Tunable stereoselectivity in the synthesis of α- and β-aryl glycosides using 1,2-α-anhydrosugars as glycosyl donors

Article abstract of DOI:10.1016/j.carres.2017.07.007

The stereochemical course of O-glycosidation of 1,2-α-D-anhydrosugars (glycal epoxides) with phenols can be tuned by varying the metal ion of the base. While the reaction of 1,2-α-D-anhydrosugars with phenols mediated by trimethylaluminium leads exclusive

Full text of DOI:10.1016/j.carres.2017.07.007

Accepted Manuscript
Tunable stereoselectivity in the synthesis of α- and β-aryl glycosides using 1,2-α-
anhydrosugars as glycosyl donors
Devaraj Somasundaram, Kalpattu K. Balasubramanian, Shanmugasundaram
Bhagavathy
PII:
S0008-6215(17)30465-2
10.1016/j.carres.2017.07.007
CAR 7421
DOI:
Reference:
To appear in: Carbohydrate Research
Received Date: 3 July 2017
Revised Date: 24 July 2017
Accepted Date: 24 July 2017
Please cite this article as: D. Somasundaram, K.K. Balasubramanian, S. Bhagavathy, Tunable
stereoselectivity in the synthesis of α- and β-aryl glycosides using 1,2-α-anhydrosugars as glycosyl
donors, Carbohydrate Research (2017), doi: 10.1016/j.carres.2017.07.007.
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ACCEPTED MANUSCRIPT
Tunable stereoselectivity in the synthesis of
-anhydrosugars as glycosyl donors
α- and β- aryl glycosides using 1,2-
α
Devaraj Somasundaram, Kalpattu K Balasubramanian (s), and Shanmugasundaram Bhagavathy(s)*
OBn
R'
-
isomer
H
O
R
2
0 examples
H
OBn
H
BnO
R'
yield 70- 90%
OH
O
OAr
R
BnO
H
+
ArOH
OBn
O
R'
H
- isomer
R'= H; R= OBn (or)
R'= OBn; R= H
O
R
6
examples
OAr
BnO
yield 75- 90%
OH
H

ACCEPTED MANUSCRIPT
Tunable stereoselectivity in the synthesis of α- and β- aryl glycosides using
1
,2-α-anhydrosugars as glycosyl donors
a
b
a
Devaraj Somasundaram, Kalpattu K Balasubramanian (s), and Shanmugasundaram Bhagavathy(s)*
a
B. S. Abdur Rahman Crescent University, Vandalur, Chennai, India
b
Indian Institute of Technology Madras, Guindy, Chennai, India
Abstract
The stereochemical course of O-glycosidation of 1,2-
can be tuned by varying the metal ion of the base. While the reaction of 1,2-
phenols mediated by trimethylaluminium leads exclusively to 1,2-cis- -O-aryl glycosides, similar
reaction mediated by caesium carbonate gives exclusively 1,2-trans- -O-aryl glycosides. In contrast,
α
-D
-anhydrosugars (glycal epoxides) with phenols
α-D-anhydrosugars with
α
β
reaction with phenoxides generated from Grignard reagent and calcium salts affords mixture of the
anomers.
Keywords 1,2-anhydrosugars, Glycal epoxides, aryl glycosides, stereoselective, glycosidation
1
.0 Introduction
Naturally occurring carbohydrates carrying aromatic aglycons have received considerable attention as
some of them are antibiotics, exhibiting chemotherapeutic and antitumor action, like vancomycin and
1
chromomycin. Glycosylated phenols of plant origin are also known; like that of Arbutin, Skimmin,
2
SennosideA and Glucofrangulin. Some of the aryl glycosides form ordered macrostructures such as
3
micelles and liquid crystalline phases. In recent years, the synthesis of aryl glycosides has received
4
considerable attention from both synthetic and medicinal chemists because of their diverse biological
5
activities and pharmaceutical potentials. The review of Marten et al gives an excellent account on
6
various methods towards synthesis of aryl glycosides. Glycosyl acetates, phosphates, halides,
trichloroacetimidates, and sulphoxides, etc., have been used as glycosyl donors with phenols in the
7
presence of Lewis or Bronsted acids to yield aromatic glycosides. Glycal derivatives with good leaving
groups at the allylic position can be readily converted into 2,3-unsaturated aryl glycosides by treatment
8
of phenols; either thermally or using Lewis acids and Pd complexes. Contrary to glycosylation of
alcohols and other sugar alcohols, it is not easy to obtain good yields of the glycosides of aromatic
9
10
aglycons due to dimerisation and formation of C-glycosides, especially in the case of activated
11
12
aromatic compounds. In many cases, mixtures of both the anomers have been reported. Though there
are many methods for the synthesis of aryl glycosides, there is still a need for mild, efficient and highly

ACCEPTED MANUSCRIPT
stereoselective method which will also provide a free hydroxyl at C-2 for further elaboration and access to
C-2 branched sugars.
13
The 1,2-D-anhydrosugars have also been widely used as glycosyl donors for glycosylation
reactions. Most importantly, this approach directly provides access to glycosides with a free hydroxyl
group at C-2 position of the sugar moiety that can be exploited for the synthesis of carbohydrates
1
4
containing 1,2-linkage, as found in many natural glycoconjugates, such as saponins . The
α
- and
β
-
-
15
isomers of 1,2-
D
-anhydrosugars can be accessed by oxidation of the glycals. The use of 1,2-
D
anhydrosugars as glycosyl donors for the synthesis of aryl glycosides has far less been investigated
16
compared to that of alkyl glycosides. One drawback could be that its stereochemical outcome is not
predictable when Lewis acids are employed to catalyze the ring opening reaction. The stereochemical
17
course of such reactions are influenced by external additives and electronic nature of the substitutents.
Higher selectivity in favour of -anomer has been reported when the glycosidation was conducted using
β
18
17a
t
17d
gold complex, PTC condition
and KO Bu.
Recently, Tanaka et al have reported 1,2-cis-α-
19a
stereoselective glucosylation and 1,2-cis- -stereoselective mannosylation of alcohols utilizing catalytic
β
19b
amount of boronic esters of these alcohols . Regioselective and 1,2- cis- stereoselective glycosylation
of sugar 1,2-diols and 1,3-diols using catalytic amount of cyclic boronate esters derived from these diols
2
0
is also known. The utility of this novel methodology for the stereoselective synthesis of 1,2-cis-
glycosides has not been explored. This triggered our interest to investigate the stereochemistry and ease of
glycosidation of 1,2- -anhydrosugars with phenols mediated by triphenyl borate, aluminium phenoxide,
titanium phenoxide as well as by phenoxides derived from other common metal ions like Mg, Ca, Cu etc.,
Herein we describe a very facile 1,2-cis- -stereoselective O-glycosidation of phenols with 1,2-
anhydroglucose and 1,2- -anhydrogalactose mediated by Me Al which is superior to the glycosidation
mediated by B(OPh) in terms of yield , stereoselectivity and reaction time.
α-aryl
D
α
α-D-
α-
D
3
3
2
.0 Result and Discussion
The substrates, 1,2-
α
-
D
-anhydroglucose 1 and galactose 4 were obtained by stereoselective
-gucal and d-galactal respectively via in situ generation of
oxidation of 3,4,6-tri-O-benzyl-
dimethyldioxirane (DMDO) using oxone/acetone in a biphasic system. The reaction of 1 with
phenoxides of monovalent metals like Li, Na, K and Cs afforded exclusively the -O-aryl glycoside 3a
Table 1, entries 1-5). Cs CO was found to be the best base in terms of yield and reaction time (Table 1,
entry 4). The phenoxides of Mg, Ca and Cu yielded mixture of - and -anomers, but Mg salt showed a
greater preference for -anomer, while Ca and Cu salts exhibited preference to -anomer 2a. In contrast
to these metal phenoxides, B(OPh) favoured -anomer 2a (Table1, entry 10 ) at ambient temperature.
prepared from titaniumisoproxide yielded exclusively -O-phenyl glycoside 2a (Table1, entry
D
2
1
β
(
2
3
α
β
β
α
α
3
Ti(OPh)
4
α

ACCEPTED MANUSCRIPT
1
3
2), albeit in relatively lower yield. Interestingly, the reaction of 1 with phenol in the presence of Me Al
afforded exclusively the
α-O-phenyl glycopyranoside 2a in high yield. This reaction was extremely fast
and proceeded to completion in a matter of 3-5 minutes that too at ambient temperature. The crude
2
2
product from all these reactions was analyzed by NMR and HPLC for determining the anomeric ratios.
The structure of 2a was further confirmed by converting it to the known phenyl-2,3,4,6–tetra-O-benzyl-
α
-
2
3a
23b
D
-glucopyranoside and phenyl 2-O-acetyl-3,4.6-tri-O-benzyl-
turned out to be the best mediator for obtaining exclusively the -anomer in high yield and short reaction
time and Cs CO for the synthesis of - anomer. These data reveal that the anomeric selectivity on
-anhydrosugar can be fine tuned by varying the metal counter ion of the
α-
D
-glucopyranoside.
3
Thus, Me Al
α
β
2
3
glycosidation of 1,2-
α-D
phenoxide.
Table 1. Glycosidation of 1,2-D-anhydrosugar 1 with different metal phenoxides
22
Metal ion
Entry
2a :3a
Solvent
Reaction condition
Yield (%)
precursor
α : β
1
2
3
4
5
6
7
8
9
NaH
Na CO
K CO
Toluene
Toluene
RT, 30 min
Reflux, 45 min
Reflux, 45 min
Reflux, 15 min
RT, 20 min
73
83
85
90
74
65
76
75
73
88
90
82
β
β
β
β
β
only
only
only
only
only
2
3
3
Toluene
2
3
Cs CO
Toluene
2
CH
3
Li
DCM: DEA
DCM: THF
Toluene
CH MgCl
RT, 150 min
Reflux, 15 min
Reflux, 30 min
Reflux, 30 min
RT, 30 min
10 : 90
91 : 9
92 : 8
91 : 9
92 : 8
3
CaH2
CaCO
3
Toluene
CuCO3
Toluene
1
0
1
2
B(OPh)3
Toluene
1
1
Al(CH
3
)
3
DCM: Toluene
RT, 5 min
α
α
only
only
(
a
Ti(OPh)4
Toluene
RT, 15 min
(a
i
24
prepared from the reaction of Ti(O pr) with phenol and isolated.
4

