Preparation and reactions of 2-chloroethyl 1-thio-β-D-glycopyranosides derived from D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-glucose

Article abstract of DOI:10.1135/cccc19961489

Chloroethyl 1-thio-β-D-glycopyranosides of the D-galacto and D-gluco configurations 5a-5c were prepared by alkylation of the corresponding 1-thio-β-D-hexopyranoses 3a-3c with 1-bromo-2-chloroethane followed by deacetylation. The starting 1-thio-β-D-hexopyranoses were obtained from the acetylated glycopyranosyl halides via isothiouronium salts. It was demonstrated that the chloroethyl thioglycosides 5a-5c undergo hydrolysis in aqueous solutions to give the 2-hydroxyethyl thioglycosides 6a-6c and reducing hexoses and that this hydrolysis proceeds via episulfonium salts. The hydrolysis was monitored by ¹H and ¹³C NMR spectroscopy. In 1% aqueous solutions of sodium carbonate containing phenol or aniline, the thioglycosides 5a-5c provide, in addition to the above hydrolysis products, also the phenoxyethyl and phenylaminoethyl thioglycosides 9a, 10a and 9b, 10b, respectively.

Full text of DOI:10.1135/cccc19961489

Chloroethyl Thioglycosides
1489
PREPARATION AND REACTIONS OF 2-CHLOROETHYL
1-THIO-β-D-GLYCOPYRANOSIDES DERIVED FROM D-GALACTOSE,
D-GLUCOSE, AND 2-ACETAMIDO-2-DEOXY-D-GLUCOSE
a1
b
Miloslav CERNY , Tomas TRNKAa2 and Milos BUDESINSKY
a Department of Organic Chemistry, Charles University, 128 40 Prague 2, Czech Republic;
e-mail: 1 mila@prfdec.natur.cuni.cz, 2 trnka@prfdec.natur.cuni.cz
b Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic,
166 10 Prague 6, Czech Republic; e-mail: milos.budesinsky@uochb.cas.cz
Received March 29, 1996
Accepted May 28, 1996
Chloroethyl 1-thio-β-D-glycopyranosides of the D-galacto and D-gluco configurations 5a–5c were pre-
pared by alkylation of the corresponding 1-thio-β-D-hexopyranoses 3a–3c with 1-bromo-2-chloro-
ethane followed by deacetylation. The starting 1-thio-β-D-hexopyranoses were obtained from the
acetylated glycopyranosyl halides via isothiouronium salts. It was demonstrated that the chloroethyl
thioglycosides 5a–5c undergo hydrolysis in aqueous solutions to give the 2-hydroxyethyl thioglycosides
6a–6c and reducing hexoses and that this hydrolysis proceeds via episulfonium salts. The hydrolysis
1
was monitored by H and 13C NMR spectroscopy. In 1% aqueous solutions of sodium carbonate con-
taining phenol or aniline, the thioglycosides 5a–5c provide, in addition to the above hydrolysis prod-
ucts, also the phenoxyethyl and phenylaminoethyl thioglycosides 9a, 10a and 9b, 10b, respectively.
Key words: 2-Halogenoethyl thioglycosides; Synthesis; Nucleophilic substitution; Mechanism of hy-
1
drolysis; H and 13C NMR.
Thioglycosides are known to be more reluctant to undergo acid hydrolysis than glyco-
sides and not to be split by normal glycosidases1. This property of thioglycosides is
utilized in affinity chromatography2 and in the preparation of enzyme formation in-
ducers. In view of those facts, investigation of the feasibility of functionalizing
polymeric carriers, proteins and/or peptides with thioglycosyl groups under mild condi-
tions in aqueous solutions is of interest. Glycosylation agents for this purpose may
include 2-haloethyl thioglycosides, containing an atom of chlorine, bromine or iodine
in their molecules; such compounds have been examined only scarcely so far. The
present work was aimed at developing a suitable procedure for the preparation of such
substances and investigating their behaviour as glycosylation agents.
