Synthesis and characterization of N-acyl-tetra-O-acyl glucosamine derivatives

Article abstract of DOI:10.1039/c3ra46007j

Novel 1,3,4,6-tetra-O-acyl-N-acyl-d-glucosamine derivatives were synthesized from glucosamine hydrochloride (GlcN·HCl) by the acylation with pyridine as a catalyst. A derivative of tetra-O-acetyl glucosamine contained ketoprofen, a non-steroidal anti-inflammatory drug (NSAID) with analgesic and antipyretic effects, was first synthesized. In analysis of the NMR spectra, the ratio of α:β-anomer showed that penta-acyl-d- glucosamine derivatives and N-acetylated glucosamines containing O-acyl groups have been only the α-anomer. Meanwhile, both the intermediates and the glucoconjugate compound of ketoprofen have only the β-anomer.

Full text of DOI:10.1039/c3ra46007j

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Synthesis and characterization of N-acyl-tetra-O-
acyl glucosamine derivatives†
Cite this: RSC Adv., 2014, 4, 6239
a
a
ab
and Chan Imb
*
*
Chi-Hien Dang, Cong-Hao Nguyen, Thanh-Danh Nguyen
Novel 1,3,4,6-tetra-O-acyl-N-acyl-D-glucosamine derivatives were synthesized from glucosamine
hydrochloride (GlcN$HCl) by the acylation with pyridine as a catalyst. A derivative of tetra-O-acetyl
glucosamine contained ketoprofen, a non-steroidal anti-inflammatory drug (NSAID) with analgesic and
antipyretic effects, was first synthesized. In analysis of the NMR spectra, the ratio of a:b-anomer showed
that penta-acyl-D-glucosamine derivatives and N-acetylated glucosamines containing O-acyl groups
have been only the a-anomer. Meanwhile, both the intermediates and the glucoconjugate compound of
ketoprofen have only the b-anomer.
Received 24th October 2013
Accepted 17th December 2013
DOI: 10.1039/c3ra46007j
www.rsc.org/advances
glucoconjugates of NSAIDs might lead to reduce ulcerogenic
potency, increase bioavailability and possess coordinative
effects on osteoarthritis.
Introduction
Rheumatoid arthritis1–4 is a common disease in the elderly.
Glucosamine is a precursor for glucosaminoglycans, which are
major components of joint cartilage. The glucosamine
supplement may inuence the cartilage structure. Therefore,
the glucosamine may be proposed to treat the arthritis and
alleviate symptoms.5–8 In recent years, the drugs containing
glucosamine derivatives9–11 have been widely used to treat and
restore the damaged cartilage. Advantages of the drug con-
taining glucosamine strictly treated the arthritis without
causing side effects. The research of Poustie12 showed that the
acyl derivatives of glucosamine on the amino group (–NH2)
possessed stronger activity than glucosamine itself in the
treatment of arthritis. In particular, N-butyryl-D-glucosamine
was also the most active component. Moreover, Some tetra-O-
acyl-N-acyl-D-glucosamine13,14 were important intermediates in
the oligosaccharide synthesis. The acetate and the n-butyrate
esters of glucosamine have demonstrated activity against
cancer cells.15,16
Some acyl derivatives of this amino sugar with fatty acids
have been previously reported in the literature.14,15,23 However,
their NMR spectra data has not revealed whether or not inu-
ence of N- and O-substituted groups to the a:b-isomer ratio of
these derivatives. Our initial research24 revealed that the short
fatty acid groups have been giving the isomer ratio by the rules.
In this paper, we describe the synthesis and NMR spectral data
analysis of a series penta-acyl-D-glucosamine, 1,3,4,6-tetra-O-
acyl-N-acyl-D-glucosamine derivatives and a novel glucoconju-
gate of ketoprofen, which is prepared from GlcN$HCl. In
synthesis of the glucoconjugate compound, a series of the
compounds containing O-acetyl groups was also prepared.