ACCEPTED MANUSCRIPT
3
We further explored other in situ methods for generating Al(OPh) (Table 2). In case of alumina,
the reaction was rather slow and incomplete at ambient temperature, but the reaction was highly
stereoselective furnishing only -anomer. Under reflux conditions in toluene, it could be driven to
completion, but with a slight loss of stereoselectivity affording a mixture of the anomeric glycosides 2a
and 3a with predominant -anomer (Table 2, entry 2). Aluminium isopropoxide was found to be a better
base for in situ generation of Al(OPh) when compared to alumina as it yielded only the -anomer. It is to
be noted here that no isopropyl glycoside was formed during this reaction. However, the reaction was
α
α
3
α
2
3
5
rather slow when compared to Me Al mediated reaction. The glycosidation of 1 with Al(OPh) at
3
ambient temperature was very slow in CH Cl , but addition of toluene as co-solvent accelerated the
2
2
reaction.
Table 2. Glycosidation of 1a and phenol with various Aluminum reagents
a)
Reaction
Yield
2a : 3a
Entry Metal ion precursor
Solvent
condition
RT, 12 Hrs
Reflux, 15 min
RT, 5 min
(%)
α : β
b)
1
2
3
4
5
6
Al O
Toluene
Toluene
40
α
only
2
3
3
Al O
95
95
82
78
85
95 : 5
2
Al(CH
3
)
3
CH
CH
2
Cl
2
: Toluene
α
only
only
only
only
Al(O-iPr)3
Toluene
RT, 15min
α
α
α
c)
Al(OPh)3
CH Cl2
RT, 120 min
RT, 15 min
2
c)
Al(OPh)
3
2
Cl
2
: Toluene
a)
b)
c)
25
Isolated yield after purification. Reaction incomplete Reaction performed with isolated Al(OPh) , no phenol added.
3
Scheme 1. Synthesis of stereoselective α- and β-O-aryl glycosides.
Based on these findings, we chose Me
stereoselective O-glycosidation reaction of 1 with phenols (Scheme 1). Me
reaction of various phenols with 1 went to completion in a few minutes at ambient temperature to afford
exclusively the respective -aryl glycosides 2a-o in high yields (Table 3). This reaction protocol exhibited
3
Al as the mediator to study the generality of this 1,2-cis-
α-
3
Al mediated glycosidation
α

ACCEPTED MANUSCRIPT
a fair degree of functional group tolerance. Functional groups such as CN, F, Cl, Br, OMe and CHO
groups were found to be compatible excepting p-nitro group (entry 11). However, in this case the reaction
could be driven successfully by using alumina instead of Me Al to afford 2j in good yields. Also, the
3
synthesis of
naphthyl glycosides. 4- methyl- umbelliferone (Table 3, entry 15) too underwent smooth glycosylation
with 1 affords the corresponding -anomer 2o in moderate yields. The galactal epoxide 4 was also found
to be a versatile substrate for the 1,2-cis- stereoselective O-aryl glycosidation mediated by Me Al
enabling the synthesis of several aryl -galactosides 5a-e in good yields (Table 3, entries 16-20).
α-naphthyl glycoside 2m could be achieved with no trace of formation of any isomeric C-
α
α
3
α-D
Table 3. Me Al mediated glycosidation of 1,2-
α
-D-anhydro sugars for the synthesis of α-O-aryl
3
glycosides.
1
a)
Entry
Substrate
R
R
Ar
Product Yield (%)
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
4
4
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
OBn
H
H
Phenyl
2a
2b
2c
2d
2e
2f
95
82
88
86
H
2-Me-phenyl
3-Me-phenyl
4-Me-phenyl
4-OMe-phenyl
2-naphthyl
4-F-phenyl
2-Cl-phenyl
3-Br-phenyl
H
H
c)
H
84
73
87
78
90
H
H
2g
2h
2i
H
H
b)
d)
1
1
1
1
1
1
1
1
1
1
2
0
1
2
3
4
5
6
7
8
9
0
H
4-NO -phenyl
2j
72
76
75
2
H
2-isopropyl-phenyl
4-CN-phenyl
1-naphthyl
2k
2l
H
c)
H
2m
2n
2o
5a
5b
5c
5d
5e
76
68
54
c)
c)
H
4-CHO-phenyl
4-Me-comarin-7-yl
Phenyl
H
OBn
OBn
OBn
OBn
OBn
92
H
2-Me-phenyl
4-Me-phenyl
4-F-phenyl
84
86
80
76
H
H
H
4-CN-phenyl
a)
b)
c)
Isolated yield after purification; Al O used instead of Me Al; trace amount of the free sugar arising out of epoxide
2
3
3
d)
with water; >98% α-anomer

ACCEPTED MANUSCRIPT
1
7a-c
Traditionally, synthesis of aryl
β
2 3
-glycosides have been reported using bases like K CO ,
t
17d
17a-c
KO Bu, and also at times in biphasic system using PTC like 18-crown-6,
with additives like
17a
26
tetramethylguanidine. The “balanced base” Cs CO is known to be superior for O-arylation of phenols
2
3
2
7
and N-alkylation of amines. However, it has not been explored for the synthesis of aryl glycosides. We
have observed that the ring opening of 1 and 4 with phenols in toluene mediated by Cs CO proceeded
2
3
well affording exclusively aryl
β-glycosides 3a-d and 6a-b, respectively in high yields, shorter duration
and without the need of any external additives or catalyst (Scheme 1, Table 4)
Table 4. Cs
glycosides.
2
CO
3
mediated glycosidation of 1,2-
α
-D
-anhydro sugars for the synthesis of β-O-aryl
28
1
a)
Entry
Substrate
R
R
Ar
Product Yield (%)
1
2
3
4
5
1
1
1
1
4
4
OBn
OBn
OBn
OBn
H
H
Phenyl
3a
3b
3c
3d
6a
6b
90
86
88
85
88
76
H
2-Me-phenyl
3-Me-phenyl
4-Me-phenyl
Phenyl
H
H
OBn
OBn
6
H
4-OMe-phenyl
a)
Isolated yield after column chromatographic purification.
Scheme 2. Proposed mechanism for the stereoselectivity of the glycosidation of 1 and 4.

ACCEPTED MANUSCRIPT
Mechanistically, depending upon the conditions, the stereochemical outcome may be either under
kinetic or thermodynamic control. Exclusive stereoselectivity in favour of
α-anomer in the case of
Al(Me) mediated glycosidation of 1 and 4 can be rationalised as outlined in Scheme 2. Initial
3
3+
complexation of Al metal centre to the oxygen of the epoxide to form (A), followed by cleavage of the
C-O bond, facilitated by sugar ring oxygen, would lead to the formation of the aluminate oxecarbenium
ion intermediate (B). Subsequent intramolecular transfer of the phenoxide ligand from the aluminate
complex (B) to the anomeric carbon would result in stereoselective formation of the
similar syn-addition mechanism has been proposed by Rainer et al for -C-arylation of 1 using triaryl
aluminium. and by Nakagava et al for the glycosidation of sugar cis-1,2-diol and 1,3-diols catalysed by
α-anomer 2 and 5. A
α
29
20
cyclic boronate ester.
This proposed mechanism is in consistent with our finding that no isopropyl glycoside was
formed when the reaction of the epoxide 1 with Al(OPh) was done in the presence of stoichiometric
amounts of isopropanol. In case of Cs CO promoted glycosylation, the possibility of internal ligand
3
2
3
transfer does not exist and hence the reaction course takes the S 2 pathway leading to the formation of the
N
β
-glycosides via trans-ring opening of the epoxide ring. However, formation of anomeric mixture of the
glycosides in the cases of Mg, Ca and Cu ions indicates that both S
occurring simultaneously.
N N
1 and S 2 type mechanisms are
3
.0 Conclusions
In summary, we have developed a highly stereoselective and practical method for the synthesis of
α
-O-aryl glycosides promoted by Me
3
Al and
β
-O-glycosides by Cs
2
CO
3
. This glycosylation protocol is
extremely fast, high yielding, easy to carry out and amenable for scale up.
4
.0 General experimental considerations
CH Cl was dried by distilling over CaH
2
2
2
under argon. Products obtained were purified over silica gel (60
Å, 230-400 mesh) in flash column chromatography using ethyl acetate and hexane as eluant. Analytical
thin-layer chromatography (TLC) was performed on pre-coated silica gel plates (Ultra Pure Silica Gel
Plates purchased from Merck), visualized with a Spectroline UV254 lamp. Products were purified flash
column chromatography are reported as v/v ratios. Melting points were obtained using Sigma Melting
Point apparatus, and are uncorrected. UV specral analysis was done by using Shimadzu UV-2600
spectrophotometer. Specific optical rotations were determined on a JASCO P2000 Polarimeter under the
1
13
conditions indicated using the sodium D line (589 nm). H and C NMR were recorded at 400 MHz and
5
00 MHz on a Bruker spectrometer. Proton chemical shifts were internally referenced to the residual

