Sulfonated graphene oxide as highly efficient catalyst for glycosylation

Article abstract of DOI:10.1080/07328303.2015.1120874

Heterogeneous sulfonated graphene oxide for the first time has been used as a green and efficient catalyst for atom-economic glycosylation of unprotected, unactivated glycosyl donors or 2,3,4,6-tetra-O-acetylglycosyltrichloroacetimidate with various accep

Full text of DOI:10.1080/07328303.2015.1120874

Journal of Carbohydrate Chemistry
ISSN: 0732-8303 (Print) 1532-2327 (Online) Journal homepage: http://www.tandfonline.com/loi/lcar20
Sulfonated graphene oxide as highly efficient
catalyst for glycosylation
Raju S. Thombal & Vrushali H. Jadhav
To cite this article: Raju S. Thombal & Vrushali H. Jadhav (2016): Sulfonated graphene
oxide as highly efficient catalyst for glycosylation, Journal of Carbohydrate Chemistry, DOI:
10.1080/07328303.2015.1120874
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Date: 15 February 2016, At: 02:59

JOURNAL OF CARBOHYDRATE CHEMISTRY
, VOL. , NO. , –
http://dx.doi.org/./..
Sulfonated graphene oxide as highly efficient catalyst for
glycosylation
Raju S. Thombal and Vrushali H. Jadhav
Division of Organic Chemistry, National Chemical Laboratory (CSIR-NCL), Pune, India
ABSTRACT
ARTICLE HISTORY
Received  September 
Accepted  November 
Heterogeneous sulfonated graphene oxide for the first time
has been used as a green and efficient catalyst for atom-
economic glycosylation of unprotected, unactivated glycosyl
donors or 2,3,4,6-tetra-O-acetylglycosyltrichloroacetimidate
with various acceptors basically in the absence of solvent.
The unprotected, unactivated glycosyl donors afforded
mixtures of α- and β-glycosides, while the 2,3,4,6-tetra-O-
acetylglycosyltrichloroacetimidate afforded β-glycosylated
products with high yields and selectivity. The main advantages
of this methodology are easy catalyst preparation, no need for
dry reagents and reaction conditions, easy catalyst separation
and recycling, and high product yields.
KEYWORDS
Sulfonated graphene oxide;
reusability; glycol donor;
glycosyl acceptor;
glycosylation
GRAPHICAL ABSTRACT
Introduction
Glycosylation is an important reaction to synthesize carbohydrate derivatives and
an array of novel therapeutic agents and has thus gained significant attention and
witnessed vast development over the last few decades.[1] Glycosidic bond forma-
tion is a crucial step in oligosaccharide synthesis, but despite many efforts, there is
still a need to identify a general, mild, and convenient glycosylation promoter to
achieve high yields. To date, a number of homogeneous systems like BF3·Et2O,[2]
Sc(OTf)3,[3] TMSOTf,[4] TBSOTf,[5] AgOTf,[6] Ti(OtBu)4,[7] and sulphamic acid[8]
have been used as promoters for the glycosylation reaction. They are strong and
moisture sensitive and hence suffer from drawbacks, such as corrosion and con-
tamination, and need neutralization after the reaction. As a result, the workup is
CONTACT VrushaliH. Jadhav
(CSIR-NCL), Pune-, India.
vh.jadhav@ncl.res.in
DivisionofOrganicChemistry, NationalChemicalLaboratory
©  Taylor & Francis Group, LLC

