Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl Fluorides in the Presence of Calcium Ion and Trimethylamine

Article abstract of DOI:10.1021/jacs.5b13384

We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and a tertiary amine base promote the reaction with high site-selectivity for either the 3′-position or 1′-position of the fructofuranoside unit. Because nonenzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of the hydroxyl group array in sucrose. The solution conformation of various monodeoxysucrose analogs revealed the co-operative nature of the hydroxyl groups in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the same time.

Full text of DOI:10.1021/jacs.5b13384

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Article
Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl
Fluorides in the Presence of Calcium Ion and Trimethylamine
Guillaume Pelletier, Aaron Zwicker, C. Liana Allen, Alanna Schepartz, and Scott J. Miller
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.5b13384 • Publication Date (Web): 09 Feb 2016
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Journal of the American Chemical Society
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Aqueous Glycosylation of Unprotected Sucrose Employing
Glycosyl Fluorides in the Presence of Calcium Ion and Trime-
thylamine
Guillaume Pelletier, Aaron Zwicker, C. Liana Allen, Alanna Schepartz,* and Scott J. Miller.*
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Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06520-8107.
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KEYWORDS: aqueous, carbohydrate, glycosylation, glycosyl fluoride, sucrose
ABSTRACT: We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield
the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and
a tertiary amine base promote the reaction with high site-selectivity for either the 3'-position or 1'-position of the fructo-
furanoside unit. Because non-enzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were
carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of hydrox-
yl group array in sucrose. The solution conformation of various mono-deoxysucrose analogs revealed the cooperative na-
ture of the hydroxyl group in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the
same time.
Introduction
and acceptor, while hydrolysis does not conspire to pre-
vent the coupling.
The advancement of carbohydrate science depends
critically on the ability to synthesize complex sugars in a
highly selective manner. Tremendous successes have been
achieved in carbohydrate synthesis, both in terms of effi-
ciency and complexity in many synthetic settings.1 Specif-
ically, a large number of methods for the construction of
the challenging glycosidic linkage has emerged. Most la-
boratory syntheses rely on the use of activating groups to
enable glycosidic bond formation via bimolecular substi-
tution (SN2) or via an activated oxocarbenium intermedi-
ate (SN1).2 The electrophilicity of these intermediates ne-
cessitates a protecting group strategy for successful cou-
pling, avoiding reaction with other undesired hydroxyl
groups.3 It also precludes the use of aqueous solvent.
Thus, protecting group-free synthetic glycosylation reac-
tions under aqueous conditions towards oligosaccharides
are scarce.4 Enzymatic methods using glycosyl transferas-
es or hydrolases,5,6,7 however, afford efficient and selective
reactions in buffered water, employing pre-fashioned sug-
ar nucleotides or non-reducing sugar as the glycosyl do-
nors (Figure 1).8 The enzymatic catalysts harness consid-
erable molecular complexity to achieve the necessary pre-
cision in the active site such that the transition state fa-
vors glycosylation between a glycosyl donor
With the long-term objective of developing efficient
and selective glycosylation reactions independent of en-
zyme specificities, we aimed to discover the requirements
for non-enzymatic glycosylation reactions conducted in
water and with no protecting group used at any stage.9
Initially, we sought to search for simple glycosyl donors
that would be potentially reactive at the C1-position,
while exhibiting stability in water. In this context, we se-
lected glycosyl fluorides as the donor,10 which have been
extensively studied by Jencks as models of substrates in-
volved in the hydrolysis of glycosidic bonds (Scheme 1a).11
More precisely, Jencks showed that α-D-glucosyl fluoride
(1a) reacts in an aqueous solution of sodium azide and
acetate salts to produce the corresponding β-anomers 2a-
b, overcoming the formation of D-glucose. However, the
aqueous solvolysis of glycosyl fluorides in the presence of
different alcohols as potential nucleophiles revealed a
preference for reaction with water. No glycosylations of
weakly nucleophilic alcohol acceptors were observed.
These results theoretically preclude glycosylation with
typical polyol acceptors in the absence of an activator (or
catalyst).
Scheme 1: Stereoinvertive substitution of α-F-glucose (1a)
using simple nucleophiles in water.
O
H
B
O
H
a)
b)
Intimate Ion-Pair
HO
HO
H
H
O
NaN3 (2.0 M), D2O, 30 °
21 h (83%)
C
O
O
O
H
HO
N3
O
OR
Glycosylation
HO
HO
HO
HO
HO
O
H
O
O
b
HO
HO
Hydrolysis
OH
HO
HO
O
β
HO
O
O
H
OR
O
a
2a
O
HO
H
HO
OH
HO
α
HO
O
H
O
H
OH2
HO
HO
HO
C
HO
F
reducing monomer
oligosaccharide
LG
AcONa (2.0 M), D2O, 30 °
21 h (40%)
O
O
F
α-F-glucose (1a)
HO
OAc
Active site of the enzyme
LG = UDP, GDP, CMP
β
HO
2b
• Hydrolysis or Glycosylation via SN1 (oxocarbenium) or SN
2
Complete inversion (SN2)
= HFPN or TFE
Figure 1: Competition between hydrolysis (H2O (a), in
red) and glycoside bond formation (acceptor (b), in blue)
for a given activated donor in the active site of an enzyme.
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Subsequent experimentation disclosed that these reac- enzymatic, chemoselective glycosylation reactions be-
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tions were found to be concerted only in presence of
strong nucleophiles. These postulates were later revisited
by Chan and Bennet, who observed 1a to react with weak-
ly nucleophilic alcohols, such as 1,1,1-trifluoroethanol
(TFE) or hexafluoro-1-propanol (HFPN), under anhydrous
conditions.12 Substitution occurs via an SNi-like pathway,
wherein the fluoride and an oxocarbenium-like species
are present in the transition-state as an intimate, non-
solvated ion-pair (Scheme 1b).12,13 The capability of the
leaving fluoride ion to engage in hydrogen bonding allows
for a general acid/base catalysis mechanism to ensue.12a,14
The conclusions of these reports, as well as the wide-
spread applications of glycosyl fluorides as “transition
state analogue substrates” (TSAS) for hydrolase enzymes
grounded our interest in these monomers as potential
substrates for aqueous glycosylation.15
tween glycosyl fluorides and sucrosyl acceptors. The
unique nature of the transformations is elucidated
through independent synthesis and evaluation of eight
unique deoxysucrose substrates. These experiments cul-
minate in the delineation of the specific hydroxyl group
array that is required for successful aqueous glycosyl
transfer. These findings may offer a framework for the
generalization of this approach beyond sucrose, providing
a possible bridge between non-enzymatic glycosylation
and the aqueous environments endemic to enzymatic
catalysis.
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Results and Discussion
Discovery of an Aqueous Glycosylation of Sucrose.
