Odorless eco-friendly synthesis of thio- and selenoglycosides in ionic liquid

Article abstract of DOI:10.1055/s-0030-1260966

An environmentally benign odorless methodology for the preparation of 1,2-trans-thio- and selenoglycosides is reported. In a one-pot condition, the reductive cleavage of disulfides and diselenides using triethylsilane and borontrifluoride diethyletherate combination followed by the reaction of the in situ generated thiolate and selenoetes with glycosyl acetate derivatives in recyclable room-temperature ionic liquid, [BMIM]BFresulted in excellent yields of thio- and selenoglycosides avoiding the use of obnoxious thiols/selenols and metallic catalysts.

Full text of DOI:10.1055/s-0030-1260966

LETTER
1905
Odorless Eco-Friendly Synthesis of Thio- and Selenoglycosides in Ionic Liquid
Synthesis of
Thio-
b
and Selenog
hlycosides in
i
Ionic
L
j
iquid it Sau, Anup Kumar Misra*
Division of Molecular Medicine, Bose Institute, P-1/12, C. I. T. Scheme VII M, Kolkata 700054, India
Fax +91(33)23553886; E-mail: akmisra69@gmail.com
Received 1 April 2011
Similar to the thioglycosides, selenoglycosides have also
Abstract: An environmentally benign odorless methodology for
the preparation of 1,2-trans-thio- and selenoglycosides is reported.
In a one-pot condition, the reductive cleavage of disulfides and di-
selenides using triethylsilane and borontrifluoride diethyletherate
been used in carbohydrate chemistry for the preparation of
oligosaccharides, C-glycosides, glycoconjugates, etc.14
Selenoglycosides can be selectively activated in the pres-
combination followed by the reaction of the in situ generated ence of thioglycosides and hence become attractive inter-
thiolate and selenoetes with glycosyl acetate derivatives in recycla-
mediates
in
the
oligosaccharide
synthesis.15
ble room-temperature ionic liquid, [BMIM]·BF4 resulted in excel-
lent yields of thio- and selenoglycosides avoiding the use of
obnoxious thiols/selenols and metallic catalysts.
Selenoglycosides are usually prepared by treating glyco-
syl halides with selenium under sodium borohydride re-
duction conditions16 or by treating glycosyl acetate with
arylselenol derived from the reduction of phenyldise-
lenide in the presence of BF3·OEt2.17 Resembling the
thioglycosides, preparation of selenoglycosides also suf-
fers from a number of shortcomings including the use of
malodorous reagents, incompatibility of base-labile pro-
tecting groups, and use of organic solvents. Therefore,
there is a constant need to develop an odorless, environ-
mentally benign reaction protocol for the preparation of
thio- and selenoglycosides. It was envisaged that reduc-
tion of disulfides and diselenides under a metal-free con-
dition followed by the treatment with glycosyl acetates in
one-pot in room-temperature ionic liquid (RTIL) could
provide a green protocol for the preparation of thio- and
selenoglycosides avoiding malodorous thiols. Since com-
bination of triethylsilane and borontrifluoride diethyl-
etherate (BF3·OEt2) has been found as useful reducing
agent in the regioselective ring opening of acetal ring in
carbohydrate derivatives,18 we sought to explore this re-
agent in the reduction of disulfides/diselenides. We also
presumed that BF3·OEt2 present in the reaction medium
could activate the glycosyl acetates to react with in situ
generated thiolates/selenoates in one pot. In the current
scenario, RTIL appeared to be the most attractive reaction
solvents for the development of green methodologies.19 A
number of organic transformations useful in the synthetic
carbohydrate chemistry have been successfully carried
out in ionic liquids (IL).20 In this communication, we wish
to report our findings on the treatment of disulfides/dise-
lenides with a combination of triethylsilane and BF3·OEt2
Key words: thioglycoside, selenoglycoside, disulfide, diselenide,
triethylsilane, ionic liquid
Thioglycosides are useful intermediates for the synthesis
of complex oligosaccharides as well as natural products.1,2
They have been widely used as effective and stable gly-
cosyl donors in the synthetic carbohydrate chemistry
where a wide range of protecting-group manipulations are
involved.3 They also act as practical precursors for the
preparation of glycosyl fluorides,4 sulfoxides, and sul-
fones, which have applications in the O- and C-glycosyla-
tions as glycosyl donors.5,6 Besides their important roles
in the glycosylations, thioglycosides have been evaluated
as effective inhibitors of several glycosidase enzymes be-
cause of their structural similarities to the O-glycosides.7,8
Thioglycosides can serve as orthogonal glycosyl donors
by acting as donors as well as acceptors depending on the
reaction conditions.9 Conventionally, per-O-acetylated
thioglycosides are prepared by the treatment of glycosyl
acetates with obnoxious thiols10 or trimethylsilylthiol de-
rivatives in the presence of a Lewis acid.11 Use of mal-
odorous and toxic thiols, formation of anomerized
products, and requirement of large quantity of chlorinated
organic solvents are major drawbacks of these methods.
