A dehydrative glycosylation protocol mediated by nonafluorobutanesulfonyl fluoride (NfF)

Article abstract of DOI:10.1016/j.tet.2020.131800

A new dehydrative glycosylation protocol that proceeds through selective activation of glycosyl hemiacetals with nonafluorobutanesulfonyl fluoride (NfF) has been disclosed. Contrary to the major classical glycosylation reactions that proceed under acidic

Full text of DOI:10.1016/j.tet.2020.131800

Tetrahedron 78 (2021) 131800
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Tetrahedron
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A dehydrative glycosylation protocol mediated by
nonafluorobutanesulfonyl fluoride (NfF)
,
, *
Yu Tang a, D. Prabhakar Reddy a b, Biao Yu a
a State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry,
University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
b Innovation Research Institute of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, 1200 Cai Lun Road, Shanghai, 201203,
China
a r t i c l e i n f o
a b s t r a c t
Article history:
A new dehydrative glycosylation protocol that proceeds through selective activation of glycosyl hemi-
acetals with nonafluorobutanesulfonyl fluoride (NfF) has been disclosed. Contrary to the major classical
glycosylation reactions that proceed under acidic or neutral conditions, the present glycosylation reac-
tion proceeds under mild basic conditions. In the absence of an external acceptor, self-condensation of
the glycosyl hemiacetal occurs, providing the corresponding symmetrical 1,10-disaccharides in high
yields.
Received 17 October 2020
Received in revised form
19 November 2020
Accepted 22 November 2020
Available online 1 December 2020
© 2020 Elsevier Ltd. All rights reserved.
Keywords:
Dehydrative glycosylation
Nonafluorobutanesulfonyl fluoride
Glycosyl hemiacetal
1,10-Disaccharide
Glycoside
1. Introduction
combination with Tf2O to modulate the activation process [7], such
co-promoters include tetrabutylammonium bromide [4a], [1,2-
The construction of glycosidic linkages represents a central issue
in glycochemistry, and new glycosylation methods are continu-
ously being developed [1aee]. Of the various glycosylation strate-
gies developed, the dehydrative glycosylation which allows for the
direct use of glycosyl hemiacetals as glycosyl donors that react with
alcoholic acceptors under mild activating conditions, is a very
attractive alternative; and a number of dehydrative glycosylation
conditions have been reported during the past few decades
[2aeh,3aec]. Among these dehydrative glycosylation conditions,
selective transformation of the C1-hemiacetal into glycosyl triflate
by a triflating reagent (usually Tf2O) followed by glycosylation
represents a straightforward approach [4aec] [5a,b], [6a,b]. To
realize such a glycosylation process, the first problem to address is
how to selectively activate the C1-hemiacetal without affecting the
alcoholic acceptor, since a triflating reagent (such as Tf2O) could
triflate both the hemiacetal and the acceptor. The second problem
to address is how to avoid self-condensation of the C1-hemiacetal.
To solve these problems, usually a co-promoter was used in
benzenediolato(2)-O,O’]oxotitanium [8], diphenyltin sulfide [9],
diphenyl sulfoxide [10a,b], dibutyl sulfide [11], phthalic anhydride
[12], triphenylphosphine oxide [13a,b], cyclic phosphonium anhy-
drides [14], and 2-aryl-1,3-dithiane 1-oxide [2a]. In the presence of
these co-promoters, a much mild activating species was generated,
thus to enable selective activation of the C1-hemiacetal. In 2014, a
direct Tf2O mediated dehydrative glycosylation was reported [15],
and the key to success is the addition of a strained olefin into the
reaction system to act as an acid scavenger.
It was noted that Tf2O, a rather strong sulfonating agent, has
been used in most of these dehydrative glycosylation protocols
[16aed]. We envisioned that a milder sulfonating agent could
selectively react with the glycosyl C1-hemiacetal in the presence of
a mild base without affecting the alcoholic acceptor, thus would
enable
a dehydrative glycosylation. Nonafluorobutanesulfonyl
fluoride (C4F9SO2F, NfF) [17], a readily available colorless liquid
(boiling point at 64 ꢀC), attracted our attention, because it could
selectively react with the deprotonated phenolic hydroxyl group
under mild heterogeneous basic conditions [18,19aec]. Given the
fact that the acidity of the glycosyl C1-hemiacetal (pKa ~12) is
stronger than an ordinary alcoholic hydroxyl group (pKa ~16) [20],
* Corresponding author.
E-mail address: byu@sioc.ac.cn (B. Yu).
https://doi.org/10.1016/j.tet.2020.131800
0040-4020/© 2020 Elsevier Ltd. All rights reserved.

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
we expected that this reagent would be capable of selectively
activating the depontoned glycosyl C1-hemiacetal (B) to generate a
reactive glycosyl nonaflate intermediate (C), which could immedi-
ately react with the co-existed acceptor to afford the glycosylation
product (Scheme 1). Herein, we report our preliminary attempts to
develop a novel NfF mediated dehydrative glycosylation protocol.
temperature in the presence of 300 w/w% 3 Å molecular sieves.
The scope of this reaction was next investigated, and the results
were given in Scheme 2. With respect to acceptor scope, apart from
primary alcohol (2a and 2d), secondary alcohol 2b and tertiary
alcohol 2c could also be glycosylated in high yields under the
optimized conditions. With respect to donor scope, armed pyr-
anosyl donors including benzylated glucosyl donors 1a and 1b,
benzylated rhamnosyl donor 1c, and armed furanosyl donors,
including diacetone-mannofuranosyl donor 1d and benzylated
arabinofuranosyl donor 1e were suitable donors for the present
glycosylation protocol. Under standard conditions, the glycosyla-
2. Results and discussion
The dehydrative glycosylation of alcoholic acceptor 2-
methoxyethanol (2a) using 2,3,4,6-tetra-O-benzyl-D-glucopyr-
anose 1a as donor mediated by NfF was chosen as a model reaction.