Following Jencks’ and our own investigations into reac-
tions of minimally protected carbohydrates,11,21 we studied
the reactivity of α-D-glucosyl fluoride 1a towards an aque-
ous solution of sucrose, a complex carbohydrate acceptor
(Scheme 2).22 When treated with 0.5 equivalent of sucrose
in the absence of any additives, compound 1a hydrolyzes
slowly and cleanly to generate α- and β-D-glucopyranose
(3a and 3b respectively) in 9% yield after 48 hours at
room temperature. In a separate control experiment, 1.0
equiv. of Ca(NO3)2·4H2O was found to accelerate hydroly-
sis of 1a, while no glycosylation was observed. This behav-
ior was found to be general, as the replacement of Ca2+
with other main group salts (Li+, K+, Na+, Mg2+, Ba2+, Cs+)
or water soluble transition metals (Cu2+, Ni2+, La3+, Zr4+)
led to no reaction or to a comparable rate of hydrolysis
for the fluoride 1a. The addition of an aqueous base
(NMe3) alone also furnished the hydrolysis products
3a/3b, along with the cyclization product 1,6-anhydro-β-
glucose 4.12a Strong bases (NaOH or NaOMe, for example)
were found to give extensive amounts of compound 4 and
degradation by-products. On the other hand, addition of
both Ca(NO3)2·4H2O and trimethylamine afforded the
glycosylation product 7a in 20% yield (with respect to
sucrose) after 48 hours. A close examination of both the
Inspired by the divalent metal cation-dependent na-
ture of many glycosyltransferases,16 we postulated that a
combined Lewis acid/Lewis base approach might provide
the necessary transition state organization to favor glyco-
sylation of the glycosyl fluoride while outcompeting hy-
drolysis (Figure 2). This strategy could also enhance the
reactivity of any alcohol towards substitution. A close
comparison can be made with traditional synthetic strat-
egies that rely on an alcohol chelation when metals are
employed as catalysts for hydroxyl group functionaliza-
tion in organic solvents.1c As part of this analysis, we were
aware of the affinity of various sugars for certain water-
soluble main group metal salts, including Ca2+, Na+, K+
and Mg2+, and this could be exploited to achieve complex-
ation-induced glycosylation.17,18
(a) Typical synthetic glycosylation
PGO
PGO
PGO
PGO
PGO
O
O
O
O
Activator
PGO
OR
OR
HO
O
PGO
organic solvent
OPG
OPG
OPG
LG
Donor
Acceptor
Disaccharide
Activator = H+, Lewis acids, Transition metals
(b) Protecting group-free aqueous glycosylation
HO
M+
HO
HO
HO
O
HO
HO
O
base
O
O
1
O
HO
unpurified and purified reaction mixtures by H NMR in
OR
OR
aqueous solvent
HO
OH
OH
OH
LG
D2O revealed that the reaction proceeded with both com-
plete stereochemical inversion of the anomeric center of
the glycosyl donor and with complete regioselectivity for
the 3’ position of the fructofuranoside unit of sucrose.22
This was confirmed by a HMBC NMR analysis of 7a be-
tween the carbon at position C-3’ of the fructofuranose
unit and the axial proton H-1’’, geminal to the newly
formed O-β-Glc anomeric linkage (highlighted in cyan,
Scheme 2).22
• Regioselectivity?
• Stereoselectivity?
• Reactivity?
SN
2
HO
HO
HO
HO
O
O
OR
= Ca2+, Na+, Mg2+
M+
OH
HO
M+
LG
Figure 2: Synthetic glycosylation strategies for prepara-
tion of di- and oligosaccharides: (a) a fully protected do-
nor with a suitable anomeric leaving group reacts with a
partially protected acceptor to form a disaccharide in or-
ganic solvent; (b) both water soluble donor and acceptor
react to form the same bond without the need for direct-
ing/protecting groups.
In addition to the previously detected side-reactions
(towards 3a, 3b, 4), we observed the formation of a small
quantity of D-fructose (Fru) (6). Interestingly, hydrolysis
of α-D-glucosyl fluoride donor 1a to D-glucose appears to
rearrange to form D-fructose (6) under the reaction con-
ditions (with CaCl2 instead of Ca(NO3)2•4H2O).23
Toward the development of such a reaction, we chose
to examine sucrose as the glycosyl acceptor due to its
high solubility in water, intrinsic natural abundance and
low cost. Furthermore, as a polyol, this substrate offers
ample opportunity to explore site-selectivity in parallel
with the development of a glycosylation reaction.19,20 We
describe herein the successful elaboration of non-
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Scheme 2: Observed reaction pathways and formation of
a new trisaccharide (7a)
marked dependence of the conversion to 7a on the con-
centration of sucrose in the aqueous medium.
1
2
3
4
5
6
7
8
O
Table 1: Selected optimized parameters for the glycosyla-
HO
O
tion
HO
α
O
O OH
3'
OH
OH
M+ (I or II)
HO
HO
HO
1,6-anhydro-β-Glc (4)
O
α-F-Glucose (1a)
HO
HO
HO
HO
O
O OH
O
OH
HO
O
HO
HO
H2O
NMe3
O
45% aq. NMe3
RT, 16 h
H2O
NaOMe
O
Degradation
H2O
HO
HO
HO
HO
OH
β
OH
HO
HO
HO
α-D-Glc (3a)
β-D-Glc (3b)
HO
sucrose (0.1 mmol)
(7a)
9
HO
HO
HO
O
Hydrolysis
M+ or M2+
(equiv)
Conc. α-F-Glc Conversion
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HO
HO
HO
Entry
1a
(M)a
1.0
(equiv)
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
7.0
7.0
7.0
7.0
6.0
6.0
to 7a (%)b
OH
O
F
HO
HO
HO
Ca2+
O
H2O
NMe3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Ca(NO3)2 (8)c
NaNO3 (8)
42
<5
<5
<5
<5
40
17
<5
50
69
71
NMe3
F
OH
OH
NMe3/CaCl2
HO
HO
5
1.0
1.0
1.0
1.0
1.0
1.0
1.5
0.50
0.50
0.50
0.40
0.30
0.20
0.30
0.30
Fructose (6)
Isomerisation
Sucrose
NMe3/Ca2+
KNO3 (8)
HO
1'
HO
OH
O
CaCO3 (8)
O
α
4'
O OH
3'
O
CaSO4 (8)c
O
HO
6
HO
HO
HO
HO
HO
O
CaBr2 (8)c
O
O
β
HO
4
OH
6'
2
HO
HO
3'
HMBC
correlation
HO
HO
3
Ca(OTf)2 (8)
Ca(OTf)2 (8)
Ca(NO3)2 (8)c
Ca(OTf)2 (8)
Ca(OTf)2 (7)
Ca(OTf)2 (7)
Ca(OTf)2 (7)
Ca(OTf)2 (7)
Ca(OTf)2 (6)
Ca(OTf)2 (6)
H
HO
HO
Sucrose
β-D
-Glc-(1→3)-β-D-Fru-(2→1)-
-α-D-Glc (7a)
Glycosylation
This precedented glucose/fructose rearrangement is also
known to occur with simultaneous epimerization of D-
glucose (Glc) (3a/3b) to D-mannose, which we also ob-
served. Thus, we suspect that 6 is formed from an isomer-
ization process and not from the decomposition of su-
crose and/or 7a. Indeed, extensive decomposition of su-
crose or 7a does not occur when they are treated with
Ca2+ and aqueous NMe3 in the absence of 1a. In addition,
we were able to identify and characterize the β-
trimethylammonium glucosyl fluoride 5, generated from
stereoinvertive nucleophilic addition of NMe3 to 1a.
Through control experiments, we also found that product
5 is formed when 1a is subjected to the reaction condi-
tions in the absence of the glycosyl donor.22,24 The for-
mation of any epoxide intermediate formed from 1a was
not observed.25
79
81
77
82
69d
17
Ca(OTf)2 (6)
0.30
6.0
87 (80)e,f,g
Concentration of sucrose in the aqueous solvent (M). b Conversion to 7a (%)
a
determined by 1H NMR. c Hydrate of the salt was employed d Reaction diluted
in 30% aq. NMe3 instead of 45% aq. NMe3. e Reaction performed at 30 °C in-
stead of RT. f Reaction performed on 1.0 mmol of sucrose instead of 0.1 mmol.
g Isolated yield in parentheses.