Few other comparatively odorless conditions have also
been developed in the recent past, which include (a) zinc-
mediated cleavage of disulfides and reaction of the in situ
generated thiolates with glycosyl bromides,12 and (b)
preparation of S-glycosylisothiouronium salts followed
by treatment with alkyl halides under mild basic condi-
tions.13 Besides their usefulness, they have serious limita-
tions including the use of metallic salts, unstable glycosyl
bromides and organic solvents, pregeneration of S-glyco-
syl isothiouronium salts from unstable glycosyl halides,
etc.
OAc
O
AcO
SR1
AcO
R1SSR1 or R2SeSeR2
OAc
O
OAc
(0.7 equiv)
AcO
AcO
OAc
Et3⋅SiH (1.5 equiv),
BF3⋅OEt2 (1.5 equiv)
[BMIM]⋅BF4
OAc
OAc
O
AcO
AcO
SeR2
OAc
r.t., 1–1.5 h
R1 = aryl; R2 = aryl, alkyl
SYNLETT 2011, No. 13, pp 1905–1911
Advanced online publication: 25.07.2011
DOI: 10.1055/s-0030-1260966; Art ID: D10011ST
© Georg Thieme Verlag Stuttgart · New York
x
x
.x
x
.2
0
1
1
Scheme 1 One-pot preparation of thio- and selenoglycosides by the
reduction of disulfides/diselenides using triethylsilane and BF3·OEt2
followed by reaction with glycosyl acetates in [BMIM]·BF4.

1906
A. Sau, A. K. Misra
LETTER
followed by reaction with glycosyl acetates in one pot in hour. After experimentation, it was observed that treat-
IL to furnish thio- and selenoglycosides under environ- ment of compound 1 with phenyl disulfide (0.7 equiv), tri-
mentally benign odorless reaction conditions (Scheme 1). ethylsilane (1.5 equiv of phenyl disulfide), and BF3·OEt2
(1.5 equiv of phenyl disulfide) in [BMIM]·BF4 (1.0 mL
per mmol of substrate) furnished 85% yield of compound
13 together with minor quantity (ca. 5%) of a-isomer in
one hour at room temperature. Following similar reaction
In a set of initial experiments, a mixture of b-D-glucose
pentaacetate (1) and phenyl disulfide (0.5–1.5 equiv) was
treated with triethylsilane (1.0–2.0 equiv of phenyl disul-
fide) and BF3·OEt2 (1.0–2.5 equiv of phenyl disulfide) in
conditions a series of thioglycosides have been prepared
1-butyl-3-methylimidazolium
tetrafluoroborate
from different sugar acetates using phenyl disulfide, tolyl
disulfide, naphthyl disulfide, etc. in excellent yield
(Table 1).
