Thiazoles in glycosylation reactions: Novel synthesis of thiazole thioglycosides

Article abstract of DOI:10.1002/hc.21404

This research reports a novel method for synthesizing new thiazole thioglycosides. This series of thiazole thioglycosides were designed by the reaction of potassium cyanocarbonimidodithioate 2 with benzoyl acetonitrile 3a and ethyl bromoacetate 3b in the presence of ethanol-KOH to give the corresponding potassium 4-amino-5-substituted-thiazole-2-thiolates 4a,b. The latter compounds were treated with peracetylated sugar bromides 6a,b in DMF to give high yields of the corresponding thiazole thioglycosides 7a-d. Treatment of thiazole salts 4a,b with hydrochloric acid gave the corresponding 3-mercaptothiazole derivatives 5a,b. The latter compounds were reacted with peracetylated sugars 6 in sodium hydride in DMF to produce the S-glycosyl compounds 7a-d. Ammonolysis of the protected thiazole thioglycosides 6a-h gave the corresponding free thiazole thioglycosides 8a-d. The compounds have been characterized by ¹³C NMR, ¹H NMR, and IR.

Full text of DOI:10.1002/hc.21404

Received: 15 June 2017
DOI: 10.1002/hc.21404
Revised: 17 September 2017
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R E S E A R C H A R T I C L E
Thiazoles in glycosylation reactions: Novel synthesis of thiazole
thioglycosides
Mamdouh A. Abu-Zaied1
Galal H. Elgemeie2
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1Green Chemistry Department, National
Research Centre, Giza, Egypt
2Chemistry Department, Faculty of Science,
Helwan University, Helwan, Cairo, Egypt
Abstract
This research reports a novel method for synthesizing new thiazole thioglycosides.
This series of thiazole thioglycosides were designed by the reaction of potassium
cyanocarbonimidodithioate 2 with benzoyl acetonitrile 3a and ethyl bromoacetate 3b
in the presence of ethanol-KOH to give the corresponding potassium 4-amino-5-sub
stituted-thiazole-2-thiolates 4a,b. The latter compounds were treated with peracety-
lated sugar bromides 6a,b in DMF to give high yields of the corresponding thiazole
thioglycosides 7a-d. Treatment of thiazole salts 4a,b with hydrochloric acid gave the
corresponding 3-mercaptothiazole derivatives 5a,b. The latter compounds were re-
acted with peracetylated sugars 6 in sodium hydride in DMF to produce the S-
glycosyl compounds 7a-d. Ammonolysis of the protected thiazole thioglycosides
6a-h gave the corresponding free thiazole thioglycosides 8a-d. The compounds have
been characterized by 13C NMR, 1H NMR, and IR.
Correspondence
Galal H. Elgemeie, Chemistry Department,
Faculty of Science, Helwan University,
Helwan, Cairo, Egypt.
Email: elgemeie@yahoo.com
P-glycoprotein antagonist activity as well as against human
colon carcinoma cells.[13] In light of the above findings and
1
INTRODUCTION
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The thiazole nucleus plays an important role in medicinal
chemistry, making it one of the intensively studied hetero-
cycles.[1] Tiazofurin (2-(β-d-ribofuranosyl)thiazole) is a
well-known synthetic C-nucleoside with interesting antican-
cer activity in a variety of tumor systems (Figure 1).[2] The
Tiazofurin biological activity is rendered to its potential to in-
hibit inosine monophosphate dehydrogenase which will lead
to shutdown of guanine nucleotide synthesis.[3] In spite of the
known efficacy of Tiazofurin, its high toxicity and lack of
specificity represent a problem for its clinical use.[4] For this
reason, many Tiazofurin analogues were synthesized aiming
to produce derivatives with reduced toxicity.[5] As a part of
our recent program directed toward syntheses of catabolically
stable nucleoside analogues, we have recently reported on the
synthesis and antiviral activity of a number of heterocyclic
thioglycosides that have an interesting cytotoxic activity such
as pyridine thioglycosides,[6] pyrimidine thioglycosides,[7]
imidazole thioglycosides,[8] oxadiazole thioglycosides,[9]
thiophene thioglycosides,[10] quinoline thioglycosides,[11]
and thienopyrazole thioglycosides.[12] We have reported
that the thioglycosides of dihydropyridine show a strong
previous reports on thiazole thioglycosides,[14,15] the purpose
of this work was to design, synthesize, and investigate the
biological activity of novel thiazole thioglycosides carrying
carbohydrate residues by forming S-glycosidic bonds.