At a higher concentration of sucrose (>1.0 M) and with 8
equivalents of Ca(OTf)2, no reactivity is observed; howev-
er, with a more dilute solution (0.5 M) in sucrose, an im-
proved 69% conversion to 7a is obtained (c.f., entries 7,8
and 10). Interestingly, this important jump in reactivity is
also observed with Ca(NO3)2·4H2O, but to a lesser extent
(42% at 1.0 M to 50% at 0.5 M, entries 1 and 9). When the
reaction is conducted in the presence of 7.0 equivalents of
both Ca(OTf)2 and 1a, we found that a concentration of
0.30 M in sucrose was optimal (entry 13).26 The equiva-
lents of calcium salt and fluoride donor could be adjusted
to 6.0 equivalents without a concomitant decrease in re-
activity (82%, entry 15), but further decreasing the equiva-
lents impeded the reaction rate and lower yields of 7a
were observed.22 Modifying the base and/or ratio of base
relative to water was detrimental since hydrolysis of 1a
was found to be more extensive (69% with 30% aq. NMe3,
entry 16). We were able to achieve glycosylation on a
practical scale by elevating the temperature to 30 °C,
which afforded the desired product in 80% isolated yield
(1.0 mmol of sucrose, entry 17). The product 7a can be
readily purified by column chromatography. Assessment
of its purity by conventional NMR and combustion analy-
sis demonstrated that the monosaccharides by-products,
Optimization of Conditions. With the striking observa-
tion that 7a can be formed under aqueous conditions, we
decided to optimize the glycosylation reactions condi-
tions to give this isomer in high yields (Table 1). Initially,
we found that an excess of 1a (5 equivalents) and a high
concentration of Ca(NO3)2·4H2O (8 equivalents) led to an
improved efficiency such that 42% conversion to 7a could
be obtained as a single stereo- and regioisomer (entry 1,
with respect to sucrose as the limiting reagent). A screen
of various additives revealed that only Ca2+ salts are effec-
tive at promoting glycosylation over hydrolysis of 1a (e.g.
no reaction was observed with NaNO3 and KNO3, entries
2-3). A strong effect of the counterion was observed, with
dissociated anions (CaBr2·xH2O and Ca(OTf)2, more solu-
ble salts) affording reactivity, whereas no reactivity was
observed with insoluble or partially soluble salts contain-
ing more basic counterions (CaCO3 or CaSO4·2H2O, en-
tries 4-7). With salts possessing highly dissociable coun-
terions (e.g., triflate, nitrate, iodide), we observed a
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Scheme 3: Scope of the 3’-glycosylation using Ca(OTf)2 optimized conditionsa,b,c
1
2
3
4
HO
O
O
Ca(OTf)2
α-F-Glycoside (1)
α
HO
O
O
O
HO
RO
OR
3'
O
O
45% aq. NMe3
30 ϒC to RT, 16 h
O
HO
RO
OR
HO
β
5
HO
(7)
6
OH
7
8
9
HO
O
OH
O
HO
HO
HO
HO
O
HO
O
O
HO
OH
O OH
O OH
O
HO
O
HO
O OH
HO
HO
O
O
HO
O
O
HO
O OH
HO
HO
HO
HO
OH
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11
12
13
14
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O
OH
O
HO
HO
HO
HO
O
O
HO
HO
HO
O
O
O
O
HO
O
OH
HO
HO
HO
HO
HO
O
O
HO
HO
HO
HO
HO
HO
HO
HO
HO
HO
HO
HO
7a, 80% (1.0 mmol)
7b, 76% (0.87 mmol)
7c, 59% (1.0 mmol)
7d, 55%d (0.71 mmol)
HO
OH
HO
HO
O
O OH
O
HO
O
O OH
O
OH
O
O OH
O
HO
O
OH
HO
HO
HO
O
HO
HO
O
OH
O
HO
HO
HO
O
HO
O
HO
HO
O
OH
HO
O
HO
OH
OH
HO
O
OH
HO
O
O
HO
HO
O
O
HO
HO
HO
HO
HO
O
OH
OH
HO
HO
HO
HO
OH
7f, 47%d (0.08 mmol)
7e, 88% (0.2 mmol)
7g, 91% (0.08 mmol)
OH
HO
OH
Cl
HO
HO
O
O
O
Cl
O
O OH
O OH
O OH
O OH
N3
HO
HO
HO
O
O
O
O
HO
HO
HO
O
HO
O
HO
HO
HO
OTBDPS
O
O
HO
HO
N3
O
O
Cl
O
O
O
HO
HO
OH
OH
HO
HO
HO
HO
HO
HO
O
HO
BnO
HO
HO
HO
HO
HO
HO
HO
OH
7h, 74%d (1.0 mmol)
7j, 80%d,e (1.0 mmol)
7i, 73% (0.75 mmol)
7k, 0% (0.1 mmol)
a Reaction conditions: Ca(OTf)2 (6.0 equiv), α-F-Glycoside (1a or 1b) (6.0 equiv), 0.30 M in sucrose derivative in 45% aq. NMe3, 30 °C, 4 h then RT o/n. b Isolated yield
(%) after flash chromatography. Regio- and stereoselectivity determined by analysis of H, 13C, COSY, HSQC, and HMBC (see Supporting Information). Isolated
c
1
d
yield obtained after peracetylation with Ac2O, DMAP (cat.) in pyridine. e Reaction stirred for 2 hours at 30 °C only instead of 4 hours at 30 °C and RT o/n.
charides possessing a O-β-Gal and O-α-Glc linkage, re-
spectively, at the 4-position of the Glc unit of the sucrose
charide 7a (Ac2O/DMAP in pyridine)22 provided a deriva-
backbone. α-Fluoro-D-glucose (1a) could also be effective-
silica gel or residual calcium salts are indeed removed by
this method. Alternatively, peracetylation of the trisac-
ly replaced with α-fluoro-D-maltose (1b) in the presence
the of lactosyl fructofuranoside, providing the pentamer
7f in 47% yield (the remainder of the mass consisting of
starting material). Synthetic sucrose substrates were also
found to be compatible with the reaction conditions
(74%, 7h; 69%, 7i; 80%, 7j). 7j is also a potential precursor
to aminoglycoside scaffolds, a renowned family of antibi-
otics27 and inhibitors of the dextransucrase enzymes of
microorganisms responsible for dental caries.28 However,
sucralose, an approved no-calorie sweetener,29 could not
be converted into the corresponding trisaccharide 7k.
tive that is soluble in conventional organic solvents.
Reaction Scope. Encouraged by these results with su-
crose, we decided to investigate the glycosylation of other
sucrose-like oligosaccharides (Scheme 3). We were eager
to see if the high selectivity observed for product 7a could
be translated to more complex polyols. For example, xy-
losucrose, raffinose pentahydate, and stachyose hydrate,
oligosaccharides of biosynthetic origin and readily ob-
tained from commercial suppliers, afforded the desired
glycosylated products 7b, 7c, and 7d in practical yields (in
76%, 59%, 55% yields respectively). With stachyose, the
product and starting saccharide were found to co-elute,
and peracylation (with Ac2O/DMAP in pyridine) of the
mixture was necessary in order to isolate the pure prod-
uct.
Mechanism-Driven Studies. The differences between
sucrose and sucralose are subtle; chlorine atoms replace
the hydroxyl groups at positions 4 (Glc), 1’ (Fru), and 6’
(Fru). The chlorine at position 4 (Glc) of sucralose is also
in the inverted axial configuration in contrast to the su-
crose equatorial hydroxyl group.
