7.18 (m, 15 H, AreH),
6.08 (t, J ¼ 9.5 Hz, 1 H, H-3), 5.35 (t, J ¼ 9.5 Hz, 1 H, H-4), 5.21 (dd,
J ¼ 9.5 Hz, 4.0 Hz, 1 H, H-2), 5.14 (d, J ¼ 3.5 Hz, 1 H, H-1), 4.29e4.19
(m, 1 H, H-5), 3.46 (s, 3 H, OCH3), 2.96e2.94 (m, 2 H, H-6ab); 13C
a
-
D
-glucopyranosyl)-6,6′-di-
a]
ꢁ 13 (c 1.0,
D
d
Bis-(methyl 2,3,4-tri-O-benzyl-
sulfide (8): Yield: 452 mg, 94%; Colorless oil. [
CHCl3); 1H NMR (500 MHz, CDCl3):
7.25e7.17 (m, 15 H, AreH),
a
-D
-glucopyranosyl)-6,6′-di-
a]
þ 27 (c 1.0,
D
d
NMR (125 MHz, CDCl3): d 165.6 (PhCO), 165.4 (2 C; 2 PhCO),
4.95 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.86 (d, J ¼ 11.5 Hz, 1 H, PhCH), 4.77
(d, J ¼ 11.0 Hz, 1 H, PhCH), 4.73 (d, J ¼ 12.0 Hz, 1 H, PhCH), 4.61 (d,
J ¼ 12.5, 1 H, PhCH), 4.56 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.52 (d,
133.4e128.2 (AreC), 96.8 (C-1), 72.2 (C-2), 72.0 (C-3), 70.3 (C-4),
68.2 (C-5), 55.6 (OCH3), 41.6 (C-6); HRMS for C56H50O16S2 [MþH]þ:
Calcd. 1043.2618; found: 1043.2600.
3

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
Table 2
Preparation of non-anomerically linked symmetric glycosyl disulfides from glycosyl halide via the formation of corresponding Bunte salt.
7-12
1-6
Sl. No.
1
Glycosyl halide
Product
Time (h)a
8
Yield (%)b
96
1
7
2
2
94
2
8
3
2
96
3
9
4
5
6
4
6
6
90
96
95
10
4
5
6
11
12
a
Time required for the formation of corresponding Bunte salt.
Isolated yield.
b
Bis-(methyl 2,3,4-tri-O-benzoyl-
disulfide (12): Yield: 495 mg, 95%; Colorless oil. [
CHCl3); 1H NMR (500 MHz, CDCl3):
8.09e7.21 (m, 15 H, AreH),
a
-
D
-mannopyranosyl)-6,6′-
(AreC), 98.5 (C-1), 70.5 (C-5), 69.9 (C-3), 69.8 (C-4), 69.2 (C-2), 55.4
(OCH3), 41.9 (C-6); HRMS for C56H50O16S2 [MþH]þ: Calcd.
1043.2618; found: 1043.2600.
a]
þ 77 (c 1.0,
D
d
5.81 (dd, J ¼ 10.0 Hz, 3.5 Hz, 1 H, H-3), 5.67 (t, J ¼ 10.0 Hz, 1 H, H-4),
5.59 (br s, 1 H, H-2), 4.86 (br s, 1 H, H-1), 4.29e4.25 (m, 1 H, H-5),
3.49 (s, 3 H, OCH3), 3.03e3.02 (m, 2 H, H-6ab); 13C NMR (125 MHz,
Typical reaction condition for the preparation of glycosyl
aryl disulfide (13): To a solution of compound 1 (370 mg, 1.0 mmol)
in DMSO-H2O (5 mL; 9:1 v/v) was added Na2S2O3,5H2O (375 mg,
1.5 mmol) and the reaction mixture was stirred at 80 ꢀC for 8 h. The
CDCl3):
d 165.5 (PhCO), 165.2 (PhCO), 165.1 (PhCO), 133.4e128.2
4

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
Table 3
Preparation of non-anomerically linked glycosyl aryl disulfides from glycosyl iodides via the formation of Bunte salt.
13-28
1-6
Sl. No.
1
Glycosyl halide
Aryl thiol
Product
Time (min)a
Yield (%)b
82
45
1
13
2
3
4
1
60
30
45
80
84
86
14
1
15
1
16
17
18
5
6
7
60
30
30
78
83
88
2
2
2
19
(continued on next page)
5

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
Table 3 (continued)
Sl. No.
8
Glycosyl halide
2
Aryl thiol
Product
Time (min)a
Yield (%)b
82
30
20
9
30
86
82
80
3
21
10
3
30
22
22
11
45
5
6
23
12
30
85
24
13
6
30
84
25
14
6
30
80
26
15
6
45
86
27
6

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
Table 3 (continued)
Sl. No.
16
Glycosyl halide
Aryl thiol
Product
Time (min)a
60
Yield (%)b
78
6
28
a
Time required after the formation of Bunte salt.
Isolated yield.
b
reaction mixture was cooled to room temperature and 2,6-
dimethylthiophenol (155 mg, 1.1 mmol) and Et3N (0.2 mL,
2 mmol) were added to it. After stirring the reaction mixture at
room temperature for 45 min (Table 3), it was diluted with satd. aq.
NaHCO3 (10 mL) and extracted with EtOAc (10 mL). The organic
layer was dried (Na2SO4) and concentrated under reduced pressure.