{[BMIM]·BF4; 0.5–2.0 mL per mmol of substrate} at
room temperature. To our satisfaction, the reaction pro-
ceeds well and resulted in the formation of phenyl 2,3,4,6-
tetra-O-acetyl-1-thio-b-D-glucopyranoside (13) in one
Table 1 Preparation of Thioglycosides by Reductive Cleavage of Disulfides Using Et3SiH–BF3·OEt2 Followed by Reaction with Glycosyl
Acetates in [BMIM]·BF4 at Room Temperature
Entry
1
Glycosyl acetate
Disulfidesa
Thioglycosides
Time (h)
1.0
Yield (%)b
85c,21
OAc
O
OAc
O
AcO
AcO
AcO
AcO
PhSSPh (9)
OAc
SPh
STol
OAc
OAc
1
13
OAc
O
AcO
2
3
TolSSTol (10)
NapSSNap (11)
1.0
1.2
86d,10g
AcO
OAc
14
OAc
O
AcO
AcO
8822
SNap
OAc
15
OAc
O
AcO
4
5
PNPSSPNP (12)
PhSSPh (9)
1.5
1.0
80
SPNP
AcO
OAc
16
OAc
O
OAc
O
AcO
AcO
AcO
AcO
AcO
AcO
8623
OAc
SPh
2
17
OAc
O
AcO
AcO
AcO
6
7
TolSSTol (10)
PhSSPh (9)
1.0
1.0
8510g
STol
18
AcO
AcO
AcO
OAc
O
OAc
O
78e,24
SPh
OAc
AcO
OAc
OAc
3
19
AcO
OAc
O
8
9
TolSSTol (10)
NapSSNap (11)
1.0
1.2
7610g
STol
AcO
OAc
20
AcO
AcO
21
OAc
O
7522
SNap
OAc
Synlett 2011, No. 13, 1905–1911 © Thieme Stuttgart · New York

LETTER
Synthesis of Thio- and Selenoglycosides in Ionic Liquid
1907
Table 1 Preparation of Thioglycosides by Reductive Cleavage of Disulfides Using Et3SiH–BF3·OEt2 Followed by Reaction with Glycosyl
Acetates in [BMIM]·BF4 at Room Temperature (continued)
Entry
10
Glycosyl acetate
Disulfidesa
Thioglycosides
Time (h)
1.0
Yield (%)b
9225
OAc
SPh
Me
AcO
O
Me
AcO
O
PhSSPh (9)
AcO
AcO
OAc
OAc
4
22
STol
Me
AcO
O
11
12
TolSSTol (10)
PhSSPh (9)
1.0
1.5
8810g
AcO
OAc
23
OAc
O
OAc
O
AcO
AcO
AcO
AcO
8026
OAc
SPh
NPhth
NPhth
5
24
OAc
O
OAc
O
AcO
AcO
AcO
AcO
OAc
O
OAc
O
13
PhSSPh (9)
1.5
8527
AcO
AcO
O
O
SPh
SPh
OAc
OAc
AcO
AcO
OAc
OAc
6
25
AcO
AcO
OAc
O
OAc
O
OAc
O
OAc
O
14
15
PhSSPh (9)
PhSSPh (9)
1.5
1.5
8427
O
O
AcO
7
AcO
AcO
AcO
AcO
AcO
OAc
OAc
26
OAc
O
OAc
O
OAc
O
OAc
O
AcO
AcO
AcO
AcO
8227
O
O
AcO
OAc
AcO
AcO
SPh
AcO
OAc
OAc
8
27
a Ph: phenyl; Tol: 4-methylphenyl, Nap: 2-naphthyl, PNP: 4-nitrophenyl.
b Isolated yield.
c Together with some a-isomer (ca. 5%).
d Together with some a-isomer (ca. 10%).
e Together with some a-isomer (ca. 10%).