The reaction was carried out in chlorinated hydrocarbon solvents in
the presence of an inorganic base and 3 Å molecular sieves at room
temperature or 65 ꢀC. After the reaction, the glycosylated product
tion yields were typically high. It was noteworthy that the
a-
selectivity of the glucosylation applying benzylated glucosyl donors
could be turned by switching the donor from 6-O-benzyl donor 1a
to 6-O-acetyl donor 1b [22,23]. Thus, the glycosylation of perben-
zylated glucosyl donor 1a with acceptor 2a and 2b afforded gly-
cosides 3a and 3b in 87% and 94% yield, respectively, with only
3a was isolated via flash column chromatography and the a/b ratio
was determined by NMR analysis. The results were summarized in
Table 1. In our initial attempt, the mole ratio of donor 1a/acceptor
2a/NfF was 1/2/5.3, K2CO3 (11.7 eq.) was chosen as the base,
ClCH2CH2Cl as the solvent, and no molecular sieves were added
(entry 1). The reaction proceeded rather slowly at room tempera-
ture (less than 50% conversion after 3 days); at 65 ꢀC, the reaction
moderate stereoselectivity (
of 6-O-acetyl donor 1b with acceptors 2a-2d afforded the corre-
sponding glycosides 3c-3f in 88e99% yield with good -selectivity
4.5/1). Apart from glucosyl donor 1b, diacetone-
mannofuranosyl donor 1d was also found to be an -selective
donor, with product 3h being isolated in 88% yield with a high
selectivity (
¼ 7.7/1). The other two tested benzylated donors,
rhamnosyl donor 1c and
glycosylation products 3g and 3i in 93% and 85% yield with mod-
erate -selectivity ( -selectivity ( ¼ 1/2.5),
¼ 2.7/1) and
respectively.
a
/b
¼ 1.7/1), whereas the glucosylation
a
(a/b >
a
a-
proceeded smoothly, after 25 h, the yield of 3a reached 78% (a/
a
/b
L-
b
¼ 1.7/1), with a small amount of 1a remained unreacted. We next
D-arabinofuranosyl donor 1e, afforded the
switched the base to Cs2CO3 (5 eq.), under otherwise similar con-
ditions, the reaction proceeded smoothly at room temperature;
a
a
/b
b
a/b
after 22 h, the yield of 3a reached 82% (
a/b
¼ 1.7/1) (entry 2). Again,
it was noted that a small amount of 1a remained unreacted, neither
extended reaction times nor additional equivalents of NfF or base
improved the yield or conversion. Mechanistically, during this re-
action 1 equiv. of acid (C4F9SO3H) was generated, which could
subsequently be neutralized by the base to generate 1 equiv. of
water from the resultant H2CO3. As the reaction proceeded, the
concentration of acceptor 2a decreased while the concentration of
water increased; the generated water could compete with acceptor
2a, leading to incomplete conversion of the acceptor 2a. To solve
this problem, we added 3 Å molecular sieves to the reaction system
to sequester the generated water. Gratifyingly, full conversion was
achieved and the glycosylated product 3a was isolated in 97% yield
Inspired by the successful results with alcoholic acceptors, we
next explored the present glycosylation with glycoside acceptors.
Thus, the glycosylation between glycoside acceptor 1,2:3,4-di-O-
isopropylidene-a-D-galactopyranose 4 (1.5 eq.) and glucosyl donor
1b (1.0 eq.) was performed under the standard conditions. After the
reaction, the products were isolated and characterized, and the
results were shown in Scheme 3. The desired glycosylation product
5 was isolated in only 58% yield (
di-O-isopropylidene-6-O-nonafluorobutanesulfonyl-
a
/
b
¼ 3.7/1). Interestingly, 1,2:3,4-
a-D
-gal-
actopyranose 6 was isolated in 56% yield (based on 4); another side
product turned out to be glucosyl fluoride 7, being isolated in 12%
yield (
a
/
b
¼ 5/1). In addition, the unreacted donor 1b was recovered
(
a/
b
¼ 1.4/1) (entry 3). Reducing the ratio of donor 1a/acceptor 2a/
NfF to 1/1.5/2 still led to the formation of product 3a in a satisfying
87% yield (
¼ 1.7/1) (entry 4). Further reducing the ratio of donor
1a/acceptor 2a/NfF to 1/1.5/1.5, the yield of 3a dropped to 83% (
¼ 2/1) (entry 5). When the reaction was conducted in the pres-
ence of excess donor (donor 1a/acceptor 2/NfF ¼ 1.6/1/3.2), the
yield of 3a retained at a high level (87%,
in 28% yield. These results demonstrated that the hydroxyl group of
a glycoside acceptor could be sulfonated under the present dehy-
drative conditions, thus competing with the glycosylation pathway
to diminish the glycosylation yield [24].
a/b
a
/
b
When the glucosyl donor was used in excess, the formation of
self-condensation product 1,10-disaccharide was observed [25a,b].
Thus, the self-condensation of hemiacetal donors in the absence of
acceptors under the present dehydrative glycosylation conditions
was investigated. The results were summarized in Scheme 4.
Starting from glucosyl donor 1a, symmetrical 1,10-disaccharide 8
a
/b
¼ 1.2/1; entry 6). When
the base was replaced with CaO, no glycosylated product was
observed (entry 7). The performance of organic bases were also
tested. In the presence of DIPEA, no glycosylation reaction occurred
(entry 8); in the presence of DBU, the reaction proceeded rapidly,
was isolated in 85% yield (aa
/
ab
/
bb ¼ 24/15/1), with glucosyl
after 18 h, the glycosylation product 3a was formed in 32% yield (a/
fluoride 9 being isolated in 15% yield (
a
/b
¼ 1/5). When rhamnosyl
b
¼ 1/4; entry 9), with the major side product being identified to be
donor 1c was charged under similar conditions, 1,10-dirhamnosides
10aa and 10ab were isolated in 70% and 28% yields, respectively.
the corresponding glucosyl fluoride. Taking into account the prac-
ticality and efficiency, the optimal reaction conditions were
established as follows: the mole ratio of donor 1a/acceptor 2a/NfF/
CsCO3 was 1/1.5/2/2, the reaction was performed in CH2Cl2 at room
When starting from 2-deoxy-
D
-glucosyl donor 11, symmetrical 1,10-
disaccharide 12aa and 12ab were isolated in 39% and 40% yields,
Scheme 1. Reaction design.
2

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
Table 1
Optimization of reaction conditions.
Entry
1a/2a/NfF
Base (eq.)
3 Å MS (w/w)
Solvent
T (oC)
Time
Yield of 3a
a/
bc
1
2
3
4
5
6
7
8
9
1/2/5.3
1/2/4.4
1/2/2.9
1/1.5/2
1/1.5/1.5
1.6/1/3.2
1/2/2.9
1/1.5/2
1/1.5/2
K2CO3 (11.7)
Cs2CO3 (5.0)
Cs2CO3 (3.6)
Cs2CO3 (2.0)
Cs2CO3 (1.5)
Cs2CO3 (4.0)
CaO (5.0)
0
0
ClCH2CH2Cl
ClCH2CH2Cl
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
65
RT
RT
RT
RT
RT
RT
RT
RT
25 h
22 h
6 h
4 h
5 h
18 h
5 h
18 h
18 h
78%a
82%a
97%a
87%a
83%a
87%a
NR
1.7/1
1.7/1
1.4/1
1.7/1
2/1
1.2/1
_
_
300%
300%
300%
300%
300%
300%
300%
DIPEA (2.0)
DBU (2.0)
NR
32%b
1/4
a
Isolated yield.
b
c
NMR yield.