The crude product was passed through a short pad of SiO2 using
hexane-EtOAc (6:1) as eluant to give pure symmetrical glycosyl
disulfide derivative (13) (338 mg, 82%). Following similar reaction
conditions, compounds 14e28 were prepared (Table 3).
Analytical data of symmetrical glycosyl disulfide derivative
(13e28):
J ¼ 7.5 Hz, 2.0 Hz, 1 H, H-3), 4.24e4.21 (m, 2 H, H-2, H-4), 4.01e3.99
(m, 1 H, H-5), 3.75 (s, 3 H, OCH3), 2.86e2.83 (m, 2 H, H-6ab), 1.44 (s,
3 H, CH3), 1.36 (s, 3 H, CH3), 1.26 (s, 6 H, 2 CH3); 13C NMR (125 MHz,
CDCl3):
d
160.1e112.5 (AreC), 109.3 [(CH3)2C(O)2], 108.7
[(CH3)2C(O)2], 96.6 (C-1), 71.6 (C-3), 70.9 (C-4), 70.5 (C-2), 66.2 (C-
5), 55.2 (OCH3), 38.2 (C-6), 26.0 (2 CH3), 25.0 (CH3), 24.4 (CH3);
HRMS for C19H26O6S2 [MþH]þ: Calcd. 415.1249; found: 415.1232.
Methyl 2,3,4-tri-O-benzyl-6-deoxy-6-(2-napthyldithio)-a-D-
glucopyranoside (17): Yield: 497 mg, 78%; Colorless oil. [
a
]
D þ 26
(c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
d
7.93e6.97 (m, 22 H,
AreH), 4.80 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.63 (ABq, J ¼ 10.0 Hz, 2 H, 2
PhCH), 4.59 (br s, 1 H, H-1), 4.50 (br s, 2 H, 2 PhCH), 4.44 (d,
J ¼ 11.0 Hz, 1 H, PhCH), 3.80e3.76 (m, 2 H, H-3, H-5), 3.68 (br s, 1 H,
H-2), 3.65 (t, J ¼ 9.5 Hz, 1 H, H-4), 3.24 (s, 3 H, OCH3), 3.14 (dd,
J ¼ 13.5 Hz, 2.0 Hz, 1 H, H-6a), 2.85 (dd, J ¼ 13.5 Hz, 2.0 Hz, 1 H, H-
6-Deoxy-6-(2,6-dimethylphenyldithio)-1,2:3,4-di-O-iso-
propylidene-
Colorless oil. [
a
-
]
D
-galactopyranose (13): Yield: 338 mg, 82%;
a
þ 30 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
D
d
7.43e6.86 (m, 3 H, AreH), 5.44 (d, J ¼ 5.0 Hz, 1 H, H-1), 4.55 (dd,
6b); 13C NMR (125 MHz, CDCl3):
d 138.3e126.0 (AreC), 98.8 (C-1),
J ¼ 8.0 Hz, 2.0 Hz, 1 H, H-3), 4.28 (dd, J ¼ 7.5 Hz, 1.5 Hz, 1 H, H-2),
4.23 (dd, J ¼ 5.0 Hz, 2.5 Hz, 1 H, H-4), 4.05e4.03 (m, 1 H, H-5),
2.82e2.80 (m, 2 H, H-6ab), 2.27 (s, 6 H, 2 CH3), 1.45 (s, 3 H, CH3), 1.36
(s, 3 H, CH3), 1.27 (s, 6 H, 2 CH3); 13C NMR (125 MHz, CDCl3):
80.2 (C-2), 77.6 (C-3), 75.0 (PhCH2), 74.6 (C-4), 72.7 (PhCH2), 72.1
(PhCH2), 70.2 (C-5), 54.7 (OCH3), 41.2 (C-6); HRMS for C38H38O5S2
[MþH]þ: Calcd. 639.2239; found: 639.2222.
Methyl
2,3,4-tri-O-benzyl-6-deoxy-6-(4-
d
136.2e127.9 (AreC), 109.3 [(CH3)2C(O)2], 108.7 [(CH3)2C(O)2], 96.6
chlorophenyldithio)-
a
-
D
-glucopyranoside (18): Yield: 516 mg,
(C-1), 71.5 (C-3), 70.9 (C-4), 70.6 (C-2), 66.3 (C-5), 37.6 (C-6), 26.0 (2
CH3), 25.0 (CH3), 24.5 (CH3), 21.1 (CH3), 19.5 (CH3); HRMS for
C
83%; Colorless oil. [
CDCl3):
a
]
þ 42 (c 1.0, CHCl3); 1H NMR (500 MHz,
D
d
7.34e7.06 (m, 19 H, AreH), 4.90 (d, J ¼ 11.0 Hz, 1 H, PhCH),
20H28O5S2 [MþH]þ: Calcd. 413.1456; found: 413.1438.