In a comparative study, a number of imidazolium IL, for diselenide took slightly longer time in comparison to the
example, [BMIM]·PF6, [BMIM]·OTf, and [BMIM]·Cl phenyl diselenide.
were also examined as reaction solvent. The best results
The findings on the cleavage of diselenides using a com-
were obtained using [BMIM]·BF4 in terms of solubility of
bination of triethylsilane and BF3·OEt2 followed by reac-
the substrates and yield of the products obtained
tion with glycosyl acetates in [BMIM]·BF4 are listed in
(Table 2). After successful preparation of thioglycosides,
Table 3. The products were obtained by aqueous workup
the reaction conditions have been applied for the prepara-
and extraction with ethyl acetate. In most of the cases, ex-
tion selenoglycosides using phenyl diselenide, benzyl di-
clusive 1,2-trans thio- and selenoglycoside derivatives
selenide, etc. in place of disulfides. Excellent yield of
were obtained. All known compounds gave acceptable 1H
selenoglycosides were achieved under similar reaction
NMR and 13C NMR spectra that matched the reported da-
conditions. In the preparation of selenoglycosides, benzyl
ta. The recycling property of the IL was evaluated by per-
Table 2 Preparation of Thioglycoside 13 Using Phenyl Disulfide and Et3SiH–BF3·OEt2 followed by Reaction with Glycosyl Acetate 1 in Dif-
ferent Ionic Liquids at Room Temperature
Entry
Glycosyl acetate
Thioglycoside
IL
Time (h)
Yield (%)
1
2
3
4
OAc
O
[BMIM]·BF4
[BMIM]·PF6
[BMIM]·OTf
[BMIM]·Cl
1.0
3.5
7.0
85
76
55
40
OAc
O
AcO
AcO
AcO
AcO
SPh
OAc
OAc
OAc
10.0
13
1
Synlett 2011, No. 13, 1905–1911 © Thieme Stuttgart · New York

1908
A. Sau, A. K. Misra
LETTER
forming the reaction in recovered [BMIM]·BF4. The disulfides and diselenides followed by the reaction of in
recovered IL was reused at least four times without signif- situ generated thiolates and selenoates with glycosyl ace-
icant loss of efficiency providing almost similar yield of tates in IL [BMIM]·BF4. Operational simplicity, green,
selenoglycoside derivative (Table 3, entry 1).
stereoselective formation of 1,2-trans-thio- and -sele-
noglycosides in recyclable IL avoiding the use of mal-
odorous thiols/selenols make this protocol better to the
existing methodologies in this area.
In summary, an odorless, environmentally benign, high-
yielding methodology has been developed for the prepa-
ration of a series of 1,2-trans-thio- and -selenoglycosides
through triethylsilane–BF3·OEt2-mediated reduction of
Table 3 Preparation of Selenoglycosides by Reductive Cleavage of Diselenides Using Et3SiH–BF3·OEt2 Followed by Reaction with Glycosyl
Acetates in [BMIM]·BF4 at Room Temperature
Entry
1
Glycosyl acetate
Diselenides
Thioglycosides
Time (h)
1.0
Yield (%)a
88b,15a
87c,15a
82d,15a
80e,15a
OAc
O
OAc
O
AcO
AcO
AcO
AcO