The
a/b
ratio was determined by quantitative13C NMR analysis according to reference method (ref. 21).
respectively. Interestingly, an elimination-glycosylation product,
i.e., unsymmetrical 1,10-disaccharide 13aa, was also isolated in 8%
yield. The configurations of the two anomeric centers of product 13
were assigned by NOE experiments, and no other anomer of 13 was
isolated from the reaction mixture. The formation of product 13
indicated the presence of a Ferrier-like reaction pathway in the
present glycosylation system [26].
(water ꢁ 50 ppm) were purchased from Innochem. Thin layer
chromatography (TLC) was performed on TLC Silica Gel 60 F254
(Merck). The TLC plates were visualized with UV light and/or by
staining with EtOH/H2SO4 (8%, v/v). Flash column chromatography
was performed on Silica Gel 60 (40e64 mm, Fluka, Canada). NMR
spectra were measured on Bruker AM 400, Agilent 500 or 600 MHz
NMR spectrometer at 25 ꢀC. 1H and 13C NMR signals were calibrated
to the residual proton and carbon resonance of the solvent (CDCl3:
dH ¼ 7.26 ppm; dC ¼ 77.16 ppm or CD2Cl2: dH ¼ 5.32 ppm;
dC ¼ 53.86 ppm). High-resolution mass spectra were recorded with
IonSpec 4.7 Tesla FTMS or APEXIII 7.0 Tesla FTMS. Optical rotations
were measured on an Anton Paar MCP5500 polarimeter.
General procedure for the NfF mediated dehydrative glyco-
sylation. A 25 mL glass Schlenk flask fitted with a resealable Teflon
valve was equipped with a magnetic stir bar and charged with
glycosyl donor (0.185 mmol, 1.0 eq), alcoholic acceptor
(0.278 mmol, 1.5 eq), Cs2CO3 (0.370 mmol, 2.0 eq), and 3 Å mo-
lecular sieves (300 mg), then, under argon protection, dry CH2Cl2
(2.0 mL) was added, followed by NfF (0.370 mmol, 2.0 eq), the flask
was sealed and stirred at room temperature (25e35 ꢀC) until TLC
indicated complete conversion. The mixture was filtered through a
pad of celite, washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in
vacuo. The crude product was purified by flash column chroma-
tography on silica gel (eluting with petroleum ether/ethyl acetate)
to give the desired glycosylation product.
3. Conclusion
In summary, we have disclosed a new dehydrative glycosylation
protocol mediated by nonafluorobutanesulfonyl fluoride (NfF). The
reaction proceeds via selective activation of the deprotonated
glycosyl hemiacetal with the mild nonaflating agent NfF to form
reactive glycosyl nonaflate intermediates, which subsequently
react with the co-existed alcoholic acceptor to deliver the glyco-
sylation product. The reagents employed in this protocol are readily
available and the protocol is operatically simple. A series of armed
pyranosyl and furanosyl donors are shown to be suitable donors,
and primary, secondary and tertiary alcoholic acceptors are suitable
acceptors. In contrast to many other glycosylation protocols that
proceed under acidic or neutral conditions, the present reaction
proceed under mild basic conditions. Moreover, the present pro-
tocol also provides a convenient approach to the self-condensation
of glycosyl hemiacetals to provide symmetrical 1,10-disaccharides.
2-Methoxyethyl 2,3,4,6-tetra-O-benzyl-
side (3a). A reaction mixture of glycosyl donor 1a (0.185 mmol,
100 mg) and acceptor 2a (22 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry
a,b-D-glucopyrano-
4. Experimental section
m
CH2Cl2 was stirred for 6 h in the presence of Cs2CO3 (0.370 mmol,
121 mg, 2.0 eq), 3 Å molecular sieves (300 mg), and NfF
General. All reactions were performed using oven-dried glass-
ware under an atmosphere of argon. Commercial reagents were
used without further purification unless specialized. Crushed 3 Å
molecular sieves were activated through flame-drying under high
vacuum immediately prior to use. Extra dry dichloromethane
(0.370 mmol, 68
petroleum ether/ethyl acetate ¼ 4/1. Yield of 3a: 95 mg, 87%,
¼ 1.7/1. The spectral data of 3a was identical with the literature
data [27].
mL, 2.0 eq) under the standard conditions. Eluent:
a/
b
(water
ꢁ
30 ppm) and extra dry 1,2-dichloroethane
3

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
Scheme 2. Dehydrative glycosylation of alcohols mediated by NfF.
Scheme 3. Dehydrative glycosylation of donor 1b and glycoside acceptor 4 mediated by NfF.
Cyclohexyl
(3b). A reaction mixture of glycosyl donor 1a (0.185 mmol, 100 mg)
and acceptor 2b (29 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry CH2Cl2
was stirred for 18 h in the presence of Cs2CO3 (0.370 mmol, 121 mg,
2.0 eq), 3 Å molecular sieves (300 mg), and NfF (0.370 mmol, 68 L,
2.0 eq) under the standard conditions. Eluent: petroleum ether/
ethyl acetate ¼ 10/1. Yield of 3b: 108 mg, 94%, ¼ 1.7/1. The
spectral data of 3b was identical with the literature data [28].
2-Methoxyethyl 6-O-acetyl-2,3,4-tri-O-benzyl- -gluco-
pyranoside (3c). reaction mixture of glycosyl donor 1b
(0.18 mmol, 88 mg) and acceptor 2a (22 L, 0.278 mmol, 1.5 eq) in
2,3,4,6-tetra-O-benzyl-
a
,
b
-
D
-glucopyranoside
NfF (0.370 mmol, 68 mL, 2.0 eq) under the standard conditions.