2
R. S. THOMBAL AND V. H. JADHAV
Figure . Schematic representation of sulfonated graphene oxide.
tedious. Very low temperatures and absolutely dry conditions are required for gly-
cosylation reactions too. These catalysts are difficult to separate from the reaction
mixture and cannot be reused. Such methods do not promote green synthesis and
atom efficiency. Hence, there is still a need to develop an efficient process for gly-
cosylation from both academic and industrial points of view. Recently, Liu et al.[9]
synthesized a biomass-derived carbonaceous heterogeneous catalyst and used it for
glycosylation reactions of various sugars. They compared this catalyst with other
homogeneous catalyst systems for glycosylation reaction and found that the het-
erogeneous catalyst works well, giving good yields of glycosylation products. Het-
erogeneous catalytic processes have advantages over homogeneous catalytic systems
such as straightforward catalyst separation, catalyst regeneration, and relatively low
cost, which makes them more applicable. To overcome the above said difficulties
in glycosylation and develop new glycosylation protocols, we herewith report the
glycosylation of unprotected, unactivated glycosyl donors and glycosylation of gly-
cosyl trichloroacetimidates with various acceptors using sulfonated graphene oxide
as an inexpensive, efficient, reusable, and environmentally benign catalyst, which
gave high yields of the glycosides.
Results and discussion
Graphene oxide was obtained from graphene by the Hummers method[10] and con-
tained a high density of hydrophilic functional groups such as hydroxyl, carboxyl,
and epoxy groups. Sulfonation of graphene oxide using chlorosulfonic acid afforded
sulfonated graphene oxide by known procedure.[11] The FT-IR and P-XRD data was
found to be consistent with that reported. A schematic representation of sulfonated
graphene oxide is shown in Figure 1. Sulfonated graphene oxide was reported to be a
highly efficient, recyclable solid acid catalyst for a number of reactions due to its low
cost, metal-free composition, and expected high stability and high reusability.[12]
Intrigued by these previous studies and our work in this field,[13] we were inter-
ested in examining whether sulfonated graphene oxide could be used as an efficient
carbon catalyst for the glycosylation reaction.
Glycosylation of unprotected sugars is important and practical as it avoids
protection-deprotection steps required for synthesis of glycosyl donors and hence

JOURNAL OF CARBOHYDRATE CHEMISTRY
3
Table . Optimization of reaction time, temperature, and catalyst loading in glycosylation of
D-glucose with allyl alcohol using sulfonated graphene oxide catalyst in the absence of a solvent.
Allyl alcohol
(mmol)
Catalyst loading
(wt %)
Entry
Time (h)
Temp (°C)
Yielda (%)












.
.
.
.































rt








rt



rt











aIsolated yields.
is economical. Thus, initially, we studied glycosylation reactions of the unprotected
sugars like D-glucose with allyl alcohol as an acceptor using the sulfonated graphene
oxide catalyst without using any solvent. To confirm the effect of sulfonation on
graphene oxide, we initially tried glycosylation of D-glucose with allyl alcohol using
5 wt% graphene oxide as catalyst with respect to glycosyl donor in the absence of sol-
vent. No glycosylation was found to occur even at higher temperatures, indicating
that sulfonating groups on graphene oxide play an important role in the glycosyla-
tion reaction.
We optimized the glycosylation reaction conditions using sulfonated graphene
oxide catalyst. D-Glucose and allyl alcohol were used as the substrates. As the reac-
tion was carried out without using solvent, it was necessary to fix the amount
of acceptor required to gain maximum yield of the glycosylated product. When
2.5 mmol of allyl alcohol was used, the alcohol was not sufficient to dissolve the
glycosyl donor. To this undissolved solution, 5 wt% of the catalyst was added and
then stirred at different temperatures, but probably due to incomplete solubility of
the sugar, low yields of the glycosides were obtained (Table 1, entries 1–4). When
5.0 mmol of allyl alcohol and 5 wt% of the catalyst were used, good yields of gly-
cosylated products at different temperatures were obtained. At room temperature,
a reaction did not occur (Table 1, entry 5), and it was sluggish at 40°C (Table 1,
entry 6). A 62% yield of the glycoside was obtained at 60°C, while a 94% yield was
obtained at 80°C (Table 1, entries 7 and 8). The catalyst concentration was also stud-
ied using 1 wt%, 5 wt%, and 10 wt% of the catalyst. Traces of glycosylated product
were observed using 1 wt% of the catalyst, while 5 wt% of catalyst gave maximum
yield of the product at 80°C. Increasing the catalyst concentration further to 10 wt%
did not have any significant impact on yields of the product (Table 1, entries 9–12).