Results and discussion
Synthesis
The glucosamine derivatives containing both N-acyl groups and
O-acyl groups were prepared via two ways. First, 1,3,4,6-tetra-O-
acyl-N-acylglucosamine, which was generated in two steps from
commercially available GlcN$HCl, was synthesized by N-acety-
lation reaction of GlcN$HCl carried out with the various acid
anhydrides in sodium methoxide solution to give the
compounds 1–4. Esterication of these compounds was then
performed by treatment with acid anhydrides in the presence of
pyridine as the method previously reported.24 In the second
approach, the penta-O-acyl glucosamine derivatives 13–15 were
directly prepared from GlcN$HCl and acetic anhydride, pro-
pionic anhydride or butyric anhydride by using pyridine as a
catalyst (Scheme 1).
NSAIDs17–19 have also been used in the treatment of rheu-
matoid arthritis. In this purpose, Numerous NSAIDs ester
derivatives have been synthesized to reduce gastro intestinal
side-effect. It was also known that glucoconjugates could be
transported by cellular glucose transporters. Therefore, the
glucoconjugates of NSAIDs were recently prepared with the
objective of increasing the bioavailability of antioxidant and
anti-inammatory drugs such as, ibuprofen,20 aspirin, diclofe-
nac and indomethacin.21,22 These ndings indicated that the
aDepartment of Pharmaceutical Chemistry, Institute of Chemical Technology, VAST,
Vietnam. E-mail: dangchihien@gmail.com; Tel: +84 8 38238265
bDepartment of Chemistry, Konkuk University, Korea. E-mail: danh5463bd@yahoo.
com; Tel: +82 2 4503415
The synthesis of glucoconjugate of NSAIDs has been
described by different methods using various acetylated
glucosamine analogues as glycosyl donors.12,21 A synthesis of 18
† Electronic supplementary information (ESI) available: 1D and 2D NMR data of
novel compounds. See DOI: 10.1039/c3ra46007j
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Scheme 1 Synthesis of tetra-O-acyl-N-acyl-D-glucosamine derivatives from GlcN$HCl.
from GlcN$HCl using esterication of NH2 of glucosamine by
ketoprofen chloride12 and followed the acetylation of all four
OH groups of sugar ring by acetic anhydride was attempted.
However, in our experiment, ketoprofen chloride as a key
intermediate obtained from ketoprofen and thionyl chloride
were synthesized in a low yield. Alternatively, the use of 1,3,4,6-
tetra-O-acetyl-b-D-glucosamine hydrochloride (17) as a glycosyl
donor12,25 gave good yield as described in Scheme 2.
Compound 16 was obtained from commercially available
GlcN$HCl in a procedure that used p-anisaldehyde for protec-
tion of –NH2 group in 67.82% yield. Acetylation and removal of
the p-methoxybenzylidene group with HCl in acetone were to
give 17 in 91.3% yield. The ester 18 was obtained by esterifying
ketoprofen with amine glycosyl compound 17 in the presence of
DCC/DMF–Py–Et3N in 51.5% yield aer purication by silica gel
column chromatography.
NMR spectra
The structure of the synthesized N-acyl, tetra-O-acyl-N-acyl-D-
glucosamine and glucoconjugate derivatives was conrmed by
1H and 13C NMR spectroscopy (see Table 1 and 3, respectively).
Analysis of the NMR spectra of 7 and 9–12 showed that structure
and size of N-acyl group affected the chemical shis of a and
b-anomer. Simultaneously, the a:b-anomer ratios of the acyl-
ated glucosamines, that were determined by comparison of
proton coupling constants of the H-1 peaks in the 1H NMR
spectra, depended on the length of the carbon chain of the acyl
groups at C-1 and C-2 of glucosamine. However, the chemical
shis of the sugar ring protons or carbons of 16–18 were not
affected by the substituted groups which had the source from
p-anisaldehyde or ketoprofen.
