Triflic acid-mediated synthesis of thioglycosides

Article abstract of DOI:10.1039/c9ob01610d

An efficient synthesis of thioglycosides from per-acetates in the presence of triflic acid is described. The developed protocol features high reaction rates and product yields. Some reactive sugar series give high efficiency in the presence of sub-stoichiometric trifluoromethanesulfonic acid (TfOH) in contrast to other known protocols that require multiple equivalents of Lewis acids to reach high conversion rates.

Full text of DOI:10.1039/c9ob01610d

View Article Online
View Journal
Organic &
Biomolecular
Chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Excopy, Y.
Singh and A. V. Demchenko, Org. Biomol. Chem., 2019, DOI: 10.1039/C9OB01610D.
Volume 15
Number 47
21 December 2017
Pages 9945-10124
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Organic &
Biomolecular
Chemistry
Accepted Manuscripts are published online shortly after acceptance,
rsc.li/obc
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
ISSN 1477-0520
PAPER
I . J. Dmochowski et al.
Oligonucleotide modifi cations enhance probe stability for
shall the Royal Society of Chemistry be held responsible for any errors
single cell transcriptome in vivo analysis (TIVA)
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
rsc.li/obc

Page 1 of 4
Organic & Biomolecular Chemistry
View Article Online
DOI: 10.1039/C9OB01610D
Triflic Acid-Mediated Synthesis of Thioglycosides
Samira Escopy, Yashapal Singh, and Alexei V. Demchenko*
Department of Chemistry and Biochemistry, University of Missouri – St. Louis, One University Boulevard, St. Louis,
Missouri 63121, USA; e-mail: demchenkoa@umsl.edu
ABSTRACT: An efficient synthesis of thioglycosides from per-acetates in the presence of triflic acid is described. The
developed protocol features high reaction rates and product yields. Some reactive sugar series give high efficiency in the
presence of sub-stoichiometric TfOH in contrast to other known protocols that require multiple equivalents of Lewis acids
to reach high conversion rates.
Carbohydrates are the most abundant biomolecules that
play crucial roles in many biological processes and their
involvement in all diseases has been proven.1 However, the
stereoselective synthesis of complex carbohydrates is still
a challenge in glycosciences.2,3 The key aspect of the
oligosaccharide assembly is the attachment of various
monosaccharaide units via a glycosidic bond.4-7 The
linkage is constructed by a chemical glycosylation reaction
that involves a nucleophilic displacement of a leaving
group of the glycosyl donor with a hydroxyl moiety of the
glycosyl acceptor in the presence of an activator is
employed.8
temperature was allowed to gradually increase after 1 h.
Further increment in the amount of triflic acid to 80 mol
% produced thioglucoside 2 in an excellent yield of 94% in
1 h (entry 3). Since many other thioglycosylations demand
low temperature to maintain the stereoselectivity we
investigated the temperature effect on the outcome of the
TfOH-promoted reaction. When essentially the same
reaction in the presence of 0.8 equiv of TfOH was set at rt,
excellent yield of 97% albeit compromised stereoselectivity
(α/β = 1/5.0) were achieved (entry 4). This result confirms
that low reaction temperature is required for maintaining
complete
β-stereoselectivity
of
TfOH-catalyzed
thioglycosidation of 1.