4
R. S. THOMBAL AND V. H. JADHAV
Table . Glycosylation of unprotected and unactivated glycosyl donors with various acceptors using
sulfonated graphene oxide catalyst in the absence of a solventa.
Yieldb
(%)
Entry
Glycosyl donor
Acceptor
Time(h)









aReaction of  mmol of glycosyl donor and  mmol of glycosyl acceptor.
bIsolated yields.
Inspired by these results, we began to demonstrate the catalytic activity of this
catalyst on various unprotected and unactivated sugars. As seen from Table 2, the
neat glycosylation of glucose afforded a mixture of pyranoside and furanoside allyl
glycosides (94%), but the ratio was difficult to judge from 1H NMR due to overlap-
ping of peaks. Xylose gave a 3:1 α,β-mixture of pyranoside allyl glycoside, whereas
ribose gave a 5:1 α:β-mixture of furanoside allyl glycosides in 96% and 97% yields,
respectively (Table 2, entries 1–3). In the case of unprotected sugars, the glycosy-
lation reaction probably leads to the thermodynamically stable anomers, produced
directly or via anomerization of a kinetic product. Different temperatures, different
activators, and different solvents may also give rise to different amounts of anomeric
glycosides formed.[14] In our case, use of a high-temperature and solvent-free con-
dition may have favored the formation of mixtures of anomeric glycosides.
With the success of glycosylation of unprotected and unactivated sugars, we then
studied the catalytic activity of sulfonated graphene oxide on the glycosylation reac-
tions of 2,3,4,6-tetra-O-acetylglycosyl trichloroacetimidate using various primary,
secondary, and hindered acceptors. 2,3,4,6-Tetra-O-acetylglycosyl trichloroacetim-
idate was prepared from D-glucose by a known procedure.[15] Initially, we tried the
glycosylation of 2,3,4,6-tetra-O-acetylglycosyl trichloroacetimidate with 5 mmol of
allyl alcohol at 80°C (Table 3, entry 1). The reaction proceeded smoothly in 4 h form-
ing selectively β-glycoside as seen from the 1H and 13C NMR in a 97% yield. We then
tried the glycosylation using various acceptors including propagyl alcohol, 2-butene
diol, 1-adamantanemethanol, undecanol, and oleyl alcohol, which afforded the gly-
cosylated products in excellent yields (Table 3, entries 2–6). Secondary alcohols like
cyclohexanol, (−) menthol, and cholesterol also gave excellent yields of the glyco-
sylated products (Table 3, entries 7–9). Glycosylation with t-butanol did not give
any glycosylated product due to the less reactivity of tertiary alcohol (Table 3, entry

5

6

JOURNAL OF CARBOHYDRATE CHEMISTRY
7
Figure . Reusability of sulfonated graphene oxide catalyst.
10). Generally, the high reactivity of glycosyl trichloroacetimidate often leads to side
reactions or decomposition of the donor before reacting with the acceptor, thus sig-
nificantly decreasing the yield of the reaction. However, this was not observed in
our case, and fortunately, the trichloroacetimidate was found to be sufficiently sta-
ble during the reaction at high temperatures. Thus, all the glycosylation reactions
proceeded smoothly, giving high yields and selectivity of the desired products. To
our knowledge, this is the first report of glycosylation of glycosyl trichloroacetim-
idate without use of any solvent (expect entries 4 and 9). This process can thus be
considered highly efficient and economic.
As it is very convenient to recover the catalyst by simple filtration at the end of
the reaction, the solid catalyst could be readily reused for the next run of reaction
without any further activation. Therefore, the recycled sulfonated graphene oxide
catalyst without any regeneration step could be readily used in the glycosylation of
D-glucose with allyl alcohol at 80°C. As shown in Figure 2, it can be conveniently
recycled for five subsequent runs, having no impact on reaction time or the yields
of glycosylated products.
Conclusion
In summary, we have demonstrated an efficient way for the glycosylation of unpro-
tected and unactivated glycosyl donors using sulfonated graphene oxide as a cata-
lyst in the absence of solvent. Glycosyl trichloroacetimidate was also employed for
glycosylation of various alcohols, giving high yields and stereoselectivity of the gly-
cosides. This catalyst was also air and moisture stable, was easily recovered, and
showed high reusability, making the glycosylation reactions simple, economical, and
efficient. Some advantages of using this catalyst system were no need for dry and
moisture-sensitive reagents or low temperature and no need for molecular sieves.