PhSeSePh (28)
SePh
SeBn
OAc
OAc
OAc
1
30
OAc
O
AcO
AcO
2
3
BnSeSeBn (29)
PhSeSePh (28)
1.0
1.0
82
OAc
31
OAc
O
OAc
O
AcO
AcO
AcO
AcO
AcO
AcO
8514a
OAc
SePh
2
32
OAc
O
AcO
AcO
AcO
4
5
6
BnSeSeBn (29)
PhSeSePh (28)
PhSeSePh (28)
1.0
1.0
1.0
80
SeBn
33
AcO
AcO
AcO
OAc
O
OAc
O
8612a
SePh
SePh
AcO
OAc
OAc
OAc
34
3
OAc
Me
AcO
O
Me
AcO
O
O
9015a
AcO
AcO
OAc
OAc
35
4
SeBn
Me
7
BnSeSeBn (29)
1.0
82
AcO
AcO
OAc
36
OAc
O
OAc
O
AcO
AcO
AcO
AcO
8
9
PhSeSePh (28)
BnSeSeBn (29)
1.2
1.5
8815a
SePh
OAc
NPhth
NPhth
5
37
OAc
O
AcO
AcO
8228
SeBn
NPhth
38
Synlett 2011, No. 13, 1905–1911 © Thieme Stuttgart · New York

LETTER
Synthesis of Thio- and Selenoglycosides in Ionic Liquid
1909
Table 3 Preparation of Selenoglycosides by Reductive Cleavage of Diselenides Using Et3SiH–BF3·OEt2 Followed by Reaction with Glycosyl
Acetates in [BMIM]·BF4 at Room Temperature (continued)
Entry
Glycosyl acetate
Diselenides
Thioglycosides
Time (h)
1.5
Yield (%)a
OAc
O
OAc
AcO
AcO
O
AcO
AcO
OAc
O
OAc
O
10
BnSeSeBn (29)
72
AcO
AcO
O
O
OAc
OAc
AcO
SeBn
SePh
AcO
OAc
OAc
6
39
AcO
AcO
OAc
O
OAc
O
OAc
O
OAc
O
11
12
PhSeSePh (28)
BnSeSeBn (29)
1.5
1.5
75
70
O
AcO
O
AcO
AcO
AcO
AcO
AcO
OAc
OAc
7
40
AcO
OAc
O
OAc
O
O
AcO
AcO
SeBn
AcO
OAc
41
a Isolated yield.
b Fresh [BMIM]·BF4.
c 1st recycled [BMIM]·BF4.
d 2nd recycled [BMIM]·BF4.
e 3rd recycled [BMIM]·BF4.
Typical Experimental Conditions
Dolle, R. E.; Papahatjis, D. P.; Randall, J. L. J. Am. Chem.
Soc. 1984, 106, 4189. (e) Dolle, R. E.; Nicolaou, K. C.
J. Am. Chem. Soc. 1985, 107, 1691. (f) Nicolaou, K. C.;
Bockovich, N. J.; Carcanague, D. R.; Hummel, C. W.; Even,
L. F. J. Am. Chem. Soc. 1992, 114, 8701.
To a mixture of penta-O-acetyl-b-D-glucopyranose (1, 390.0 mg;
1.0 mmol), phenyl disulfide (155.0 mg, 0.71 mmol) or phenyl dise-
lenide (220.0 mg, 0.70 mmol), and TES (170.0 mL, 1.06 mmol) in
[BMIM]·BF4 (1.0 mL) was added BF3·OEt2 (130.0 mL, 1.05 mmol),
and the reaction mixture was allowed to stir at 20 °C for 1 h
(Tables 1 and 3). After completion, the reaction mixture was poured
into H2O and extracted with EtOAc. The organic layer was succes-
sively washed with sat. NaHCO3 and H2O, dried (Na2SO4), and con-
centrated under reduced pressure to give the crude product, which
was purified by crystallization from EtOH or by column chromatog-
raphy using hexane–EtOAc (5:1) as eluent to furnish pure com-
pound 13 or 30 (Tables 1 and 3).29 The aqueous layer was
evaporated to dryness, and the crude mass was passed through a
short pad of SiO2 using EtOAc as eluent to furnish [BMIM]·BF4,
which was dried at 70–80 °C under reduced pressure before its re-
use.
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2003, 14, 2861. (b) Witczak, Z. J.; Whistler, R. L.
Heterocycles 1982, 19, 1719.
(17) (a) Gerz, M.; Matter, H.; Kessler, H. Angew. Chem., Int. Ed.