4.80 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.72e4.68 (m, 2 H, 2 PhCH), 4.58 (d,
J ¼ 12.0 Hz, 1 H, PhCH), 4.44 (d, J ¼ 4.0 Hz, 1 H, H-1), 4.42 (d,
J ¼ 11.5 Hz, 1 H, PhCH), 3.90 (t, J ¼ 9.0 Hz, 1 H, H-3), 3.82e3.79 (m,
1 H, H-5), 3.39 (dd, J ¼ 9.5 Hz, 3.5 Hz, 1 H, H-2), 3.29 (s, 3 H, OCH3),
3.20 (t, J ¼ 9.5 Hz, 1 H, H-4), 3.02 (dd, J ¼ 13.5 Hz, 3.5 Hz, 1 H, H-6a),
2.66 (dd, J ¼ 13.5 Hz, 3.5 Hz, 1 H, H-6b); 13C NMR (125 MHz, CDCl3):
6-Deoxy-6-(3,4-dichlorophenyldithio)-1,2:3,4-di-O-iso-
propylidene-
Colorless oil. [
d
a
-
]
D
-galactopyranose (14): Yield: 361 mg, 80%;
þ 44 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
a
D
7.56e7.19 (m, 3 H, AreH), 5.44 (d, J ¼ 5.0 Hz, 1 H, H-1), 4.55 (dd,
J ¼ 8.0 Hz, 2.5 Hz, 1 H, H-3), 4.24 (dd, J ¼ 5.0 Hz, 2.5 Hz, 1 H, H-2),
4.20e4.18 (m,1 H, H-6a), 3.97e3.89 (m,1 H, H-5), 2.88e2.85 (m,1 H,
H-6b), 1.41 (s, 3 H, CH3), 1.36 (s, 3 H, CH3), 1.26 (s, 3 H, CH3), 1.25 (s,
d
138.6e127.6 (AreC), 97.8 (C-1), 81.8 (C-5), 80.5 (C-3), 80.0 (C-4),
75.7 (PhCH2), 75.0 (PhCH2), 73.3 (PhCH2), 68.9 (C-2), 55.2 (OCH3),
41.3 (C-6); HRMS for C34H35ClO5S2 [MþH]þ: Calcd. 623.1692;
found: 623.1676.
Methyl
methylphenyldithio)-
3 H, CH3); 13C NMR (125 MHz, CDCl3):
d 137.2e126.5 (AreC), 109.4
[(CH3)2C(O)2], 108.7 [(CH3)2C(O)2], 96.6 (C-1), 71.6 (C-3), 70.9 (C-4),
70.4 (C-2), 66.3 (C-5), 38.7 (C-6), 25.9 (2 CH3), 24.9 (CH3), 24.5
(CH3); HRMS for C18H22Cl2O5S2 [MþH]þ: Calcd. 453.0364; found:
453.0346.
2,3,4-tri-O-benzyl-6-deoxy-6-(3-
-glucopyranoside (19): Yield: 530 mg,
a
-
D
88%; Colorless oil. [
CDCl3):
a
]
þ 53 (c 1.0, CHCl3); 1H NMR (500 MHz,
D
6-Deoxy-6-(2-bromophenyldithio)-1,2:3,4-di-O-iso-
d
7.7.31e6.93 (m, 19 H, AreH), 4.90 (d, J ¼ 11.0 Hz, 1 H,
propylidene-
Colorless oil. [
d
a
-
]
D
-galactopyranose (15): Yield: 390 mg, 84%;
PhCH), 4.77 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.71e4.68 (m, 2 H, 2 PhCH),
4.57 (d, J ¼ 12.0 Hz, 1 H, PhCH), 4.46 (d, J ¼ 5.0 Hz, 1 H, PhCH), 4.44
(d, J ¼ 2.0 Hz, 1 H, H-1), 3.90 (t, J ¼ 9.0 Hz, 1 H, H-3), 3.85e3.77 (m,
1 H, H-5), 3.40 (dd, J ¼ 9.5 Hz, 3.5 Hz, 1 H, H-2), 3.30 (s, 3 H, OCH3),
3.22 (t, J ¼ 9.5 Hz, 1 H, H-4), 3.07 (dd, J ¼ 13.0 Hz, 2.0 Hz, 1 H, H-6a),
2.69 (dd, J ¼ 13.0 Hz, 2.0 Hz, 1 H, H-6b), 2.24 (s, 3 H, CH3); 13C NMR
a
þ 21 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
D
7.74e6.98 (m, 4 H, AreH), 5.44 (d, J ¼ 5.0 Hz, 1 H, H-1), 4.55 (dd,
J ¼ 7.5 Hz, 2.0 Hz, 1 H, H-3), 4.25e4.22 (m, 2 H, H-2, H-4), 4.08e3.98
(m, 1 H, H-5), 2.85e2.81 (m, 2 H, H-6ab), 1.46 (s, 3 H, CH3), 1.36 (s,
3 H, CH3), 1.26 (s, 3 H, CH3), 1.25 (s, 3 H, CH3); 13C NMR (125 MHz,
CDCl3):
d
137.3e121.4 (AreC), 109.3 [(CH3)2C(O)2], 108.8
(125 MHz, CDCl3): d 138.7e125.5 (AreC), 97.8 (C-1), 81.9 (C-5), 80.5
[(CH3)2C(O)2], 96.6 (C-1), 71.6 (C-3), 70.9 (C-4), 70.5 (C-2), 66.1 (C-
5), 37.7 (C-6), 26.0 (2 CH3), 25.0 (CH3), 24.5 (CH3); HRMS for
C
(C-3), 80.0 (C-4), 75.7 (PhCH2), 74.9 (PhCH2), 73.3 (PhCH2), 69.0 (C-
2), 55.2 (OCH3), 41.6 (C-6), 21.4 (CH3); HRMS for C35H38O5S2
[MþH]þ: Calcd. 603.2239; found: 603.2225.
18H23BrO5S2 [MþH]þ: Calcd. 463.0248; found: 463.0233.