ACCEPTED MANUSCRIPT
proton resonance in CDCl
3
(
δ
7.26 ppm). Carbon chemical shifts were internally referenced to the
dueterated solvent signals in CDCl
3
(δ 77.20 ppm). FT-IR spectra were recorded on a JASCO 6300
spectrometer with samples loaded as neat. Mass spectra were recorded on a JEOL GCMATE II GC-MS
instrument.
5
.0 General experimental procedure for glycosidation of 1 & 4 using Me Al:
3
To a solution of phenol (1.1 equiv.) in 1mL of CH Cl , 2.0 M solution of Me Al in toluene ( 0.04 mL,
2
2
3
0
.33 equiv.) was added at ambient temperature followed by the addition of 1,2-anhydrosugar 1 or 4 (100
mg , 1.0 equiv.) under nitrogen atmosphere. After 5 min (as monitored by TLC), about 5 ml of water was
added and worked up. Reaction mixture was extracted using CH Cl , concentrated in vacuo and purified
2
2
by flash column chromatography using 5% ethyl acetate and n-hexane as mobile phase, to afford α-O-aryl
glycosides 2a-o or 5a-e, respectively.
5
.1
Phenyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2a)
30
-1
White solid (95%); m.p.: 103
̊
C;
[α]D = +26. 5 ̊( c 1.0, CH Cl ); IR (cm ): 3518, 3061, 3030, 2914,
2 2
1
2
3
884, 1597, 1453, 1049, 1024, 729, 696, 474; H NMR(CDCl ,500MHz,
δ
): 2.21 (d, 1H, J = 10Hz, OH),
3
.61 (d, 1H, J =10Hz, H-6a), 3.76 (d, 1H, J = 15Hz, H-4), 3.80 (d, 1H, J =10Hz, H-6b), 3.87-3.91 (m, 2H,
H-2 & H-3), 3.96-4.08 (t, 1H, J = 10, 10Hz, H-5), 4.44, 4.51, 4.62, 4.84, 4.92, 4.98 (6d, 6H, -CH Ph),
2
1
3
5
6
8
1
.60 (bs, 1H, H-1), 7.02-7.15 (m, 5H, Ar-H), 7.23-7.35 (m, 15H, Ar-H); C NMR (CHCl , 125MHz, δ):
3
8.2 (t, C-6), 71.2 (d, C-3), 72.7 (d, C-2), 73.5 (d, Ar-C), 75.1 (d, Ar-C), 75.5 (d, Ar-C), 76.8 (d, C-4),
3.2 (d, C-5), 97.2 (d, C-1), 116.7, 122.7, 127.8, 127.8, 127.8, 127.9, 127.9, 127.9, 128.0, 128.4, 128.4,
28.5, 128.5, 128.6, 129.6 (20d, Ar-C), 137.8, 138.1, 138.6, 156.4 (4s, Ar-C); HRMS(TOF MS
ES+)Calculated for C H O : 507.2899; found: 507.2902.
33
34
6
5
.2
2-methylphenyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2b)
30
-1
Off-white semi solid (82%); [α]D = + 29.3 (̊ c 1.0, CH Cl ); IR (cm ) 3436, 2915, 2867, 1125, 1029,
2 2
1
7
33, 693, 474; H NMR(CDCl ,500MHz): δH 2.03 (d, 1H, J = 9 Hz, -OH), 2.23 (s, 3H, -CH ), 3.62-3.66
3
3
(
m,1H, H-6a), 3.77 (bd, 1H, H-6b), 3.80 (bd, 1H, H-4), 3.85-3.89 (m, 2H, H-2 & H-3), 3.94-3.98 (m, 1H ,
H-5), 4.46, 4.55, 4.62, 4.86, (4H, 4d, J= 12, 11, 12, 11 Hz, 2* -O-CH -Ph), 4.91-4.97 (m, 2H, -O-CH
Ph) 5.57 (d, 1H, J= 3.5Hz, H-1), 6.94 (t,1H, J= 7.5, 7 Hz, Ar-H), 7.13 ( bd, 2H, J= 7.5 Hz , Ar-H), 7.16
2
2
-

ACCEPTED MANUSCRIPT
13
(
m, 1H, Ar-H) 7.16-7.41 (m, 15H, Ar-H); C NMR(CHCl
3
, 125MHz): 16.3 (q, C), 68.3 (t, C-6), 71.4 (d,
C-3), 72.8 (d, C-2), 73.5 ,75.1 ,75.4 (3t, C-Ar), 75.8 (d, C-4), 82.9 (d, C-5), 97.4 (d, C-1), 114.7, 122.4,
1
1
27.1(3d, Ar-C), 127.3 (s, Ar-C), 127.5, 127.7, 127.8, 127.9, 127.9, 127.9, 128.0, 128.1, 128.3, 128.4,
28.4, 128.5, 128.6, 130.9 (14d, Ar-C), 137.9, 138.1,138.5, 154.8 (4s, Ar-C); HRMS calculated for
C H O Na : 563.2404; found: 563.2397.
3
4
36
6
5
.3
3-methylphenyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2c)
30
-1
Off-white solid (88 %); m.p.: 83
̊
C ;
[
α
]D = -33.8 (
̊ c 1.0, CH Cl ); IR(cm ) 3353, 2921, 1454, 1126,
2 2
1
1
063, 1028, 730, 693, 474; H NMR (CDCl
3
,500MHz): δ 2.16 (d, 1H, J= 8.5 Hz, -OH), 2.31 (s, 3H, -
H
3
CH ), 3.63 (bd, 1H, J= 11 Hz, H-6a), 3.75 (dd, 1H, J= 3.5 , 5, 2.5 Hz , H4), 3.78 (d, 1H, J= 10 Hz, H6-
b), 3.87-3.89 (m,1H, H2), 3.90 (d, 1H , J= 7 Hz, H3), 3.97 (t, 1H , H-5), 4.45, 4.53, 4.61, 4.85, 4.91, 4.98
(
6d , 6H, J= 12, 11.5, 12, 11, 11, 11 Hz, 3* -O-CH -Ph), 5.58 (d, 1H, J= 3.5Hz, H-1), 6.85 (d, 1H, J=
2
1
3
7
.5Hz, Ar-H), 6.90-6.93 (m, 2H, Ar-H), 7.14 -7.17(m, 1H, Ar-H) 7.24-7.41 (m, 15H, Ar-H); C NMR
, 125MHz): 21.4 (q, C), 68.3 (t, C-6), 71.2 (d, C-3), 72.8 (d, C-2), 73.4, 75.0,75.4 (3t, Ar-C), 77.3
d, C-4), 83.2 (d, C-5), 97.3 (d, C-1), 113.7,117.6, 123.5,127.7, 127.7, 127.7, 127.8, 127.9, 127.9, 128.3,
28.4, 128.5, 129.3 (13d, Ar-C), 137.9, 138.2, 138.7, 139.7, 156.5 (5s, Ar-C); HRMS calculated for
(
(
CHCl
3
1
C H O Na : 563.2404; found: 563.2397.
3
4
36
6
5
.4
4-methylphenyl 3,4,5-tri-O-benzyl-
α-
D-glucopyranoside (2d)
3
0
-1
Off-white solid (86 %); m.p.: 88 ̊ C ; [α]D = +8.5 (̊ c 1.0, CH Cl ); IR(cm ) 3510, 2915,2881, 1455,
2
2
1
1
112, 1051, 730, 692, 469; H NMR (CDCl ,500MHz): δH 2.19 (d, 1H, J= 9.0 Hz, -OH), 2.29 (s,3H, -
3
3
CH ), 3.61 (d,1H, J= 10.5 Hz, H-6a), 3.75 (dd, 1H, J= 3, 3.5, 4 Hz, H-4), 3.78 (d, 1H, J= 10 Hz, H-6b),
3
4
.86-3.87 (m, 1H, H2), 3.92 (d, 1H , J= 10 Hz, H-3), 3.95- 3.99 (m, 1H, H-5), 4.44, 4.52, 4.60, 4.84, 4.90,
.98 (6d, 6H, J= 12, 10.5, 12, 10.5, 11, 11Hz , 3* -O-CH -Ph), 5.54 (d, 1H,J= 3.5Hz, H1), 6.98-7.00 ( ab
2
q , 2H, J= 8.5Hz Ar-H), 7.03 (ab q , 4H, J= 8.5Hz, 8.5 Hz, Ar-H), 7.15 (d, 2H, J= 12Hz, Ar-H), 7.22-
1
3
7
7
1
3
.41 ( m,13H, Ar-H); C NMR (CHCl , 125MHz): 20.6 (q, C), 68.4 (d, C-6), 71.2 (d, C-3), 72.9 (d, C-2),
3.5, 75.1 ,75.5 (3t, Ar-C), 77.3 (d, C-4), 83.3 (d, C-5), 97.5 (d, C-1), 116.8, 127.7, 127.8, 127.9, 127.9,
27.9, 128.4, 128.4, 128.5, 130.0 (10d, Ar-C), 132.1, 137.9, 138.2, 138.7, 154.3 (5s, Ar-C ); HRMS
calculated for C H O Na : 563.2404; found: 563.2398.
3
4
36
6