Eluent: petroleum ether/ethyl acetate ¼ 3/1. Yield of 3c: 86 mg,
25
m
88%,
a
/
b
¼ 4.5/1. 3c: colorless syrup; [
a
]
¼ 44.5 (c 1.6, CH2Cl2); 1H
D
NMR (400 MHz, CDCl3)
d
7.42e7.21 (m, 16H), 5.07e4.93 (m, 1.17H),
m
4.93e4.71 (m, 3.7H), 4.68 (d, J ¼ 12.2 Hz, 0.92H), 4.56 (d, J ¼ 10.9 Hz,
1.09H), 4.45 (d, J ¼ 7.8 Hz, 0.26H), 4.38e4.16 (m, 2.7H), 4.04 (t,
J ¼ 9.3 Hz, 1.0H), 3.92 (d, J ¼ 10.2 Hz, 0.8H), 3.80e3.44 (m, 6.73H),
3.37 (s, 3.58H), 2.08e1.96 (m, 3.72H); 13C NMR (126 MHz, CDCl3)
a/b
a
,b
-D
d 170.79, 170.75, 138.76, 138.52, 138.23, 138.19, 137.93, 137.81,
A
137.58, 128.57, 128.52, 128.50, 128.47, 128.45, 128.40, 128.30, 128.21,
128.19, 128.16, 128.12, 128.08, 128.02, 128.00, 127.96, 127.94, 127.91,
127.87, 127.85, 127.73, 127.70, 103.95, 97.09, 84.65, 82.11, 81.97,
80.00, 77.33, 75.79, 75.08, 74.78, 73.04, 72.86, 71.77, 71.69, 70.19,
m
2.0 mL dry CH2Cl2 was stirred for 18 h in the presence of Cs2CO3
(0.370 mmol, 121 mg, 2.0 eq), 3 Å molecular sieves (300 mg) and
4

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
Scheme 4. Formation of 1,10-disaccharides via self-condensation mediated by NfF.
69.23, 68.64, 67.07, 66.94, 63.20, 63.12, 59.03, 58.99, 58.97, 20.89;
HRMS (ESI) calcd for C32H38NaO8 [MþNa]þ 573.2464, found
573.2459.
75.07, 74.95, 74.92, 74.90, 74.76, 72.85, 72.50, 68.21, 68.10, 63.55,
63.35, 62.74, 53.47, 45.34, 42.71, 42.43, 36.26, 36.10, 30.72, 30.66,
20.84; HRMS (ESI) calcd for C39H46NaO7 [MþNa]þ 649.3141, found
649.3136.
n-Pent-4-enyl 6-O-acetyl-2,3,4-tri-O-benzyl-
anoside (3d). A reaction mixture of glycosyl donor 1b (0.185 mmol,
91 mg) and acceptor 2d (29 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry
CH2Cl2 was stirred for 18 h in the presence of Cs2CO3 (0.370 mmol,
121 mg, 2.0 eq), molecular sieves (300 mg) and NfF
(0.370 mmol, 68 L, 2.0 eq) under the standard conditions. Eluent:
petroleum ether/ethyl acetate ¼ 6/1. Yield of 3d: 95 mg, 91%,
¼ 4.5/1. The spectral data of 3d was identical with the literature
data [29].
Cyclohexyl 6-O-acetyl-2,3,4-tri-O-benzyl-
side (3e). A reaction mixture of glycosyl donor 1b (0.185 mmol,
91 mg) and acceptor 2b (29 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry
CH2Cl2 was stirred for 18 h in the presence of Cs2CO3 (0.370 mmol,
121 mg, 2.0 eq), molecular sieves (300 mg) and NfF
(0.370 mmol, 68 L, 2.0 eq) under the standard conditions. Eluent:
petroleum ether/ethyl acetate ¼ 6/1. Yield of 3e: 93 mg, 88%,
¼ 5.5/1. The spectral data of 3e was identical with the literature
data [30].
1-Adamantanyl
pyranoside (3f).
a,b-D-glucopyr-
2-Methoxyethyl
side (3g). A reaction mixture of glycosyl donor 1c (0.185 mmol,
81 mg) and acceptor 2a (22 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry
CH2Cl2 was stirred for 24 h in the presence of Cs2CO3 (0.370 mmol,
121 mg, 2.0 eq), molecular sieves (300 mg) and NfF
(0.370 mmol, 68 L, 2.0 eq) under the standard conditions. Eluent:
2,3,4-tri-O-benzyl-a,b-L-rhamanopyrano-
m
m
3
Å
m
3 Å
a
/
m
b
petroleum ether/ethyl acetate ¼ 5/1. Yield of 3g: 85 mg, 93%,
a/
25
b
¼ 2.7/1. 3g: yellow syrup; [
a
]
¼ 18.8 (c 3.6, CH2Cl2); 1H NMR
D
a
,b-
D
-glucopyrano-
(500 MHz, CDCl3) d 7.52e7.43 (m, 1.2H), 7.43e7.20 (m, 19.2H),
5.03e4.97 (m, 0.62H), 4.95 (d, J ¼ 10.6 Hz, 1.2H), 4.89 (d, J ¼ 12.5 Hz,
0.54H), 4.84e4.81 (m, 0.83H), 4.81e4.71(m, 2.07), 4.68e4.65 (m,
0.76H), 4.65e4.61 (m, 2.33H), 4.51 (d, J ¼ 11.9 Hz, 0.51H), 4.44 (d,
J ¼ 17.5 Hz, 0.85H), 4.32e4.26 (m, 0.4H), 4.07e4.01 (m, 0.46H), 3.96
(d, J ¼ 3.0 Hz, 0.45H), 3.91 (d, J ¼ 3.2 Hz, 0.47H), 3.90e3.86 (m,
1.32H), 3.78e3.67 (m, 1.89H), 3.68e3.52 (m, 4.1H), 3.52e3.48 (m,
1.54H), 3.46 (dd, J ¼ 9.4, 3.0 Hz, 0.52H), 3.41 (s, 1.1H), 3.35 (s, 2.38H),
1.38 (d, J ¼ 6.1 Hz, 1.29H), 1.34 (d, J ¼ 6.1 Hz, 3.1H); 13C NMR
m
3
Å
m
a
/
b
6-O-acetyl-2,3,4-tri-O-benzyl-
reaction mixture of glycosyl donor 1b
a
,b
-D
-gluco-
(101 MHz, CDCl3) d 138.85, 138.70, 138.63, 138.57, 138.44, 138.25,
A
128.52, 128.43, 128.39, 128.16, 128.12, 128.06, 127.94, 127.69, 127.64,
127.59, 127.53, 127.45, 101.57, 98.09, 82.08, 80.57, 80.22, 80.18,
75.50, 74.86, 74.00, 73.90, 72.85, 72.19, 71.97, 71.60, 71.35, 70.19,
68.69, 68.06, 66.96, 66.35, 59.11, 18.07; HRMS (ESI) calcd for
(0.183 mmol, 90 mg) and acceptor 2c (0.278 mmol, 42 mg, 1.5 eq) in
2.0 mL dry CH2Cl2 was stirred for 18 h in the presence of Cs2CO3
(0.370 mmol, 121 mg, 2.0 eq), 3 Å molecular sieves (300 mg) and
NfF (0.370 mmol, 68
mL, 2.0 eq) under the standard conditions.