Since their invention in 1909 by Fisher,9 thioglycosides
have become key building blocks both for modification of
monosaccharides and for construction of glycans.10-15
Numerous methods for the preparation of thioglycosides
have been established.16-27 The most commonly employed
pathway is Lewis acid-mediated thioglycosidation of per-
acetylated sugars in the presence of stoichiometric
amounts (2-5 equiv) of TMSOTf, BF •Et O, ZrCl , SnCl ,
Table 1. Optimization of the reaction conditions for
thioglycosidation of penta-acetate 1 with ethanethiol
OAc
O
OAc
O
AcO
AcO
AcO
AcO
EtSH (2 equiv), TfOH
CH2Cl2, MS 3Å
OAc
SEt
AcO
AcO
2
1
Entry T °C Catalyst (equiv)
Time
4 h
Yield of 2, Ratio α/β
26%, β only
70%, β only
94%, β only
97%, 1/5.0
3
2
4
4
etc.28-30 A variety of other approaches such as one-pot
acetylation-thioglycosidation of unprotected
sugars,17,26,27,31,32
including Bronsted-acid-mediated
1
2
3
4
5
6
7
TfOH (0.2)
TfOH (0.5)
TfOH (0.8)
TfOH (0.8)
TfOH (1.0)
TfOH (1.2)
BF3•OEt2 (0.8)
0rt
0rt
0
3 h
1 h
reactions are also known.33 Although many of these
conditions provide good stereoselectivity and yields,
excess of promoter requirement indicates the limitation of
this methodology. Herein we report that even a sub-
stoichiometric amount of triflic acid can promote
thioglycosidation of per-acetates of different sugar series.
rt
45 min
35 min
20 min
24 h
0
87%, β only
75%, β only
55%, β only
0
0rt
Further increase in the amount of triflic acid to 1.0 and 1.2
equiv reduced the reaction time to 35 and 20 min, but the
yields declined to 87 and 75%, respectively (entries 5 and
6). We hence concluded that the reaction in the presence
of 0.8 equiv TfOH (entry 3) offers the most advantageous
combination of the reaction efficiency and rate. For
comparison, when the same amount of boron trifluoride
diethyl etherate (BF3•Et2O) was used, thioglycoside 2 was
obtained in a modest yield of 55% after 24 h (entry 7). This
Our first attempts to standardize the reaction conditions
involved common glucose pentaacetate 1 that was set to
react with 2.0 equiv of ethanethiol in dichloromethane at
0 °C. The key results of this study are surveyed in Table 1.
Thus, when catalytic amount of triflic acid (0.2 equiv) was
applied at 0 °C, thioglucoside 234,35 was afforded in 26%
yield in 4 h (entry 1). Prolonged experiments showed that
the starting material did not consume even after 24 h, and
the product yield remained practically the same.
Increasing the triflic acid to 50 mol % produced
thioglycoside 2 in a respectable yield of 70% in 3 h (entry
2). These experiments were started at 0 °C, and the
result is consistent with
a
common method of
thioglycosylation that demands excess BF3•Et2O to drive
this reaction to completion.21,30

Organic & Biomolecular Chemistry
Having standardized the reaction conditions for the
Page 2 of 4
View Article Online
DOI: 10.1039/C9OB01610D
AcO
PhSH,
OAc
O
TfOH (0.8
equiv), 30
min
synthesis of ethylthio glucoside 2, we moved to expand the
scope of this reaction to other sugar series and other
aglycone types. The key results of this study are
summarized in Table 2. Thus, the reaction of galactose
pentaacetate 3 with ethanethiol in the presence of 0.8
equiv of TfOH afforded thiogalactoside 436,37 in 90% yield
in 30 min (entry 1). Expectedly, the reaction with much less
reactive mannose penta-acetate 5 was slow, and ethylthio
mannoside 626,37 was obtained in only 26% yield. To achieve
the preparative outcome of this reaction, the amount of
TfOH was increased to 2.0 equiv. In this case,
thiomannoside 6 was isolated in a respectable yield of 85%
(entry 2). Even under these fortified conditions, the
reaction remained fairly sluggish and required 8 h to
complete. Also 2-phthalimido glucose tetra-acetate 738
required similar reaction conditions (2.0 equiv of TfOH) to
produce the corresponding ethylthio glycoside 838,39 in 73%
yield (β-only) in 4 h. When the amount of TfOH was
increased to 2.5 equiv, this reaction produced
thioglucoside 8 in 96% in 45 min (entry 3). Per-acetylated
sialic acid 940 produced the corresponding ethylthio
sialoside 1041,42 in 70% yield (α/β = 1/1.0) in 45 min (entry
4). Our standard reaction conditions (0.8 equiv of TfOH)
were also employed for thioglycosidation of lactose octa-
acetate 1143-45 to produce thiolactoside 1246 in 70% yield in
6 h (entry 5).