Strikingly, under the optimized Ca(OTf)2 conditions,
we obtained exclusively the 3’-glycosylated products with
no significant quantities of products derived from alter-
In search of an explanation for this striking regioselec-
tivity exhibited by sucrose-like compounds, and the ab-
sence of reactivity for sucralose, we encountered reports
by Davies comparing the intramolecular hydrogen bond-
ing networks within various sucrose derivatives.30 A con-
clusion from these studies is that sucrose possesses two
prominent and competing conformations (A and B) in
DMSO-d6 (eq. 1). These conformations arise from a strong
1
nate sites of glycosylation (by H NMR analysis of the un-
purified reaction mixture). This is perhaps most impres-
sive for stachyose (7d), which possesses 14 distinct hy-
droxyl groups as candidate acceptor sites, each in a differ-
ent chemical environment. Moreover, the reaction condi-
tions could be transposed accordingly to lactosyl fructo-
furanoside (88%, 7e) and erlose (91%, 7g), two other sac-
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Journal of the American Chemical Society
intramolecular hydrogen bond between the 1’-hydroxyl Data Analysis. An understanding of the conformation of
1
2
3
4
5
6
7
8
(Fru) and 2-hydroxyl (Glc), and between the 3’-hydroxyl
(Fru) and 2-hydroxyl (Glc). However, the substitution of
OH-1’ with a Cl atom precludes the latter interaction, and
only the first hydrogen bond is present in sucralose.
sucrose and its deoxygenated derivatives would offer in-
sight into the remarkable regioselectivity observed in this
glycosylation reaction. Toward this end, we studied the
solution structures of all species (c.f., eq 1), looking for
differences that correspond to a specific hydroxyl group
deletion.30 For example, we suspected that elimination of
the 2-Glc hydroxyl might have a profound effect on the
sucrose conformation in solution (OH replaced for H, in
red, eq. 2)
O
OH
HO
O
1'
O
3'
H
O
O
1 : 2
O
H
H
H
H
O
O
(1)
OH
O
3'
O
O
2
H
O
2
H
O
H
O
O
1'
H
O
O
O
H
O
9
H
H
H
A
B
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
These differences in the hydrogen-bonding network of
sucrose and sucralose as well as the observed impact of
the various hydroxyl groups on the effectiveness of glyco-
sylation led us to interrogate each of them individually. In
order to do so, we performed a complete deoxygenation
scan by single hydroxyl group deletion present in sucrose.
We synthesized each of the deoxysucroses (8a-8h) follow-
ing either reported literature procedures or conventional
orthogonal protecting group strategies (See Supporting
Information for extensive details).22,31 We then submitted
them to the optimized 3’-glycosylation conditions (c. f.
conditions of Scheme 3).
OH
HO
O
OH
Fructose Anomeric
C−O bond rotation
O
O
O
H
H
O
O
OH
(2)
HO
HO
OH
H
HO
HO
2
H
2
HO
HO
OH
HO
HO
2-Deoxysucrose (8d)
OH-1' → OH-2
Non-present
OH-3' → OH-2 H-Bonding in 8d
Davies and O’Leary used equilibrium isotope effects to
elucidate intramolecular hydrogen bonding arrays in pol-
yol substrates.30,32 Thus, we elected to examine qualitative
correlations among sucrose, sucralose, and deoxysucroses
8a-8h (Table 3). The nature of these solution confor-
mations was probed using the SIMPLE 1H NMR technique
(Secondary Isotopic Multiplets of Partially Labelled Enti-
ties; SIMPLE) in DMSO-d6, in which intermolecular H-to-
D exchange between substrates (or with solvent) is slow.30
The SIMPLE phenomenon observed by Davies for sucrose
at OH-2, OH-1’, and OH-3’ is amplified at these sites
(highlighted in blue, eq. 1), and is explained by invoking
several cooperative hydrogen bonds between the other
OH-groups that are present. Consequently, when these
interactions are absent, as in the case of OH-to-Cl substi-
tutions in sucralose, the SIMPLE effects are attenuated.29
Remarkable and nearly binary results were observed
with all permutations (Table 2). 2-Deoxysucrose (8d), 1’-
deoxysucrose (8e), and 3’-deoxysucrose (8f) are complete-
ly inactive under the reaction conditions. On the contra-
ry, 6-deoxysucrose (8a), 4-deoxysucrose (8b), and 6’-
deoxysucrose (8h) all give nearly full conversions and
yields for the 3’-glycosylated trimers (90%, 82%, and 93%
yields respectively for 9a, 9b, and 9h).
Table 2: 3’-Glycosylation of Various Deoxysucroses under
Optimized Ca(OTf)2 Conditions.a,b
OH
HO
O
O OH
3'
α
Ca(OTf)2
α-F-Glucose (1a)
OH
For the purpose of our study, we compared the equi-
librium isotopic perturbations associated with the pre-
dominant OH-1’àOH-2 and OH-3’àOH-2 H-bonds ini-
tially reported for sucrose and sucralose in DMSO-d6 by
Davies (Table 3).30 Deoxysucrose derivatives that undergo
highly efficient 3’-glycosylation (8a, 8b, 8g and 8h; c.f.,
HO
O
HO
O
O OH
HO
HO
OH
O
O
45% aq. NMe3
30 °C to RT, 16 h
O
HO
HO
HO
HO
HO
β
OH
HO
HO
HO
mono-Deoxysucrose (8)
(9)
1
Table 2, entries 1, 2, 7 and 8) reveal SIMPLE H NMR data
Deoxysucrose
derivative (8)
Conversion Yield 9
Entry
(%)c
92
88
<5
0
(%)d
90
82
N.D.
0
that is homologous with sucrose itself. More precisely,
slightly more downfield isotopic shifts for OH-2 (+85 and
+79 x 10-4 ppm) associated with the OH-1’àOH-2 intra-
molecular hydrogen bonds are observed with deoxy-
sucrose 8a and 8b, in comparison to sucrose (+70 x 10-4
ppm). Notably, these substrates provide somewhat faster
reactions than sucrose under identical Ca-mediated gly-
cosylation conditions. Yet the magnitude of the corre-
sponding isotopic shift decreases for substrate 8c (+56 x
10-4 ppm) and it is absent altogether for 2-deoxysucrose
8d. This may reflect a weaker hydrogen bond in the case
of 8c, and the absence of critical hydrogen-bonding for
8d. Accordingly, the glycosylation for those substrates
was found to be greatly inhibited (c.f., Table 2, entries 3
and 4). Notably, other poor substrates for the glycosyla-
tion reactions also reflect significantly altered intramo-
lecular hydrogen-bonding arrays in comparison to su-
crose.
1
6-Deoxysucrose (8a)
4-Deoxysucrose (8b)
3-Deoxysucrose (8c)
2-Deoxysucrose (8d)
1’-Deoxysucrose (8e)
3’-Deoxysucrose (8f)
4’-Deoxysucrose (8g)
6’-Deoxysucrose (8h)
2
3
4
5
6
7
8
0
0
0
0
65
100
60
93
a
Each color denotates a position where an hydroxyl group was selectively
b
removed. Reaction conditions: deoxysucrose (0.214 mmol), Ca(OTf)2 (6.0
equiv), α-F-Glucose (6.0 equiv), 0.30 M in deoxysucrose in 45% aq. NMe3,
c
1
d
30°C, 4 h then rt, o/n. Conversion (%) determined by H NMR. Yield (%)
isolated by flash chromatography.
3-Deoxysucrose (8c) and 4’-deoxysucrose (8g) exhibit
intermediate activity, the former giving very low conver-
sion (<5%).
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1
Table 3. Magnitudes and Signs of Isotope Effects Observed by SIMPLE H NMR analysis on 8a-8h vs sucrose and su-
cralose.