The 2-haloethyl thioglycopyranosides were prepared by a modification of the pub-
lished procedure3,4. The starting compounds, viz. acetylated α-D-glycopyranosyl halides
1a–1c, were converted to isothiouronium salts 2a–2c by reaction with thiourea in acetone,
and split3,5 to the corresponding acetylated 1-thio-β-D-glycopyranoses 3a–3c. Alkyla-
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1490
Cerny, Trnka, Budesinsky:
tion of the latter with 1-bromo-2-chloroethane or 1,2-dibromoethane, with subsequent
nucleophilic substitution of chlorine with bromine or iodine as appropriate, gave the
acetylated 2-haloethyl β-D-thioglycopyranosides 4a–4g. The corresponding 2-hydroxy-
ethyl thioglycosides 4h, 4i were obtained by analogous alkylation with 2-iodoethanol
or by reaction with oxirane. Deacetylation of the thioglycosides 4a–4c, 4h, 4i with
sodium methoxide in methanol gave the thioglycosides 5a–5c or 6a, 6b, respectively.
Attempts at a similar deacetylation of the bromoethyl and iodoethyl thioglycosides 4d–4g
were accompanied by splitting off of the halogen and formation of solvolysis products,
mainly 2-methoxyethyl thioglycosides, which were not in the focus of our interest.
The chloroethyl thioglycosides 5a–5c are well soluble in water but their aqueous
solutions hydrolyze slowly, whereupon the chlorine atom is substituted by a hydroxy
group giving rise to the 2-hydroxyethyl thioglycosides 6a–6c; simultaneously, a side
reaction occurs, during which the C(1)–S bond is split and an anomeric mixture of the
X
CH2OAc
CH2OAc
CH2OAc
NH2
NH2
R3
R2
R3
R2
R3
R2
O
O
O
S
C
SH
OAc
OAc
OAc
X
R1
R1
R1
R1
OAc
R2 R3
R1
R2 R3
OAc Br
R1
R2 R3
H OAc
X
X
H
OAc Br
OAc
H
OAc
1a
1b
1c
2a
2b
2c
3a
OAc OAc H
NHAc OAc H
Br
Cl
OAc OAc H
NHAc OAc H
Br
Cl
OAc OAc H
NHAc OAc H
3b
3c
CH2OAc
CH2OH
CH2OH
O
R3
R2
R3
R2
R3
R2
O
O
SCH2CH2X
SCH2CH2Cl
SCH2CH2OH
OAc
OH
OH
R1
R1
H
R1
R1
OAc
R2 R3
H OAc Cl
R1
R2 R3
R1
R2 R3
OH
OH H
X
OH
OH
OH
OH
OH
H
4a
5a
5b
5c
6a
OAc OAc H
NHAc OAc H
Cl
Cl
OH H
4b
4c
4d
4e
4f
6b
6c
NHAc OH H
NHAc OH H
OAc
OAc OAc H
OAc OAc I
OAc OAc H
OAc OAc OH
OAc OAc H OH
H
OAc Br
Br
H
I
4g
4h
4i
H
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Chloroethyl Thioglycosides
1491
corresponding hexoses, viz. D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-glu-
cose, is formed. The time development of the hydrolysis and the structure of its pro-
1
ducts were monitored by H and 13C NMR spectroscopy in deuterium oxide solutions.
The reaction mixture compositions in 48 h are given in Table I.
The NMR data of the starting chloroethyl thioglycosides 5a–5c were measured im-
mediately after dissolution. The 2-hydroxyethyl thioglycosides 6a–6c are the major hy-
drolysis products, whose NMR data were obtained after allowing the solutions of the
compounds 5a–5c to stand for several hours; authentic samples were also measured.
The replacement of the chlorine atom by the hydroxy group manifests itself most mar-
kedly by upfield shifts of signals of the S–CH2 hydrogens (about –0.2 ppm) and the
anomeric H-1 hydrogen (about –0.05 ppm). The expected downfield shift of the CH2X
hydrogen signal (about 0.1 ppm), on the other hand, is overlapped to a considerable
extent by the signals in the region of δ 3.5–3.9. The 13C NMR spectra exhibit a marked
downfield shift for the CH2X group (approximately 17 ppm) while the signals of the
1
remaining carbons are very little affected (<1 ppm). The H and 13C NMR data of
substances 5a–5c, 6a–6c are given in Tables II and III. The reducing hexopyranoses,
1
which are formed in small amounts, were identified based on the H and 13C NMR
spectra of authentic samples.