ACCEPTED MANUSCRIPT
5
.5
4-methoxyphenyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2e)
3
D
0
-1
Off-white solid (84%); m.p.: 98
̊
C ;
[
α]
= +5.9 ( ); IR(cm ) 3431, 2917, 2863, 1502,
̊
c 1.0, CH
2
Cl
2
1
1
1
3
4
206, 1123, 1056, 1029, 737, 696; H NMR (CDCl
3
,500MHz): δ 2.20 (d, 1H, J=8.5 Hz, -OH), 3.64 (d,
H
H, J=10.5Hz, H-6a), 3.73-3.77 (m, 2H, H-6b & H-4),3.76 (s, 3H, -OMe), 3.82-3.87 (m, 1H, H-3), 3.94-
.97 (m, 2H, H-5 & H-4), 4.44-4.99 (6d, 6H, 3* -O-CH -Ph), 5.51 (d, 1H,J= 4Hz, H1), 6.80 -7.04 ( ab q,
2
13
H, 4*Ar-H), 7.15-7.41 (m,15H, Ar-H); C NMR (CHCl , 125MHz): 56.1 (q, C), 68.2 (d, C-6), 71.2 (d,
3
C-3), 72.8 (d, C-2), 73.5, 75.0 ,75.5 (3t, Ar-C), 77.3 (d, C-4), 83.2 (d, C-5), 97.2 (d, C-1), 116.8, 127.7,
1
1
27.7, 127.8, 127.9, 127.9, 127.9, 128.2, 128.4, 128.4, 128.5, 128.6,129.6 (10d, Ar-C), 137.8, 138.1,
38.6, 156.4 (5s, Ar-C ); HRMScalculated for C H O (TOF MS ES+):537.3005; found: 537.3019.
34
36
7
5
.6
β
-naphthyl 3,4,5-tri-O-benzyl-
C ; [α]D = +10.4 (̊ c 1.0, CH Cl ); IR(cm ) 3516, 2917, 2880, 1594,
2 2
α-D-glucopyranoside (2f)
30
-1
Off-white solid (73 %); m.p.: 123
̊
1
1
(
458, 1361, 1123, 1047, 730, 695, 468; H NMR (CDCl ,500MHz): δH 2.28 (d, 1H, J=10Hz, -OH), 3.63
3
dd, 1H, J= 10Hz, H-6a), 3.76 (dd, 1H, J=10Hz, H-6b), 3.80-3.83 (m,1H, H-4), 3.94-3.96 (m, 2H, H-2 &
H-3), 4.04 (t, 1H, J= 10, 10Hz, H-5), 4.43, 4.53, 4.61, 4.86, 4.94, 5.00 (6d, 6H, J= 12, 10, 10, 10, 10, 10
Hz, 3* -O-CH -Ph), 5.74 (d, 1H, J= 5Hz, H-1), 7.16 (d, 1H, J= 5Hz, Ar-H), 7.23-7.37 (m, 15H, 3* -O-
2
13
CH -Ph), 7.53 (d, 1H, Ar-H), 7.72 (d, 1H, J= 10Hz, Ar-H) , 7.77 (t, 2H, J= 10, 5, 10 Hz, Ar-H).; C
2
NMR(CHCl , 125MHz): 68.2 (d, C-6), 71.3 (d, C-3), 72.8 (d, C-2), 73.5, 75.1 ,75.6 (3t, Ar-C), 77.3 (d,
3
C-4), 83.2 (d, C-5), 97.2 (d, C-1), 111.1, 126.5, 127.3, 127.7, 127.8, 127.8, 127.9, 127.9, 128.0, 128.4,
1
28.5, 128.6, 129.6 (13d, Ar-C), 129.8, 134.3, 137.7, 138.1, 138.6, 154.0 (6s, Ar-C ); HRMS calculated
for C H O (TOF MS ES+):557.3056; found: 557.3063.
37
36
6
5
.7
4-fluorophenyl 3,4,5-tri-O-benzyl-
α-
D
-glucopyranoside (2g)
30
-1
Off-white solid (87%); m.p.: 115
̊
C ;
[
α
]D = +20.7 (c 1.0, CH Cl ); IR(cm ) 3506, 2903, 1498, 1360,
̊
2
2
1
1
1
4
8
6
203, 1130, 1091, 1037, 742, 695; H NMR (CDCl ,500MHz): δH 2.22 (d, 1H, J= 8.0 Hz ,-OH,), 3.62 (d,
3
H, J=10.5Hz, H-6a), 3.73-3.78 ( m, 2H, H-6b& H-4), 3.85-3.98 (m , 3H, H-2, H-3 & H-5), 4.45, 4.53,
.61, 4.84 (4d, 4H, J= 12, 11, 12, 10.5 Hz, 2* -O-CH -Ph), 5.50 (d, 1H, J= 3.5Hz, H-1), 6.96 (t, 2H, J=
.5, 8.5 Hz, Ar-H), 7.04-7.07 (m, 2H, Ar-H) 7.15-7.41 (m,15H, Ar-H); C NMR (CHCl
8.3 (t, C-6), 71.3 (d, C-3), 72.6 (d, C-2), 73.5 , 75.1 ,75.5(3t, Ar-C ), 76.8 (d, C-4), 83.0 (d, C-5), 98.0 (d,
2
13
3
, 125MHz):
C-1), 115.9, 116.1, 118.3, 118.3, 127.6, 127.8, 127.8, 127.8, 127.9, 127.9,127.9, 128.0, 128.4, 128.4,

ACCEPTED MANUSCRIPT
1
28.5 (15d, Ar-C), 137.8, 138.0, 138.5 ,152.5 (4s, Ar-C), 157.5, 159.4 (d, Ar-C-F ); HRMS calculated for
33 33 6
C H O F Na:567.2153; found: 567.2153.
5
.8
2-chlorophenyl 3,4,5-tri-O-benzyl-
α
-
D
-glucopyranoside (2h)
3
D
0
-1
Off-white solid (78 %); m.p.: 85
̊
C ;
[
α]
= +23.4 (c 1.0, CH Cl ); IR(cm ) 3541, 2909, 1478, 1234,
̊
2
2
1
1
116, 1051, 739, 695, 447; H NMR (CDCl ,500MHz): δH 2.36 ( d, 1H, J= 10 Hz, -OH,), 3.71 (bd, 1H,
3
J= 10.5 Hz, H-6a), 3.78-3.83 (m, 2H, H-6b& H-4), 3.92 (dt,1H, J= 3.5, 3.5, 3.5 Hz, H-5), 4.02-4.06 (m,
2
5
1
H , H-3& H-2), 4.512, 4.58, 4.65, 4.92, 4.95, 5.06 (6d, 6H, J= 12, 11, 12, 11, 11, 11 Hz, 3* -O-CH -Ph),
2
.57 (d,1H, J= 3.5Hz, H-1), 7.03 (t,1H , J= 7.5, 7.5Hz, Ar-H), 7.21-7.26 (m, 3H, Ar-H), 7.28-7.47 (m,
13
3
5H, Ar-H); C NMR (CHCl , 125MHz):, 68.4 (t, C-6), 71.7 (d, C-3), 73.1 (d, C-2), 73.5, 75.1, 75.5 (3t,
Ar-C), 77.3 (d, C-4), 83.0 (d, C-5), 99.4 (d, C-1), 117.6, 124.1, 127.8 (3d, Ar-C), 127.9 (s, Ar-C), 127.9,
28.1, 128.1, 128.2, 128.3, 128.4, 128.5, 130.2 (8d, Ar-C), 137.8, 138.5, 152.3 (3s, Ar-C); HRMS
calculated for C H O Cl Na : 583.1857; found: 583.1858.
1
3
3
33
6
5
.9
3-bromophenyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2i)
3
0
-1
Off-white solid (90%); m.p.: 91
̊
C;
[
α
]D = +35.9
̊( c 1.0, CH Cl ); IR(cm ) 3362, 2866, 1581, 1462,
2 2
1
1
1
3
126, 1063, 1023, 733, 696; H NMR (CDCl
3
,500MHz): δ 2.20 (bs, 1H, -OH), 3.65 (dd, 1H, J=10.5,
H
2 Hz, H-6a), 3.78 (d, 1H, J=10.5Hz, H-6b), 3.83 (d, 1H, J= 9.5 Hz, H-4), 3.89-3.90 (m,1H, H-2), 3.91-
.92 (m, 1H, H-3), 3.99 (d, 1H, J= 9Hz, H-5), 4.48, 4.57, 4.66, 4.88 (4d, 4H, J= 12, 10.5, 12, 11Hz, 2* -
O-CH -Ph), 4.98 (q, 2H, J= 11, 6, 11 Hz, -O-CH -Ph ), 5.61 (d, 1H, J= 3.5Hz, H-1), 6.78 (m, 1H, Ar-H),
2
2
1
3
6
.88-6.93 (m, 2H, Ar-H), 7.18-7.19 (m, 1H, Ar-H) 7.20-7.44 (m, 15H, Ar-H); C NMR (CHCl3,
25MHz): 68.2 (d, C-6), 71.5 (d, C-3), 72.5 (d, C-2), 73.5, 75.0 , 75.5 (3t, -O-CH2-Ph), 76.8 (d, C-4),
2.9 (d, C-5), 97.4 (d, C-1), 104.5, 104.7, 109.4, 109.6, 112.4, 112.4, 127.6, 127.8, 127.8, 127.8, 127.9,
27.9, 128.0, 128.0, 128.1, 128.3, 128.4, 128.4, 128.4, 128.5, 128.6, (21d, Ar-C), 130.3, 130.4, 137.7,
38.0, 138.5, 157.5, 157.6, 162.4, 164.4 (s, Ar-C); HRMS calculated for C H O Br (TOF MS
1
8
1
1
33
33
6
ES+):585.2004; found: 585.2014.
5
.10
4-nitrophenyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2j)
3
D
0
-1
Yellowish semi solid (72%); m.p.: 128.5
̊
C ;
[
α]
= +3.2 (
̊
c 1.0, CH
2
Cl
2
); IR(cm ) 3535, 2894, 1596,
1
1
487, 1455, 1267, 1158,1089, 1044, 974, 736, 689; H NMR (CDCl
3
,500MHz):
δ
H
2.31 (bs, 1H, -OH),