Engl. 1993, 32, 269. (b) Aloui, M.; Chambers, D. J.;
Cumpstey, I.; Fairbanks, A. J.; Redgrave, A. J.; Seward,
C. M. P. Chem. Eur. J. 2002, 8, 2608.
(18) (a) Debenham, S. D.; Toone, E. J. Tetrahedron: Asymmetry
2000, 11, 385. (b) Aravind, A.; Baskaran, S. Tetrahedron
Lett. 2005, 46, 743. (c) Aravind, A.; Mohanty, S. K.; Pratap,
T. V.; Baskaran, S. Tetrahedron Lett. 2005, 46, 2965.
(19) (a) Jain, N.; Kumar, A.; Chauhan, S.; Chauhan, S. M. S.
Tetrahedron 2005, 61, 1015. (b) Murugesan, S.; Linhardt,
R. J. Curr. Org. Synth. 2005, 2, 437.
(20) (a) Pakulski, Z. Synthesis 2003, 2074. (b) Galan, M. C.;
Jouvin, K.; Alvarez-Dorta, D. Carbohydr. Res. 2010, 345,
45. (c) Park, T.-J.; Weiwer, M.; Yuan, X.; Baytas, S. N.;
Munoz, E. V.; Murugesan, S.; Linhardt, R. J. Carbohydr.
Res. 2007, 342, 614. (d) Rencurosi, A.; Lay, L.; Russo, G.;
Caneva, E.; Poletti, L. J. Org. Chem. 2005, 70, 7765.
(e) Forsyth, S. A.; MacGarlane, D. R.; Thomson, R. J.; von
Itzstein, M. Chem. Commun. 2002, 714. (f) Zhang, J.;
Ragauskas, A. J. Carbohydr. Res. 2005, 340, 2812.
(21) Dasgupta, F.; Garegg, P. J. Acta Chem. Scand. 1989, 43,
471.
Yellow solid; mp 180–182 °C; [a]D –32.7 (c 1.2, CHCl3). IR
(KBr): 2923, 2368, 1753, 1344, 1220, 1042, 770 cm–1. 1H
NMR (200 MHz, CDCl3): d = 8.16 (d, J = 8.9 Hz, 2 H), 7.59
(d, J = 8.8 Hz, 2 H), 5.28 (t, J = 9.2 Hz each, 1 H, H-3), 5.08
(t, J = 9.7 Hz each, 1 H, H-2), 5.04 (t, J = 9.6 Hz each, 1 H,
H-4), 4.89 (d, J = 10.0 Hz, 1 H, H-1), 4.25–4.21 (m, 2 H, H-
6a,b), 3.85–3.80 (m, 1 H, H-5), 2.10, 2.08, 2.04, 2.0 (4 s, 12
H, 4 COCH3). 13C NMR (50 MHz, CDCl3): d = 170.2, 169.9,
169.2, 169.0, 147.6, 141.6, 131.7 (2 C), 124.1 (2 C), 84.6,
76.6, 74.0, 70.0, 68.3, 62.2, 21.0, 20.9, 20.8 (2 C). ESI-MS:
m/z = 508.1 [M + Na]+. Anal. Calcd for C20H23NO11S
(485.10): C, 49.48; H, 4.78. Found: C, 49.25; H, 5.0.
Benzyl 2,3,4,6-Tetra-O-acetyl-1-seleno-b-D-gluco-
pyranoside (31)
Yellow oil; [a]D25 –30 (c 1.5, CHCl3). IR (neat): 2934, 1769,
1357, 1242, 1074, 764 cm–1. 1H NMR (300 MHz, CDCl3):
d = 7.40–7.21 (m, 5 H, ArH), 5.88 (d, J = 8.5 Hz, 1 H), 5.27
(t, J = 9.5 Hz each, 1 H), 5.06–4.89 (m, 2 H), 4.34–4.19 (m,
2 H), 3.90 (d, J = 11.1 Hz, 1 H), 3.83–3.67 (ABq, J = 12.0
Hz, 2 H), 2.08, 2.02, 1.99 (3 s, 12 H, 4 COCH3). 13C NMR
(50 MHz, CDCl3): d = 171.0, 170.8, 169.9 (2 C), 135.0–
127.0 (ArC), 78.8, 76.3, 71.7, 71.2, 69.9, 68.6, 62.0, 26.6,
21.0, 20.9 (2 C). ESI-MS: m/z = 525.0 [M + Na]+. Anal.