6-Deoxy-6-(3-methoxyphenyldithio)-1,2:3,4-di-O-iso-
Methyl
2,3,4-tri-O-benzyl-6-deoxy-6-(3-
propylidene-
Colorless oil. [
a
-
]
D
-galactopyranose (16): Yield: 356 mg, 86%;
þ 63 (c 1.0, CHCl3); 1H NMR (500 MHz,CDCl3):
methoxyphenyldithio)-
a
-
D
-glucopyranoside
(20):
Yield:
a
506 mg, 82%; Colorless oil. [
(500 MHz, CDCl3):
a
]
D
þ 21 (c 1.0, CHCl3); 1H NMR
D
d
7.15e6.66 (m, 4 H, AreH), 5.44 (d, J ¼ 5.0 Hz, 1 H, H-1), 4.54 (dd,
d
7.22e6.66 (m, 19 H, AreH), 4.89 (d, J ¼ 11.0 Hz,
7

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
Table 4
Preparation of glycosyl alkyl sulphides from glycosyl iodides via the formation of Bunte salt.
29-36
1-3
Sl. No.
1
Glycosyl halide
Alkyl halide
BnBr
Product
Time (min)a
60
Yield (%)b
85
29
1
2
3
1
All Br
60
60
80
82
30
31
1
NAPBr
4
5
NAPBr
BnBr
45
45
78
86
32
33
34
35
36
2
3
6
7
8
3
All Br
45
60
60
82
76
78
3
3
NAPBr
PMBCl
a
Time required after the formation of Bunte salt.
Isolated yield. NAP: 2-naphthylmethyl; PMB: p-methoxybenzyl.
b
8

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
1 H, PhCH), 4.77 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.71e4.68 (m, 2 H, 2
PhCH), 4.57 (d, J ¼ 12.0 Hz, 1 H, PhCH), 4.46 (d, J ¼ 11.0 Hz, 1 H,
PhCH), 4.44 (d, J ¼ 3.5 Hz, 1 H, H-1), 3.89 (t, J ¼ 9.5 Hz, 1 H, H-3),
3.88e3.81 (m, 1 H, H-5), 3.69 (s, 3 H, OCH3), 3.41 (dd, J ¼ 9.5 Hz,
3.5 Hz, 1 H, H-2), 3.30 (s, 3 H, OCH3), 3.26 (t, J ¼ 9.5 Hz, 1 H, H-4),
3.06 (dd, J ¼ 12.5 Hz, 2.0 Hz, 1 H, H-6a), 2.69 (dd, J ¼ 12.5 Hz, 2.0 Hz,
NMR (125 MHz, CDCl3):
d
165.5 (PhCO), 165.4 (PhCO), 165.3 (PhCO),
136.0e128.2 (AreC), 98.4 (C-1), 70.6 (C-5), 69.9 (C-3), 69.8 (C-4),
69.0 (C-2), 55.3 (OCH3), 40.9 (C-6), 21.0 (CH3), 20.7 (CH3); HRMS for
C
36H34O8S2 [MþH]þ: Calcd. 659.1773; found: 659.1760.
Methyl
2,3,4-tri-O-benzoyl-6-deoxy-6-(3-
chlorophenyldithio)-
80%; Colorless oil. [
CDCl3):
a-D-mannopyranoside (26): Yield: 531 mg,
1 H, H-6b); 13C NMR (125 MHz, CDCl3):
d
160.1e113.0 (AreC), 97.8
a
]
þ 55 (c 1.0, CHCl3); 1H NMR (500 MHz,
D
(C-1), 81.9 (C-2), 80.5 (C-3), 80.0 (C-4), 75.7 (PhCH2), 74.9 (PhCH2),
73.3 (PhCH2), 69.1 (C-5), 55.2 (2 C, 2 OCH3), 41.6 (C-6); HRMS for
d
8.02e6.97 (m, 19 H, AreH), 5.76 (dd, J ¼ 9.0 Hz, 2.0 Hz, 1 H,
H-3), 5.66 (t, J ¼ 9.0 Hz,1 H, H-4), 5.56 (br s, 1 H, H-2), 4.86 (br s,1 H,
H-1), 4.31e4.27 (m, 1 H, H-5), 3.46 (s, 3 H, OCH3), 3.01e2.94 (m, 2 H,
C
35H38O6S2 [MþH]þ: Calcd. 619.2188; found: 619.2176.
Methyl
2,3,4-tri-O-benzyl-6-deoxy-6-(4-
H-6ab); 13C NMR (125 MHz, CDCl3):
d 165.6 (PhCO), 165.3 (PhCO),
methylphenyldithio)-
a
-
D
-mannopyranoside (21): Yield: 517 mg,
165.2 (PhCO), 138.6e126.0 (AreC), 98.5 (C-1), 70.5 (C-5), 69.8 (C-3),
69.7 (C-4), 69.0 (C-2), 55.5 (OCH3), 41.2 (C-6); HRMS for
C
86%; Colorless oil. [
a
]
þ 48 (c 1.0, CHCl3); 1H NMR (500 MHz,
D
CDCl3):
d
7.35e6.97 (m, 19 H, AreH), 4.84 (d, J ¼ 11.0 Hz, 1 H, PhCH),
34H29ClO8S2 [MþH]þ: Calcd. 665.1070; found: 665.1056.