ACCEPTED MANUSCRIPT
3
3
.58 (bd, 1H, J=13Hz, H-6a), 3.73 (dd, 1H, d, J=10, 3 Hz , H-6b), 3.81 (d, 2H, J= 9.5 Hz, H-4 & H-2),
.93 (m, 1H, H3), 3.99 (d, 1H, J= 11Hz, H-5), 4.45, 4.55, 4.61, 4.840(4d, 4H, J= 15, 13.5, 15, 13 Hz, 2*
-
O-CH -Ph), 4.94 (dd, 2H, J= 14 , 8.5, 14 Hz, -O-CH -Ph ) 5.69 (d, 1H, J= 4.5Hz, H-1), 7.14- 7.16 (m,
2
2
1
3
1
H, Ar-H), 7.19 (d, 2H, J= 11.5 Hz , Ar-H), 7.25 -7.41 (m, 14H, Ar-H), 8.19 (d, 2H, J= 12 Hz, Ar-H); C
NMR(CHCl , 125MHz): 68.0 (d, C-6), 71.9 (d, C-3), 72.1 (d, C-2), 73.5, 75.1 , 75.6 (3t, Ar-C), 77.1 (d,
3
C-4), 82.5 (d, C-5), 97.0 (d, C-1), 116.6, 125.8, 127.9, 128.0, 128.5, 128.5, 128.6 (7d, Ar-C), 137.5,
1
5
37.8, 138.3, 142.8, 157.5, 161.5 (6s, Ar-C); HRMS calculated for C33
H
8
33 NO Na : 594.2099; found:
94.2096.
5
.11
2-isopropyl phenyl 3,4,5-tri-O-benzyl-
α-
D
-glucopyranoside (2k)
30
-1
Off-white solid (76%); m.p.: 88
̊
C;
[
α
]D = +6.4 (
̊
c 1.0, CH Cl ); IR(cm ) 3383, 2923, 1432, 1128,
2
2
1
1
2
073, 1038, 734, 693, 473; H NMR (CDCl ,500MHz): δH 1.25, 1.27 (2d, 6H, J= 3Hz, 3 Hz, 2*-CH3),
3
.04 (d, 1H, J= 6.0 Hz, -OH), 3.29 (sep, 1H, -CH), 3.69 (d,1H, J= 11 Hz, H-6a), 3.83 (dd, 1H, J= 3, 3, 3
Hz, H-4), 3.88 (d, 1H, J= 9.5 Hz, H-6b), 3.92-4.02 (m, 3H, H-2, H-3 & H-5), 4.52, 4.61, 4.61, 4.91 (4d,
4
(
H, J= 12, 10.5, 12, 10.5 Hz, 2* -O-CH -Ph), 4.99 (t, 2H, -O-CH -Ph), 5.62 (d, 1H, J= 3.5Hz, H-1), 7.05
2 2
13
t , 1H, J= 7.5, 7.5Hz , Ar-H), 7.18 (t, 1H, J= 7.5, 7.5Hz , Ar-H), 7.23-7.41(m,17H, Ar-H); C NMR
(
CHCl , 125MHz): 22.8, 22.9 (2q, C), 27.0 (d, C), 68.3 (d, C-6), 71.5 (d, C-3), 72.7 (d, C-2), 73.6, 75.1
3
,
75.3 (3t, Ar-C), 77.4 (d, C-4), 82.5 (d, C-5), 97.6 (d, C-1), 114.6, 122.6, 126.2, 126.9, 127.8, 127.8,
27.9, 128.0, 128.0, 128.1, 128.3, 128.4, 128.5, 128.6 (14d, Ar-C),137.5,137.8,138.1,138.5,153.9 (5s, Ar-
C ); HRMS calculated for C H O Na : 591.2717; found: 591.2716.
1
36
40
6
5
.12
4-cyanophenyl 3,4,5-tri-O-benzyl-
α
-
D-glucopyranoside (2l)
30
-1
Off-white solid (75%); m.p.: 103
̊
C;
[
α
]D = +8.8 (c 1.0, CH Cl ); IR(cm ) 3466, 2911, 2227, 1601,
̊
2
2
1
1
500, 1128, 1093, 1040, 740, 698, 474; H NMR (CDCl ,500MHz): δH 2.31 (bs, 1H, -OH), 3.70 (d, 1H,
3
J= 10 Hz, H-6a), 3.73 (d, 1H, J=11 Hz, H-6b), 3.79 (m, 2H, H-4 & H-2), 3.89-3.91 (bd, 1H , H-3), 3.96-
3
2
.99 (m, 1H , H-5), 4.44, 4.52, 4.59, 4.83 (4d, 4H, J= 12, 10.5, 12, 11 Hz, 2* -O-CH
2
-Ph),4.91- 4.96 (m,
1
3
H, -O-CH -Ph ), 5.64 (d, 1H, J= 3.5Hz, H-1), 7.15-7.17 (m, 4H, Ar-H), 7.24-7.57 (m, 15H, Ar-H); C
2
NMR (CHCl , 125MHz): 68.1 (t, C-6), 71.8 (d, C-3), 72.2 (d, C-2), 73.5, 75.1, 75.6 (3t, -O-CH2-Ph),
3
7
1
6.8 (d, C-4), 82.6 (d, C-5), 97.0 (d, C-1), 106.0 (s, C-CN), 117.3 (d, Ar-C),118.8 (s, CN) 127.8, 127.9,
27.9, 127.9, 128.0, 128.4, 128.5, 128.6, 134.0, 134.1 (10d, Ar-C), 137.6, 137.9, 138.4, 159.6 (4s, Ar-C);
6
HRMS calculated for C34H33NO Na : 574.2201; found: 574.2097.

ACCEPTED MANUSCRIPT
5
.13
1-naphthyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2m)
3
0
-1
Off-white solid (76%); m.p.: 133
500, 1128, 1093, 1040, 740, 698, 474; H NMR (CDCl
d, 1H, J= 10 Hz, H-6a), 3.74 (d, 1H, J=10 Hz, H-6b), 3.82 (t, 1H, J= 10, 10 Hz H-4), 3.93 (bd, 2H , H-2
H-3), 4.12 (t, 1H , J= 10, 10 Hz, H-5), 4.44, 4.52, 4.56, 4.59 (4d, 4H, J= 10, 10, 10, 10 Hz, 2* -O-CH2-
Ph),4.98 (m, 2H, -O-CH -Ph ) 5.75 (d, 1H, J= 5Hz, H-1), 7.14 (d, 2H, J= 10 Hz, Ar-H), 7.20-7.47 (m,
̊
C;
[
α
1
]
D
= +13.6 (
̊
c 1.0, CH
2
Cl
2
); IR(cm ) 3466, 2911, 2227, 1601,
1
3
,500MHz):
δ
H
2.18 (d, 1H, J= 5 Hz, -OH), 3.59
(
&
2
1
3
1
6
5
1
5
3
8H, Ar-H), 7.78 (d, 1H, J= 5 Hz, Ar-H), 8.09 (d, 1H, J= 5 Hz, Ar-H) ; C NMR (CHCl , 125MHz):
8.5 (t, C-6), 71.8 (d, C-8.8 3), 73.0 (d, C-2), 73.7, 75.3, 75.7 (3t, -O-CH2-Ph), 77.0 (d, C-4), 82.9 (d, C-
), 97.6 (d, C-1), 109.1, 121.7, 122.4, 125.9, 128.0, 128.0, 128.1, 128.4, 128.6, 128.7, 128.8 (11d, Ar-C),
34.8, 138.0, 138.3, 138.7, 152.1 (5s, Ar-C); HRMS calculated for C H O Na : 599.2408; found:
3
7
36
6
99.2405.
5
.14
4-carboxaldehyde phenyl 3,4,5-tri-O-benzyl-
α-
D-glucopyranoside (2n)
3
0
-1
Off-white solid (68%); m.p.: 132
500, 1128, 1093, 1040, 740, 698, 474; H NMR (CDCl
J= 10 Hz, H-6a), 3.72 (d, 1H, J=10 Hz, H-6b), 3.74-3.80 (m, 2H, H-4 & H-2), 3.91 (bs, 1H , H-3), 3.97-
.00 (m, 1H , H-5), 4.43, 4.52, 4.59, 4.83 (4d, 4H, J= 10, 15, 15, 10 Hz, 2* -O-CH -Ph),4.93 (s, 2H, -O-
̊
C;
[
α
1
]D = +34.8 (
̊
c 1.0, CH Cl ); IR(cm ) 3466, 2911, 2227, 1601,
2
2
1
3 H
,500MHz): δ 2.25 (bs, 1H, -OH), 3.57 (d, 1H,
4
2
CH -Ph ) 5.69 (d, 1H, J= 3.5Hz, H-1), 6.90 (d, 2H, J= 4 Hz, Ar-H), 7.13-7.37 (m, 15H, Ar-H), 7.75 (d,
2
13
2
H, J= 4Hz, Ar-H), 9.82 (s, 1H, -CHO); C NMR (CHCl , 125MHz): 68.3 (t, C-6), 71.9 (d, C-3), 72.5
3
(
d, C-2), 73.7, 75.3, 75.8 (3t, -O-CH2-Ph), 76.8 (d, C-4), 82.9 (d, C-5), 97.0 (d, C-1), 116.2,117.0 (2d, Ar-
C), 128.1, 128.2, 128.7, 128.7, 128.8, 132.2, 132.6 (7d, Ar-C), 138.0, 138.1, 138.3, 162.5 (4s, Ar-C),
1
91.2 (s, Ar-CHO); HRMS calculated for C H O Na : 577.2200; found: 577.2198.
34 34 7
5
.15
4-methyl umbelliferyl 3,4,5-tri-O-benzyl-α-D-glucopyranoside (2o)
30
-1
Off-white solid (54%); m.p.: 165
681,1652, 1576, 1454, 1336, 1158, 1126, 1068, 1019, 890, 878, 808, 755, 693;
CDCl ,500MHz): 2.36 (bs, 1H, -OH), 2.39 (s, 3H, CH ), 3.58 (bd, 1H, J=11Hz, H-6a), 3.74 (dd, 1H,
̊ C; [α]D = +53.4 ̊( c 1.0, CH Cl ); IR(cm ) 3540, 2911, 1698,
2 2
1
1
H NMR
(
3
δ
H
3
J=10.5 Hz, H-6b), 3.82 (d, 2H, J= 9.5 Hz, H-4 & H-2), 3.93 (bd, 1H, H-3), 3.99-4.01 (m, 1H, J= 11Hz,
H-5), 4.46 (d, 1H, J= 12 Hz, -O-CH -Ph), 4.53 (q, 2H, J= 10.5, 10.5, 8.5 Hz, -O-CH -Ph), 4.63 (d, 1H,
2
2
J= 12 Hz, -O-CH -Ph ), 4.83 (d, 1H, J= 11 Hz, -O-CH -Ph), 4.95 (s, 2H, -O-CH -Ph), 5.67 (d, 1H, J=
2
2
2
3
.5Hz, H-1), 6.17 (s, 1H, H-3’), 7.04 (d, 1H, J= 9Hz, Ar-H), 7.10 (s, 1H, Ar-H), 7.15 (d, 2H, J= 6.5 Hz,