Calcd for C21H26O9Se (502.07): C, 50.31; H, 5.23. Found: C,
50.08; H, 5.50.
Benzyl 2,3,4,6-Tetra-O-acetyl-1-seleno-a-D-manno-
pyranoside (33)
Yellow oil; [a]D25 +126.8 (c 1.0, CHCl3). IR (neat): 2972,
2362, 1742, 1598, 1373, 1246, 1107, 1050, 977, 756 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.28–7.09 (m, 5 H, ArH),
5.35 (br s, 1 H, H-2), 5.24 (br s, 1 H, H-1), 5.20–5.16 (m, 2
H, H-3 and H-4), 4.24–4.20 (m, 2 H, H-6ab), 3.91–3.85 (m, 1
H, H-5), 3.77–3.73 (ABq, J = 12.0 Hz, 2 H, CH2Ph), 2.07,
2.03, 1.98, 1.90 (4 s, 12 H, 4 COCH3). 13C NMR (50 MHz,
CDCl3): d = 170.2, 169.4 (2 C), 169.3, 137.6, 128.6 (2 C),
128.3 (2 C), 126.8, 77.6, 71.4, 70.6, 69.7, 65.8, 61.8, 27.4,
20.5, 20.4, 20.3, 20.2. ESI-MS: m/z = 525 [M + Na]+. ESI-
MS: m/z = 525.0 [M + Na]+. Anal. Calcd for C21H26O9Se
(502.07): C, 50.31; H, 5.23. Found: C, 50.09; H, 5.52.
Benzyl 2,3,4-Tri-O-acetyl-1-seleno-a-L-rhamno-
pyranoside (36)
Yellow oil; [a]D25 –114 (c 1.2, CHCl3). IR (neat): 2367,
1756, 1600, 1366, 1230, 955 cm–1. 1H NMR (200 MHz,
CDCl3): d = 7.28–7.14 (m, 5 H, ArH), 5.34 (br s, 1 H, H-1),
5.32–5.30 (m, 1 H, H-2), 5.18 (dd, J = 9.7, 3.0 Hz, 1 H, H-
3), 5.04 (t, J = 9.7 Hz each, 1 H, H-4), 4.12–4.02 (m, 1 H, H-
5), 3.83 (ABq, J = 12.2 Hz, 2 H, PhCH2), 2.08, 2.01, 1.93 (3
s, 9 H, 3 COCH3), 1.18 (d, J = 6.2 Hz, 1 H, CCH3). ESI-MS:
m/z = 467.0 [M + Na]+. Anal. Calcd for C19H24O7Se
(444.07): C, 51.47; H, 5.46. Found: C, 51.25; H, 5.70.
Benzyl 2,3,4,6-Tetra-O-acetyl-a-D-glucopyranosyl-
(1→4)-2,3,6-tri-O-acetyl-1-seleno-b-D-glucopyranoside
(39)
(22) Mukherjee, C. M.; Misra, A. K. J. Carbohydr. Chem. 2007,
26, 213.
(23) Martin-Lomas, M.; Khiar, N.; Garcia, S.; Koessler, J.-L.;
Nieto, P. M.; Rademacher, T. W. Chem. Eur. J. 2000, 6,
3608.
(24) Khiar, N.; Martin-Lomas, M. J. Org. Chem. 1995, 60, 7017.
(25) Pozsgay, V.; Jennings, H. J. J. Org. Chem. 1988, 53, 4042.
(26) Chowdhury, U. S. Tetrahedron 1996, 52, 12775.
(27) Tropper, F. D.; Andersson, F. O.; Grand-Maitre, C.; Roy, R.