1
2
3
4
5
6
7
8
9
SIMPLE (n x 10-4 ppm)a
Position
Sucrosec Sucralosec
8a
+85, +22
–19
8b
+79, +26
b
8c
+56, b
b
8d
N.A
0
8e
8f
8g
8h
OH-2
OH-3’
OH-1’
+70, +32
–22
+30
–13
+128
–53
+130
N.A.
–96
+78, +30 +63, +33
b
–20
–40
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
–43
N.A.
–50
–40
–39
0
N.A.
–48
a Estimated error in magnitude is ±2 x 10-4 ppm. b Isotope effect (magnitude <10 x 10-4 ppm) manifested as line broadening. c See reference 30 for literature SIMPLE 1H
NMR data.
roughly 55:45). After re-optimization,22 10a could be ob-
tained in increased yield (65% yield, 10a:7a ratio of 70:30),
For example, 8e and 8f exhibit isotopic shifts at OH-2
roughly two times higher than those observed for sucrose
(+128 and +130 x 10-4 ppm vs +70 x 10-4 ppm). Moreover,
and appreciable amounts of this pure trisaccharide could
be isolated by prep-HPLC (Scheme 4).37 The connectivity
only one hydrogen bond induces a SIMPLE effect for 8e
and 8f. This pattern is also observed for sucralose; the
single OH-3’ à OH-2 network exhibits a lower but signif-
and relative stereochemistry of this alternative regioiso-
mer were also supported by HMBC-NMR analysis22 be-
icant +30 x 10-4 ppm isotopic shift with respect to the OH-
tween the carbon at position C-1’ of the fructofuranose
unit and the axial Glc proton H-1’’ (highlighted in green,
2 (due to Cl atoms lowering the amount of cooperative
hydrogen bonds present).30a Thus, it seems likely that the
scheme 4).
hydrogen-bonding network present in sucrose plays a
critical role in determining the reactivity and selectivity
Scheme 4: Alternative Ca(OH)2-mediated 1’-glycosylation
OH
Ca(OH)2 (6.0 equiv)
α-F-Glucose (1a) (6.0 equiv)
HO
this glycosylation method. Deletion of the hydroxyl group
at positions 2-Glc, 1’-Fru and 3’-Fru not only alters the
hydrogen-bonding network, but has a profound effect on
the overall nucleophilicity of the sugar and its corre-
sponding interactions with Ca2+ under the reaction condi-
tions. All of these effects could influence the substrates’
pKa values as well. Sucrose has an estimated pKa value of
12.6 in water and the most acidic position was calculated
by Houdier and Pérez to be at the 2-hydroxyl (Glc).33 This
unusually high acidity for a polyol (versus a simple alco-
hol) is thought to be a result of this complex hydrogen-
bonding network.20b-d,34,35 We suspect that the pKa of cer-
tain deoxysucrose substrates is altered in comparison to
native sucrose as a result of the hydrogen-bonding net-
work perturbation (as observed by SIMPLE NMR). The
specifics of the interaction of the sucrosyl hydroxyl group
array under our reaction conditions may also prove highly
context dependent. For example, studies of sucrose and
C-sucrose analogs show differing affinity for Ca2+ in meth-
anol solvent.36 The present aqueous conditions, in the
presence of trimethylamine could well alter the equilibri-
um to favor Ca2+-sucrose adducts of unique reactivity,
which seems consistent with our deoxysucrose scan gly-
cosylation results.
O
O OH
65% yield
10a/7a ratio : 70:30
45% NMe3 in H2O (0.1 M)
O
HO
HO
HO
NaCl (10.0 equiv)
RT, 6 h
OH
HO
Sucrose
O
HMBC
correlation
HO
β
1'
O
O
O OH
3'
α
HO
HO
HO
HO
O
OH
O
HO
HO
O
H
α
OH
HO
O
HO
HO
HO
β
O
OH
HO
HO
O
HO
HO
(10a)
H
HO
HO
HO
(7a)
Contrary to 7a, product 10a was recently isolated by the
fermentation of plants extract and comparison of the re-
ported spectroscopic data to ours confirmed its identity.38
The regioselectivity for the formation of 10a is consistent
with a consideration of the conformational analysis.30 As
noted earlier, the 1’-hydroxyl group is hydrogen-bonded
to the 2-hydroxyl oxygen. The switch of selectivity may be
a
manifestation of a conformational change when
Ca(OH)2 is used. Since sucrose is fairly acidic, its derived
calcium alkoxide may substitute the glycosyl fluoride 1a
in a conformation different from the one adopted when
Ca(OTf)2 is used.
Conclusion
Implications for Alternate Regioselectivity. It is not
straightforward to alter the site-selectivity of the present
aqueous glycosylation with sucrose as the acceptor. For
example, we found that when the reaction is performed
with the basic and partially soluble Ca(OH)2, a moderate
level of reactivity is still observed (42% yield), albeit to a
much more complicated mixture of trisaccharides prod-
ucts. A close look into product distribution showed that
the major product formed is the 1’-glycosylated regioiso-
mer 10a over the 3’-glycosylated product 7a (in a ratio of
This glycosylation boasts several unique features: the
reaction is carried out under completely aqueous condi-
tions and high levels of glycosylation of sucrose and sev-
eral of its analogs are observed; the glycosylation pro-
ceeds with complete stereoinversion at the anomeric cen-
ter of the glycosyl donor, as well as complete regioselec-
tivity of the acceptor. From a practical perspective, all of
the reagents used are inexpensive, readily available com-
pounds and the procedure itself is experimentally simple.
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Journal of the American Chemical Society
greater for oligosaccharide synthesis when both glycosyl donor
The glycosylation products would be difficult to access
1
2
3
4
5
6
7
8
and acceptors are partially or fully unprotected. For reviews, see:
(a) Lee, D.; Taylor, M. Synthesis 2012, 3421-3431. (b) Hanessian,
S.; Lou, B. Chem. Rev. 2000, 100, 4443-4463. For recent strate-
gies, see: (c) Goff, R. D.; Thorson, J. S. Med. Chem. Commun.
2014, 5, 1036-1047 (d) Meng, B.; Zhu, Z.; Baker, D. C. Org. Biomol.
Chem. 2014, 12, 5182-5191. (e) Williams, R. J.; Paul, C. E.; Nitz, M.
Carbohydr. Res. 2014, 386, 73-77. (f) Sun, X.; Lee, H.; Lee, S.; Tan,
K. L. Nat. Chem. 2013, 5, 790-795. (g) Gouliaras, C.; Lee, D.;
Chan, L.; Taylor, M. S. J. Am. Chem. Soc. 2011, 133, 13926-13929.
(h) Lee, D.; Taylor, M. S. J. Am. Chem. Soc. 2011, 133, 3724-3727.
(i) Mamidyala, S. K.; Finn, M. G. J. Org. Chem. 2009, 74, 8417-
8420. (j) Tanaka, T.; Nagai, H.; Noguchi, M.; Kobayashi, A.;
Shoda, S.-I. Chem. Commun. 2009, 3378-3379. (k) Davis, B. G.;
Wood, S. D.; Maughan, M. A. T. Can. J. Chem. 2002, 80, 555-558.
4) There are a few examples of O-, C-, and S-glycosidic bond-
forming reactions performed in water or aqueous biphasic mix-
tures. These typically include the use of protecting groups
and/or multi-step synthesis: (a) Delacroix, S.; Bonnet, J.-P.;
Courty, M.; Postel, D.; Nguyen van Nhien, A., Carbohydr. Res.
2013, 381, 12-18. (b) Sakakura, A.; Koshikari, Y.; Akakura, M.; Ishi-
hara, K. Org. Lett. 2012, 14, 30-33. (c) Yoshida, N. et al., Chem.