8
R. S. THOMBAL AND V. H. JADHAV
Experimental
General methods
All reagents were purchased from Aldrich, Fluka, MERCK, and TCI and were used
without further purification. Water was deionized with a Millipore system as a Milli-
Q grade. NMR spectra were recorded in CDCl3 or DMSO-d6at 25°C on either a
Bruker 400 (400 MHz) or Bruker 200 (200 MHz) spectrometer. For 1H NMR spec-
tra, proton chemical shifts (δ) are given in ppm relative to tetramethylsilane (0.00
ppm) in CDCl3 or DMSO-d6. Multiplicities are indicated by s (singlet), d (doublet),
t (triplet), m (multiplet), and br (broad). For 13C NMR spectra, carbon chemical
shifts were internally referenced to the deuterated solvent signal of CDCl3 (77.16
ppm) or DMSO-d6 (39.5). HRMS was recorded on Thermo Scientific Q Exactive.
FT-IR was recorded on the Spectrum 400 instrument. PXRD was recorded on Pan-
alytical X’Pert Pro.
General procedure for glycosylation of unprotected sugars
A mixture of unactivated, unprotected sugars (1 mmol), alcohol (5 mmol), and 5
wt% sulfonated graphene oxide was taken at rt and then stirred at 80°C for the
required time. A small amount of reaction mixture was taken out at regular inter-
vals using a micropipette and diluted with methanol, and the reaction progress was
monitored by TLC. After consumption of all of the glycosyl donor, the reaction
mixture was cooled to rt and diluted with methanol, and the catalyst was separated
by filtration. The filtrate was concentrated at reduced pressure and crude products
were purified by column chromatography to remove the excess alcohol to obtain the
desired glycoside.
General procedure for glycosylation of protected sugars (Table 3, entries
1–3, 5, 6–8)
A mixture of protected sugars (1 mmol), alcohol (5 mmol), and 5 wt% sulfonated
graphene oxide was taken at rt and then stirred at 80°C for the required time. A small
amount of reaction mixture was taken out at regular intervals using a micropipette
and diluted with ethyl acetate, and the reaction progress was monitored by TLC.
After consumption of all of the glycosyl donor, the reaction mixture was cooled to rt
and diluted with ethyl acetate, and the catalyst was separated by filtration. The filtrate
was concentrated at reduced pressure, and crude products were purified by column
chromatography to remove the excess alcohol to obtain the desired glycoside.
General procedure for glycosylation of protected sugars (Table 3, entries 4, 9)
The protected sugar (1 mmol) and alcohol (1.2 mmol) were dissolved in toluene at
rt and then 5 wt% sulfonated graphene oxide was added at rt by itself, and then the