The synthesis was initiated by the condensation of cyana-
mide 1 and carbon disulfide in ethanolic potassium hydroxide
in a simple one-step protocol to give the potassium cyanocar-
bonimidodithioate 2 (Scheme 1). Compound 2 is readily reacted
with one equivalent of phenacyl bromide 3a and ethyl bromoa-
cetate 3b in ethanol-KOH at room temperature for 24 hours to
give the corresponding potassium 4-amino-5-substituted-thiazo
le-2-thiolates derivatives 4a,b in good yields. Acidification of
the latter at room temperature has resulted in the formation of
the corresponding 3-mercaptothiazole 5a,b. Compounds 4a,b
undergoes reaction with tetra-O-acetyl-α-d-glucopyranosyl bro-
mide 6a and tetra-O-acetyl-α-d-galactopyranosyl bromide 6b
in DMF at ambient temperature to give an excellent yields of
the corresponding thiazole S-glycosides 7a-d (Scheme 1). It has
been confirmed that the cis-(α) sugars maybe reacted through
SN2 reaction mechanism to give the β-glycoside reaction prod-
ucts. [16] The structures of 7a-d were proved according to their
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Heteroatom Chemistry. 2017;e21404.
https://doi.org/10.1002/hc.21404
wileyonlinelibrary.com/journal/hc
© 2017 Wiley Periodicals, Inc.
1 of 6

2 of 6
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NH2-CN
1
CS2
KOH/EtOH
r.t
N
SK
NC
SK
2
O
Br
KOH/EtOH
r.t
R
3a,b
NH2
N
R
AcO
R1
KS
S
O
O
4a,b
OAc
DMF
r.t/8h
H
r.t
Br
OAc
R2
6a,b
NH2
N
R
NH2
R
S
S
AcO
R1
N
6a,b
NaH/DMF/r.t
O
O
HS
S
OAc
O
R2
OAc
5a,b
7a-d
MeOH/NH3
r.t/10min
NH2
R
N
S
S
HO
R1
O
O
OH
R2
OH
SCHEME 1 Synthetic pathway for
8a-d
thiazole thioglycosides 7a-d and 8a-d
spectral data (IR, 13C NMR, 1H NMR). For example, the ano-
The structures of 8a-d were proved based on spectral data. Thus,
the anomeric proton in the 1H NMR spectrum for 8a appeared
as a doublet with J1,2 = 10.5 Hz at δ 4.41-4.42, confirming the
presence of only the β-D-configuration (Scheme 1).
In conclusion, a novel synthesis of interesting new class
of thiadiazoles and their corresponding thioglycosides is
reported. The results represent a new, simple, and econom-
ically effective method for the synthesis of the Tiazofurin
analogues. The simple and ambient temperature reaction
1
meric proton in the H NMR spectrum for 7a appeared as a
doublet at δ 5.33-5.34 ppm with a 10.2 Hz spin-spin coupling
constant indicating the β-configuration. The glucose protons
appeared at δ 3.98-4.92 ppm. Compounds 7a-d can also be pre-
pared by reaction of the thiazole-3-thiole derivatives 5a,b with
halo sugars 6 in DMF-sodium hydride at room temperature. The
thioglycosides 7a-d reacted with MeOH-NH3 at ambient tem-
perature to give the deprotected derivatives 8a-d in good yields.

ABU-ZAIED AnD ELGEMEIE
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The mixture was stirred magnetically until completion (TLC,
12 hours), then the resulting precipitate was collected by filtra-
tion and recrystallized from EtOH to give compounds 4a,b.