ACCEPTED MANUSCRIPT
13
Ar-H), 7.19 -7.50 (m, 15H, Ar-H); C NMR (CHCl
3
, 125MHz): 68.0 (d, C-6), 71.8 (d, C-3), 72.3 (d, C-
), 73.6, 75.1 , 75.6 (3t, Ar-C), 77.1 (d, C-4), 84.2 (d, C-5), 97.2 (d, C-1), 104.4, 112.9, 113.5 (3d, Ar-C),
15.0 (s, Ar-C), 125.7, 127.7, 127.8, 127.9, 127.9, 127.9, 128.0, 128.3, 128.4, 128.4, 128.5, 128.6 (13d,
2
1
Ar-C), 137.7, 137.9, 138.4, 152.3, 154.9, 159.1, 161.1 (7s, Ar-C); HRMS calculated for C H O Na :
37
36
8
6
31.2306; found: 631.2303.
5
.16
Phenyl 3,4,5-tri-O-benzyl-α-D-galactopyranoside (5a)
30
-1
White solid (92%); m.p.:109
̊
C;
[
α
]D = -7.4 (
̊ c 1.0, CH Cl ); IR(cm ) 3476, 3374, 2904, 1591, 1214,
2 2
1
1
6
4
1
073, 1033, 735, 694; H NMR (CDCl
3
,500MHz, δ): 2.25 (bs, 1H, OH), 3.54 (dd, 1H, J = 9, 5.5 Hz, H-
a), 3.65 (t, 1H, J = 8 Hz , 8.5 Hz, H-4), 3.80 (dd, 1H, J = 10, 2Hz, H-6b), 4.10-4.12 (m, 2H, H-3 & H-5),
.34 (dd, 1H, J = 9.5, 2.5 Hz, H-2), 4.37, 4.42, 4.59, 4.75, 4.80, 4.93 (6d, 6H, J= 11.5, 11.5, 11.5, 11.5,
1.5, 11 Hz, 3* -O-CH Ph), 5.62 (d, 1H, J= 3.5 Hz, H-1), 7.03 (t, 1H, J= 7.5, 7.5 Hz, Ar-H), 7.09 (d, 1H,
2
13
J= 8Hz, Ar-H) 7.21-7.42 (m, 18H, Ar-H); C NMR (CHCl , 125MHz,
δ
): 68.6 (t, C-6), 68.9 (d, C-3),
0.4 (d, C-2), 73.5 (t, Ar-C), 75.1 (t, Ar-C), 75.6 (t, Ar-C), 76.8 (d, C-4), 83.2 (d, C-5), 97.2 (d, C-1),
16.8, 122.7,127.8,127.8, 127.9, 127.9, 127.9, 127.9, 128.0, 128.4, 128.5, 128.5, 128.6, 128.6, 129.6
3
7
1
(
20d, Ar-C), 137.8, 138.1, 138.6, 156.4 (4s, Ar-C); HRMS calculated for C H O Na : 549.2243; found:
33 34 6
5
49.2248.
5
.17
4-methyl phenyl 3,4,5-tri-O-benzyl-
α-
D
-galactopyranoside (5b)
30
-1
White solid (84%); m.p.: 98
̊
C ;
[
α
]D = -2.7 (
̊
c 1.0, CH Cl ); IR(cm ) 3397, 2914, 1506, 1218, 1077,
2
2
1
1
032, 734, 697; H NMR (CDCl ,500MHz,
δ): 2.17 (bs, 1H, OH), 2.28 (s, 3H, Ar-CH3), 3.53 (dd, 1H, J
3
=
5.5, 6 Hz, H-6a), 3.64 (t, 1H, J = 8 Hz , 9 Hz, H-4), 3.91 (dd, 1H, J = 10, 2.5 Hz, H-6b), 4.08-4.13 (m,
2
1
H, H-3 & H-5), 4.32 (m, 1H, H-2), 4.37, 4.43, 4.59, 4.75, 4.78, 4.93 (6d, 6H, J= 11.5, 11.5, 11.5, 12, 12,
1 Hz, 3* -O-CH Ph), 5.57 (d, 1H, J= 4 Hz, H-1), 6.98 (d, 2H, J= 9 Hz, Ar-H), 7.06 (d, 2H, J= 8Hz, Ar-
2
13
H) 7.22-7.42 (m, 15H, Ar-H); C NMR (CHCl , 125MHz,
δ
): 20.6 (q, Ar-C), 68.6 (t, C-6), 68.9 (d, C-3),
0.3 (d, C-2), 72.5 (t, Ar-C), 73.8 (d, C-4), 74.8 (t, Ar-C), 79.6 (d, C-5), 98.0 (d, C-1), 117.1, 127.8,127.9,
28.2, 128.3, 128.4, 128.6, (7d, Ar-C), 137.9, 138.2, 138.5, 154.6 (4s, Ar-C); HRMS calculated for
3
7
1
C H O Na : 563.2404; found: 563.2388.
3
3
36
6
5
.18
4-methoxy phenyl 3,4,5-tri-O-benzyl-α-D-galactopyranoside (5c)