JOURNAL OF CARBOHYDRATE CHEMISTRY
9
reaction mixture was stirred at 80°C for the required time. The reaction progress
was monitored directly by TLC. After consumption of all of the glycosyl donor, the
reaction mixture was cooled to rt, and the catalyst was separated by filtration and
washed with ethyl acetate. The filtrate was then concentrated at reduced pressure,
and crude products were purified by column chromatography to obtain the desired
glycoside.
Allyl 2,3,4,6-tetra-O-acetyl-β-(D)-glucopyranoside (Table 3, entry 1)
25
White crystals; Yield 97%; Rf = 0.2 (EtOAc-Pet ether = 1:2); mp = 73–75°C, [α]D
= –13.4 (c = 1.03, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 2.01 (s, 3H), 2.02 (s, 3H),
2.05 (s, 3H), 2.09 (s, 3H), 3.65–3.73 (m, 1H), 4.04–4.12 (m, 1H), 4.14–4.17 (m, 1H),
4.24 (d, J = 4.5 Hz, 1H), 4.29–4.40 (m, 1H), 4.56 (d, J = 7.8 Hz, 1H), 4.98–5.07 (m,
1H), 5.12 (d, J = 9.4 Hz, 1H), 5.17–5.23 (m, 2H), 5.23–5.33 (m, 1H), 5.76–5.95 (m,
1H)); 13C NMR (CDCl3, 50 MHz) δ 20.6, 20.66, 20.7, 61.8, 68.3, 70.0, 71.2, 71.7, 72.8,
99.4, 117.6, 133.2, 169.3, 169.4, 170.3, 170.6; HRMS (ESI) m/z [M + Na]+ calcd for
C17H24O10Na 411.1267, found 411.1262.
Propargyl 2,3,4,6-tetra-O-acetyl-β-(D)-glucopyranoside (Table 3, entry 2)
White crystalline solid; Yield 97%; Rf = 0.3 (EtOAc-Pet ether = 1:2); mp 113–114°C;
[α]D25 –22.93 (c = 1.5, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 2.01 (s, 3H), 2.03 (s,
3H), 2.06 (s, 3H), 2.09 (s, 3H), 2.48 (t, J = 2.2 Hz, 1H), 3.71–3.75 (m, 1H), 4.11–4.17
(m, 1H), 4.26–4.30 (m, 1H), 4.37 (d, J = 2.7 Hz, 2H), 4.78 (d, J = 7.8 Hz, 1H), 5.0–
5.04 (m, 1H), 5.11 (t, J = 10.0 Hz, 1H), 5.25 (t, J = 9.6 Hz, 1H); 13C NMR (CDCl3,
50 MHz) δ 20.5, 20.6, 29.6, 55.8, 60.3, 61.6, 68.1, 70.8, 71.8, 72.6, 75.4, 78.0, 98.0,
169.3, 169.4, 170.2, 170.6; HRMS (ESI) m/z [M + Na]+ calcd for C17H22O10Na
409.1111, found 409.1105.
4-Hydroxybut-2-enyl tetra-O-acetyl-β-(D)-glucopyranoside (Table 3, entry 3)
White solid; Yield 94%; Rf = 0.3 (EtOAc-Pet ether = 1:1); mp 95–97°C; [α]D25 –2.44
(c = 0.5, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 2.01 (s, 3H), 2.03 (s, 3H), 2.06 (s,
3H), 2.10 (s, 3H), 3.69–3.70 (m, 1H), 4.15–4.21 (m, 3H), 4.24 (d, J = 4.5 Hz, 1H),
4.28 (t, J = 5.9 Hz, 1H), 4.32 (bs, 1H), 4.35–4.39 (m, 1H), 4.58 (d, J = 7.7 Hz, 1H),
4.98–5.03 (m, 1H), 5.09 (t, J = 9.6 Hz, 1H), 5.21 (t, J = 9.6 Hz, 1H), 5.6–5.67 (m,
1H), 5.83–5.89 (m, 1H); 13C NMR (CDCl3, 50 MHz) δ 20.6, 20.7, 20.73, 58.5, 61.9,
64.3, 68.4, 71.2, 71.7, 72.7, 99.2, 126.7, 133.3, 169.4, 169.4, 170.3, 170.8; HRMS (ESI)
m/z [M + Na]+ calcd for C18H26O11Na 441.1373, found 441.1367.
1-Adamantylmethyl 2,3,4,6-tetra-O-acetyl-β-(D)-glucopyranoside (Table 3,
entry 4)
White solid; Yield 97%; Rf = 0.6 (EtOAc-Pet ether = 1:1); mp 132°C; [α]D26 0.95 (c
= 1.06, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 1.48–1.52 (m, 3H), 1.58–1.74 (m,