4.63 (ABq, J ¼ 10.0 Hz, 2 H, 2 PhCH), 4.60 (br s, 1 H, H-1), 4.51 (br s,
2 H, 2 PhCH), 4.46 (d, J ¼ 11.0 Hz,1 H, PhCH), 3.79e3.77 (m, 2 H, H-3,
H-5), 3.68 (br s, 1 H, H-2), 3.65 (t, J ¼ 9.5 Hz, 1 H, H-4), 3.24 (s, 3 H,
OCH3), 3.11 (dd, J ¼ 13.5 Hz, 2.0 Hz, 1 H, H-6a), 2.81 (dd, J ¼ 13.5 Hz,
2.0 Hz, 1 H, H-6b), 2.25 (s, 3 H, CH3); 13C NMR (125 MHz, CDCl3):
Methyl
2,3,4-tri-O-benzoyl-6-deoxy-6-(3-
methoxyphenyldithio)-
567 mg, 86%; Colorless oil. [
(500 MHz, CDCl3):
2.0 Hz, 1 H, H-3), 5.65 (t, J ¼ 9.0 Hz, 1 H, H-4), 5.56 (br s, 1 H, H-2),
4.86 (br s, 1 H, H-1), 4.34e4.24 (m, 1 H, H-5), 3.65 (s, 3 H, OCH3),
3.46 (s, 3 H, OCH3), 3.02e2.96 (m, 2 H, H-6ab); 13C NMR (125 MHz,
a
-
D
-mannopyranoside
(27):
Yield:
a]
þ 88 (c 1.0, CHCl3); 1H NMR
D
d
8.02e6.59 (m, 19 H, AreH), 5.76 (dd, J ¼ 9.0 Hz,
d
138.3e127.5 (AreC), 98.8 (C-1), 80.2 (C-5), 77.6 (C-3), 75.0
(PhCH2), 74.6 (C-4), 72.7 (PhCH2), 72.1 (PhCH2), 70.1 (C-2), 54.7
(OCH3), 41.0 (C-6), 21.1 (CH3); HRMS for C35H38O5S2 [MþH]þ: Calcd.
603.2239; found: 603.2227.
CDCl3):
d 165.6 (PhCO), 165.3 (PhCO), 165.2 (PhCO), 133.4e113.3
(AreC), 98.5 (C-1), 70.6 (C-5), 69.9 (C-3), 69.8 (C-4), 68.9 (C-2), 55.4
(OCH3), 55.1 (OCH3), 40.9 (C-6); HRMS for C35H32O9S2 [MþH]þ:
Calcd. 661.1566; found: 661.1554.
Methyl
2,3,4-tri-O-benzyl-6-deoxy-6-(4-
chlorophenyldithio)-
a
-
D
-mannopyranoside (22): Yield: 510 mg,
82%; Colorless oil. [
a
]
þ 31 (c 1.0, CHCl3); 1H NMR (500 MHz,
Methyl 2,3,4-tri-O-benzoyl-6-deoxy-6-(2-naphthyldithio)-a-
D
CDCl3):
d
7.7.39e7.07 (m, 19 H, AreH), 4.85 (d, J ¼ 11.0 Hz, 1 H,
D-mannopyranoside (28): Yield: 530 mg, 78%; Colorless oil.
PhCH), 4.64 (ABq, J ¼ 10.0 Hz, 2 H, 2 PhCH), 4.59 (br s, 1 H, H-1), 4.52
(br s, 2 H, 2 PhCH), 4.45 (d, J ¼ 11.5 Hz, 1 H, PhCH), 3.77e3.76 (m,
2 H, H-3, H-5), 3.68 (br s, 1 H, H-2), 3.64 (t, J ¼ 9.0 Hz, 1 H, H-4), 3.24
(s, 3 H, OCH3), 3.06 (dd, J ¼ 13.5 Hz, 4.5 Hz, 1 H, H-6a), 2.81 (dd,
J ¼ 13.5 Hz, 4.5 Hz, 1 H, H-6b); 13C NMR (125 MHz, CDCl3):
[
a
]
D þ 62 (c 1.0, CHCl3); 1H NMR (700 MHz, CDCl3):
d 8.06e7.11 (m,
22 H, AreH), 5.77 (dd, J ¼ 9.8 Hz, 3.5 Hz, 1 H, H-3), 5.66 (t, J ¼ 9.5 Hz,
1 H, H-4), 5.56 (br s, 1 H, H-2), 4.85 (br s, 1 H, H-1), 4.39e4.28 (m,
1 H, H-5), 3.44 (s, 3 H, OCH3), 3.00e2.99 (m, 2 H, H-6ab); 13C NMR
(125 MHz, CDCl3):
d 165.5 (PhCO), 165.4 (PhCO), 165.3 (PhCO),
d
138.3e127.5 (AreC), 98.9 (C-1), 80.2 (C-5), 77.6 (C-3), 75.1
133.6e126.2 (AreC), 98.5 (C-1), 70.5 (C-2), 69.9 (C-3), 69.8 (C-4),
68.9 (C-5), 55.4 (OCH3), 40.6 (C-6); HRMS for C38H32O8S2 [MþH]þ:
Calcd. 681.1617; found: 681.1628.
(PhCH2), 74.5 (C-4), 72.8 (PhCH2), 72.1 (PhCH2), 70.1 (C-2), 54.7
(OCH3), 41.1 (C-6); HRMS for C34H35ClO5S2 [MþH]þ: Calcd.
623.1692; found: 623.1680.