AcO
SPh
7
8
9
3
5
9
AcO
14 (88%, β only)
AcO
AcO
AcO
OAc
O
PhSH,
TfOH (2.0
equiv), 9 h
SPh
15 (75%, α only)
AcO
SPh
OAc
PhSH,
TfOH (2.0
equiv), 45
min
AcO
AcHN
CO2Me
O
OAc
16 (66%, 1/2.0)
p-
OAc
thiocresol,
TfOH (1.0
equiv), 30
min
O
AcO
AcO
STol
10
11
12
1
3
5
AcO
17 (88%, β only)
p-
AcO
OAc
thiocresol,
TfOH (1.0
equiv), 30
min
O
AcO
STol
AcO
18 (87%, β only)
p-
AcO
AcO
AcO
OAc
O
thiocresol,
TfOH (1.0
equiv), 2.5
h
STol
19 (88%, α only)
p-
AcO
STol
CO2Me
OAc
thiocresol,
TfOH (2.0
equiv), 30
min
AcO
O
AcHN
13
14
9
OAc
20 (85%, 1/4.0)
AcO
p-
OAc
O
AcO
AcO
O
STol
thiocresol,
TfOH (1.0
equiv), 4 h
AcO
O
11
Table 2. TfOH-promoted thioglycosidation of
AcO
OAc
21 (80%, 1/10.0)
acetylated hexoses 1, 3, 5, 7, sialic acid 9, and lactose
11
We then investigated glycosylation of other common
thiols, thiophenol and p-thiocresol, to generate SPh and
RSH (2.0 equiv)
TfOH (see Table)
O
O
STol glycosides, respectively. Glucose per-acetate
1
MS 3Å, CH2Cl2
OAc
SR
smoothly reacted with thiophenol (2.0 equiv) under the
standard conditions in the presence of 0.8 equiv TfOH at 0
°C. As a result, the desired phenylthio glucoside 1334 was
obtained in 77% yield in 1.5 h (entry 6). Galactose per-
acetate 3 very readily reacted with thiophenol under these
conditions affording phenylthio galactoside 1418,37 in 88%
yield in 30 min (entry 7). Thioglycosidation of mannose
per-acetate 5 again required excess TfOH because the
reaction under the standard conditions yielded only 31% of
thiomannoside 15.18,47 In contrast, when this reaction was
repeated in the presence of 2.0 equiv TfOH, phenylthio
mannoside 15 was obtained in 75% yield (entry 8). As in
case of ethanethiol, the reaction was sluggish and required
9 h to complete. The introduction of the SPh anomeric
group to sialic acid also required 2.0 equiv of TfOH, but it
was rather swift (45 min). As a result, phenylthio sialoside
1648,49 was obtained in 66% yield as an anomeric mixture
(α/β = 1/2.0, entry 9).