10
R. S. THOMBAL AND V. H. JADHAV
12H), 2.02 (s, 3H), 2.03 (s, 3H), 2.06 (s, 3H), 2.10 (s, 3H), 2.97 (d, J = 9.4 Hz, 1H),
3.51 (d, J = 9.4 Hz, 1H), 3.63–3.71 (m, 1H), 4.16 (dd, J = 9.4 Hz, 1H), 4.28 (dd, J
= 7.7 and 4.5 Hz, 1H), 4.43 (d, J = 7.7 Hz, 1H), 5.01 (dd, J = 9.4 and 4.8 Hz, 1H),
5.09 (t, J = 9.47 Hz, 1H), 5.21 (t, J = 9.3 Hz, 1H); 13C NMR (CDCl3, 50 MHz) δ
20.6, 20.68, 20.7, 28.0, 33.8, 37.0, 39.2, 61.9, 68.4, 71.2, 71.6, 72.7, 80.9, 101.7, 169.2,
169.4, 170.3, 170.7; HRMS (ESI) m/z [M + Na]+ calcd for C25H36O10Na 519.2206,
found 519.2201.
Undecyl 2,3,4,6-tetra-O-acetyl-β-(D)-glucopyranoside, (Table 3, entry 5)
26
White semisolid; Yield 98%; Rf = 0.6 (EtOAc-Pet ether = 1:2); [α]D –1.41 (c =
1.0, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 0.87 (t, J = 7.1 Hz, 3H), 1.24 (bs, 18H),
1.5–1.59 (m, 2H), 2.0 (s, 3H), 2.2 (s, 3H), 2.4 (s, 3H), 2.8 (s, 3H), 3.43–3.49 (m,
1H), 3.67–3.71 (m, 1H), 3.84–3.89 (m, 1H), 4.11–4.14 (m, 1H), 4.26 (dd, J = 7.8 and
4.6 Hz, 1H), 4.49 (d, J = 7.8, 1H), 4.97 (dd, J = 8, 1.4 Hz, 1H), 5.08 (t, J = 9.7, 9.5 Hz),
5.2 (t, J = 9.5, 9.2 Hz, 1H); 13C NMR (CDCl3, 50 MHz) δ 14.2, 20.5, 22.5, 25.7, 29.2,
29.5, 31.7, 61.8, 68.3, 70.2, 71.2, 71.5, 72.7, 100.7, 169.3, 169.4, 170.3, 170.7; HRMS
(ESI) m/z [M + Na]+ calcd for C25H42O10Na 525.2676, found 525.2670.
(9Z)-9-octadecenyl tetra-O-acetyl-β-(D)-glucopyranoside (Table 3, entry 6)
26
White foam; Yield 92%; Rf = 0.3 (EtOAc-Pet ether = 1:2); [α]D –6.62 (c = 0.5,
1
CHCl3); H NMR (CDCl3, 400 MHz) δ 0.89 (t, J = 8.0 Hz, 1H), 1.26 (bs, 24H),
1.5–1.67 (m, 4H), 2.01 (s, 3H), 2.03 (s, 3H), 2.05 (s, 3H), 2.09 (s, 3H), 3.44–3.5 (m,
1H), 3.67–3.72 (m, 1H), 3.85–3.90 (m, 1H), 4.14 (dd, J = 9.7 and 2.4 Hz, 1H), 4.5
(d, J = 8 Hz, 1H), 4.99 (dd, J = 7.8 and 1.4 Hz, 1H), 5.1 (t, J = 9.7 Hz, 1H), 5.21
(t, J = 9.5 Hz, 1H), 5.34–5.37 (m, 1H); 13C NMR (CDCl3, 100 MHz) δ 14.1, 20.6,
20.7, 20.8, 22.7, 25.8, 25.9, 27.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 31.9, 62.0, 68.5, 70.3,
71.3, 71.7, 72.9, 100.8, 129.8, 130.0, 169.3, 169.4, 170.3, 170.7; HRMS (ESI) m/z [M
+ Na]+ calcd for C32H54O10Na 621.3615, found 621.3609.
Cyclohexyl 2,3,4,6-tetra-O-acetyl-β-(D)-glucopyranoside (Table 3, Entry 7)
26
White solid; Yield 93%; Rf = 0.2 (EtOAc-Pet ether = 1:2); mp 107–109°C; [α]D
–10.57 (c = 1.02, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 1.24–1.26 (m, 4H), 1.38–
1.48 (m, 2H), 1.64–1.77 (m, 3H), 1.83–1.86 (m, 1H), 1.99 (s, 3H), 2.01 (s, 3H), 2.02
(s, 3H), 2.07 (s, 3H), 3.58–3.63 (m, 1H), 3.64–3.69 (m, 1H), 4.10 (dd, J = 11.9 and
2.3 Hz, 1H), 4.25 (dd, J = 11.9 and 4.5 Hz, 1H), 4.57 (d, J = 7.8 Hz, 1H), 4.95 (dd, J
= 9.6 and 8.2 Hz, 1H), 5.07 (t, J = 9.6 Hz, 1H), 5.19 (t, J = 9.6 Hz, 1H); 13C NMR
(CDCl3, 50 MHz) δ 20.6, 20.65, 20.68, 20.7, 23.5, 23.6, 25.4, 31.5, 33.1, 62.0, 68.5,
71.4, 71.5, 72.8, 78.0, 99.3, 169.2, 169.4, 170.3, 170.7; HRMS (ESI) m/z [M + Na]+
calcd for C20H30O10Na 453.1737, found 453.1731.