Methyl
methoxyphenyldithio)-
Typical reaction condition for the preparation of glycosyl
alkyl sulfide (29): To a solution of compound 1 (370 mg, 1.0 mmol)
in DMSO-H2O (5 mL; 9:1 v/v) was added Na2S2O3,5H2O (375 mg,
1.5 mmol) and the reaction mixture was stirred at 80 ꢀC for 8 h
(Table 2). The reaction mixture was cooled to room temperature
and diluted with CH3OH (5 mL). To the reaction mixture were
added Na2S,9H2O (720 mg, 3.0 mmol) followed by benzyl bromide
(0.18 mL, 1.5 mmol) and the reaction mixture was stirred at room
temperature for 1 h. The reaction mixture was diluted with satd. aq.
NaHCO3 (10 mL) and extracted with EtOAc (10 mL). The organic
layer was dried (Na2SO4) and concentrated under reduced pressure.
The crude product was passed through a short pad of SiO2 using
hexane-EtOAc (6:1) as eluant to give pure glycosyl alkyl sulfide
derivative (29) (311 mg, 85%). Following similar reaction condi-
tions, compounds 30e36 were prepared (Table 4).
2,3,4-tri-O-benzoyl-6-deoxy-6-(2-
a
-
D
-glucopyranoside
(23):
Yield:
528 mg, 80%; Colorless oil. [
(500 MHz, CDCl3):
a]
þ 17 (c 1.0, CHCl3); 1H NMR
D
d
7.96e6.69 (m, 19 H, AreH), 6.05 (t, J ¼ 10.0 Hz,
1 H, H-3), 5.33 (t, J ¼ 9.5 Hz, 1 H, H-4), 5.17 (dd, J ¼ 10.5 Hz, 3.5 Hz,
1 H, H-2), 5.11 (d, J ¼ 3.5 Hz, 1 H, H-1), 4.35e4.30 (m, 1 H, H-5), 3.74
(s, 3 H, OCH3), 3.39 (s, 3 H, OCH3), 2.94e2.92 (m, 2 H, H-6ab); 13C
NMR (125 MHz, CDCl3): d 165.7 (PhCO), 165.6 (PhCO), 165.4 (PhCO),
133.2e110.8 (AreC), 96.7 (C-1), 72.3 (C-2), 72.1 (C-4), 70.3 (C-3),
68.2 (C-5), 55.6 (OCH3), 55.5 (OCH3), 42.0 (C-6); HRMS for
C
35H32O9S2 [MþH]þ: Calcd. 661.1566; found: 661.1552.
Methyl
2,3,4-tri-O-benzoyl-6-deoxy-6-(4-
methylphenyldithio)-
547 mg, 85%; Colorless oil. [
(500 MHz, CDCl3):
a
-D
-mannopyranoside
(24):
Yield:
a]
þ 73 (c 1.0, CHCl3); 1H NMR
D
d
8.01e6.81 (m, 19 H, AreH), 5.78 (dd, J ¼ 9.5 Hz,
Analytical data of symmetrical glycosyl disulfide derivative
(29e36):
3.0 Hz, 1 H, H-3), 5.65 (t, J ¼ 10.0 Hz, 1 H, H-4), 5.56 (br s, 1 H, H-2),
4.85 (br s, 1 H, H-1), 4.33e4.29 (m, 1 H, H-5), 3.44 (s, 3 H, OCH3),
2.93e2.91 (m, 2 H, H-6ab), 2.17 (s, 3 H, CH3); 13C NMR (125 MHz,
6-S-Benzyl-1,2:3,4-di-O-isopropylidene-6-thio-
actopyranose (29): Yield: 311 mg, 85%; Colorless oil. [
1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
7.23e7.18 (m, 5 H, AreH),
a
-D
-gal-
a
]
D
þ 32 (c
CDCl3):
d
165.6 (PhCO), 165.3 (PhCO), 165.2 (PhCO), 137.7e128.2
d
(AreC), 98.4 (C-1), 70.6 (C-5), 69.9 (2 C, C-4, C-3), 68.7 (C-2),
55.4(OCH3), 40.4 (C-6); HRMS for C35H32O8S2 [MþH]þ: Calcd.
645.1617; found: 645.1606.
5.43 (d, J ¼ 5.0 Hz, 1 H, H-1), 4.54e4.51 (m, 1 H, H-3), 4.21 (br s, 1 H,
H-4), 4.15e4.11 (m, 1 H, H-2), 3.95e3.89 (m, 1 H, H-5), 3.92 (br s,
2 H, 2 PhCH2), 2.57e2.53 (m, 2 H, H-6ab), 1.50 (s, 3 H, CH3), 1.31 (s,
3 H, CH3), 1.25 (s, 6 H, 2 CH3); 13C NMR (125 MHz, CDCl3):
Methyl
2,3,4-tri-O-benzoyl-6-deoxy-6-(2,5-
dimethylphenyldithio)-
552 mg, 84%; Colorless oil. [
a
-
D
-mannopyranoside
(25):
Yield:
d 137.2e127.4 (AreC), 109.2 [(CH3)2C(O)2], 108.6 [(CH3)2C(O)2], 96.6
a
]
þ 68 (c 1.0, CHCl3); 1H NMR
(C-1), 71.5 (C-3), 70.9 (C-4), 70.5 (C-2), 66.4 (C-5), 43.3 (SPhCH2),
37.8 (C-6), 26.1 (CH3), 26.0 (CH3), 25.0 (CH3), 24.5 (CH3); HRMS for
D
(500 MHz, CDCl3):
d
8.02e6.82 (m, 18 H, AreH), 5.77 (dd, J ¼ 7.0 Hz,
2.5 Hz, 1 H, H-3), 5.65 (t, J ¼ 9.0 Hz, 1 H, H-4), 5.55 (br s, 1 H, H-2),
4.84 (br s, 1 H, H-1), 4.29e4.28 (m, 1 H, H-5), 3.42 (s, 3 H, OCH3),
C
19H26O5S [MþH]þ: Calcd. 367.1579; found: 367.1590.