C
30H36NaO6 [MþNa]þ 515.2410, found 515.2404.
Eluent: petroleum ether/ethyl acetate ¼ 6/1. Yield of 3f: 113 mg,
2-Methoxyethyl 2,3:5,6-di-O-isopropyliden-a,b-D-mannofur-
25
99%,
(400 MHz, CDCl3)
a
/
b
¼ 11/1. 3f: white solid; [
a]
¼ 50.5 (c 3.6, CH2Cl2); 1H NMR
anoside (3h). A reaction mixture of glycosyl donor 1d (0.185 mmol,
48 mg) and acceptor 2a (22 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry
CH2Cl2 was stirred for 23 h in the presence of Cs2CO3 (0.370 mmol,
121 mg, 2.0 eq), molecular sieves (300 mg) and NfF
(0.370 mmol, 68 L, 2.0 eq) under the standard conditions. Eluent:
D
d
7.53e7.00 (m, 16.4H), 5.34 (d, J ¼ 6.7 Hz, 0.09H),
m
5.34e5.12 (m, 1.53H), 5.01 (d, J ¼ 10.7 Hz, 1.0H), 4.95e4.75 (m,
2.4H), 4.68 (s, 2.0H), 4.55 (d, J ¼ 10.7 Hz, 1.12H), 4.32 (dd, J ¼ 12.2,
4.9 Hz, 0.95H), 4.19 (d, J ¼ 11.7 Hz, 1.15H), 4.14e3.99 (m, 1.78H),
3.81e3.31 (m, 2.48H), 2.26e2.06 (m, 5.6H), 2.00 (s, 3.4H), 1.92e1.76
(m, 6.3H), 1.75e1.52 (m, 12.3H); 13C NMR (126 MHz, CDCl3)
3
Å
m
petroleum ether/ethyl acetate ¼ 3/1. Yield of 3h: 59 mg, 88%,
a/
25
b
¼ 7.7/1. 3h: colorless syrup; [
a]
¼ 44.5 (c 1.3, CH2Cl2); 1H NMR
D
d
170.79, 170.75, 138.85, 138.17, 137.96, 128.53, 128.50, 128.47,
(500 MHz, CDCl3) d 5.19 (s, 0.13H), 4.99 (s, 1.00H), 4.75 (s, 1.13H),
128.43, 128.41, 128.38, 128.23, 128.20, 128.16, 128.14, 128.12, 128.09,
127.93, 127.90, 127.87, 127.84, 127.63, 127.59, 96.27, 89.72, 85.07,
82.16, 81.99, 80.06, 77.84, 77.81, 76.33, 75.72, 75.59, 75.46, 75.32,
4.68e4.57 (m, 0.98), 4.53 (d, J ¼ 5.8 Hz, 1H), 4.41e4.31 (m, 1.02H),
4.25 (s, 0.3H), 4.17e3.87 (m, 3.08H), 3.79e3.66 (m, 1.06H),
3.63e3.44 (m, 2.92H), 3.34 (s, 2.84H), 1.50e1.40 (m, 5.64H),
5

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
1.38e1.31 (m, 2.82H), 1.31e1.24 (m, 2.78H); 13C NMR (126 MHz,
81.39 (d, J ¼ 22.4 Hz), 76.53, 75.48, 75.12, 74.46 (d, J ¼ 2.1 Hz), 73.16
(d, J ¼ 5.1 Hz), 62.90, 20.95; Elemental analysis calcd (%) for
CDCl3)
d 112.60, 109.26, 106.54, 101.61, 85.06, 81.02, 80.33, 79.55,
73.22, 73.06, 71.64, 70.21, 66.95, 66.41, 59.05, 26.95, 25.93, 25.25,
24.56; HRMS (ESI) calcd for C15H26NaO7 [MþNa]þ 341.1576, found
341.1571.
C29H31FO6: C 70.43, H 6.32; found: C 70.24, H 6.38.
Component
benzyl- - glucopyranosyl-(1 / 6)-1,2:3,4-O-diisopropylidene-
-galactopyranose 5 (81 mg,
C was identified to be 6-O-acetyl-2,3,4-tri-O-
a,b-D
Cyclohexyl 2,3,4-tri-O-benzyl-
reaction mixture of glycosyl donor 1e (0.185 mmol, 78 mg) and
acceptor 2b (29 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry CH2Cl2 was
stirred for 18 h in the presence of Cs2CO3 (0.370 mmol, 121 mg, 2.0
eq), 3 Å molecular sieves (300 mg) and NfF (0.370 mmol, 68 L, 2.0
eq) under the standard conditions. Eluent: petroleum ether/ethyl
a
,b
-D-arabinofuranoside (3i). A
a
-
D
a
/
b
¼ 3.7/1, 58%) as a colorless syrup.
The spectral data of 5 was identical with the literature data [31].
Component D was identified to be the unreacted donor 1b
(26 mg, 28%).
m
m
Self-condensation of donor 1a mediated by NfF. A 25 mL glass
Schlenk flask fitted with a resealable Teflon valve was equipped
with a magnetic stir bar and charged with glycosyl donor 1a
(0.189 mmol,100 mg), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq), and 3 Å
molecular sieves (300 mg), then, under argon protection, dry
acetate ¼ 15/1. Yield of 3i: 79 mg, 85%,
a
/
b
¼ 1/2.5. 3i: colorless
25
syrup; [
a
]
¼ ꢃ59.3 (c 0.15, CH2Cl2); 1H NMR (500 MHz, CDCl3)
D
d
7.49e7.27 (m, 9.25H), 5.28 (s, 0.40H), 5.16 (d, J ¼ 4.3 Hz, 1.0H), 4.74
(d, J ¼ 11.9 Hz, 1.08H), 4.71e4.66 (m, 1.71H), 4.63 (d, J ¼ 12.0 Hz,
1.17H), 4.60 (s, 2.88H), 4.58e4.51 (m, 1.58H), 4.28 (dt, J ¼ 7.8, 3.8 Hz,
0.44H), 4.20e4.13 (m, 1.96H), 4.12e4.07 (m, 1.28H), 4.05e3.97 (m,
0.54H), 3.74e3.57 (m, 4.19), 2.00e1.85 (m, 2.92H), 1.84e1.72 (m,
3.19H), 1.63e1.55 (m, 1.57H), 1.50e1.13 (m, 7.94H); 13C NMR
CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68 mL, 2.0
eq). The flask was sealed and the mixture stirred at room temper-
ature for 18 h. The mixture was filtered through a pad of celite,
washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo. The
crude product was purified by flash column chromatography on
silica gel (eluting with petroleum ether/ethyl acetate 10/1 to 6/1) to
give two components (A and B), successively.