We assumed6 that the mechanism of hydrolysis of substances 5a–5c is similar to that
for other 2-chloroethyl sulfides7, i.e. that in the polar aqueous medium, the chloride ion
is split off with the participation of the neighbouring sulfur atom giving rise to the
unstable episulfonium salts 7, which give the hydroxyethyl thioglycosides 6a–6c, thiirane,
and hexopyranosyl cations 8 which, in turn, react with water to give the reducing
hexoses (Scheme 1).
Since the reaction of the chloroethyl thioglycosides 5a–5c is accompanied by libera-
tion of the equivalent amount of hydrogen chloride, we verified on authentic samples of
TABLE I
Reaction of chloroethyl thioglycosides 5a–5c with water. Population of the components of reaction
mixture (after 48 h standing)
Population of reaction components after 48 h standing
Starting
compound
–SCH2CH2Cl
–SCH2CH2OH
–OH(α)a
–OH(β)b
5a
5b
5c
8% (5a)
10% (5b)
5.5% (5c)
78% (6a)
74% (6b)
86% (6c)
5% (Gal-α)
9% (Gal-β)
6% (Glc-α)
10% (Glc-β)
5% (GlcNAc-α)
3.5% (GlcNAc-β)
a
b
Corresponding α-D-hexoses. Corresponding β-D-hexoses.
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Cerny, Trnka, Budesinsky:
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

Chloroethyl Thioglycosides
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Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1494
Cerny, Trnka, Budesinsky:
O
R
O
R
O
SCH CH Cl
S
SCH CH OH
2
2
2
2
Cl
+ HCl
R
5
7
6
O
R
S
Cl
+
+
R = OH or NHAc
8
SCHEME 1
hydroxyethyl thioglycosides 6a–6c that the decrease in the pH value of the reaction
medium does not cause their hydrolysis to the reducing hexoses even in several days of
standing at room temperature. In agreement with the expected hydrolysis mechanism,
we were able to demonstrate that the thiirane signal (singlet at δ 2.38) is present in the
1H NMR spectra of chloroform extracts of aqueous solutions of the chloroethyl thio-
glycosides 5a–5c; addition of the authentic sample of thiirane increases the intensity of
that signal. The mechanism of this reaction of aqueous solutions of chloroethyl thiogly-
cosides is also borne out by the facts that water-insoluble thiirane polymers separate
from the solutions and that authentic thiirane also polymerizes to poly(thiirane) in simi-
lar reaction conditions8. The thiirane polymers were characterized by their NMR spec-
tra (see Experimental).
TABLE III
Carbon-13 chemical shifts (ppm) of compounds 5 and 6 in D2O
Compound C-1
C-2
C-3
C-4
C-5
C-6
S–CH2–
–CH2–X
–NHAc
5a
5b
5c
6a
6b
6c
87.42 80.52 70.86 70.17 75.17 62.52
88.39 82.68 75.08 72.27 79.96 63.66
85.62 55.71 80.93 70.72 76.07 61.81
87.32 80.30 71.06 70.17 75.25 62.52
88.23 82.68 75.08 72.27 80.20 63.66
85.33 55.70 80.81 70.71 76.06 61.80
33.92
35.30
33.74
33.75
35.06
33.43
45.41
46.76
44.77
62.52
63.90
61.94
–
–
175.43; 23.09
–
–
175.40; 23.07
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Chloroethyl Thioglycosides
1495
Furthermore, we examined the reactions of phenol and aniline with the thioglyco-
sides 5a–5c in 1% aqueous solutions of sodium carbonate9. We found that in addition
to the hydrolysis products of the starting thioglycosides 5a–5c (see above), the corres-
ponding 2-phenoxyethyl or 2-phenylaminoethyl derivatives 9a, 10a and 9b, 10b, re-
spectively, are also formed in yields of 27–56%.