Physical characteristics and ratio of a- and b-isomer of the
glucosamine derivatives were showed in Table 2. The a-anomer
was preferred for N-acetylated glucosamine with different O-acyl
groups such as acetyl, n-propionyl, n-butyryl or even indome-
thacinyl-substituent.22 With N-phthalated glucosamine,
a
mixture of the isomers was generated from which derivatives
were substituted by shortly fatty groups on the O atom. In
exception of the above cases, the b-anomer was preferred for the
derivatives containing O-acetyl. The interesting results from
Table 2 also showed that penta-acyl-D-glucosamine derivatives
(13–15) gave more stable a-stereoisomer. In addition, N-acyl-D-
glucosamine derivatives were obtained as a mixture of isomers
in which the a-stereoisomer predominated.
Analysis of the NMR spectra of compounds 7 and 9 showed
that the H-1 signal of a-anomer appeared at higher d values
than the H-1 signal of b-anomer, owing to their different
equatorial and axial orientations (Dd ꢀ 0.5 ppm). Meanwhile,
the C-1 carbon atom of the a-anomer resonated at higher eld
than of the b-anomer (Dd ꢀ 2.1 ppm). Especially, the H-1
chemical shis of the a-anomer of N,N-phthaloyl glucosamine
derivatives were lower than chemical shis of the b-anomer.
This showed that inuence of two carbonyl groups (C]O) and
benzene ring in N,N-phthaloyl glucosamine structure caused
Scheme 2 Synthesis of D-glucosamine derivatives from GlcN$HCl and
ketoprofen.
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Table 2 Ratio of a- and b-isomer and physical characteristics of compounds 1–18
Ratio of isomers
N-Acyl groups
O-Acyl groups
(or N-substituent)
(or O-substituent)
a
b
Substances
Mp (ꢁC)
[a]2D0 (solvent)
Rf (EtOAc : PEa)
CH3CO
—
CH3CO
Priority
100%
100%
100%
100%
Priority
0%
100%
83%
Priority
0%
59%
100%
54%
66%
66%
Lower
0%
0%
0%
0%
1
13
8
5
—
200–201
113–114
155–156
151–152
—
+65 (H2O)
+86.5 (EtOH)
+95.5 (EtOH)
+80 (EtOH)
—
—
0.3 (2 : 1)
0.5 (1 : 1)
0.6 (3 : 2)
—
—
—
0.4 (1 : 1)
0.5 (2 : 1)
—
0.4 (2 : 1)
0.4 (1 : 1)
0.5 (1 : 1)
—
0.3 (1 : 1)
0.5 (1 : 1)
0.4 (2 : 1)
CH3CH2CO
CH3CH2CH2CO
Indomethacin22
—
CH3CO23
CH3CH2CO
CH3CH2CH2CO
—
CH3CH2CO
CH3CH2CH2CO
C6H4(CO)2
Lower
100%
0%
27%
Lower
100%
41%
0%
46%
34%
34%
45%
100%
100%
100%
2
184–185
—
+36 (H2O)
—
—
14
9
3
6
7
15
4
10
11
12
16
17
18
105–106
108–110
208–209
141–142
Liquid
94–95
67–69
89–90
50–52
48–49
+81 (EtOH)
+94 (EtOH)
+33 (H2O)
+33 (EtOH)
+64 (EtOH)
+65 (EtOH)
+25 (H2O)
+66 (EtOH)
+117 (EtOH)
+110 (EtOH)
+98 (CHCl3)
+27 (H2O)
+7 (CHCl3).
CH3CO
CH3CH2CO
CH3CH2CH2CO
—
CH3CO
CH3CH2CO
CH3CH2CH2CO
CH3CO
CH3CO
CH3CO
55%
0%
0%
0%
Anisaldehyde
NH2$HCl
Ketoprofen
175–176
220–222
134–135
0.4 (1 : 1)
-
0.5 (1 : 1)
a
PE: petroleum ether; EtOAc: ethyl acetate.
deshielding of H-1 in the b-anomer (Dd ꢀ 0.22 ppm) in and EtOH. Flash chromatography was performed with Silica Gel
comparison with the corresponding H-1 signal of the 60 (230–400 mesh, E Merck, Darmstadt, Germany).
a-anomer. In this case, the C-1 carbon atom of the a-anomer
resonated at lower elds than C-1 carbon atom of the b-
anomer (Dd ꢀ 0.7 ppm). Interestingly, the various N-acyl
substituted groups had a signicant inuence on the reso-
nance frequency of the sugar ring protons and carbons.
