Preparation of S-glycoside surfactants and cysteine thioglycosides using minimally competent Lewis acid catalysis

Article abstract of DOI:10.1016/j.carres.2015.12.008

Here we report a method for the preparation of anomerically pure β-S-glycopyranosides (1,2-trans-glycosides) from the corresponding peracetate donors. S-glycosylation was performed in CHCl₃ at reflux in the presence of a catalytic amount of InBr₃. Deacylation of the intermediate peracetates were achieved under Zemplén conditions. Five pyranose examples, monosaccharides D-glucose and D-galactose and disaccharides cellobiose, maltose, and lactose, were used as donors, and five thiols including an α/ω dithiol and Fmoc-L-cysteine were used as acceptors. Melting points, high res MS, [α]_D and NMR data (¹H and ¹³C, including COSY, HSQC and HMBC) are reported for compounds not previously described.

Full text of DOI:10.1016/j.carres.2015.12.008

Accepted Manuscript
Title: Preparation of s-glycoside surfactants and cysteine thioglycosides using
minimally competent lewis acid catalysis
Author: Lajos Z. Szabó, Dillon J. Hanrahanv, Evan M. Jones, Erin Martin,
Jeanne E. Pemberton, Robin Polt
PII:
S0008-6215(15)00399-7
DOI:
Reference:
http://dx.doi.org/doi: 10.1016/j.carres.2015.12.008
CAR 7108
To appear in:
Carbohydrate Research
Received date: 29-9-2015
Revised date: 3-12-2015
Accepted date: 26-12-2015
Please cite this article as: Lajos Z. Szabó, Dillon J. Hanrahanv, Evan M. Jones, Erin Martin,
Jeanne E. Pemberton, Robin Polt, Preparation of s-glycoside surfactants and cysteine
thioglycosides using minimally competent lewis acid catalysis, Carbohydrate Research (2016),
http://dx.doi.org/doi: 10.1016/j.carres.2015.12.008.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service
to our customers we are providing this early version of the manuscript. The manuscript will
undergo copyediting, typesetting, and review of the resulting proof before it is published in its
final form. Please note that during the production process errors may be discovered which could
affect the content, and all legal disclaimers that apply to the journal pertain.

Preparation of S-Glycoside Surfactants and Cysteine Thioglycosides Using
Minimally Competent Lewis Acid Catalysis
Lajos Z. Szabó, Dillon J. Hanrahan, Evan M. Jones, Erin Martin,
Jeanne E. Pemberton and Robin Polt*
Department of Chemistry and Biochemistry
BIO5
The University of Arizona
1306 E. University Blvd.
Tucson, AZ 85721
*Corresponding author
polt@u.arizona.edu
(520) 370-2654
25 November 2015
Page 1 of 14

Highlights
 Thioglycosides can be readily prepared from per-acetylated carbohydrate donors.
 S-Glycosylations are catalyzed using the minimally competent Lewis acid InBr3.
 Only β anomers are formed.
 Glycosylation of cysteine and a library of thio-glycolipids are produced by Zemplèn
deacylation.
Table of Contents/Abstract Graphic.
Abstract.
Here we report a method for the preparation of anomerically pure -S-glycopyranosides
(1,2-trans-glycosides) from the corresponding peracetate donors. S-glycosylation was
performed in CHCl3 at reflux in the presence of a catalytic amount of InBr3. Deacylation
of the intermediate peracetates were achieved under Zemplén conditions. Five
pyranose examples, monosaccharides D-glucose and D-galactose and disaccharides
cellobiose, maltose, and lactose, were used as donors, and five thiols including an /
dithiol and Fmoc-L-cysteine were used as acceptors. Melting points, high res MS, [α]D
and NMR data (1H and 13C, including COSY, HSQC and HMBC) are reported for
compounds not previously described.
Keywords: thioglycoside, S-glycosidic linkage, glycolipid, InBr3, surfactant, glycosylated
cysteine
Page 2 of 14