CH2OH
OH
CH2OH
OH
O
O
SCH2CH2X
SCH2CH2X
HO
HO
OH
NHAc
X = OC6H5
9a,
9b,
X = OC6H5
10a,
10b,
X = NHC6H5
X = NHC6H5
The corresponding phenyl glycosides or N-phenylglycosylamines failed to be identi-
fied in the reaction mixtures; this is consistent with the short lifetime of the hexopy-
ranosyl cations10, which react rapidly with the surrounding water molecules. Based on
these results we developed a method of 1-thioglycosylethylation of some proteins and
polymeric carriers in aqueous medium in physiological conditions11.
The structure of the compounds prepared within this work and their occurrence in the
4C1 conformations was proved by NMR spectroscopy (Table II).
EXPERIMENTAL
The melting points, determined on a Boëtius micro melting-point apparatus, are uncorrected. The op-
tical rotations were measured on a Bendix–Ericsson ETL-NPL 143 A polarimeter at 20 to 22 °C. The
1H and 13C NMR spectra were measured on a Varian UNITY-500 spectrometer (1H at 500 MHz;
13C at 125.7 MHz) in CDCl3, D2O, or CD3OD solutions. The 2D-COSY technique was applied to the
structural assignment of the proton signals where appropriate. The 13C NMR spectra were measured
by using the attached proton test pulse sequence. Mass spectra were measured on a ZAB-EQ (VG
Analytical) instrument using the FAB method (TG matrix, Xe ionization). Thin layer chromatography
was performed on DC Alufolien plates (Merck) having a layer of Kieselgel 60 F254. Detection con-
sisted in spraying with 50% sulfuric acid and mineralization; an UV lamp was also employed for
derivatives of aromatic compounds. Preparative chromatography was carried out in columns contain-
ing Kieselgel 60 silica gel (Merck) 70–230 mesh ASTM. The solutions were evaporated at a reduced
pressure (water jet pump) at temperatures not exceeding 40 °C. Ethylene sulfide (thiirane, purity >97%)
was obtained from Fluka Chemie AG.
2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-1-thio-β-D-glucopyranose (3c)
To a solution of the thiouronium salt12 2c (24.0 g, 54 mmol) in water (55 ml) were added potassium
disulfite (10.5 g, 47 mmol) and chloroform (100 ml), and the stirred mixture was heated on a water
bath at 80 °C for 20 min. The chloroform layer was separated, washed with water, dried with anhy-
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

1496
Cerny, Trnka, Budesinsky:
drous Na2SO4, and distilled to dryness. The product was recrystallized from ethanol. Yield 18.1 g
(91%), m.p. 165–167 °C, [α]D –19° (c 0.75, chloroform) (ref.13: m.p. 167–168 °C, [α]D –14.5° (c 0.9,
chloroform)). TLC (chloroform–methanol 15 : 1): RF 0.13. For C14H21NO8S (363.8) calculated:
46.27% C, 5.82% H, 3.85% N, 8.82% S; found: 46.21% C, 5.83% H, 3.91% N, 8.76% S.
Acetates of 2-Chloroethyl Thioglycosides 4a–4c. General Procedure
To a solution of the thiohexose 3a–3c (10 g, 27.5 mmol) in acetone (35 ml) were added a solution of
K2CO3 (3.85 g, 77 mmol) in water (30 ml) and 1-bromo-2-chloroethane (11 g, 77 mmol). The mixture
was agitated under argon at room temperature and the reaction was monitored by TLC using the
benzene–acetone 4 : 1 or ethyl acetate–benzene 2 : 1 system. After completion of the reaction
(roughly in 1 h), the reaction mixture was extracted twice with chloroform (60 ml in total), the com-
bined extracts were washed with 3% hydrochloric acid and water and dried with anhydrous sodium
sulfate, and the solvent was removed by evaporation. The remaining syrup was crystallized from an-
hydrous methanol or from a dichloromethane–ether–light petroleum mixture.