Component A was identified to be 2,3,4,6-tetra-O-benzyl-a,b-D-
glucopyranosyl fluoride 9 (15 mg, 15%) as a colorless syrup. The
spectral data of 9 was identical with the literature data [19c].
(126 MHz, cdcl3)
d 138.41, 138.26, 138.17, 138.12, 137.89, 137.78,
128.60, 128.49, 128.47, 128.45, 128.43, 128.38, 128.36, 128.16, 128.12,
127.98, 127.94, 127.88, 127.87, 127.82, 127.80, 127.77, 127.73, 127.69,
127.66, 127.60, 104.14, 98.81, 88.87, 84.07, 83.77, 83.64, 80.11, 80.04,
75.95, 74.96, 73.41, 73.38, 73.05, 72.34, 72.22, 72.13, 71.99, 69.84,
33.79, 33.73, 31.83, 31.72, 25.79, 25.68, 24.52, 24.33, 24.28, 24.14;
Component B was identified to be 2,3,4,6-tetra-O-benzyl-
glucopyranosyl-(141)-2,3,4,6-tetra-O-benzyl- -glucopyranoside 8
(84 mg, aa ab
D-
HRMS (ESI) calcd for
525.2611.
C
32H38NaO5 [MþNa]þ 525.2617, found
D
/
/
bb ¼ 24/15/1, 85%) as a colorless syrup. The spectral
The reaction of donor 1b and acceptor 4 mediated by NfF
(Scheme 3). A 25 mL glass Schlenk flask fitted with a resealable
Teflon valve was equipped with a magnetic stir bar and charged
with glycosyl donor 1b (0.189 mmol, 93 mg), glycosyl acceptor 4
(0.28 mmol, 74 mg, 1.5 eq), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq),
and 3 Å molecular sieves (300 mg), then, under argon protection,
data of 8 was identical with the literature data [25a].
Self-condensation of donor 1c mediated by NfF. A 25 mL glass
Schlenk flask fitted with a resealable Teflon valve was equipped
with a magnetic stir bar and charged with glycosyl donor 1c
(0.19 mmol, 82 mg), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq), and 3 Å
molecular sieves (300 mg), then, under argon protection, dry
dry CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68
mL,
CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68 mL, 2.0
2.0 eq). The flask was sealed and the mixture stirred at room
temperature for 18 h. The mixture was filtered through a pad of
celite, washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo.
The crude product was purified by flash column chromatography
on silica gel (eluting with petroleum ether/ethyl acetate 15/1 to 4/1
to 3/1) to give four components (A-D), successively.
eq). The flask was sealed and the mixture stirred at room temper-
ature for 24 h. The mixture was filtered through a pad of celite,
washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo. The
crude product was purified by flash column chromatography on
silica gel (eluting with petroleum ether/ethyl acetate 6/1 to 5/1) to
give two components (A and B), successively.
Component A was identified to be nonaflated acceptor 1,2:3,4-
Component A was identified to be 2,3,4-tri-O-benzyl-
a-L-
di-O-isopropylidene-6-O-nonafluorobutanesulfonyl-
actopyranose 6 (87 mg, 56%) as a colorless syrup: 1H NMR
(500 MHz, CDCl3)
a
-
D
-gal-
rhamnopyranosyl-(141)-2,3,4-tri-O-benzyl- -rhamnopyrano-
side 10aa (57 mg, 70%) as a colorless syrup. The spectral data of
10aa was identical with the literature data [25b].
a-L
d
5.53 (d, J ¼ 4.9 Hz, 1H), 4.71e4.57 (m, 3H), 4.35
(dd, J ¼ 5.1, 2.6 Hz, 1H), 4.27e4.21 (m, 1H), 4.11 (t, J ¼ 6.2 Hz, 1H),
Component
rhamnopyranosyl-(141)-2,3,4-tri-O-benzyl-
side 10ab (23 mg, 28%) as a colorless syrup. [
CH2Cl2); 1H NMR (500 MHz, CDCl3)
7.39e7.21 (m, 29H), 4.96 (d,
B
was identified to be 2,3,4-tri-O-benzyl-
a-L-
1.51 (s, 3H), 1.44 (s, 3H), 1.36e1.29 (m, 6H); 13C NMR (126 MHz,
b-L
a
-rhamnopyrano-
25
CDCl3)
d
110.28, 109.27, 96.30, 75.29, 70.84, 70.57, 70.43, 66.32,
]
¼ 12.3 (c 0.51,
D
25.98, 25.96, 24.96, 24.46; 19F NMR (471 MHz, CDCl3)
d
ꢃ80.81 (t,
d
J ¼ 9.7 Hz), ꢃ110.73 (t, J ¼ 14.4 Hz), ꢃ121.32 to ꢃ121.52 (m), ꢃ125.94
to ꢃ126.06 (m); HRMS (ESI) calcd for C16H19F9NaO8S [MþNa]þ
565.0555, found 565.0549.
J ¼ 11.2 Hz, 1H), 4.93 (d, J ¼ 10.8 Hz, 1H), 4.89 (d, J ¼ 1.8 Hz, 1H), 4.80
(d, J ¼ 12.5 Hz, 1H), 4.77 (d, J ¼ 12.5 Hz, 1H), 4.72 (d, J ¼ 12.5 Hz, 1H),
4.70e4.61 (m, 4H), 4.58 (d, J ¼ 11.9 Hz, 1H), 4.57e4.49 (m, 2H), 4.41
(s, 1H), 4.10e4.04 (m, 1H), 3.92 (dd, J ¼ 9.4, 3.1 Hz, 1H), 3.78 (d,
J ¼ 2.9 Hz, 1H), 3.69 (dd, J ¼ 3.1, 1.8 Hz, 1H), 3.63 (t, J ¼ 9.5 Hz, 1H),
3.59 (t, J ¼ 9.3 Hz, 1H), 3.42 (dd, J ¼ 9.4, 2.9 Hz, 1H), 3.30 (dd, J ¼ 9.2,
6.2 Hz, 1H), 1.33 (d, J ¼ 6.1 Hz, 3H), 1.29 (d, J ¼ 6.5 Hz, 3H); 13C NMR
Component
benzyl- - glucopyranosyl fluoride 7 (12 mg,
pale yellow solid: 1H NMR (500 MHz, CDCl3)
7.40e7.23 (m, 12.9H),
B
was identified to be 6-O-acetyl-2,3,4-tri-O-
a
,b
-D
a/b
¼ 5/1, 12%) as a
d
5.52 (dd, J ¼ 53.0, 2.7 Hz, 0.21H), 5.28 (dd, J ¼ 52.7, 6.5 Hz, 1.0H),
4.99 (d, J ¼ 10.8 Hz, 0.22H), 4.91 (d, J ¼ 11.0 Hz, 0.81H), 4.89e4.83
(m, 1.66H), 4.78 (d, J ¼ 11.0 Hz, 0.84H), 4.70 (d, J ¼ 11.2 Hz, 0.95H),
4.58 (d, J ¼ 10.9 Hz, 0.89H), 4.38 (dd, J ¼ 12.0, 2.2 Hz, 0.87H), 4.28
(dd, J ¼ 10.2, 3.2 Hz, 0.39H), 4.22 (dd, J ¼ 12.1, 4.8 Hz, 0.91H), 4.01 (d,
J ¼ 9.2 Hz, 0.36H), 3.77e3.50 (m, 3.26H), 2.05 (s, 2.02H), 2.03 (s,
(126 MHz, cdcl3)
d 139.07, 138.76, 138.67, 138.57, 138.43, 138.35,
128.51, 128.49, 128.48, 128.43, 128.40, 128.27, 128.23, 128.03, 127.87,
127.84, 127.81, 127.76, 127.71, 127.66, 127.53, 100.31, 98.92, 82.52,
80.68, 80.07, 79.88, 75.55, 75.46, 75.12, 74.21, 74.01, 73.02, 72.83,
72.33, 71.94, 69.19, 60.53, 18.11, 17.78; HRMS (ESI) calcd for
0.43H); 13C NMR (126 MHz, CDCl3)
d
170.80, 138.20, 137.69, 137.62,
C
54H58NaO9 [MþNa]þ 873.3979, found 873.3973.