Glycolipids represent a diverse class of compounds typically found in biological
membranes1 and are regarded as environmentally friendly bio-surfactants with broad
use in cosmetics, food, environmental and other industrial applications,2 as well as
potential therapeutic drug delivery systems.3, 4 Despite high surface activity,5 high
biodegradability, and low toxicity, their use is still hampered by a lack of knowledge
regarding physical properties, including phase behavior. Even less is known about the
S-linked thioglycosides. Thioglycosides (S-glycosides)6 may be regarded as relatively
inert moieties in vivo,7 or as chemical intermediates that can be oxidatively activated8 to
generate glycoside donors.9-11 Thioglycosides were previously prepared from
monosaccharide peracetates using a molar excess of BF3•Et2O or SnCl4 as promoters
by Kihlberg in the 1990’s.12 Here we disclose the catalytic use of a much weaker Lewis
acid, InBr3,13 which we dub a “minimally competent” Lewis acid.14 It should be noted that
InBr3 and other Lewis acids have been used in conjunction with the O-glycosylation of
14
trichloroacetimidate donors.15 We have previously reported the catalytic use of InBr3
and other Lewis acids16 to generate O-glycosides from weakly electrophilic peracetate
sugars.
The surfactant -S-octyl-glucopyranoside and several of its analogues were
previously prepared by S-alkylation of 2-(2,3,4,6-tetra-O-acetyl--glucopyranosyl)
thiopseudourea•HBr by Saito and Tsuchiya.17 The present approach (Figure 1) seems
to be superior, both in terms of the number of steps and in overall yield. -D-
Glucopyranose peracetate 1 was treated with two molar equivalents of 1-octanethiol in
CHCl3 at reflux for 1 hour in the presence of 1% InBr3, to form the desired -peracetate,
which was purified by short column chromatography (SiO2). No  anomer was
Page 3 of 14

observed. We propose that the formation of the S-glycoside occurs via a similar route to
the previously published O-glycoside example, resulting in only the -S-glycoside.14 The
peracetate product was deprotected using Zemplén deacylation18 to provide the desired
surfactant.17 The glycosylation produced a similar yield in PhCH3, but the reaction in
CH3CN decreased the yield.
Several mono- and disaccharide peracetates (1-5) and thiols (6-11, Table 1) were
subjected to the reaction conditions to provide a variety of S-glycosides. Bolaamphiphile
15a and mono-glycoside 16a were prepared by adjusting the stoichiometry of the
glycosyl donor and acceptor to favor either mono- or di-glycosylation of the / dithiol.
Page 4 of 14

Similar reaction conditions were applied to Fmoc-L-cysteine. Glycosylation of
neurologically active endogenous peptides has been applied to a number of systems,30
although these modifications have typically been performed by O-glycosylation. O-
glycosyl linkages have the drawback of being susceptible to enzymatic degradation and
hydrolysis. Therefore, S-glycosylated amino acid building blocks compatible with
common solid-phase peptide synthesis conditions are an attractive target. Fmoc-L-
Cys(S-D-Gal)-OH has been previously reported by Kamerling et al,29 and Pieters et al,28
although their methodology required the use of excess SnCl4. We report similar yields
using catalytic quantities of the minimally competent Lewis acid activator, and show the
broad applicability of this approach through conjugation of five mono- and disaccharide
glycosyl donors 29-33 to Fmoc-L-cysteine (Figure 2).
The importance of this study is twofold. First, only catalytic amounts of the Lewis
acid promoter are required. Secondly, weakly electrophilic peracetates, generally
regarded as synthetic intermediates rather than reactive donors, are suitable. This
reduces the number of steps and greatly expands the application of this methodology.
We have not observed the corresponding -thioglycosides in any of the reactions.
Page 5 of 14