2-Chloroethyl 2,3,4,6-tetra-O-acetyl-1-thio-β-D-galactopyranoside (4a). The starting thiohexose 3a
was prepared following refs4,5. Yield 9.9 g (85%), m.p. 76–78 °C, [α]D –10° (c 1.2, chloroform) (ref.14:
syrup, [α]D –6.4° (c 0.5, chloroform)). For C16H23ClO9S (426.9) calculated: 45.02% C, 5.43% H,
8.31% Cl, 7.51% S; found: 45.13% C, 5.46% H, 8.64% Cl, 7.65% S.
2-Chloroethyl 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranoside15 (4b). The starting thiohexose 3b
was prepared following ref.3. Yield 9.5 g (81%), m.p. 97–98 °C, [α]D –38° (c 0.7, chloroform). For
C16H23ClO9S (426.9) calculated: 45.02% C, 5.43% H, 8.31% Cl, 7.51% S; found: 45.28% C, 5.41%
H, 8.06% Cl, 7.33% S.
2-Chloroethyl 2-acetamido-3,4,6-O-acetyl-2-deoxy-β-D-glucopyranoside (4c). This compound, which was
prepared from the thiohexose 3c, crystallized directly after diluting the reaction mixture with water.
Yield 10.1 g (86%), m.p. 196–198 °C, [α]D –28° (c 0.2, chloroform). TLC (ethyl acetate–2-propanol–
water 9 : 4 : 2): RF 0.83. For C16H24ClNO8S (425.9) calculated: 45.12% C, 5.68% H, 8.32% Cl, 3.39% N,
7.53% S; found: 45.29% C, 5.63% H, 8.17% Cl, 3.25% N, 7.83% S.
2-Bromoethyl 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-galactopyranoside (4d)
The substance was prepared following ref.4 and purified for analytical purposes by chromatography
on an L 100/250 silica gel column (Lachema); elution with chloroform. Syrup, [α]D –5.7° (c 0.5,
chloroform).
2-Bromoethyl 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-glucopyranoside (4e)
The substance was prepared following ref.3 and purified by chromatography on a silica gel column;
elution with chloroform. M.p. 108–110 °C, [α]D –32° (c 0.5, chloroform).
2-Iodoethyl 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-galactopyranoside (4f)
Solution of 4d (5.0 g, 12.5 mmol) in anhydrous acetone (50 ml) was heated with sodium iodide (2.45 g,
61 mmol) to boil under a reflux condenser for 2 h. The separated sodium bromide was filtered off
and the solution was evaporated to a syrup. The latter was dissolved in chloroform and washed with
water (2 × 25 ml), and the chloroform layer was dried with anhydrous sodium sulfate and evaporated
to dryness. Yield 4.9 g (89%), syrup, [α]D –7.6° (c 0.5, chloroform). For C16H23IO9S (521.3) calcu-
lated: 36.86% C, 4.45% H, 24.85% I; found: 37.19% C, 4.51% H, 24.15% I.
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

Chloroethyl Thioglycosides
1497
2-Iodoethyl 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-glucopyranoside (4g)
The substance was prepared from the starting compound 4e by a procedure15 analogous to that used
for the iodo derivative 4f. The syrup was crystallized from ethanol. Yield 4.9 g (89%), m.p. 125–126 °C,
[α]D –35.8° (c 0.5, chloroform). For C16H23IO9S (521.3) calculated: 36.86% C, 4.45% H, 24.85% I,
6.15% S; found: 37.15% C, 4.69% H, 24.23% I, 6.27% S.
2-Hydroxyethyl 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-galactopyranoside14 (4h)
A) Thiogalactose 3a (10.9 g, 30 mmol) in acetone (30 ml) was alkylated by agitation with 2-iodo-
ethanol (5.8 g, 33 mmol) in the presence of K2CO3 (4.14 g, 30 mmol). The reaction mixture was
treated as reported above for substances 4a–4c. The syrup obtained was chromatographed on a col-
umn of Silica Gel L 100/250 (Lachema); elution with chloroform. Yield 8.1 g (70%), crystalline so-
lidified syrup, [α]D +23° (c 0.5, chloroform). TLC (benzene–ethyl acetate 1 : 1): RF 0.25. For
C16H24O10S (408.4) calculated: 47.05% C, 5.93% H, 7.85% S; found: 47.28% C, 6.02% H, 7.62% S.