O
NH2
S
N
2.1.1
Sodium 4-amino-5-benzoylthiazole-2-
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thiolate (4a)
HO
White solid (EtOH); yield (80%); mp >300°C; IR (KBr,
cm−1) υ 3346 (NH2), 3039 (aromatic H), 1714 (C=O), 1608
(C=N). C10H7KN2OS2: C, 43.77; H, 2.57; N, 10.21; S, 23.37.
Found: C, 43.60; H, 2.55; N, 10.12; S, 23.30%.
O
OH
OH
2.1.2
Potassium 4-amino-5-
Tiazofurin
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(ethoxycarbonyl)thiazole-2-thiolate (4b)
FIGURE 1 Structure of Tiazofurin
White solid (EtOH); yield (76%); mp >300°C; IR (KBr, cm−1)
υ 3374 (NH2), 1716 (C=O), 1598 (C=N). C6H7KN2O2S2: C,
29.73; H, 2.91; N, 11.56; S, 26.46. Found: C, C, 29.63; H,
2.76; N, 11.40; S, 26.33%.
conditions, clean reaction products, and availability of start-
ing materials make this approach as innovative and useful
to the present methods for the formation of thiazole glyco-
sides. Further investigations on the use of this method for the
preparation of other biologically interesting glycosides will
be investigated. The prepared thioglycosides are promising
as good starting materials for the preparation of other inter-
esting carbohydrate compounds.
2.2
(5a-d)
General procedure for the synthesis of
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To a solution of compound 4a,b (10 mmol) in water, 5 drops of
HCl (36%) was dropped at room temperature (25°C). After an
additional stirring, a precipitate thus formed was collected by fil-
tration and crystallized from EtOH to give 5a-d as a white solid.
2
EXPERIMENTAL
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All melting points were uncorrected on a Gallenkamp melt-
ing point apparatus. The IR Spectra were recorded on a Pye
Unicam Spectra-1000 (KBr disk). NMR spectra were re-
corded on a Varian 500 MHz spectrometer in (CD3)2 SO
using Si(CH3)4 as an internal standard. Elemental analy-
ses were obtained from the Micro-analytical Data Center at
Cairo University, Egypt. Progress of the reactions was judged
by TLC using aluminum sheets coated with silica gel F254
(Merck) and viewing under a short-wavelength UV lamp. All
evaporations were carried out under reduced pressure at 40°C.
2.2.1
4-Amino-2-mercaptothiazol-5-yl)
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(phenyl)methanone (5a)
White solid (EtOH); yield (78%); mp 264°C; IR (KBr, cm−1)
υ 3379 (NH2), 3028 (aromatic H), 1715 (C=O), 1593 (C=N);
1H NMR (500 MHz, DMSO): δ 7.45 (s, D2O exch., 2H,
NH2), 7.65-8.22 (m, 5H, C6H5), 13.26 (s, D2O exch., 1H,
SH).); 13C NMR: δ 122.00 (C-5), 128.11-140.00 (6C, Ar-C),
146.22 (C-4), 155.21 (C-2), 168.00 (C=O). Anal. Calcd. For
C10H8N2OS2: C, 50.83; H, 3.41; N, 11.85; S, 27.14. Found:
C, 50.77; H, 3.28; N, 11.73; S, 27.11%.
2.1
(4a,b)
General procedure for the synthesis of
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2.2.2
Ethyl 4-amino-2-mercaptothiazole-5-
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carboxylate (5b)
cyanocarbonimidodithioate 2 (10 mmol) was added to a stirred
solution of compounds 3a,b (10 mmol) in absolute ethanol
(20 mL) containing KOH (10 mmol) at room temperature.