JOURNAL OF CARBOHYDRATE CHEMISTRY
11
(−) Menthyl 2,3,4,6-tetra-O-acetyl-β-(D)-glucopyranoside (Table 3, entry 8)
White solid; Yield 94%; Rf = 0.5 (EtOAc-Pet ether = 1:2); mp 135°C; [α]D25 –3.05 (c
= 1.25, CHCl3); 1H NMR (CDCl3, 200 MHz) δ 0.73 (d, J = 4.6 Hz, 3H), 0.85 (s, 3H),
0.89 (d, J = 1.7Hz, 3H), 0.91–0.93 (m, 2H), 1.14–1.41 (m, 4H), 1.55–1.72 (m, 5H),
2.01 (s, 3H), 2.03 (s, 3H), 2.06 (s, 3H), 2.08 (s, 3H), 3.25–3.45 (m, 1H), 3.63–3.76
(m, 1H), 4.07–4.28 (m, 2H), 4.56 (d, J = 7.9 Hz, 1H), 4.97 (dd, J = 9.7 and 3.6 Hz,
1H), 5.07 (dd, J = 8.9 and 2.2 Hz, 1H), 5.21 (t, J = 9.4 Hz, 1H); 13C NMR (CDCl3,
50 MHz) δ 15.4, 15.9, 20.5, 20.6, 20.7, 20.9, 21.0, 22.3, 22.8, 25.0, 31.4, 31.6, 34.0, 34.1,
40.8, 42.8, 47.4, 48.0, 62.4, 68.7, 68.9, 71.5, 71.6, 73.0, 79.1, 83.1, 98.7, 101.9, 169.3,
169.5, 170.2, 170.4; HRMS (ESI) m/z [M + Na]+ calcd for C24H38O10Na 509.2363,
found 509.2357.
Cholesteryl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside (Table 3, entry 9)
White solid; Yield 78%; Rf = 0.2 (EtOAc-Pet ether = 1:2); mp 105°C; [α]D25 –9.68
(c = 0.52, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 0.68 (s, 3H), 0.86 (d, J = 1.7 Hz,
3H), 0.88 (d, J = 1.7 Hz, 3H), 0.92 (d, J = 6.6 Hz, 3H), 0.99 (s, 3H), 1.04–1.20 (m,
8H), 1.22–1.39 (m, 10H), 1.42–1.54 (m, 6H), 1.79–1.93 (m, 3H), 2.01 (s, 3H), 2.03
(s, 3H), 2.06 (s, 3H), 2.09 (s, 3H), 2.13–2.29 (m, 2H), 3.45–3.53 (m, 1H), 3.66–3.70
(m, 1H), 4.12 (dd, J = 10.0 and 2.2 Hz, 1H), 4.26 (dd, J = 7.5 and 4.6 Hz, 1H), 4.6
(d, J = 8 Hz, 1H), 4.97 (dd, J = 8.7 and 7.8 Hz, 1H), 5.08 (t, J = 9.7 Hz, 1H), 5.21
(t, J = 9.5 Hz, 1H), 5.36–5.37 (m, 1H); 13C NMR (CDCl3, 100 MHz) δ 11.8, 18.7,
19.3, 20.6, 20.6, 20.7, 20.8, 21.0, 22.5, 22.8, 23.8, 24.3, 28.0, 28.2, 29.4, 29.7, 31.8,
31.9, 35.7, 36.1, 36.7, 31.1, 38.9, 39.5, 39.7, 42.3, 50.15, 56.1, 56.7, 62.1, 68.5, 71.4,
71.6, 72.9, 80.1, 99.6, 122.2, 140.3, 169.3, 169.4, 170.4, 170.7; HRMS (ESI) m/z [M
+ Na]+ calcd for C41H64O10Na 739.4397, found 739.4391.
Acknowledgment
V.H.J also thanks the director of NCL for providing all the infrastructural facilities.
Funding
V.H.J. thanks DST, New Delhi, for the INSPIRE Faculty Award (IFA 12, CH-44) and Fast Track
Grant (CS-041/2013).
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