glycosyl acetate
thioglycoside
Conditions
Entry
1
Substrate
Product (yield, α/β)
0rt
AcO
OAc
AcO
OAc
EtSH, TfOH
(0.8 equiv),
30 min
O
O
AcO
OAc
AcO
SEt
AcO
AcO
3
4 (90%, β only)
AcO
AcO
AcO
AcO
OAc
OAc
O
O
EtSH, TfOH
(2.0 equiv),
AcO
AcO
2
3
OAc
SEt
8 h
5
6 (85%, α only)
OAc
OAc
O
EtSH, TfOH
(2.5 equiv),
45 min
O
AcO
AcO
AcO
AcO
OAc
SEt
NPhth
NPhth
7
8 (96%, β only)
AcO
AcO
OAc
SEt
OAc
OAc
EtSH, TfOH
(2.0 equiv),
45 min
AcO
AcHN
AcO
AcHN
CO2Me
O
CO2Me
O
4
5
6
OAc
OAc
9
10 (70%, 1/1.0)
AcO
AcO
AcO
OAc
O
AcO
OAc
O
AcO
First thioglycosylations with p-thiocresol showed that the
standard conditions provide somewhat lower efficiency
than that seen for reaction with EtSH and PhSH. For
instance, the reaction of glucose per-acetate 1 with p-
thiocresol (2.0 equiv) in the presence of 0.8 equiv TfOH at
0 °C provided STol glucoside 1726,34,50in a modest yield of
70%. The utility of this reaction was enhanced by
increasing the amount of TfOH to stoichiometric (1.0
OAc
EtSH, TfOH
(0.8 equiv),
6 h
AcO
O
AcO
O
SEt
O
AcO
O
OAc
AcO
OAc
AcO
11
OAc
12 (70%, β only)
OAc
PhSH,
TfOH (0.8
equiv), 1.5
h
O
O
AcO
AcO
AcO
OAc
AcO
SPh
AcO
AcO
1
13 (77%, β only)

Page 3 of 4
Organic & Biomolecular Chemistry
View Article Online
DOI: 10.1039/C9OB01610D
equiv). We have also observed that these reactions can be
successfully performed at rt. When glucose penta-acetate 1
was reacted with p-thiocresol under these modified
conditions, thioglycoside 17 was obtained in 88% yield in
30 min (entry 10). Galactose per-acetate 3 also very readily
reacted with p-thiocresol affording tolylthio galactoside
1850,51 in 87% yield in 30 min (entry 11). Even
thioglycosidation of mannose per-acetate 5 was very
efficient under these conditions producing tolylthio
mannoside 1927,33 in 88% yield in 2.5 h (entry 12). The
introduction of the STol anomeric group to sialic acid 9
under these reaction conditions produced moderate
efficiency for the synthesis of tolylthio sialoside 2033 (69%,
α/β = 1/3.0), but it was rather swift (45 min). When this
coupling was performed in the presence of excess TfOH
(2.0 equiv) at rt, tolylthio sialoside 20 was obtained both in
a higher yield and higher stereoselectivity (85%, α/β =
1/4.0, entry 13). Also, lactose octa-acetate 11 reacted
smoothly under similar conditions (1.0 equiv of TfOH at rt)
producing tolylthio lactoside 2133 in 4 h in a good yield of
80% (α/β = 1/10.0, entry 14).
In conclusion, we developed a simple methodology for the
preparation of thioglycosides promoted by triflic acid.
Many reactions still required stoichiometric TfOH, typical
range from 0.8 equiv for SEt introduction to 3.5 equiv for
STaz imidate synthesis. Our initial attempts to lower the
amount of TfOH led to sluggish reactions (16-24 h or
longer) and modest yields due to the inability to fully
consume the starting material. The scope of this approach
was investigated and found to be consistently effective for
the synthesis of various thioglycosides in application to
different sugar series. Complete stereoselectivity, high
yields, and relatively fast reaction rates have been
achieved. We have also demonstrated the compatibility of
the developed protocol to multi-gram preparation of
thioglycosides (see the SI for details). We have also
explored a possibility of conducting this reaction in the
absence of molecular sieves. While most reactions were
successful even without molecular sieves, the reaction
yields were generally 10-20% lower due to competing
hydrolysis leading to unreactive hemiacetal/hemiketal side
products.
We then briefly investigated a possibility of expanding this
methodology to the synthesis glycosyl thioimidates that
found some synthetic utility in the recent years. The
synthesis S-thiazolinyl (STaz) imidate, was also deemed
possible, but required excess of both HSTaz and TfOH, up
to 3.5 equiv each. The key results of this study are
summarized in Table 3. Glucose per-acetate 1 produced the
desired thioimidate 2234,52 in 76% yield in 6 h (entry 1).