Asian J. 2011, 6, 1876-1885. (d) Sato, S.; Naito, Y.; Aoki, K. Carbo-
hydr. Res. 2007, 342, 913-918. (e) Jensen, K. J. J. Chem. Soc., Perkin
Trans. 1 2002, 2219-2233.
5) Fore reviews, see: (a) Bojarová, P.; Rosencrantz, R. R.; El-
ling, L.; Křen, V. Chem. Soc. Rev. 2013, 42, 4774-4797. (b) Wang,
L.-X.; Davis, B. G. Chem. Sci. 2013, 4, 3381-3394. (c) Kadowaka, J.-
i. Chem. Rev. 2011, 111, 4308-4345. (d) Kobayashi, S.; Makino, A.
Chem. Rev. 2009, 109, 5288-5353. (e) Hehre, E. J. Carbohydr. Res.
2001, 331, 347-368. (f) Kren, V.; Thiem, J. Chem. Soc. Rev. 1997,
26, 463-473. (g) David, S.; Augé, C.; Gautheron, C. Adv. Carbo-
hydr. Chem. Biochem. 1991, 49, 175-237.
6) For glycosyl transferase examples, see: (a) Singh, S.;
Philipps, Jr., G. N.; Thorson, J. S. Nat. Prod. Rep. 2012, 29, 1201-
1237. (b) Gantt, R. W.; Peltier-Pain, P.; Thorson, J. S. Nat. Prod.
Rep. 2011, 28, 1811-1853. (b) Blanchard, S. Thorson, J. S. Curr.
Opin. Chem. Biol. 2006, 10, 263-271. (c) Hancock, S. M.; Vaughan,
M. D.; Withers, S. G. Curr. Opin. Chem. Biol. 2006, 10, 509-519.
(d) Williams, S. J.; Withers, S. G. Carbohydr. Res. 2000, 327, 27-
46 (e) van den Eijnden, D. H. in Carbohydrates in Chemistry and
Biology, Ernst, B.; Hart, G. W.; Sinay, P. (Eds.), Wiley-VCH,
Weinheim, 2000, Vol. 1, pp. 589–624. (d) Gambert, U.; Thiem, J.
Top. Curr. Chem. 1997, 186, 21-43.
7) For glycosyl hydrolase examples, see: (a) Desmet, T.;
Soetaert, W.; Bojarová, P.; Křen, V.; Dijkhuizen, L.; Eastwick-
Field, V.; Schiller, A. Chem.–Eur. J. 2012, 18, 10786-10801. (b) Hu-
sain, Q. Crit. Rev. Botechnol. 2010, 30, 41-62. (c) Murata, T.; Usui,
T. Trends Glycosci. Glycotechnol. 2000, 12, 161-174. (d) Scigelova,
M.; Singh, S.; Crout, D. H. G. J. Mol. Catal. B-Enzym. 1999, 6,
483-494.
8) (a) Ohrlein, R. in Carbohydrates in Chemistry and Biology,
Ernst, B.; Hart, G. W.; Sinay, P. (Eds.), Wiley-VCH, Weinheim,
2000, Vol. 1, pp. 625–646. (b) Nikaido, H.; Hassid, W. Z. Adv.
Carbohydr. Chem. Biochem. 1971, 26, 351-483 (c) Caputto, R.;
Leloir, L. F.; Cardini, E.; Paladini, A. C. J. Biol. Chem. 1950, 184,
333-350.
9) (a) Young, I. S.; Baran, P. S. Nat. Chem. 2009, 1, 193-205. (b)
Shenvi, R. A.; O’Malley, D. P.; Baran, P. S. Acc. Chem. Res. 2009,
42, 530-542. (c) Hoffmann, R. W. Synthesis 2006, 3531-3541.
10) For the activation and application of fully protected glyco-
syl fluorides, see: (a) Toshima, K. Carbohydr. Res. 2000, 327, 15-
27. (b) Akçay, G.; Ramphal, J. Y.; d’Alarcao, M.; Kumar, K. Tetra-
hedron Lett. 2015, 56, 109-114. (c) Partridge, K. M.; Bader, S. J.;
Buchan, Z. A.; Taylor, C. E.; Montgomery, J. Angew. Chem., Int.
Ed. 2013, 52, 13647-13650. (d) Shivatar, S. S.; Chang, S.-H.; Tsai,
T.-I; Ren, C.-T.; Chuang, H.-Y.; Hsu, L.; Lin, C.-W.; Li, S.-T.; Wu,
using any currently reported glycosylation methods and
their synthesis is yet unreported in the literature. More
broadly, the mechanistic basis for the unique reactivity
foreshadow well for the exploration of substrates beyond
sucrose.
Could
other
metal
ion/basic
addi-
tive/carbohydrate combinations be found that allow for
the related aqueous glycosylations of other substrates so
that the scope could be expanded? This critical question
is the focus of ongoing studies in our laboratories.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
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ASSOCIATED CONTENT
Supporting Information. Additional figures, experimental
details and characterization. This material is available free of
charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
* scott.miller@yale.edu, alanna.schepartz@yale.edu
Author Contributions
The manuscript was written through contributions of all
authors. All authors have given approval to the final version
of the manuscript.
Funding Sources
The authors declare no competing financial interests.
ACKNOWLEDGMENT
This work was initially supported by the W. M. Keck Founda-
tion and later by National Institutes of Health (NIH
GM068649). The authors would like to thank Prof. Daniel J.
O’Leary for insightful discussions. G.P. is grateful to NSERC
(PDF) and FQRNT (B3) for post-graduate fellowships.
ABBREVIATIONS
Glc, glucose; Gal, galactose; Fru, fructose; aq., aqueous;
HSQC, Heteronuclear Single Quantum Correlation spectros-
copy; HMBC, Heteronuclear Multiple Bond Correlation;
TSAS, transition state analogue substrate; HFPN, hexafluoro-
1-propanol; TFE, trifluoroethanol; SIMPLE, Secondary Iso-
tope Multiplets of Partially Labeled Entities; UDP, uridine
diphosphate; CMP, cytidine monophosphate; GDP, guano-
sine diphosphate.
REFERENCES
1) (a) Nigudkar, S. S.; Demchenko, A. V. Chem. Sci. 2015, 6,
2687-2704. (b) Seeberger, P. H. Acc. Chem. Res. 2015, 48, 1450-
1463. (c) McKay, M. J.; Nguyen, H. M. ACS Catal. 2012, 2, 1563-
1595. (d) Mydock, L. K.; Demchenko, A. V. Org. Biomol. Chem.
2010, 8, 497-510. (e) Zhu, X.; Schmidt, R. R. Angew. Chem., Int.
Ed. 2009, 48, 1900-1932. (f) Boltje, B. T.; Buskas, T.; Boons, G.-J.
Nat. Chem. 2009, 1, 611-622. (g) Smoot, J. T.; Demchenko, A. V.
Adv. Carbohydr. Chem. Biochem. 2009, 62, 161-250. (h) Wang, Y.;
Ye, X.-S.; Zhang, L.-H. Org, Biomol. Chem. 2007, 5, 2189-2200. (i)
Jung, K.-H.; Müller, M.; Schmidt, R. R. Chem. Rev. 2000, 100,
4423-4442.
2) (a) Bohé, L.; Crich, D. Carbohydr. Res. 2015, 403, 48-59. (b)
Satoh, H.; Manabe, H. Chem. Soc. Rev. 2013, 42, 4297-4309.