Synthesis 1991, 734.
Yellow oil; [a]D25 +51 (c 1.0, CHCl3). IR (neat): 3023, 1764,
1418, 1257, 1086, 769 cm–1. 1H NMR (400 MHz, CDCl3):
d = 7.32–7.20 (m, 5 H, ArH), 5.40–5.23 (m, 2 H), 5.18–5.09
(m, 1 H), 5.06–4.88 (m, 2 H), 4.86–4.76 (m, 1 H), 4.54–4.49
(m, 1 H), 4.46–4.38 (m, 1 H), 4.26–4.16 (m, 2 H), 4.06–3.82
(m, 5 H), 3.58–3.49 (m, 1 H), 2.13, 2.07, 1.99, 1.96, 1.95,
1.94 (6 s, 21 H, 7 COCH3). ESI-MS: m/z = 813.1 [M + Na]+.
Anal. Calcd for C33H42O17Se (790.16): C, 50.19; H, 5.36.
Found: C, 50.0; H, 5.60.
(28) Tiwari, P.; Misra, A. K. Tetrahedron Lett. 2006, 47, 2345.
(29) Spectral data of products, which have not been reported
earlier, are presented below.
Phenyl 2,3,4,6-Tetra-O-acetyl-b-D-galactopyranosyl-
(1→4)-2,3,6-tri-O-acetyl-1-seleno-b-D-glucopyranoside
(40)
Synlett 2011, No. 13, 1905–1911 © Thieme Stuttgart · New York

LETTER
Yellow oil; [a]D25 +9 (c 1.0, CHCl3). IR (neat): 3036, 1790,
Synthesis of Thio- and Selenoglycosides in Ionic Liquid
1911
Benzyl 2,3,4,6-Tetra-O-acetyl-b-D-galactopyranosyl-
(1→4)-2,3,6-tri-O-acetyl-1-seleno-b-D-glucopyranoside
(41)
1432, 1276, 1094, 766 cm–1. 1H NMR (400 MHz, CDCl3):
d = 7.56–7.26 (m, 5 H, ArH), 5.30–5.28 (m, 1 H), 5.16 (t,
J = 9.1 Hz each, 1 H), 5.05 (dd, J = 7.3 Hz each, 1 H), 4.94–
4.82 (m, 3 H), 4.51–4.46 (m, 1 H), 4.42 (d, J = 7.9 Hz, 1 H),
4.12–4.02 (m, 3 H), 3.85–3.81 (m, 1 H), 3.70 (t, J = 9.1 Hz
each, 1 H), 3.62–3.56 (m, 1 H), 2.13, 2.07, 2.05, 2.01, 2.0,
1.94 (6 s, 21 H, 7 COCH3). ESI-MS: m/z = 799.1 [M + Na]+.
Anal. Calcd for C32H40O17Se (776.14): C, 49.55; H, 5.20.
Found: C, 49.32; H, 5.50.
Yellow oil; [a]D25 +21 (c 1.0, CHCl3). IR (neat): 3023, 1767,
1424, 1281, 1089, 769 cm–1. 1H NMR (400 MHz, CDCl3):
d = 7.30–7.27 (m, 5 H, ArH), 5.40–5.28 (m, 2 H), 5.20–4.88
(m, 4 H), 4.54–4.44 (m, 2 H), 4.22–4.06 (m, 4 H), 4.02–3.86
(m, 2 H), 3.82–3.70 (m, 1 H), 3.56–3.48 (m, 1 H), 2.17, 2.15,
2.14, 2.06, 2.03, 2.0, 1.97 (7 s, 21 H, 7 COCH3). ESI-MS:
m/z = 813.1 [M + Na]+. Anal. Calcd for C33H42O17Se
(790.16): C, 50.19; H, 5.36. Found: C, 50.0; H, 5.58.
Synlett 2011, No. 13, 1905–1911 © Thieme Stuttgart · New York