1. Experimental Section
1
1.1 Materials and Instrumentation. H and 13C NMR spectra were recorded on a
Bruker 400 (400 MHz) spectrometer using CDCl3 and D3COD as solvents with TMS as
the internal standard. All NMR spectra were analyzed and interpreted using
MestReNova® software. First-order chemical shifts and coupling constants were
obtained from 1D spectra; proton and carbon resonances were assigned from COSY,
HSQC and HMBC experiments. Mass spectrometry was achieved on a Thermo
Finnigan LCQ Deca with positive and negative detection and a 1:1 CH3OH:H2O solvent
system. Optical rotation measurements were performed using a JASCO P-1010
polarimeter using the Na D line (589 nm) in MeOH at room temperature, and specific
rotation was determined using the JASCO software package. For flash chromatography
Silia Flash P60 Silica Gel, 40-63 µm, 60 Å (Silicycle, R1200308) was employed and a
Biotage, Inc. Horizon HPFC system was utilized.
Preparative HPLC separations were performed on a Gilson HPLC using a
Phenomenex C-18 reverse phase column (1000 Å, 50 x 250 mm) with a flow rate of 25
mL/min and detection at 280 nm. Solvent systems A: 5% acetonitrile in 0.1% aqueous
F3CCOOH and B: 80% acetonitrile in 0.1% aqueous F3CCOOH were used. A Dikma
Technologies Inspire C-18 column (4.6 x 250 mm) and a flow rate of 1.0 mL/min was
used for analytical HPLC separations. Thin layer chromatography (TLC) was performed
on silica gel 60 F254 (Merck) with detection by UV light and charring with H2SO4.
Solvents were dried and distilled according to literature procedures or purchased as
anhydrous solvents from a manufacturer. All chemicals were purchased from Aldrich
Chemical Company, Acros Chemicals, Chem-Impex International, or EMD Chemicals.
Page 6 of 14

1.2
Alkyl--1-thio-D-glycopyranoside
(12a-14a,
16a-28a).
Peracetyl--D-
glycopyranose (1-5, 10 mmol), InBr3 (106 mg, 0.3 mmol, 0.03 eq), and alkane-1-thiol
(20 mmol, 2 eq) were suspended in CHCl3 (7 mL). The reaction mixture was heated to
reflux with magnetic stirring. The course of the reaction was followed by TLC
(hexane:EtOAc 1:1). After 1 hour the peracetate starting material could no longer be
detected by TLC. The reaction was cooled to RT, diluted with CH2Cl2 (20 mL) and this
solution was applied to a short column (4 cm x 12 cm) of SiO2. The HOAc that was
formed from the reaction and the excess alkane-1-thiol were eluted with hexanes. The
desired thio-glycoside peracetate was eluted with hexanes:EtOAc 7:3. The fractions
containing the desired material were combined, concentrated in vacuo, and the
1
intermediate peracetates (12-14, 16-28) were characterized by 1D, 2D, H-NMR and
13CNMR in CDCl3 (in Tables).
Zemplén’s method was used to deprotect the peracetates.18 The thio-
glycopyranoside peracetates were dissolved in anhydrous CH3OH (100 mL) and the
basicity was adjusted to pH = 9 by addition NaOCH3. After 16 hours the deacetylation
was deemed complete by TLC. Dowex® resin (H+ form) was added until the pH was
slightly acidic, the resin was filtered off, and the solution was concentrated, to provide
12a-14a, 16a-28a, which were characterized.
1.3 1,10 Dithio--D-glucopyranosyl-decane (15a) Peracetyl--D-glucopyranose (25
mmol), InBr3 (3 mmol, 0.03 eq), and decane-1,10-dithiol (10 mmol, 1 eq) were reacted
using the previous method to provide 15a. M.p. 124-132 °C (crystallization from MeOH
Page 7 of 14