6-S-Allyl-1,2:3,4-di-O-isopropylidene-6-thio-
a-
D-galactopyr-
2.96e2.95 (m, 2 H, H-6ab), 2.26 (s, 3 H, CH3), 2.04 (s, 3 H, CH3); 13
C
anose (30): Yield: 253 mg, 80%; Colorless oil. [
a
]
þ 43 (c 1.0,
D
9

M. Kundu and A.K. Misra
Tetrahedron xxx (xxxx) xxx
CHCl3); 1H NMR (500 MHz, CDCl3):
d
7.5.81e5.71 (m, 1 H, CH]CH2),
PhCH), 4.49 (br s, 2 H, 2 PhCH), 4.40 (d, J ¼ 11.0 Hz, 1 H, PhCH), 3.99
(br s, 2 H, 2 SPhCH), 3.71e3.59 (m, 4 H, H-2, H-3, H-4, H-5), 3.26 (s,
3 H, OCH3), 2.87 (dd, J ¼ 13.5 Hz, 2.0 Hz, 1 H, H-6a), 2.71 (dd,
J ¼ 13.5 Hz, 2.0 Hz, 1 H, H-6b); 13C NMR (125 MHz, CDCl3):
5.46 (d, J ¼ 5.0 Hz, 1 H, H-1), 5.16e5.09 (m, 2 H, CH]CH2),
4.56e4.55 (m,1 H, H-3), 4.27e4.24 (m, 2 H, H-2, H-4), 4.13e3.99 (m,
1 H, H-5), 3.29e3.27 (m, 2 H, SCH2), 2.84e2.82 (m, 2 H, H-6ab), 1.45
(s, 3 H, CH3),1.37 (s, 3 H, CH3),1.28 (s, 3 H, CH3),1.27 (s, 3 H, CH3); 13
C
d 138.2e125.8 (AreC), 98.9 (C-1), 80.1 (C-2), 77.5 (C-3), 74.9
NMR (125 MHz, CDCl3):
d
133.3 (CH]CH2), 118.6 (HC]CH2), 109.1
(PhCH2), 74.6 (C-4), 72.8 (PhCH2), 72.1 (PhCH2), 70.7 (C-5), 54.8
(OCH3), 43.9 (SPhCH2), 42.3 (C-6); HRMS for C39H40O5S [MþH]þ:
Calcd. 621.2674; found: 621.2660.
[(CH3)2C(O)2], 108.7 [(CH3)2C(O)2], 96.6 (C-1), 71.5 (C-3), 70.9 (C-4),
70.5 (C-2), 66.5 (C-5), 41.9 (SCH2), 38.5 (C-6), 26.1 (CH3), 25.9 (CH3),
25.0 (CH3), 24.4 (CH3); HRMS for C15H24O5S [MþH]þ: Calcd.
317.1422; found: 317.1411.
Methyl 6-S-(p-methoxybenzyl)-2,3,4-tri-O-benzyl-6-thio-a-
D
-mannopyranoside (36): Yield: 468 mg, 78%; Colorless oil.
6-S-(2-Naphthylmethyl)-1,2:3,4-di-O-isopropylidene-6-thio-
[
a
]
D þ 56 (c 1.0, CHCl3);1H NMR (500 MHz, CDCl3):
d 7.26e7.23 (m,
a
-
]
D
-galactopyranose (31): Yield: 341 mg, 82%; Colorless oil.
15 H, AreH), 7.12 (d, J ¼ 8.5 Hz, 2 H, AreH), 6.71 (d, J ¼ 8.5 Hz, 2 H,
AreH), 4.85 (d, J ¼ 11.5 Hz, 1 H, PhCH), 4.63 (ABq, J ¼ 8.5 Hz, 2 H, 2
PhCH), 4.60 (d, J ¼ 3.0 Hz, H-1), 4.51e4.48 (m, 3 H, 3 PhCH), 3.79 (br
s, 2 H, 2 SPhCH), 3.88e3.78 (m, 1 H, H-3), 3.72 (br s, 1 H, H-2),
3.68e3.61 (m, 5 H, H-4, H-5, SCH2PhOCH3), 3.25 (s, 3 H, OCH3), 2.92
(dd, J ¼ 9.0 Hz, 2.5 Hz, 1 H, H-6a), 2.74 (dd, J ¼ 9.0 Hz, 2.5 Hz, 1 H, H-
[
a
D þ 37 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
d 7.73e7.18 (m,
7 H, AreH), 5.44 (d, J ¼ 5.0 Hz, 1 H, H-1), 4.50 (dd, J ¼ 8.0 Hz, 2.5 Hz,
1 H, H-3), 4.24e4.21 (m,1 H, H-4), 4.06 (dd, J ¼ 8.0 Hz,1.5 Hz,1 H, H-
2), 4.02 (br s, 2 H, 2 SPhCH), 3.96e3.94 (m, 1 H, H-5), 2.67e2.55 (m,
2 H, H-6ab), 1.52 (s, 3 H, CH3), 1.31 (s, 3 H, CH3), 1.26 (s, 3 H, CH3), 1.22
(s, 3 H, CH3); 13C NMR (125 MHz, CDCl3):
d
134.5e125.9 (AreC),
6b); 13C NMR (125 MHz, CDCl3):
d 158.9e113.9 (AreC), 98.9 (C-1),
109.2 [(CH3)2C(O)2], 108.7 [(CH3)2C(O)2], 96.6 (C-1), 71.5 (C-3), 70.8
(C-4), 70.5 (C-5), 66.5 (C-2), 43.6 (SPhCH2), 38.1 (C-6), 26.1 (CH3),
25.9 (CH3), 25.0 (CH3), 24.3 (CH3); HRMS for C23H28O5S [MþH]þ:
Calcd. 417.1735; found: 417.1726.