128.75, 128.68, 128.64, 128.61, 128.30, 128.25, 128.22, 128.19, 128.16,
Self-condensation of donor 11 mediated by NfF. A 25 mL glass
128.13, 128.01, 127.98, 109.66 (d, J ¼ 216.9 Hz), 83.56 (d, J ¼ 10.5 Hz),
Schlenk flask fitted with a resealable Teflon valve was equipped
6

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
with a magnetic stir bar and charged with glycosyl donor 11
(0.185 mmol, 80 mg), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq), and 3 Å
molecular sieves (300 mg), then, under argon protection, dry
References
[1] (a) L. Krasnova, C.H. Wong, J. Am. Chem. Soc. 141 (2019) 3735e3754;
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(c) M. Panza, S.G. Pistorio, K.J. Stine, A.V. Demchenko, Chem. Rev. 118 (2018)
8105e8150;
CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68 mL, 2.0
eq). The flask was sealed and the mixture stirred at room temper-
ature for 24 h. The mixture was filtered through a pad of celite,
washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo. The
crude product was purified by flash column chromatography on
silica gel (eluting with petroleum ether/ethyl acetate 6/1 to 4/1) to
give three components (A-C), successively.
(d) B. Yu, Acc. Chem. Res. 51 (2018) 507e516;
(e) Y. Yang, X. Zhang, B. Yu, Nat. Prod. Rep. 32 (2015) 1331e1355.
[2] For some recent reports on dehydrative glycosylation reactions, see: (a) L. Cai,
J. Zeng, T. Li, Y. Xiao, X. Ma, X. Xiao, Q. Zhang, L. Meng, Q. Wan, Chin. J. Chem.
38 (2020) 43e49;
(b) M.-Y. Hsu, S. Lam, C.-H. Wu, M.-H. Lin, S.-C. Lin, C.-C. Wang, Molecules 25
(2020) 1103;
Component A was identified to be 4,6-di-O-benzyl-2,3-dideoxy-
(c) J.R. Romeo, L. McDermott, C.S. Bennett, Org. Lett. 22 (2020) 3649e3654;
(d) W. Xu, W. Liu, X. Li, P. Xu, B. Yu, Acta Chim. Sinica 78 (2020) 767e777;
(e) J.C. Mizia, C.S. Bennett, Org. Lett. 21 (2019) 5922e5927;
(f) T. Ghosh, A. Mukherji, P.K. Kancharla, Eur. J. Org Chem. (2019) 7488e7498;
(g) S. Manhas, M.S. Taylor, Carbohydr. Res. 470 (2018) 42e49;
(h) T. Ghosh, A. Mukherji, H.K. Srivastava, P.K. Kancharla, Org. Biomol. Chem.
16 (2018) 2870e2875.
a
-D-threo-hex-2-enopyranosyl-(141)-3,4,6-tri-O-benzyl-2-
deoxy-
syrup: [
a
a
-
D
-arabinohexopyranoside 13aa (5.4 mg, 8%) as a colorless
25
]
¼ 79.5 (c 0.24, CH2Cl2); 1H NMR (600 MHz, CD2Cl2)
D
d
7.36e7.21 (m, 24H), 6.11 (dt, J ¼ 10.2, 1.4 Hz, 1H), 5.74 (ddd,
J ¼ 10.3, 2.9, 1.9 Hz, 1H), 5.35 (dd, J ¼ 3.7, 1.4 Hz, 1H), 5.27e5.25 (m,
1H), 4.89 (d, J ¼ 10.9 Hz, 1H), 4.64 (d, J ¼ 11.5 Hz, 2H), 4.62e4.54 (m,
4H), 4.54e4.44 (m, 3H), 4.10 (dq, J ¼ 9.4, 1.7 Hz, 1H), 3.95 (ddd,
J ¼ 11.4, 8.8, 5.0 Hz, 1H), 3.90 (ddd, J ¼ 9.4, 4.2, 2.7 Hz, 1H),
3.79e3.72 (m, 2H), 3.73e3.65 (m, 3H), 3.56 (t, J ¼ 9.1 Hz, 1H), 2.28
[3] For reviews on dehydrative glycosylation reactions, see: (a) S. O’Neill,
J. Rodriguez, M.A. Walczak, Chem. Asian J. 13 (2018) 2978e2990;
(b) A.V. Demchenko, Handbook of Chemical Glycosylation: Advances in
Stereoselectivity and Therapeutic Relevance, Wiley, Chichester, 2008;
(c) D.Y. Gin, J. Carbohydr. Chem. 21 (2002) 645e665.
[4] (a) J. Leroux, A.S. Perlin, Carbohydr. Res. 67 (1978) 163e178;
(b) A.A. Pavia, J.M. Rocheville, S.N. Ung, Carbohydr. Res. 79 (1980) 79e89;
(c) J.M. Lacombe, A.A. Pavia, J.M. Rocheville, Can. J. Chem. 59 (1981) 473e481.