– Et2O), [α]D -36.5° (c 0.13, in MeOH), MS (ESI HRMS) for C22H42O10S2 (+Na)
553.21116, found 553.21195 [M+Na]+.
1-Thio--D-glucopyranosyl-10-thiol-decane (16a) M.p. 95-97°C (crystallization from
MeOH – Et2O), [α]D -17.8° (c 0.20, in MeOH), MS (ESI HRMS) for C16H32O5S2 (+Na)
391.15834, found 391.15875 [M+Na]+.
Decyl-β-thio-cellobioside (21a) M.p. 200-214°C (crystallization from MeOH – Et2O),
[α]D -22.1° (c 0.26, in MeOH), MS (ESI HRMS) for : C22H42O10S (+Na) 521.23909, found
521.24009 [M+Na]+.
Decyl-β-thio-lactoside (27a) M.p. Decomp. ~200°C (crystallization from MeOH –
Et2O), [α]D -18.3° (c 0.40, in MeOH), MS (ESI HRMS) for C22H42O10S (+Na) 521.23909,
found 521.24000 [M+Na]+.
1.4 Nα-Fluoren-9-ylmethoxycarbonyl-S-(peracetyl-β-D-glyco-pyranosyl)-L-cysteine
(29-33). Peracetyl--D-glycopyranose (0.6 mmol, 2eq), InBr3 (21 mg, 0.06 mmol, 0.2
eq), and Nα-fluoren-9-ylmethoxycarbonyl-L-cysteine (11, 103 mg, 0.3 mmol, 1 eq) were
suspended in CHCl3 (1.5 mL). The reaction mixture was heated to reflux with magnetic
stirring. The course of the reaction was followed by analytical HPLC. After 1 hour HPLC
indicated >80% conversion (see Table 1) of Fmoc-Cys(SH)-OH to the desired product.
Additional reaction time yielded no further reaction progress that could be detected by
HPLC. The reaction mixture was concentrated in vacuo, and the residue was purified by
preparative HPLC on a C18 reverse phase column with H2O-CH3CN gradient. The
appropriate fractions were freeze-dried and the solid residue was characterized.
Page 8 of 14

Nα-Fluoren-9-ylmethoxycarbonyl-S-(peracetyl-β-D-cellobiosyl)-L-cysteine
(31)
Phase transition point 104-105 °C (lyophilization from CH3CN/H2O), [α]D -20.7° (c 0.15,
in MeOH), MS (ESI HRMS) for C44H51NO21S (+Na) 984.25665, found 984.25901
[M+Na]+.
Nα-Fluoren-9-ylmethoxycarbonyl-S-(peracetyl-β-D-maltobiosyl)-L-cysteine
(32)
Phase transition point 103-104 °C (lyophilization from CH3CN/H2O), [α]D +21.5° (c 0.14,
in MeOH), MS (ESI HRMS) for C44H51NO21S (+Na) 984.25665, found 984.25866
[M+Na]+.
Nα-Fluoren-9-ylmethoxycarbonyl-S-(peracetyl-β-D-lactosyl)-L-cysteine (33) Phase
transition point 109-110 °C (lyophilization from CH3CN/H2O), [α]D -20.6 (c 0.17, in
MeOH), MS (ESI HRMS) for C44H51NO21S (+Na) 984.25665, found 984.25817 [M+Na]+.
Acknowledgements. We acknowledge support of this research through grants from the
NSF/EPA Networks for Sustainable Molecular Design and Synthesis (NSMDS) program
(CHE-1339597), the Michael J. Fox Foundation, and the Migraine Research
Foundation.
Page 9 of 14