ACCEPTED MANUSCRIPT
30
D
-1
White solid (86%); m.p.:103
̊
C ;
[
α
]
= -32.4 (
̊
c 1.0, CH
2 2
Cl ); IR(cm ) 3394, 2913, 1502, 1208, 1108,
1
1
3
4
1
7
6
075, 1029, 735, 696; H NMR(CDCl
3
,500MHz, δ
): 2.25 (bs, 1H, OH), 3.56 (dd, 1H, J = 6, 9 Hz, H-6a),
.62-3.65 (m, 1H, H-4), 3.75 (s, 3H, -O-CH3), 3.90 (dd, 1H, J = 10, 2.5 Hz, H-6b), 4.07 (bs, 1H, H-3),
.14 (t, 1H, J= 6.5 Hz, 6.5 Hz, H-5), 4.31 (bs, 1H, H-2), 4.39, 4.45, 4.59, 4.75, 4.08, 4.93 (6d, 6H, J=
1.5, 12, 11.5, 11.5, 11.5, 11 Hz, 3* -O-CH Ph), 5.48 (d, 1H, J= 4 Hz, H-1), 6.79 (d, 2H, J= 9 Hz, Ar-H),
2
13
.02 (d, 2H, J= 8Hz, Ar-H) 7.23-7.42 (m, 15H, Ar-H); C NMR (CHCl
8.8 (t, C-6), 68.9 (d, C-3), 70.4 (d, C-2), 72.5 (t, Ar-C), 73.5 (t, Ar-C), 73.9 (d, C-4),74.8 (t, Ar-C), 79.6
d, C-5), 98.9 (d, C-1), 114.6, 118.7,127.7,127.8, 127.8, 127.8, 128.2, 128.3, 128.4, 128.4, 128.6 (11d,
Ar-C), 137.9, 138.2, 138.4, 155.3 (4s, Ar-C); HRMS calculated for C H O Na : 579.2353; found:
3
, 125MHz, δ): 55.6 (q, O-C),
(
33
36
7
5
79.2345.
5
.19
4-fluoro phenyl 3,4,5-tri-O-benzyl-
α-
D-galactopyranoside (5d)
30
-1
White solid (80%); m.p.:121
̊
C;
[
α
]D = -15.4
130, 1091, 1037, 742, 695; H NMR (CDCl ,500MHz,
a), 3.55 (d, 1H, J = 7.5 Hz, H-6b) , 3.72 (d, 1H, J = 12.5 Hz, H-4), 4.01-4.30 (m, 2H, H-3 & H-5), 4.36
̊
2
2
1
1
6
3
δ): 2.22 (bs, 1H, OH), 3.48 (d, 1H,J = 6.0 Hz, H-
(
bs, 1H, H-2), 4.37, 4.50, 4.51, 4.54, 4.66, 4.86 (6d, 6H, J= 10, 11.5, 11.5, 11.5, 11.5, 11.5 Hz, 3* -O-
CH Ph), 5.44 (d, 1H, J= 4 Hz, H-1), 6.88 (d, 2H, J= 7.5Hz, Ar-H), 6.96 (d, 1H, J= 8Hz, Ar-H) 7.15-7.34
2
1
3
(
m, 15H, Ar-H); C NMR (CHCl
3
, 125MHz,
3.5 (t, Ar-C), 74.9 (t, Ar-C), 76.8 (d, C-4), 79.4 (d, C-5), 98.6 (d, C-1), 115.8, 115.9, 116.0, 116.1, 116.2,
16.2, 118.6, 118.7, 127.8,127.8, 128.3 (11d, Ar-C), 137.8, 138.0, 138.3, 152.9, 157.7 (5s, Ar-C);
δ): 68.7 (t, C-6), 68.8 (d, C-3), 70.6 (d, C-2), 72.5 (t, Ar-C),
7
1
HRMS calculated for C H FO Na : 567.2153; found: 567.2147.
3
3
33
6
5
.20
4-cyano phenyl 3,4,5-tri-O-benzyl-
α-
D
-galactopyranoside (5e)
30
-1
White solid (76%); m.p.:141
̊
C;
[
α
]D = -30.5
̊
2
2
1
1
5
128, 1093, 1040, 740, 698, 474; H NMR (CDCl ,500MHz,
δ
): 2.37 (bs, 1H, OH), 3.47 (dd, 1H, J = 6,
3
.5, 9.5 Hz, H-6a), 3.58 (t, 1H, J = 7.5 Hz , 9 Hz, H-4), 3.88 (dd, 1H, J = 10, 2.5, 2 Hz, H-6b), 3.95 (t, 1H,
J= 6.5, 6.5 Hz, H-3), 4.04 (bs, 1H, H-5), 4.32 (d, 1H, J = 6 Hz, H-2), 4.34, 4.37, 4.54, 4.67, 4.76, 4.87
(
6d, 6H, J= 11.5, 11.5, 11, 11.5, 11.5, 11 Hz, 3* -O-CH Ph), 5.62 (d, 1H, J= 3.5 Hz, H-1), 7.10 (d, 2H, J=
2
1
3
8
6
.5 Hz, Ar-H), 7.14-7.36 (m, 15H, Ar-H), 7.40 (d, 1H, J= 8.5 Hz, Ar-H); C NMR (CHCl , 125MHz,
δ):
3
8.5 (t, C-6), 68.6 (d, C-3), 71.1 (d, C-2), 73.6 (t, Ar-C), 75.0 (t, Ar-C), 75.6 (t, Ar-C), 76.9 (d, C-4), 79.2
(
d, C-5), 97.5 (d, C-1), 105.9 (s, CN), 117.5 (d, Ar-C), 119.0 (s, Ar-CN), 127.9, 128.2, 128.5, 128.5,

ACCEPTED MANUSCRIPT
1
5
6
28.7, 134.1 (6d, Ar-C), 137.7, 137.9, 138.3, 160.1 (4s, Ar-C); HRMS calculated for C34H33NO Na :
74.2200; found: 574.2195.
6
.0
2 3
General procedure for glycosidation of 1,2-anhydrosugars 1 or 4 using Cs CO :
A mixture of phenol (1.1 equiv.) and Cs
atmosphere for 15 min. 1,2-anhydrosugar (100mg, 1.0 equiv.) 1 or 4 was added and refluxed for 15 min
as monitored by TLC). The reaction mixture was filtered, washed with ethyl acetate, concentrated in
vacuo and the crude viscous product purified by flash column chromatography using 5% ethyl acetate and
n-hexane as mobile phase, to afford -O-arylglycosides3a-d or 6a-c.
2 3
CO (1 equiv.) in toluene was refluxed under nitrogen
(
β
[
1]
6
.1
Phenyl 3,4,5-tri-O-benzyl-β-D-glucopyranoside (3a)
30
D
-1
White solid (90%);m.p.: 99° C [
α
]
= -27.6 (
2 2
̊ c 1.0, CH Cl ); IR(cm ) 3457, 2859, 1498, 1219, 1050,
1
7
3
37, 692; H NMR (CDCl
3
,500MHz):
δ
H
2.52 (s,1H, -OH), 3.69 (d, 1H, J= 8.5 Hz, H-6a), 3.71-3.76 ( m,
H, H-6b, H-4 & H-2), 3.83 (bd, 1H, H-3), 3.88 (t,1H, J= 7.5, 8Hz, H5), 4.56 (q , 2H, J= 12, 11.5 Hz, -
O-CH -Ph), 4.61-4.93 (5H, m,2*-O-CH -Ph& H1 ), 7.07-7.25 (m, 5H, 5*Ar-H,), 7.28-7.43 (m, 15H, Ar-
2
2
13
H); C NMR (CHCl , 125MHz): 68.8 (t, C-6), 73.5 (t, Ar-C), 74.4 (d, C-3), 75.1 (t, Ar-C),75.3 (t, Ar-C),
3
7
1
5.4 (d, C-2), 77.5 (d, C-4), 84.4 (d, C-5), 100.9 (d, C-1), 116.9, 122.8 (2d, Ar-C), 127.6, 127.8, 127.8,
27.9, 127.9, 128.0, 128.4, 128.4, 128.5, 128.5, 128.5, 129.5 (12d, Ar-C), 138.0, 138.1, 138.5, 157.2 (4s,
Ar-C).
[
1]
6
.2
2-methylphenyl 3,4,5-tri-O-benzyl-
β-
D
-glucopyranoside (3b)
30
-1
1
White solid (86%); [
α
]D = -4.5 (
̊
c 1.0, CH Cl ); IR(cm ) 3405, 2916, 1567, 1255, 1056, 736, 692; H
2
2
NMR (CDCl ,500MHz): δH2.27 (s, 3H, Ar-Me ), 2.41 (d, 1H, J= 1.5 Hz, -OH), 3.60-3.62 (m, 1H, H-6a,),
3
3
4
9
.66-3.73 (m, 3H, H-6b, H-4 & H-2 ),3.77-3.80 (bd, 1H, H-3), 3.88 (t, 1H, J= 8.0, 8.0 Hz, H-5), 4.52,
.59, (2d, 3H, J= 12, 10 Hz, -O-CH -Ph), 4.83 (d, 1H, J= 7.5 Hz, H-1), 4.86, 4.88, 4.95 (3d, 3H, J= 10,
, 11.5 Hz, 2*-O-CH -Ph), 6.95 (t, 1H, J= 7.0, 7.5 Hz , Ar-H),7.068 (t, 2H, J= 8.0, 9.0 Hz , Ar-H),7.13
2
2
13
(
t, 1H, J= 9.0, 7.5 Hz, Ar-H), 7.20-7.39 (m, 15H, Ar-H); C NMR (CHCl , 125MHz):16.40 (q, Ar- CH )
3 3
6
8.8 (t, C-6), 73.5 (t, Ar-C), 74.56 (d, C-3), 75.0 (t, Ar-C),75.3 (t, Ar-C), 75.4 (d, C-2), 77.5 (d, C-4), 84.6
(
d, C-5), 101.5 (d, C-1), 115.5, 127.0 , 127.6, 127.7, 127.7, 127.8, 127.8, 127.9, 128.0, 128.0, 128.3,
28.4, 128.4, 128.4, 128.5, 128.5, 130.8 (17d, Ar-C), 138.0, 138.1, 138.5,155.5 (4s, Ar-C).
1