B) A gentle stream of oxirane was fed for roughly 2 h into a solution of thiogalactose 3a (7.2 g,
20 mmol) in chloroform (50 ml). After completion of the reaction (TLC, see above), the reaction
mixture was nitrogen purged and extracted consecutively with 5% sodium hydroxide (25 ml), 5%
sulfuric acid (25 ml), and water. After drying, the chloroform solution was evaporated and chroma-
tographed (see procedure A). Yield 6.7 g (88%), properties identical with those of the product pre-
pared sub A).
2-Hydroxyethyl 2,3,4,6-Tetra-O-acetyl-1-thio-β-D-glucopyranoside (4i)
A) The substance was prepared by alkylation of compound 3b (10.9 g, 30 mmol) with 2-iodoetha-
nol (5.8 g, 33 mmol) by procedure A for substance 4h above. Yield 10.5 g (86%), m.p. 70–73 °C,
[α]D –14° (c 0.5, chloroform). TLC (benzene–ethyl acetate 1 : 1): RF 0.24. For C16H24O10S (408.4)
calculated: 47.05% C, 5.93% H, 7.85% S; found: 47.32% C, 6.21% H, 7.62% S.
B) The substance was obtained by reacting compound 3b (7.2, 20 mmol) with oxirane as described
in procedure B for substance 4h above. Yield 6.6 g (87%).
Preparation of the Free Thioglycosides 5a–5c, 6a, 6b by Deacetylation after Zemplén
To a solution of acetylated thioglycoside 4a–4c, 4h, 4i (10 g) in anhydrous methanol (100 ml) was
added sodium methoxide prepared from sodium (0.1 g) and methanol (10 ml). The system was
allowed to stand for 2 h at room temperature or overnight in a refrigerator at 0 °C, during which the
deacetylation was accomplished (TLC monitoring using the benzene–acetone 4 : 1 or ethyl acetate–
2-propanol–water 9 : 4 : 2 system). Where the crystalline product failed to separate, the solution was
neutralized by adding a catex (Dowex 50 W × 8 in the H+ cycle) and evaporated to a syrup. Addi-
tional fractions were obtained from the mother liquors on crystallization from methanol.
2-Chloroethyl 1-thio-β-D-galactopyranoside (5a). M.p. 93–98 °C (decomposition), [α]D –23° (c 0.8,
water), (ref.4: m.p. 92–98 °C, [α]D –24.6° (c 0.5, water)), yield 5.5 g (91%). The product crystallizes
with an approximately equimolar amount of methanol, which can be removed by drying in a vacuum
over P2O5 at 64 °C. For C8H15ClO5S (258.7) calculated: 37.14% C, 5.84% H, 13.70% Cl, 12.39% S;
found: 37.19% C, 5.84% H, 13.81% Cl, 12.37% S.
2-Chloroethyl 1-thio-β-D-glucopyranoside (5b). Yield 5.4 g (90%) of a partly crystallized syrup,
whose purification for elemental analysis failed; [α]D –38° (c 0.7, water).
2-Chloroethyl 2-acetamido-2-deoxy-1-thio-β-D-glucopyranoside (5c). Yield 6.24 g (89%), m.p. 174–176 °C
(dec.), [α]D –34° (c 0.4, methanol). For C10H18ClNO5S (299.8) calculated: 40.06% C, 6.05% H, 11.83% Cl,
4.67% N, 10.69% S; found: 37.89% C, 6.10% H, 11.53% Cl, 4.43% N, 10.51% S.