References and Footnotes.
1. Brown, D.A., London, E., J. Membr. Biol., 1998; 164:103-114.
2. Kitamoto, D., Morita, T., Fukuoka, T., Konishi, M.-a., Imura, T., Curr. Opin.
Colloid In., 2009; 14:315-328.
3. Salim, M., Minamikawa, H., Sugimura, A., Hashim, R., Medchemcomm, 2014;
5:1602-1618.
4. Rodrigues, L.R., J. Colloid Interface Sci., 2015; 449:304-316.
5. Niraula, B.B., Chun, T.K., Othman, H., Misran, M., Colloid. Surface. A, 2004;
248:157-166.
6. Fischer, E., Delbrück, K., Ber. Dtsch. Chem. Ges., 1909; 42:1476-1482.
7. Macauley, M.S., Stubbs, K.A., Vocadlo, D.J., J. Am. Chem. Soc., 2005;
127:17202-17203.
8. Veeneman, G.H., Vanleeuwen, S.H., Vanboom, J.H., Tetrahedron Lett., 1990;
31:1331-1334.
9. Zhu, X., Schmidt, R.R., Angew. Chem. Int. Ed., 2009; 48:1900-1934.
10. Lloyd, D., Bennett, C.S., J. Org. Chem., 2014; 79:9826-9829.
11. Codée, J.D.C., Litjens, R., van den Bos, L.J., Overkleeft, H.S., van der Marel,
G.A., Chem. Soc. Rev., 2005; 34:769-782.
12. Salvador, L.A., Elofsson, M., Kihlberg, J., Tetrahedron, 1995; 51:5643-5656.
13. Coss, C., Carrocci, T., Maier, R.M., Pemberton, J.E., Polt, R., Helv. Chim.
Acta, 2012; 95:2652-2659.
14. Lefever, M.L., Szabo, L.Z., Anglin, B., Ferracane, M., Hogan, J., Cooney, L.,
Polt, R., Carbohydr. Res., 2012; 351:121-125.
15. Mattson, A.L., Michel, A.K., Cloninger, M.J., Carbohydr. Res., 2012;
347:142-146.
16. Keyari, C.M., Polt, R., J. Carbohydr. Chem., 2010; 29:181-206.
17. Saito, S., Tsuchiya, T., Chem. Pharm. Bull., 1985; 33:503-508.
18. Zemplén, G., Kunz, A., Ber. Dtsch. Chem. Ges., 1924; 57:1357-1359.
19. Galema, S.A., Engberts, J., vanDoren, H.A., Carbohydr. Res., 1997; 303:423-
434.
20. Van Doren, H.A., Van Der Geest, R., Kellogg, R.M., Wynberg, H., Carbohydr.
Res., 1989; 194:71-78.
21. Yde, M., Debruyne, C.K., Carbohydr. Res., 1973; 30:205-206.
22. Dahlhoff, W.V., Radkowski, K., Riehl, K., Zugenmaier, P., Z. Naturforsch. B,
1995; 50:1079-1085.
23. Defaye, J., Gadelle, A., Pedersen, C., US Patent 5,118,804, 1991.
24. Mousty, C., Maurice, C., Mousset, G., Schöllhorn, B., Lefeuvre, M.,
Plusquellec, D., J. Colloid Interface Sci., 1996; 184:671-679.
Page 10 of 14

25. Kumpulainen, A.J., Persson, C.M., Eriksson, J.C., Langmuir, 2004; 20:10534-
10541.
26. Mori, M., Kasuya, M.C.Z., Mizuno, M., Hatanaka, K., Int. J. Carbohydr.
Chem., 2011; 8 pp.
27. Katayama, H., Asahina, Y., Hojo, H., J. Pept. Sci., 2011; 17:818-821.
28. Branderhorst, H.A., Liskamp, R.A.J., Pieters, R.J., Tetrahedron, 2007;
63:4290-4296.
29. Maljaars, C.E.P., Halkes, K.M., de Oude, W.L., van der Poel, S., Pijnenburg,
N.J.M., Kamerling, J.P., J. Carbohydr. Chem., 2005; 24:353-367.
30. Jones, E.M., Polt, R., Front. Chem. (Lausanne, Switz.), 2015; 3:40.
Page 11 of 14

Figure 1. Preparation of -Thioglycosides.
Figure 2. Preparation of L-Cysteine -thio-Glycosides.
Page 12 of 14

Table 1. Results of InBr3 Promoted Glycosylations
Thioglycosides from InBr3 promoted glycosylations of various thiolipids (6-10) and Fmoc-L-cysteine (11) with five
peracetylated mono- and disaccharides (1-5) to produce compounds 12-33. After Zemplén deacylation of the lipids,
compounds 12a-28a were isolated and characterized. Compounds 12a,19, 20 13a,20 14a,20 17a,19, 21 18a,22 19a,22 20a,23
22a,24 23a,23 24a,25 25a,24 26a,23 28a,26 29,27 and 3028, 29 have been previously reported using alternate reaction
conditions. Previously reported deacylated thioglycosides are noted in Lit. % indicates combined yields.
Donors
Sulfide Acceptors
R′=
R=
Ac
H
Lit
%
Ac
H
Lit
%
Ac
H
Lit
%
Ac
H
Lit
%
Ac
H
Lit
%
Ac
Lit
%
19,20
20
20
27
12
12a
81
13
13a
88
14
14a
84
15
15a
—
86
16
16a
—
69
29
72
28,
29
19,21
22
22
24
24
26
17
20
23
26
17a
20a
23a
26a
89
88
85
87
18
21
24
27
18a
21a
24a
27a
90
66
87
82
19
22
25
28
19a
22a
25a
28a
92
76
88
80
30
31
32
33
81
65
85
83
23
—
—
—
—
23
25
23
—
Page 13 of 14

Page 14 of 14