Galactose per-acetate 3 afforded STaz galactoside 2352 in
76% yield in 5 h (entry 2). Reaction of mannose per-acetate
5 again required longer reaction time (16 h), but we
managed to obtain STaz mannoside 2452 in 66% yield
(entry 3). It should be noted that all of these reactions were
completely stereoselective (Table 3), whereas previous
syntheses of STaz imidates from per-acetates in the
presence of excess BF3•Et2O at high temperature often led
to anomeric mixtures.52
EXPERIMENTAL SECTION
A general procedure for thioglycosidation of per-
acetylated compounds 1, 3, 5, 7, 9 and 11 (see the SI for
further details). TfOH (0.8-3.5 equiv) was added dropwise
to a mixture containing a thiol (2.0 equiv or 3.5 equiv for
HSTz), per-acetate (1.0 equiv) in anhydrous CH2Cl2 (10 mL
per gram of per-acetate) and freshly activated molecular
sieves (3 Å) and the resulting mixture was stirred under
argon for the time and at the temperature specified in
tables. After that, the reaction mixture was diluted with
CH2Cl2 and subjected to conventional aqueous work-up.
The organic layer was separated, dried, and concentrated
under reduced pressure. The residue was purified either by
crystallization (Et2O-hexanes, mostly with Glc and Gal
derivatives) or by column chromatography for most Man
and aminosugar derivatives (EtOAc-hexanes gradient
elution) to give the target thioglycosides. Anomeric ratios
(or anomeric purity) were determined by comparison of
Table 3. TfOH-promoted synthesis of STaz imidates
22-24 from per-acetates
1
the integral intensities of relevant signals in H NMR
spectra.
HSTaz (3.5 equiv)
TfOH (3.5 equiv)
O
N
O
Supporting Information. Additional experimental details
and complete NMR spectral data for all synthesized
compounds. This material is available free of charge via the
Internet at
MS 3Å, CH2Cl2, rt
OAc
glycosyl acetate
S
S
STaz imidate
Entry Substrate Time Product (yield, α/β)
OAc
O
ACKNOWLEDGMENT
AcO
AcO
STaz
1
2
1
3
6 h
5 h
This work was supported by awards from the NSF (CHE-
1800350) and NIGMS (GM120673). SE is indebtful to the SACM
for profiding her with the graduate fellowship.
AcO
22 (76%, β only)
AcO
OAc
O
AcO
STaz
AcO
REFERENCES
23 (76%, β only)
AcO
(1) Varki, A. Glycobiology 2017, 27, 3-49.
OAc
(2) Nigudkar, S. S.; Demchenko, A. V. Chem. Sci. 2015, 6, 2687–2704.
(3) Crich, D. Acc. Chem. Res. 2010, 43, 1144-1153.
(4) Adero, P. O.; Amarasekara, H.; Wen, P.; Bohe, L.; Crich, D. Chem.
Rev. 2018, 118, 8242-8284.
O
AcO
AcO
3
5
16 h
STaz
24 (66%, α only)
(5) Kulkarni, S. S.; Wang, C. C.; Sabbavarapu, N. M.; Podilapu, A. R.;
Liao, P. H.; Hung, S. C. Chem. Rev. 2018, 118, 8025-8104.
(6) Nielsen, M. M.; Pedersen, C. M. Chem. Rev. 2018, 118, 8285-8358.

Organic & Biomolecular Chemistry
Page 4 of 4
View Article Online
DOI: 10.1039/C9OB01610D
(31) Tai, C. A.; Kulkarni, S. S.; Hung, S. C. J. Org. Chem. 2003, 68,
8719-8722.
(7) Panza, M.; Pistorio, S. G.; Stine, K. J.; Demchenko, A. V. Chem.