White solid (EtOH); yield (70%); mp 240°C; IR (KBr,
cm−1) υ 3389 (NH2), 1716 (C=O), 1589 (C=N); H NMR
1
R
7
a
R1
R2
R
R1
H
R2
3,4,5
R
8
a
C6H5
OH
a
H
OAc
C6H5
OEt
C6H5
OEt
b
OEt
C6H5
OEt
H
OH
H
b
c
H
OAc
H
b
OH
c
C6H5
OEt
OAc
OAc
FIGURE 2 List of synthesized
d
OH
H
d
H
derivatives 3-5, 7a-d, 8a-d

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ABU-ZAIED AnD ELGEMEIE
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(500 MHz, DMSO): δ 1.42 (t, 3H, J = 6.4 Hz, CH3), 4.52 (q,
2H, CH2), 7.25 (s, D2O exch., 2H, NH2), 13.22 (s, D2O exch.,
1H, SH); 13C NMR: δ 16.23 (CH3), 63.52 (CH2), 124.64
(C-5), 147.36 (C-4), 157.71 (C-2), 169.46 (C=O). Anal.
Calcd. For C6H8N2O2S2: C, 35.28; H, 3.95; N, 13.71; S,
31.39. Found: C, C, 35.23; H, 3.79; N, 13.63; S, 31.24%.
2.3.4
Ethyl 4-amino-2-(2′,3′,4′,6′-tetra-
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O-acetyl-β-d-glucopyranosylthio)thiazole-5-
carboxylate (7b)
White solid (EtOH) yield (80%); mp 234°C; [α]D25 = +11.2
(c = 1 g/dL, EtOH);IR(KBr, cm−1)υ3378(NH2), 2967(CH),
1756 (4C=O), 1715 (C=O); 1H NMR (500 MHz, DMSO): δ
1.42(t, 3H, J = 6.4 Hz, CH3), 2.03-2.26 (4s, 12H, 4xOAc),
4.12 (m, 2H, 2H-6′), 4.26 (m, 1H, H-5′), 4.38 (q, 2H, CH2),
4.42 (t, 1H, J = 9.2 Hz, H-4′), 4.54 (t, 1H, J = 9.1 Hz, H-
2.3
General procedure for the synthesis of
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(7a-d)
3′), 4.84 (t, 1H, J = 9.2 Hz, H-2′), 5.42-5.43 (d, 1H, J1′-2′
=
2.3.1
Method A
9.5 Hz, H-1′), 7.34 (s, D2O exch., 2H, NH2); 13C NMR: δ
16.42 (CH3), 22.19 (4xOAc), 61.14(CH2), 62.44 (C-6′),
68.28 (C-5′), 72.54 (C-4′), 73.64 (C-3′), 77.64 (C-2′), 84.26
(C-1′), 127.19 (C-5), 145.64 (C-4), 168.48 (C-2), 169.84
(C=O), 174.56 (4C=O). Anal. Calcd. For C20H26N2O11S2: C,
44.94; H, 4.90; N, 5.24; S, 12.00. Found: C, 44.84; H, 4.84;
N, 5.16; S, 11.92%.
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To a solution of 4a,b (10 mmol) in dry DMF (20 mL), a
solution of 2,3,4,6-tetra-O-acetyl-α-d-gluco or (galacto)
pyranosyl bromide 6a,b (10 mmol) in DMF was dropped
within 30 minutes. Stirring was continued for 6 hours.
After completion, the reaction mixture was poured into ice
water, and the resulting precipitate was collected by fil-
tration, dried, and recrystallized from EtOH to give com-
pounds 7a-d.
2.3.5
4-Amino-2-(2′,3′,4′,6′-tetra-O-acetyl-
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β-d-galactopyranosylthio) thiazol-5-yl)(phenyl)
methanone (7c)
2.3.2
Method B
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White solid (EtOH) yield (80%); mp 246°C; [α]D25 = +19.5
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3384 (NH2), 3041 (ar-
omatic H), 2922 (CH), 1756 (4C=O), 1594 (C=N); 1H NMR
(500 MHz, DMSO): δ 2.03-2.16 (4s, 12H, 4xOAc), 3.88 (m,
2H, 2H-6′), 4.36 (m, 1H, H-5′), 4.69 (t, 1H, J = 9.4 Hz, H-
4′), 4.75 (t, 1H, J = 9.4 Hz, H-3′), 4.89 (t, 1H, J = 9.2 Hz
H-2′), 5.46-5.47 (d, 1H, J1′-2′ = 10.6 Hz, H-1′), 7.59 (s, D2O
exch., 2H, NH2), 7.71-7.92 (m, 5H, C6H5); 13C NMR: δ 22.15
(4xOAc), 62.65 (C-6′), 67.71 (C-4′), 69.74 (C-2′), 74.68 (C-
3′), 76. 44 (C-5′), 84.78 (C-1′), 124.05 (C-5), 129.49-140.62
(6C, Ar-C), 145.25 (C-4), 169.36 (C-2), 172.28 (4C=O),
201.43 (C=O). Anal. Calcd. For C24H26N2O10S2: C, 50.87;
H, 4.63; N, 4.94; S, 11.32. Found: C, 50.82; H, 4.48; N, 4.82;
S, 11.14%.