3) Stereocontrolled synthetic glycosyl transfers of partially or
fully unprotected glycosyl donors have been achieved through
several strategies. However, the selectivity challenge is much
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 9
C.-Y.; Wong, C.-H. J. Am. Chem. Soc. 2013, 135, 15382-15391. (e)
2008, 61, 217-292. (d) Queneau, Y.; Fitremann, J.; Trombotto, S.
C. R. Chim. 2004, 7, 177-188.
1
2
3
4
5
6
7
8
Saha, J.; Peczuh, M. W. Chem.-Eur. J. 2011, 17, 7357-7365. (f)
Durham, T. B.; Blanchard, N.; Savall, B. M.; Powell, N. A.; Roush,
W. R. J. Am. Chem. Soc. 2004, 126, 9307-9317. (g) Nicolaou, K. C.;
Chucholowski, A.; Dolle, R. E.; Randall, J. L. J. Chem. Soc., Chem.
Commun. 1984, 1155-1156. (h) Nicolaou, K. C.; Dolle, R. E.; Papa-
hatjis, D. P.; Randall, J. L. J. Am. Chem. Soc. 1984, 106, 4189-4192.
(i) Hashimoto, S.; Hayashi, M.; Noyori, R. Tetrahedron Lett. 1984,
25, 1379-1382. (j) Mukaiyama, T.; Murai, Y.; Shoda, S. Chem. Lett.
1981, 431-432.
21) (a) Allen, C. L.; Miller, S. J. Org. Lett. 2013, 15, 6178-6181. (b)
Han, S.; Miller, S. J. J. Am. Chem. Soc. 2013, 135, 12414-12421. (c)
Pathak, T. P.; Miller, S. J. J. Am. Chem. Soc. 2013, 135, 8415-8422.
(d) Lewis, C. A.; Miller, S. J. Angew. Chem., Int. Ed. 2006, 45,
5616-5619. (e) Lewis, C. A.; Sculimbrene, B. R.; Xu, Y.; Miller, S. J.
Org. Lett. 2005, 7, 3021-3024. (f) Griswold, K. S.; Miller, S. J. Tet-
rahedron 2003, 59, 8869-8875.
22) See Supporting Information for reaction details.
9
11) (a) Banait, N. S.; Jencks, W. P., J. Am. Chem. Soc. 1991, 113,
7951-7958; (b) Banait, N. S.; Jencks, W. P., J. Am. Chem. Soc. 1991,
113, 7958-7963.
12) (a) Chan, J.; Tang, A.; Bennet, A. J. J. Am. Chem. Soc. 2012,
134, 1212-1220. (b) Sinnott, M. L.; Jencks, W. P. J. Am. Chem. Soc.
1980, 102, 2026-2032.
13) Chan, J. Sannikova, N.; Tang, A. Bennet, A. J. J. Am. Chem.
Soc. 2014, 136, 12225-12228.
14) (a) Stubbs, J. M.; Marx, D. J. Am. Chem. Soc. 2003, 125,
10960-10962. (b) Zhang, Y.; Bommuswamy, J.; Sinnot, M. L. J.
Am. Chem. Soc. 1994, 116, 7557-7563.
15) For examples, see: (a) Kittl, R.; Withers, S. G. Carbohydr.
Res. 2010, 345, 1272-1279. (b) Kobayashi, S. J. Polym. Sci., Part A:
Polym. Chem. 2005, 43, 693-710. (c) Armand, S.; Drouillard, S.;
Schülein, M.; Henrissat, B.; Driguez, H. J. Biol. Chem. 1997, 272,
2709-2713.
16) (a) Gloster, T. M. Curr. Opin. Struct. Biol. 2014, 28, 131-141.
(b) Lairson, L. L.; Henrissat, B.; Davies, G. J.; Withers, S. G. Annu.
Rev. Biochem. 2008, 77, 521-555. (c) Dürr, G.; Strayle, J.; Plemper,
R.; Elbs, S.; Klee, S. K.; Catty, P.; Wolf, D. H.; Rudolph, H. K. Mol.
Biol. Cell. 1998, 9, 1149-1162.
17) (a) Nakagawa, Y.; Watanabe, Y.; Igarashi, Y.; Ito, Y.; Ojika,
M. Bioorg. Med. Chem. Lett. 2015, 25, 2963-2966. (b) Czugler, M.;
Pintér, I. Carbohydr. Res. 2011, 346, 1610-1616. (c) Kato, T.; Tsu-
bono, K.; Kamo, O.; Kato, T.; Furihata, K.; Fujimoto, T.; Machin-
ami, T.; Tashiro, M. Magn. Reson. Chem. 2009, 47, 948-952. (d)
Zhuo, K.; Liu, H.; Zhang, X.; Liu, Y.; Wang, J. Carbohydr. Res.
2008, 343, 2428-2432. (e) Vega-Cantu, Y. I.; Hauge, R. H.; Nor-
man, L. R.; Powell, R. J.; Billups, W. E. Biomacromolecules 2006,
7, 441-445. (f) Fujimoto, T.; Oku, K.; Tashiro, M.; Machinami, T.
J. Carbohydr. Chem. 2006, 25, 521-532. (g) Gege, C.; Geyer, A.;
Schmidt, R. R. Eur. J. Org. Chem. 2002, 2475-2485. (h) Ashton, P.
R.; Gattuso, G.; Königer, R.; Stoddart, J. F.; Williams, D. J. J. Org.
Chem. 1996, 61, 9553-9555.
18) The approach illustrated in Figure 2b is reminiscent of the
metal-directed acetal and stannylene acetal formation on polyol-
containing carbohydrates: (a) Iwasaki, F.; Maki, T.; Onomura,
O.; Nakashima, W.; Matsumura, Y. J. Org. Chem. 2000, 65, 996-
1002. (b) Martinelli, M. J.; Vaidyanathan, R.; Pawlak, J. M.;
Nayyar, N. K.; Dhokte, U. P.; Doecke, C. W.; Zollars, L. M. H.;
Moher, E. D.; Van Khau, V.; Kosmrjl, B. J. Am. Chem. Soc. 2002,
124, 3578-3585. (c) Voight, E. A.; Rein, C.; Burke, S. D. J. Org.
Chem. 2002, 67, 8489-8499. (d) Gyurcsik, B.; Nagy, L. Coord.
Chem. Rev. 2000, 203, 81-149. (e) Evtushenko, E. V. Carbohydr.
Res. 2012, 359, 111-119. (f) Clarke, P. A.; Kayaleh, N. E.; Smith, M.
A.; Baker, J. R.; Bird, S. J.; Chan, C. J. Org. Chem. 2002, 67, 5226-
5231. (g) Angyal, S. J. Aust. J. Chem. 2000, 53, 567-570. (h) Angyal,
S. J. Adv. Carbohydr. Chem. Biochem. 1989, 47, 1-43.
23) (a) Caes, B. R.; Palte, M. J.; Raines, R. T. Chem. Sci. 2013, 4,
196-199. (b) Moliner, M.; Román-Leshkov, Y.; Davis, M. E. Proc.
Natl. Acad. Sci. U.S.A. 2010, 107, 6164-6168. (c) Tanase, T.; Takei,
T.; Hidai, M.; Yano, S. Carbohydr. Res. 2001, 333, 303-312. (d)
Bermejo-Deval, R.; Orazov, M.; Gounder, R.; Hwang, S.-J.; Davis,
M. E. ACS Catal. 2014, 4, 2288-2299. (e) Angyal, S. J. Carbohydr.
Res. 1997, 300, 279-281. (f) Yanagihara, R.; Soeda, K.; Shiina, S.;
Osanai, S.; Yoshikawa, S. Bull. Chem. Soc. Jpn. 1993, 66, 2268-
2272. (g) Tanase, T.; Murata, T.; Yano, S.; Hidai M.; Yoshikawa, S.