[5] For recent and original works on glycosyl triflates intermediates, see: (a)
(ddd, J ¼ 13.0, 5.1, 1.5 Hz,1H),1.71 (ddd, J ¼ 13.1, 11.4, 3.8 Hz,1H); 13
C
NMR (151 MHz, CD2Cl2)
d 139.39, 139.26, 138.94, 138.91, 138.66,
130.97, 128.72, 128.69, 128.64, 128.60, 128.29, 128.27, 128.15, 128.11,
128.04, 127.98, 127.90, 127.86, 127.79, 126.83, 93.81, 89.91, 78.67,
77.77, 75.22, 73.70, 73.62, 71.91, 71.88, 71.57, 70.78, 70.25, 69.73,
69.64, 35.51; HRMS (ESI) calcd for C47H50NaO8 [MþNa]þ 765.3403,
found 765.3398.
ꢀ
A.G. Santana, L. Montalvillo-Jimenez, L. Díaz-Casado, F. Corzana, P. Merino,
~
ꢀ
ꢀ
ꢀ
ꢀ
F.J. Canada, G. Jimenez-Oses, J. Jimenez-Barbero, A.M. Gomez, J.L. Asensio,
J. Am. Chem. Soc. 142 (2020) 12501e12514;
(b) D. Crich, S. Sun, J. Am. Chem. Soc. 119 (1997) 11217e11223.
ꢀ
[6] For reviews on glycosyl triflates, see (a) L. Bohe, D. Crich, in: C.S. Bennett (Ed.),
Glycosylation with Glycosyl Sulfonates in Selective Glycosylations: Synthetic
Methods and Catalysts, Wiley, Hoboken, NJ, 2017, pp. 115e133;
(b) P.O. Adero, H. Amarasekara, P. Wen, L. Bohe, D. Crich, Chem. Rev. 118
(2018) 8242e8284.
Component B was identified to be 3,4,6-tri-O-benzyl-2-deoxy-
ꢀ
a
-D-arabino- hexopyranosyl-(141)-3,4,6-tri-O-benzyl-2-deoxy-
a-
D
-arabinohexopyranoside 12aa (31 mg, 39%) as a colorless syrup.
[7] S.K. Mulani, W.-C. Hung, A.B. Ingle, K.-S. Shiau, K.-K.T. Mong, Org. Biomol.
Chem. 12 (2014) 1184e1197.
The spectral data of 12aa was identical with the literature data [32].
Component C was identified to be 3,4,6-tri-O-benzyl-2-deoxy-
[8] S. Suda, T. Mukaiyama, Chem. Lett. (1991) 431e434.
[9] T. Mukaiyama, K. Matsubara, S. Suda, Chem. Lett. (1991) 981e984.
[10] (a) B.A. Garcia, J.L. Poole, D.Y. Gin, J. Am. Chem. Soc. 119 (1997) 7597e7598;
(b) B.A. Garcia, D.Y. Gin, J. Am. Chem. Soc. 122 (2000) 4269e4279.
[11] H.M. Nguyen, Y. Chen, S.G. Duron, D.Y. Gin, J. Am. Chem. Soc. 123 (2001)
8766e8772.
a
-D-arabino- hexopyranosyl-(141)-3,4,6-tri-O-benzyl-2-deoxy-b-
D
-arabinohexopyranoside 12ab (32 mg, 40%) as a colorless syrup:
25
[
a
]
¼ 45.9 (c 0.73, CH2Cl2); 1H NMR (500 MHz, CDCl3)
d 7.41e7.17
D
(m, 30H), 5.23 (d, J ¼ 3.4 Hz, 1H), 4.92 (d, J ¼ 6.0 Hz, 1H), 4.90 (d,
J ¼ 5.9 Hz, 1H), 4.73e4.46 (m, 10H), 4.36 (d, J ¼ 12.1 Hz, 1H), 4.12
(dd, J ¼ 9.9, 2.6 Hz, 1H), 4.08e4.00 (m, 1H), 3.76e3.62 (m, 5H),
3.60e3.49 (m, 2H), 3.42 (dd, J ¼ 7.7, 4.3 Hz, 1H), 2.36e2.25 (m, 2H),
[12] K.S. Kim, D.B. Fulse, J.Y. Baek, B.-Y. Lee, H.B. Jeon, J. Am. Chem. Soc. 130 (2008)
8537e8547.
[13] (a) T. Mukaiyama, S. Suda, Chem. Lett. 19 (1990) 1143e1146;
(b) M. Mossotti, L. Panza, J. Org. Chem. 76 (2011) 9122e9126.
[14] R. Dyapa, L.T. Dockery, M.A. Walczak, Org. Biomol. Chem. 15 (2017) 51e55.
[15] G. Chen, Q. Yin, J. Yin, X. Gu, X. Liu, Q. You, Y.L. Chen, B. Xiong, J. Shen, Org.
Biomol. Chem. 12 (2014) 9781e9785.
[16] For glycosylation reactions that proceeds via non-perfluorated glycosyl sul-
fonates intermediates, see: (a) S. Koto, T. Sato, N. Morishima, S. Zen, Bull.
Chem. Soc. Jpn. 53 (1980) 1761e1762;
1.85e1.62 (m, 2H); 13C NMR (126 MHz, CDCl3)
d 139.01, 138.91,
138.58, 138.54, 138.44, 138.38, 128.55, 128.47, 128.46, 128.39,
128.35, 128.13, 127.97, 127.82, 127.81, 127.77, 127.74, 127.64, 127.62,
127.60, 127.51, 99.19, 98.08, 79.61, 78.26, 78.00, 77.59, 75.41, 75.07,
74.87, 73.45, 72.10, 71.62, 71.58, 69.38, 68.60, 37.06, 35.67; HRMS
(ESI) calcd for C54H58NaO9 [MþNa]þ 873.3979, found 873.3973.
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€
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Declaration of competing interest
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The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
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Acknowledgements
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Financial support from the National Natural Science Foundation
of China (21871290, 22031011, and 21621002), Key Research Pro-
gram of Frontier Sciences of CAS (ZDBS-LY-SLH030), and Strategic
Priority Research Program of CAS (XDB20020000) are
acknowledged.
[24] According to a reviewer comment, we attempted pre-activation strategy,
thus, a mixture of glucosyl donor 1a (1.0 eq), NfF (2.0 eq), Cs2CO3 (2 eq), and
3 Å MS (300% w/w) in dry CH2Cl2 was stirred at ꢃ40 ꢀC for 2 h, then glycoside
acceptor 4 (1.5 eq) was added, and the mixture was stirred at ꢃ40 ꢀC for 12 h.
TLC and NMR analysis indicated that no reaction occurred
Appendix A. Supplementary data
Supplementary data related to this article can be found at
https://doi.org/10.1016/j.tet.2020.131800.
7

Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
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