Rev. 2018, 118, 8105−8150.
(8) Handbook of chemical glycosylation: advances in stereoselectivity
and therapeutic relevance; Demchenko, A. V., Ed.; Wiley-VCH:
Weinheim, Germany, 2008.
(9) Fischer, E.; Delbrück, K. Ber. Dtsch. Chem. Ges. 1909, 42, 1476-
1482.
(10) Codee, J. D. C.; Litjens, R. E. J. N.; van den Bos, L. J.; Overkleeft,
H. S.; van der Marel, G. A. Chem. Soc. Rev. 2005, 34, 769-782.
(11) Goswami, M.; Ellern, A.; Pohl, N. L. Angew. Chem. Int. Ed. Engl.
2013, 52, 8441-8445.
(12) Goswami, M.; Ashley, D. C.; Baik, M. H.; Pohl, N. L. J. Org. Chem.
2016, 81, 5949-5962.
(13) Vibhute, A. M.; Dhaka, A.; Athiyarath, V.; Sureshan, K. M. Chem.
Sci. 2016, 7, 4259-4263.
(14) Lacey, K. D.; Quarels, R. D.; Du, S.; Fulton, A.; Reid, N. J.;
Firesheets, A.; Ragains, J. R. Organic letters 2018, 20, 5181-5185.
(15) Saliba, R. C.; Wooke, Z. J.; Nieves, G. A.; Chu, A. A.; Bennett, C.
S.; Pohl, N. L. B. Org. Lett. 2018, 20, 800-803.
(16) Pakulski, Z.; Pierozynski, D.; Zamojski, A. Tetrahedron 1994, 50,
2975-2992.
(17) Agnihotri, G.; Tiwari, P.; Misra, A. K. Carbohydr. Res. 2005, 340,
1393-1396.
(32) Huang, L. C.; Liang, P. H.; Liu, C. Y.; Lin, C. C. J. Carbohydr.
Chem. 2006, 25, 303-313.
(33) Chao, C.-S.; Chen, M.-C.; Lin, S.-C.; Mong, K.-K. T. Carbohydr.
Res. 2008, 343, 957-964.
(34) Parameswar, A. R.; Imamura, A.; Demchenko, A. V.: Synthesis of
thioglycosides and thioimidates from peracetates. In Carbohydrate
Chemistry: Proven Synthetic Methods; Kovac, P., Ed.; CRC Press,
2012; Vol. 1; pp 187-196.
(35) Contour, M. O.; Defaye, J.; Little, M.; Wong, E. Carbohydr. Res.
1989, 193, 283-287.
(36) Ibatullin, F. M.; Selivanov, S. I.; Shavva, A. G. Synthesis 2001, 419-
422.
(37) Valerio, S.; Iadonisi, A.; Adinolfi, M.; Ravida, A. J. Org. Chem.
2007, 72, 6097-6106.
(38) Landström, J.; Bergström, M.; Hamark, C.; Ohlson, S.; Widmalm,
G. Org. Biomol. Chem. 2012, 10, 3019-3032.
(39) McGeary, R. P.; Wright, K.; Toth, I. J. Org. Chem. 2001, 66, 5102-
5105.
(40) Marra, A.; Sinay, P. Carbohydr. Res. 1989, 190, 317-322.
(41) Tsvetkov, Y. E.; Nifantiev, N. E. Synlett 2005, 9, 1375-1380.
(42) Marra, A.; Sinay, P. Carbohydr. Res. 1989, 187, 35-42.
(43) Hudson, C. S.; Johnson, J. M. J. Am. Chem. Soc. 1915, 37, 1270-
1275.
(44) Hronowski, L. J. J.; Szarek, W. A.; Hay, G. W.; Krebs, A.; Depew,
W. T. Carbohydr. Res. 1989, 190, 203-218.
(45) Hou, S. J.; Saksena, R.; Kováč, P. Carbohydr. Res. 2008, 343, 196-
210.