ACCEPTED MANUSCRIPT
[
1]
6
.3
3-methylphenyl 3,4,5-tri-O-benzyl-
β-
D
-glucopyranoside (3c)
30
D
-1
White solid (88%);[
α
]
= -87.3 (
̊
c 1.0, CH
2
Cl
2
); IR(cm ) 3407, 2915, 1505, 1224, 1103, 1061, 1028,
1
7
6
4
,
33, 694; H NMR (CDCl
3
,500MHz):
δ
H
2.30 (s, 3H, Ar-Me ), 2.45 (bs, 1H, -OH), 3.67-3.72 (m, 4H, H-
a,H-6b, H-4 & H-2 ),3.80 (dd, 1H, J= 1.5, 1.5 Hz, H-3), 3.83 (bs, 1H, H-5), 4.53, 4.59, 4.85, 4.86, 4.87,
.88, 4.96 (7d, 7H, J= 12, 10, 12, 7.5, 11, 11.5, 11 Hz, 3* -O-CH -Ph & H-1), 7.16 (i, 1H, J= 7.5, 7.5 Hz
2
13
Ar-H),7.21 ( bd, 2H, J= 6Hz, Ar-H,), 7.27-7.4 (m,15H, Ar-H); C NMR (CHCl , 125MHz): 21.6 (t,
3
Ar- CH
3
) 69.0 (d, C-6), 73.7 (t, Ar-C), 74.6(d, C-3), 75.2 (t, Ar-C),75.4 (d, Ar-C), 75.6 (d, C-2), 77.4 (d,
C-4), 84. 5 (d, C-5), 101.1 (d, C-1), 114.0, 117.9, 123.8, 127.7, 127.9, 127.9, 128.0, 128.1,128.5, 128.6,
1
28.6, 129.4 (12d, Ar-C), 138.2, 138.2, 138.7, 139.7, 157.4 (5s, Ar-C).
[
1]
6
.4
4-methylphenyl 3,4,5-tri-O-benzyl-
β-
D
-glucopyranoside (3d)
30
-1
White solid (85%);[
α
]D = -25.4 (
̊
c 1.0, CH Cl ); IR(cm ) 3505, 3227, 3032, 1505, 1220, 1126, 1036,
2
2
1
7
6
1
38, 695; H NMR (CDCl ,500MHz): δH2.17 (s, 3H, Ar-Me ), 2.30 (bs, 1H, -OH), 3.58-3.72 (m, 4H, H-
3
a,H-6b, H-4 & H-2 ), 3.79 (dd, 1H, J= 11.5, 2 Hz, H-3), 3.81 (bd, 1H, H-5), 4.51, 4.57, 4.59(3d, 3H, J=
0, 13.5, 15 Hz, -O-CH -Ph), 4.82 (d, 1H, J= 9.5 Hz, H-1), 4.86, 4.87, 4.95 (3d, 3H, J= 13.5, 14.5, 14 Hz,
2
-
O-CH -Ph), 6.97 (d, 1H, J= 10.5 Hz, Ar-H), 7.07 ( d, 2H, J= 10.5 Hz, Ar-H,), 7.21-7.40 (m,15H, Ar-
2
13
H); C NMR (CHCl , 125MHz): 20.6 (t, Ar- CH ) 68.8 (d, C-6), 73.5 (t, Ar-C), 74.4 (d, C-3), 75.1 (t,
3
3
Ar-C), 75.3 (d, Ar-C), 75.4 (d, C-2), 77.4 (d, C-4), 84. 4 (d, C-5), 101.3 (d, C-1), 117.0, 127.6, 127.8,
1
27.9, 128.0, 128.3, 128.4, 128.5, 129.9 (9d, Ar-C), 138.1, 138.2, 138.7, 145.7, 157.5 (5s, Ar-C).
[
1]
6
.5
Phenyl 3,4,5-tri-O-benzyl-
β
-
D
-galactopyranoside (6a)
30
-1
White solid (88%); [
α
]D = -48.5 (
̊
c 1.0, CH Cl ); IR (cm ) 3371, 2892, 1593, 1490, 1223, 1113, 1058,
2
2
1
7
32, 695; H NMR (CDCl
3
,500MHz):
H
δ 2.55 (bs, 1H, -OH), 3.56 (dd, 1H, J= 7.5, 2.5 Hz, H-6a ), 3.68
(
bd, 2H, H-6b& H-4), 3.76 (t, 1H, J= 6.5, 6.5 Hz, H-3), 4.01 (d, 1H, J= 2Hz, H-5), 4.27 (t, 1H, J= 6.5, 9
Hz, H-2), 4.45, 4.51, 4.67, 4.73, 4.80 (5d, 5H, J= 12, 11.5, 11.5, 12, 12 Hz, -O-CH -Ph), 4.91 (d, 1H, J=
2
7
.5 Hz, H-1), 4.95 (d, H, J= 11.5 Hz, -O-CH -Ph), 7.04 (t, 1H, J= 7.5, 7 Hz, Ar-H), 7.09 (d, 2H, J= 8 Hz,
2
13
Ar-H,), 7.26-7.42 (m,15H, Ar-H); C NMR (CHCl
3
, 125MHz): 68.8 (d, C-6), 71.1(d, C-3), 72.5 (t, Ar-
C), 72.8 (d, C-2), 73.6 (t, Ar-C), 74.1 (d, C-4), 74.6 (d, Ar-C), 81.8 (d, C-5), 101.3 (d, C-1), 117.0,
1
1
17.1, 122.6, 127.7, 127.7, 127.8, 127.9, 128.2, 128.3, 128.4, 128.6, 129.4, 129.6 (13d, Ar-C), 137.8,
38.0, 138.4, 157.2 (4s, Ar-C).

ACCEPTED MANUSCRIPT
[
1]
6
.6
4-methoxy phenyl 3,4,5-tri-O-benzyl-
β-
D
-galactopyranoside (6b)
30
D
-1
White solid (76%); [
α]
= -40.8 (
̊
c 1.0, CH
2 2
Cl ); IR (cm ) 3371, 2892, 1593, 1490, 1223, 1113, 1058,
1
7
4
7
9
7
1
1
1
32, 695; H NMR (CDCl
3
,500MHz): δ
H
2.40 (bs, 1H, -OH), 3.56- 3.60 (m, 1H, H-6a ), 3.67- 3.73 (m,
H, H-6b&OMe), 3.78- 3.84 (m, 4H, H-3, H-4, H-2 & H-5), 4.53, 4.58, 4.60, 4.75, 4.86, 4.88, 4.95 (7d,
H, J= 12, 11.5, 11.5, 12, 12, 11, 11 Hz, -O-CH -Ph& H-1), 6.80 (d, 2H, J=9 Hz, Ar-H), 7.04 (d, 2H, J=
2
13
Hz, Ar-H,), 7.20-7.40 (m,15H, Ar-H); C NMR (CHCl , 125MHz): 55.6 (q, O-CH ), 68.4 (d, C-6),
3
3
1.1 (d, C-3), 72.8 (t, Ar-C), 73.5 (d, C-2), 75.1 (t, Ar-C), 75.5 (d, C-4), 77.3 (d, Ar-C), 81.6 (d, C-5),
02.6 (d, C-1), 114.7, 114.8, 116.1, 118.2, 127.6, 127.7, 127.8, 127.9,127.9, 128.0, 128.0, 128.1, 128.1,
28.1, 128.3, 128.4, 128.4, 128.4, 128.5, 128.6, 128.6, 129.7 (22d, Ar-C), 137.9, 138.1, 138.6,150.4,
55.3 (5s, Ar-C).
Acknowledgement
The authors are grateful to DST (SR/S1/OC11/2010) for funding and SAIF & Dept. of chemistry, IITM
for spectral data. Support from INSA is gratefully acknowledged.
Notes and references
1
(a) Boeckler, G. A.; Gershenzon, J.; Unsicker, S. B. Phytochemistry
Wu, X-C.; Chen, W-F.; Qian, C-D.; Li, O.; Li, P.; Wen, Y-P. The Journal of Microbiology
5, 499-504; (c) Kahne, D.; Leimkuhler, C.; Lu, W. Chem. Rev. 2005, 105, 425-448.
Skarbek, J. D.; Speedie, M. K.; in Antitumor Compounds of Natural Origin, ed. A. Aszalos, CRC
Press, Boca Raton, FL, 1981
Jeffry, G. A. Acc. Chem. Res.
(a) Austin, D.J.; Meyers, M.B. Phytochemistry
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1
2
2
2 In H NMR, H-1 of 2a
(
α
-anomer) resonates as a doublet (J = 3.5 Hz) at δ 5.64, while H-1 of 3a
1
3
(
β
-anomer) appears at around
appears at 97 and that of 2b at
phase HPLC in 100% CH CN (R for 2a = 4.18 and 3a = 3.94).
δ
4.9 that merges with benzylic protons. In C NMR, C-1 of 2a
δ
δ
110. The anomeric purity & ratios were confirmed by reverse
3
t
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equiv.) with Me Al in 1:1 CH Cl /toluene and compared with authentic data: T. Mole, Australian
3
2
2
Journal of Chemistry, 1963, 16, 794.
2
2
2
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,
,
β-O
gone for further generalisation.
2
9 Rainer, J. D.; Cox, J. M. Org. Lett., 2000, 2, 2707-2709.

ACCEPTED MANUSCRIPT
Tunable stereoselectivity in the synthesis of α- and β- aryl glycosides using
1
,2-α-anhydrosugars as glycosyl donors
Devaraj Somasundaram, Kalpattu K Balasubramanian (s), and Shanmugasundaram Bhagavathy(s)*

ACCEPTED MANUSCRIPT
Highlights
•
Although varieties of methods are known for
β
-selectivity, none is reported for
α-selectivity. Our
strategy provides a route for facile and exclusive synthesis of
α
- and -aryl glycosides.
β
•
•
•
It is shown that the stereoselectivity of the glycosidation can be tuned by varying the metal
counter ion of the phenoxides.
High yielding and unusually fast (less than 5 minutes at ambient temperatutre) when mediated by
trimethylaluminium as metal precursor.
Ring opening of 1,2-D-anhydrosugars provides access to glycosides with a free hydroxyl group
at C-2 position of the sugar moiety that can be exploited for the synthesis of carbohydrates
containing 1,2-linkage