80.2 (C-2), 77.6 (C-3), 75.0 (PhCH2), 74.6 (C-4), 72.8 (PhCH2), 72.1
(PhCH2), 70.7 (C-5), 55.2 (OCH3), 54.8 (OCH3), 43.0 (SPhCH2), 42.3
(C-6); HRMS for C36H40O6S [MþH]þ: Calcd. 601.2624; found:
601.2615.
Methyl 6-S-(2-naphthylmethyl)-2,3,4-tri-O-benzyl-6-thio-a-
D
-glucopyranoside (32): Yield: 484 mg, 78%; Colorless oil.
Declaration of competing interest
[
a
]
þ 32 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
d 7.78e7.12
D
(22 H, AreH), 4.87 (d, J ¼ 10.5 Hz, 1 H, PhCH), 4.85e4.66 (m, 3 H, 3
PhCH), 4.56 (d, J ¼ 12.0 Hz, 1 H, PhCH), 4.44 (d, J ¼ 3.0 Hz, 1 H, H-1),
4.34 (d, J ¼ 11.0 Hz, 1 H, PhCH), 3.95 (s, 2 H, 2 PhCH), 3.84 (t,
J ¼ 9.5 Hz, 1 H, H-3), 3.68e3.51 (m, 1 H, H-5), 3.39 (dd, J ¼ 10.0 Hz,
3.5 Hz,1 H, H-2), 3.27 (s, 3 H, OCH3), 3.10 (t, J ¼ 9.5 Hz,1 H, H-4), 2.74
(dd, J ¼ 13.5 Hz, 2.0 Hz, 1 H, H-6a), 2.46 (dd, J ¼ 13.5 Hz, 2.0 Hz, 1 H,
The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
Acknowledgements
H-6b); 13C NMR (125 MHz, CDCl3):
d 138.1e125.9 (AreC), 97.8 (C-1),
M.K. thanks CSIR, New Delhi for providing Senior Research
Fellowship. The work is supported by SERB, New Delhi (Project No.
CRG/2019/000352 dated January 23, 2020) (AKM) and Bose
Institute.
81.8 (C-2), 80.6 (C-5), 79.9 (C-3), 75.7 (PhCH2), 74.9 (PhCH2), 73.4
(PhCH2), 69.3 (C-4), 55.2 (OCH3), 43.9 (SPhCH2), 42.3 (C-6); HRMS
for C39H40O5S [MþH]þ: Calcd. 621.2674; found: 621.2662.
Methyl 6-S-benzyl-2,3,4-tri-O-benzyl-6-thio-
a-
D-mannopyr-
anoside (33): Yield: 490 mg, 86%; Colorless oil. [
a
]
þ 72 (c 1.0,
D
Appendix A. Supplementary data
CHCl3); 1H NMR (500 MHz, CDCl3):
d 7.32e7.18 (m, 20 H, AreH),
4.85 (d, J ¼ 11.0 HZ, 1 H, PhCH), 4.66 (ABq, J ¼ 8.5 Hz, 2 H, 2 PhCH),
4.59 (br s, 1 H, H-1), 4.51 (br s, 1 H, PhCH), 4.48 (d, J ¼ 11.5 Hz, 1 H,
PhCH), 3.83 (s, 2 H, SPhCH), 3.77 (dd, J ¼ 8.5 Hz, 3.0 Hz, 1 H, H-3),
3.68 (br s, 1 H, H-2), 3.66e3.62 (m, 2 H, H-4, H-5), 3.24 (s, 3 H,
OCH3), 2.88 (dd, J ¼ 10.0 Hz, 3.5 Hz, 1 H, H-6a), 2.71 (dd, J ¼ 10.0 Hz,
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.tet.2021.132242.
References
3.5 Hz, 1 H, H-6b); 13C NMR (125 MHz, CDCl3):
d 138.3e127.3
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138.4e127.6 (AreC, CH]CH2), 118.4 (CH]CH2), 98.9 (C-1), 80.2
(C-2), 77.7 (C-3), 75.1 (PhCH), 74.6 (C-4), 72.8 (PhCH), 72.1 (PhCH),
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D
-mannopyranoside (35): Yield: 472 mg, 76%; Colorless oil.
[
a
]
D þ 41 (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3):
d 7.77e7.18 (m,
22 H, AreH), 4.78 (d, J ¼ 11.0 Hz, 1 H, PhCH), 4.65e4.59 (m, 2 H, 2
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