To a solution of 5a-b (10 mmol) in dry DMF (20 mL), NaH
(15 mmol) was added portionwise through 15 minutes, and
the solution was stirred at room temperature for another
30 minutes. Then, a solution of 2,3,4,6-tetra-O-acetyl-α-
d-gluco or (galacto) pyranosyl bromide 6a,b (10 mmol) in
DMF was dropped within 30 minutes, and the reaction mix-
ture was stirred at room temperature until completion (TLC,
5-10 hours). After completion, the reaction mixture was
poured on ice water, and the resulting precipitate was col-
lected by filtration, dried, and recrystallized from EtOH to
give compounds 7a-d.
2.3.3
4-Amino-2-(2′,3′,4′,6′-tetra-O-acetyl-
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β-d-glucopyranosylthio) thiazol-5-yl)(phenyl)
methanone (7a)
2.3.6
Ethyl 4-amino-2-(2′,3′,4′,6′-tetra-
White solid; (EtOH) yield (84%); mp 220°C; [α]D25 = +9.6
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3385 (NH2), 3035
(aromatic H), 2933 (CH), 1756 (4C=O), 1718 (C=O), 1597
(C=N); 1H NMR (500 MHz, DMSO): δ 1.98-2.08 (4s, 12H,
4xOAc), 3.98 (m, 2H, 2H-6′), 4.52 (m, 1H, H-5′), 4.61 (t,
1H, J = 9.2 Hz, H-4′), 4.83 (t, 1H, J = 9.3 Hz, H-3′), 4.92
(t, 1H, J = 9.3 Hz, H-2′), 5.33-5.34 (d, 1H, J1′-2′ = 10.2 Hz,
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O-acetyl-β-d-galactopyranosylthio)thiazole-5-
carboxylate (7d)
White solid (EtOH) yield (86%); mp 234°C; [α]D25 = +20.0
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3371 (NH2), 3032
(aromatic H), 2929 (CH), 1752 (4C=O), 1722 (CO),
1
1598 (C=N); H NMR (500 MHz, DMSO): δ 1.34 (t,
3H, J = 6.4 Hz, CH3), 2.01-2.13 (4s, 12H, 4xOAc),
3.96 (m, 2H, 2H-6′), 4.36 (q, 2H, CH2), 4.47(m, 2H,
H-6′),4.58(m, 1H,H-5′), 4.65 (t, 1H, J = 9.2 Hz, H-4′),
4.79 (t, 1H, J = 9.3 Hz, H-3′), 4.86 (t, 1H, J = 9.4 Hz,
H-2′), 5.58-5.59 (d, 1H, J1′-2′ = 8.7 Hz, H-1′), 6.98 (s,
D2O exch., 2H, NH2); 13C NMR: δ 16.21 (CH3), 22.43
(4xOAc), 61.47(CH2), 62.42 (C-6′), 68.26 (C-4′), 70.54
H-1′), 7.46 (s, D2O exch., 2H, NH2), 7.72-7.94 (m, 5H,
C6H5);
13C
NMR: δ 21.31 (4xOAc), 62.33 (C-6′), 66.95
(C-4′), 67.86 (C-2′), 75.86 (C-3′), 78.64 (C-5′), 84.65 (C-
1′), 125.17 (C-5), 130.63-139.64 (6C, Ar-C), 146.17(C-4),
168.54 (C-2), 173.38 (4C=O), 204.29 (C=O). Anal. Calcd.