(18) Weng, S.-S.; Lin, Y.-D.; Chen, C.-T. Org. Lett. 2006, 8, 5633-5636.
(19) Dasgupta, F.; Garegg, P. J. Acta Chem. Scand. 1989, 43, 471-475.
(20) Fried, J.; Walz, D. E. J. Am. Chem. Soc. 1949, 71, 140-143.
(21) Ferrier, R. J.; Furneaux, R. H. Carbohydr. Res. 1976, 52, 63-68.
(22) Ferrier, R. J.; Furneaux, R. H.: 1,2-trans-1-Thioglycosides. In
Methods in Carbohydrate Chemistry; Whistler, R. L., BeMiller, J.
N., Eds.; Academic Press: New York - London, 1980; Vol. 8; pp
251-253.
(46) Niggemann, J.; Kamerling, J. P.; Vliegenthart, J. F. G. J. Chem. Soc.,
Perkin Trans. 1 1998, 3011-3020.
(23) Pozsgay, V.; Jennings, H. J. Tetrahedron Lett. 1987, 28, 1375-1376.
(24) Bennet, S.; von Itzstein, M.; Kiefel, M. J. Carbohydr. Res. 1994,
259, 293-299.
(25) Li, P.; Sun, L.; Landry, D. W.; Zhao, K. Carbohydr. Res. 1995, 275,
179-184 and references therein.
(26) Mukhopadhyay, B.; Kartha, K. P. R.; Russell, D. A.; Field, R. A. J.
Org. Chem. 2004, 69, 7758-7760.
(27) Chatterjee, D.; Paul, A.; Rajkamal, R.; Yadav, S. RSC Adv. 2015, 5,
29669-29674.
(28) Garegg, P. J. Adv. Carbohydr. Chem. Biochem. 1997, 52, 179-205.
(29) Oscarson, S.: Thioglycosides. In Carbohydrates in Chemistry and
Biology; Ernst, B., Hart, G. W., Sinay, P., Eds.; Wiley-VCH:
Weinheim, New York, 2000; Vol. 1; pp 93-116.
(47) Ahmadipour, S.; Pergolizzi, G.; Rejzek, M.; Field, R. A.; Miller, G.
J. Org. Lett. 2019, 21, 4415-4419.
(48) Parameswar, A. R.; Mueller, D.; Liu, L.; Meo, C. D.; Demchenko,
A. V.: Synthesis of thioglycosides and thioimidates from glycosyl
halides In Carbohydrate Chemistry: Proven Synthetic Methods;
Kovac, P., Ed.; CRC Press, 2012; Vol. 1; pp 181-186.
(49) Kirchner, E.; Thiem, F.; Dernick, R.; Heukeshoven, J.; Thiem, J. J.
Carbohydr. Chem. 1988, 7, 453-486.
(50) Kondo, H.; Aoki, S.; Ichikawa, Y.; Halcomb, R. L.; Ritzen, H.;
Wong, C. H. J. Org. Chem. 1994, 59, 864-877.
(51) Panza, M.; Mannino, M. P.; Baryal, K. N.; Demchenko, A. V.: A
facile synthesis and characterization of p-tolyl 2,3,4,6-tetra-O-
benzoyl-1-thio-β-D-galactopyranoside. In Carbohydrate Chemistry:
Proven Synthetic Methods; Wrodnigg, T., Ed.; CRC Press, 2019;
Vol. 5; pp in press.
(30) Zhong, W.; Boons, G.-J.: Glycoside synthesis from 1-
sulfur/selenium-substituted
derivatives:
thioglycosides
in
oligosaccharide synthesis. In Handbook of Chemical Glycosylation;
Demchenko, A. V., Ed.; Wiley-VCH: Weinheim, Germany, 2008;
pp 261-303.
(52) Pornsuriyasak, P.; Demchenko, A. V. Chem. Eur. J. 2006, 12, 6630-
6646.