Chem. Lett. 1987, 1409-1412.
24) (a) Iddon, L.; Bragg, R. A.; Harding, J. R.; Pidathala, C.;
Bacsa, J.; Kirby, A. J.; Stachulski, A. V. Tetrahedron 2009, 65,
6396-6402. (b) Micheel, F.; Micheel, H. Ber. Dtsch. Chem. Ges. B
1932, 65B, 258-261. (c) Leehman, M. R.; Thompson, C. D.; Marvel,
C. S. J. Am. Chem. Soc. 1933, 55, 1977-1981.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
25) Dyfverman, A.; Lindberg, B. Acta Chem. Scand. 1950, 4,
878-884.
26) In runs in which the concentration is higher than 0.5 M in
sucrose, the reactants were found to be partially soluble
throughout the course of the reaction, thus creating some repro-
ducibility issues at an early stage of the optimization. The reac-
tion can be run in more dilute aqueous solutions (0.20 M or 0.1
M wrt sucrose) without hampering the conversion. A concentra-
tion of 0.3 M was found to be more practical and consistent.
27) (a) Hermann, T. Cell. Mol. Life Sci. 2007, 64, 1841-1852. (b)
Magnet, S.; Blanchard, J. D. Chem. Rev. 2005, 105, 477-498. (c)
Sutcliffe, J. A. Curr. Opin. Microbiol. 2005, 8, 534-542. (d) Vaku-
lenko, S. B.; Mobashery, S. Clin. Microbiol. Rev. 2003, 16, 430-450.
28) (a) Lee, C. G.; Park, J. K. Appl. Microbiol. Biotechnol. 2015,
99, 7495-7503. (b) Binder, T. P.; Robyt, J. F. Carbohydr. Res. 1985,
140, 9-20. (c) Thaniyavarn, S.; Singh, S.; Maynard, C. M.; Taylor,
K. G.; Doyle, R. J. Carbohydr. Res. 1981, 96, 134-137.
29) (a) Schiffman, S. S.; Rother, K. I. J. Toxicol. Environ. Health
B. Crit. Rev. 2013, 16, 399-455. (b) DuBois, G. E.; Prakash, I. Annu.
Rev. Food Sci. Technol. 2012, 3, 353-380. (c) Hough, L.; Phadnis, S.
P. Nature 1976, 263, 800.
30) (a) Christofides, J. C.; Davies, D. B.; Martin, J. A.;
Rathbone, E. B. J. Am. Chem. Soc. 1986, 108, 5738-5743. (b) Chris-
tofides, J. C.; Davies, D. B. J. Chem. Soc., Chem. Commun. 1985,
1533-1534. (c) Christofides, J. C.; Davies, D. B. J. Am. Chem. Soc.
1983, 105, 5099-5105. See also (d) Lemieux, R. U.; Bock, K. Jpn. J.
Antibiot. 1979, 32, S163-S177.
31) (a) Barton, D. H. R.; McCombie, S. W. J. Chem. Soc., Perkin
Trans. 1 1975, 1574-1585. (b) Chatgilialoglu, C.; Ferreri, C. Res.
Chem. Intermed. 1993, 19, 755-775.
32) While the magnitude of SIMPLE effects seems well-
correlated with intramolecular hydrogen bonding, the absolute
sign of the chemical shift perturbation can be highly context
dependent and difficult to interpret. See: (a) Vasquez, Jr., T. E.;
Bergset, J. M.; Fierman, M. B.; Nelson, A.; Roth, J.; Khan, S. I.;
O’Leary, D. J. J. Am. Chem. Soc. 2002, 124, 2931-2938. (b) Craig, B.
N.; Janssen, M. U.; Wickersham, B. M.; Rabb, D. M.; Chang, P. S.;
O’Leary, D. J. J. Org. Chem. 1996, 61, 9610-9613. (c) Anderson, C.;
E.; Britt, D. K.; Sangji, S.; O’Leary, D. J.; Anderson, C. D.; Rych-
novsky, S. D. Org. Lett. 2005, 5, 5721-5723. (d) O’Leary, D. J.;
Hickstein, D. D.; Hansen, B. K. V.; Hansen, P. E. J. Org. Chem.
2010, 75, 1331-1342. (e) Anderson, C. E.; Pickrell, A. J.; Sperry, S.
19) Thiem reported a seminal non-selective glycosylation of
unprotected sucrose employing glycosyl chlorides, NaH in DMF.
All possible OH positions of sucrose were glycosylated with no
chemoselectivity. See: Steinmann, A.; Thimm, J.; Thiem, J. Eur. J.
Org. Chem. 2007, 5506-5513.
20) (a) Daudé, D.; Remaud-Simeon, M.; André, I. Nat. Prod.
Rep. 2012, 29, 945-960. (b) Queneau, Y.; Pinel, C.; Scherrmann,
M.-C. C. R. Chim. 2011, 14, 688-699. (c) Queneau, Y.; Jarosz, S.;
Lewandowski, B.; Fitremann, J. Adv. Carbohydr. Chem. Biochem.
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L.; Vasquez, Jr., T. E.; Custer, T. G.; Fierman, M. B.; Lazar, D. C.;
see: (b) Poppe, L.; van Halbeek, H. J. Am. Chem. Soc. 1992, 114,
1
2
3
4
5
6
7
8
Brown, Z. W.; Iskenderian, W. S.; Hickstein, D. D.; O’Leary, D. J.
Heterocycles 2007, 72, 469-495.
33) (a) Houdier, S.; Pérez, S. J. Carbohydr. Res. 1995, 14, 1117-
1132. (b) Woolley, E. M.; Tomkins, J.; Hepler, L. G. J. Solution
Chem. 1972, 1, 341-351.
34) (a) Engelsen, S. B.; Péres, S. Carbohydr. Res. 1996, 292, 21-
38. (b) Lichtenthaler, F. W.; Immel, S.; Pokinskyj, P. Liebigs Ann.
1995, 1939-1947. (c) Immel, S.; Lichtenthaler, F. W. Liebigs Ann.
1995, 1925-1938. (d) Hamann, C. H.; Fischer, S.; Polligkeit, H.;
Wolf, P. J. Carbohydr. Chem. 1993, 12, 173-190.
1092-1094. (c) Hervé du Penhoat, C.; Imberty, A.; Roques, N.;
Michon, V.; Mentech, J.; Descotes, G.; Pérez, S. J. Am. Chem. Soc.
1991, 113, 3720-3727. (d) McCain, D. C.; Markley, J. L. J. Am. Chem.
Soc. 1986, 108, 4259-4264. (e) Adams, B.; Lerner, L. J. Am. Chem.
Soc. 1992, 114, 4827-4829.
37) Both regioisomers (10a and 7a) were found to co-elute by
conventional flash chromatography. In order to get pure 10a, a
subsequent separation by semi-prep HPLC was needed (XBridge
Prep Amide 5μL BEH glycan column using a gradient of 80%
MeCN in 20% aq. NH4OH 0.1% buffer to 50% MeCN in 50% aq.
NH4OH 0.1% buffer).
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35) Matwiejuk, M.; Thiem, J. Eur. J. Org. Chem. 2012, 2180-
2187.
36) (a) O’Leary, D. J.; Kishi, Y. Tetrahedron Lett. 1994, 35, 5591-
5594. For different conformational analysis of sucrose in water,
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13
14
15
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17
18
19
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22
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25
26
27
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30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
38) Kawazoe, N.; Okada, H.; Fukushi, E.; Yamamori, A.; On-
odera, S.; Kawabata, J.; Shiomi, N. Open Glycosci. 2008, 1, 25-30.
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