For C24H26N2O10S2: C, 50.87; H, 4.63; N, 4.94; S, 11.32.
Found: C, 50.64; H, 4.55; N, 4.78; S, 11.19%.

ABU-ZAIED AnD ELGEMEIE
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(C-2′), 74.28 (C-3′), 76.18 (C-5′), 84.56 (C-1′), 121.45
(C-5), 148.24 (C-4), 168.29 (C-2), 169.66 (C=O), 172.16
(4C=O). Anal. Calcd. For C20H26N2O11S2: C, 44.94; H,
4.90; N, 5.24; S, 12.00. Found: C, 44.82; H, 4.80; N, 5.18;
S, 12.12%.
146.31 (C-4), 166.18 (C-2), 168.45 (C=O). Anal. Calcd. For
C12H18N2O7S2: C, 39.34; H, 4.95; N, 7.65; S, 17.50. Found:
C, 39.23; H, 4.82; N, 7.58; S, 17.38%.
2.4.3
4-Amino-2-(β-d-galactopyranosylthio)
|
thiazol-5-yl)(phenyl)methanone (8c)
2.4
(8a-d)
General procedure for the synthesis of
White solid (EtOH); yield (72%); mp 166°C; [α]D25 = +14.1
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3522 (OH), 3427
(NH2), 3049 (aromatic H), 2939 (CH), 1708 (C=O); 1H NMR
(500 MHz, CDCl3) δ 3.37-3.46 (m, 2H, 2H-6′), 3.58 (m.1H, H-
5′), 3.62 (t, 1H, J = 9.1 Hz, H-4′), 3.87 (t, 1H, J = 9.4 Hz, H-3′),
4.15 (t, 1H, J = 9.1 Hz, H-2′), 4.36-4.37 (d, 1H, J1′-2′ = 10.2 Hz,
H-1′), 4.81 (s, D2O exch., 1H, 6′-OH), 4.92-5.08 (s, D2O exch.,
3H, 2′-OH, 3′-OH, and 4′-OH), 7.29 (s, D2O exch., 2H, NH2),
7.65-8.17 (m, 5H, C6H5); 13C NMR: δ 62.56 (C-6′), 68.29
(C-5′), 72.82 (C-4′), 74.63 (C-3′), 79.62 (C-2′), 84.58 (C-1′),
126.92 (C-5), 130.53-142.36 (6C, Ar-C), 148.44 (C-4), 167.68
(C-2), 206.24 (C=O). Anal. Calcd. For C16H18N2O6S2: C,
48.23; H, 4.55; N, 7.03; S, 16.09. Found: C, 48.10; H, 4.42; N,
7.01; S, 15.88%.
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Dry gaseous ammonia was passed through a solution
of protected nucleoside 7a-d (10 mmol) in dry metha-
nol (20 mL) for 10 minutes with cooling and stirring,
then the reaction mixture was stirred at room temper-
ature until the reaction was judged complete by TLC
(9-10 hours) using (CHCl3/MeOH 9:1) (Rf, 0.54-0.56).
The resulting mixture was concentrated under reduced
pressure to afford a solid residue which is washed sev-
eral times by boiling chloroform. The residue was dried
and recrystallized from EtOH to give corresponding
compounds 8a-d.