Collect. Czech. Chem. Commun. (Vol. 61) (1996)

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Cerny, Trnka, Budesinsky:
2-Hydroxyethyl 1-thio-β-D-galactopyranoside (6a). Yield 4.9 g (83%), m.p. 148–150 °C, [α]D –21° (c 0.7,
water) (ref.4: m.p. 151–152 °C, [α]D –21.4° (c 0.5, water); ref.16: m.p. 148.5–150 °C, [α]D –21.8° (c 0.55,
water)).
2-Hydroxyethyl 1-thio-β-D-glucopyranoside (6b). Yield 4.8 g (81%), m.p. 98–99 °C, [α]D –55° (c 0.27,
water). For C8H16O6S (240.3) calculated: 39.98% C, 6.66% H, 13.33% S; found: 40.31% C, 6.50% H,
13.28% S.
Reactions of Phenol or Aniline with Chloroethyl Thioglycosides 5a and 5c. Preparation of Thiogly-
cosides 9a, 9b, 10a, 10b
Phenol (1.88 g, 20 mmol) or aniline (1.86 g, 20 mmol) and chloroethyl thioglycoside 5a (1 g, 3.9
mmol) or 5c (1 g, 3.3 mmol) were added to a solution of sodium carbonate (1 g, 9.4 mmol) in water
(100 ml), and the whole was stirred vigorously at room temperature for 24 h. The reaction was moni-
tored by TLC using the ethyl acetate–2-propanol–water 9 : 4 : 2 system. After all the starting chlo-
rothioglycoside had reacted, the reaction mixture was extracted with benzene (3 × 10 ml), the pH of
the aqueous solution was adjusted with acetic acid to pH 7, and the solution was filtered with acti-
vated carbon and evaporated to dryness. The residue was treated as given below, and chromato-
graphed on a silica gel column (50 g) using the ethyl acetate–2-propanol–water 16 : 2 : 1 system.
2-Phenoxyethyl 1-thio-β-D-galactopyranoside (9a). The evaporation residue was dissolved in water
and the solution was demineralized (Dowex 50 W × 8 in the H+ cycle) and evaporated to dryness.
The residue was chromatographed on a silica gel column. Substance 5a (1 g) gave the thioglycoside
9a in a yield of 0.34 g (28%); the product was recrystallized from ethanol. M.p. 103–105 °C, [α]D
–24° (c 1.8, methanol). TLC: RF 0.39. For C14H20O6S (316.4) calculated: 53.15% C, 6.37% H,
10.13% S; found: 52.83% C, 6.37% H, 10.06% S.
2-Phenylaminoethyl 1-thio-β-D-galactopyranoside (9b). The evaporation residue was extracted
with hot anhydrous methanol, the solvent was removed by evaporation, and the residue was chroma-
tographed on a silica gel column. Thioglycoside 5a (2.7 g) and aniline afforded thioglycoside 9b
(0.68 g, 56%), which was recrystallized from an ethanol–ether mixture. M.p. 127 – 130 °C, [α]D –26°
(c 0.27, ethanol). TLC: RF 0.34. For C14H21NO5S (315.4) calculated: 53.32% C, 6.71% H, 4.44% N,
10.17% S; found: 53.04% C, 6.86% H, 4.34% N, 10.16% S.
2-Phenoxyethyl 2-acetamido-2-deoxy-1-thio-β-D-glucopyranoside (10a). The product crystallized
directly from the reaction mixture and was recrystallized from ethanol. Thioglycoside 5c and phenol
gave thioglycoside 10a in a yield of 0.5 g (42%). M.p. 200–202 °C, [α]D –31° (c 0.23, methanol).
TLC: RF 0.44. FAB MS, m/z: 358 (M + H), 380 (M + Na). For C16H23NO6S (357.0) calculated:
53.77% C, 6.49% H, 3.92% N, 8.97% S; found: 53.24% C, 6.60% H, 3.70% N, 8.60% S.
2-Phenylaminoethyl 2-acetamido-2-deoxy-1-thio-β-D-glucopyranoside (10b). The evaporation
residue was extracted with 2-propanol, the solvent was removed by evaporation, and the residue was
chromatographed on a silica gel column. Thioglycoside 5c (1.0 g) gave substance 10b in a yield of
0.49 g (41%). M.p. 152–154 °C, [α]D –31° (c 0.11, ethanol). TLC: RF 0.48. FAB MS, m/z: 357 (M + H),
379 (M + Na), for C16H24N2O5S calculated m/z 356.