2.4.1
4-Amino-2-(β-d-glucopyranosylthio)
|
thiazol-5-yl)(phenyl)methanone (8a)
2.4.4
Ethyl 4-amino-2-(β-d-
|
galactopyranosylthio)thiazole-5-carboxylate
Whitesolid(EtOH);yield(66%);mp180°C;[α]D25 = +17.4
(8d)
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3542 (OH), 3432
1
White solid (EtOH); yield (80%); mp 178°C; [α]D25 = +16.7
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3507 (OH), 3421
(NH2), 2951 (CH), 1713 (C=O); 1H NMR (500 MHz,
DMSO): δ 1.43 (t, 3H, J = 6.6 Hz, CH3), 3.46 (m, 2H, 2H-
6′), 3.64 (m, 1H, H-5′), 3.77 (t, 1H, J = 9.4 Hz, H-4′), 4.33
(t, 1H, J = 9.2 Hz, H-3′), 4.46 (t, 1H, J = 9.1 Hz H-2′), 4.48
(q, 2H, CH2), 5.26-5.27 (d, 1H, J1′-2′ = 10.9 Hz, H-1′), 7.53
(s, D2O exch., 2H, NH2); 13C NMR: δ 15.27 (CH3), 60.42
(CH2), 61.59(CH2),62.62 (C-6′), 67.26 (C-5′), 75.471 (C-
4′), 77.35 (C-3′), 79.36 (C-2′), 86.39 (C-1′), 126.46 (C-5),
148.26 (C-4), 166.23 (C-2), 169.31 (C=O). Anal. Calcd. For
C12H18N2O7S2: C, 39.34; H, 4.95; N, 7.65; S, 17.50. Found:
C, 39.23; H, 4.82; N, 7.58; S, 17.38%.
(NH2), 3052 (aromatic H), 2936 (CH), 1710 (C=O); H
NMR (500 MHz, CDCl3) δ 3.43-3.46 (m, 2H, 2H-6′), 3.52
(m.1H, H-5′), 3.76 (t, 1H, J = 9.3 Hz, H-4′), 3.92 (t, 1H,
J = 9.1 Hz, H-3′), 4.02 (t, 1H, J = 9.2 Hz, H-2′), 4.41-4.42
(d, 1H, J1′-2′ = 10.5 Hz, H-1′), 4.84 (s, D2O exch., 1H,
6′-OH), 4.98-5.14 (s, D2O exch., 3H, 2′-OH, 3′-OH, and
4′-OH), 7.34 (s, D2O exch., 2H, NH2), 7.72-8.14 (m, 5H,
C6H5); 13C NMR: δ 62.26 (C-6′), 69.42 (C-5′), 70.37 (C-
4′), 74.26 (C-3′), 76.44 (C-2′), 85.47 (C-1′), 125.34 (C-
5), 132.14-141.42 (6C, Ar-C), 147.34 (C-4), 169.23 (C-2),
203.45 (C=O). Anal. Calcd. For C16H18N2O6S2: C, 48.23;
H, 4.55; N, 7.03; S, 16.09. Found: C, 48.10; H, 4.42; N,
7.01; S, 15.88%.
2.4.2
Ethyl 4-amino-2-(β-d-
ORCID
|
glucopyranosylthio)thiazole-5-carboxylate (8b)
Galal H. Elgemeie
http://orcid.org/0000-0003-3268-5975
White solid (EtOH); yield (80%); mp 177°C; [α]D25 = +15.8
(c = 1 g/dL, EtOH); IR (KBr, cm−1) υ 3541 (OH), 3367
(NH2), 2,933 (CH), 1711 (C=O); 1H NMR (500 MHz,
DMSO): δ 1.36(t, 3H, J = 6.51 Hz, CH3), 3.64 (m, 2H, 2H-
6′), 3.76 (m, 1H, H-5′), 4.03 (t, 1H, J = 9.1 Hz, H-4′), 4.11
(t, 1H, J = 9.3 Hz, H-3′), 4.34 (t, 1H, J = 9.2 Hz, H-2′), 4.52
(q, 2H, CH2), 5.33-5.34 (d, 1H, J1′-2′ = 10.3 Hz, H-1′), 7.62
(s, D2O exch., 2H, NH2); 13C NMR: δ 15.54 (CH3), 59.68
(CH2), 61.14(CH2),62.15 (C-6′), 69.36 (C-5′), 73.31 (C-
4′), 76.29 (C-3′), 79.44 (C-2′), 86.47 (C-1′), 125.22 (C-5),
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How to cite this article: Abu-Zaied MA, Elgemeie
GH. Thiazoles in glycosylation reactions: Novel
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