NMR Monitoring of Hydrolysis of Chloroethyl Thioglycosides 5a–5c
A) The chloroethyl thioglycoside 5a, 5b, or 5c (0.1 mmol) was dissolved in deuterium oxide and
its NMR spectrum was measured immediately. Subsequently, the solution was allowed to stand at
room temperature and stirred occasionally. In 30 or 60 min the solution was extracted with deuterio-
chloroform (1 ml) and the spectra of the two phases were measured. The aqueous phase contained,
in addition to the starting substance, the α and β anomers of the reducing hexose (D-galactose, D-glu-
cose or 2-acetamido-2-deoxy-D-glucose) and the corresponding 2-hydroxyethyl thioglycoside 6a, 6b,
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or 6c. The H NMR spectrum of the chloroform layer exhibited the thiirane signal (singlet at δ 2.38),
whose intensity increased on addition of the authentic sample.
B) Solution of the chloroethyl thioglycoside 5a, 5b, or 5c in deuterium oxide was allowed to stand
at room temperature, and the decomposition was monitored by NMR spectroscopy. The reaction mix-
ture composition in 48 h of standing is given in Table I. The fractions of the components were deter-
mined based on the intensities of signals of the anomeric carbons C-1, hydrogens H-1, and hydrogens
in the CH2OH or CH2Cl group in the aglycone part of the glycoside. A small quantity of a white
amorphous precipitate separated slowly from the solution due to the polymerization of thiirane. The
precipitate was mixed with water, centrifuged, and dried over P2O5, and its NMR spectra were
measured in hexadeuteriodimethyl sulfoxide. The spectra contained signals identical with those of
poly(thiirane) formed from authentic thiirane in aqueous hydrochloric acid in conditions simulating
those of hydrolysis of chloroethyl thioglycosides (see later), as well as signals corresponding to the
sugar parts. The presence of hexoses and hydroxyethyl glycosides in the reaction mixture after the
hydrolysis of the chloroethyl thioglycosides 5a–5c was also demonstrated by chromatography on a
Whatman No. 4 paper using the butanol–acetic acid–water 4 : 1 : 3 system, applying detection with
ammoniacal solution of silver nitrate and heating. Before application, the solution samples were neu-
tralized with the anex Dowex 2 in the HO– cycle.
Polymerization of Authentic Thiirane in 1 M HCl
Thiirane (0.6 g, 10 mmol) was added to 1 M HCl (10 ml), and the mixture was agitated occasionally
at room temperature. Gradually, the solution became turbid and a white amorphous substance precipi-
tated. The precipitate was separated by centrifugation, rinsed with distilled water, and dried over
P2O5. The poly(thiirane) so obtained was partly dissolved in hexadeuteriodimethyl sulfoxide, and its
13C and 1H NMR spectra were measured. The 13C NMR spectrum only displayed signals of carbon
atoms in the CH2–S group (δ 24.51, 27.41, 31.48, 31.64, 31.76. 31.97, 32.02, 34.07, 35.20) and in the
CH2–O group (δ 61.24). Similarly, the 1H NMR spectrum showed signals of hydrogen atoms in the
CH2–S group at δ 2.45–2.91 and in the CH2–O group at δ 3.53–3.75 at the ratio of approximately 12 : 1
in favour of the former group.
Stability of Hydroxyethyl Thioglycosides 6a, 6b in 1 M HCl
Solutions of the substances 6a, 6b (10 mg) in 1 M HCl (2 ml) were allowed to stand at room tem-
perature for 7 days, and their composition was monitored by TLC on silica gel using the chloroform–
2-propanol–concentrated ammonia–water 10 : 10 : 1 : 1 system. No reducing hexoses were detected
with 50% sulfuric acid and mineralization.
This work was partly supported by the Fund for the Development of Universities, Grant No. 40781
(1994).
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