Analysis of the NMR spectra of 1–4 conrmed the empirical
rules in the NMR spectroscopy of carbohydrates. Firstly, the
axial orientation of the anomeric OH group in the a-anomer
caused absorption at higher d values of equatorially oriented H-
1 protons in comparison with the corresponding b-anomer (Dd
ꢀ 0.5 ppm). The C-1 carbon atom of the b-anomer resonated at
lower elds than the C-1 carbon atom of the a-anomer (Dd ꢀ 4
ppm). These were compatible with the previous report.26
Moreover, the C-2 carbon atom of the b-anomer was deshielded
in comparison with the corresponding C-2 carbon atom of the
a-anomer (Dd ꢀ 2.5 ppm).
Procedure for the synthesis of 1,3,4,6-tetra-O-acyl-N-acyl-D-
glucosamine derivatives and penta-acyl-D-glucosamine
derivatives
General procedure for synthesis of N-acyl-D-glucosamine
derivatives (1–4). Sodium (8.0 g, 34.8 mmol) was added slowly to
50 mL of anhydrous methanol followed by 5.0 g (23.2 mmol) of
Glu$HCl under nitrogen atmosphere. The solution was stirred
for 15 min and the precipitate was ltered off. To this ltrate,
anhydride acid (34.8 mmol) was added under nitrogen atmo-
sphere. The reaction mixture was stirred at room temperature
for 1 h and then cooled to 0 ꢁC overnight. The N-acylated
compounds were collected by ltration, washed withꢁ cold
methanol (25 mL), diethyl ether (50 mL) and dried at 60 C.
N-Acetyl-D-glucosamine (1). 1H NMR (500 MHz, D2O) d 5.17
(1H, J ¼ 3.5 Hz), 4.68 (1H, d, J ¼ 8.5 Hz), 3.8 (2H, m), 3.74 (2H,
dd, J ¼ 7.0, 2.5 Hz), 3.69 (2H, ddd, J ¼ 15.5, 5.5, 1.5 Hz), 3.62 (2H,
dd, J ¼ 10.0, 8.5 Hz), 3.42 (2H, m), 2.02 (6H, s). 13C NMR (125
MHz, D2O) d 174.80, 174.54, 94.98, 90.89, 76.00, 73.59, 71.62,
70.74, 70.14, 69.91, 60.81, 60.66, 56.76, 54.13, 22.23, 21.96.
N-Propyl-D-glucosamine (2). 1H NMR (500 MHz, D2O) d 5.17
Experimental
General methods
Melting points were measured with a Electrothermal Model
9200 (England). The 1H and 13C NMR spectra (CDCl3, d6-DMSO (1H, J ¼ 3.5 Hz), 4.66 (1H, d, J ¼ 12.0 Hz), 3.90–3.71 (8H, m), 3.65
or D2O, internal TMS) were measured with a Bruker Avance 500 (2H, m), 3.5 (1H, m), 3.43 (1H, m), 2.32–2.26 (4H, q, 7.5 Hz),
NMR Spectrometer. Optical rotations were measured on a 1.12–1.08 (6H, t, 7.5 Hz). 13C NMR (125 MHz, D2O) d 178.77,
Polarimeter Model ADP 220 (Bellingham – Stanley Ltd, England) 178.55, 95.04, 90.95, 76.02, 73.93, 71.65, 70.72, 70.20, 69.98,
3
ꢁ
in a 1 cm cell at 20 C. Thin layer chromatography (TLC) was 60.84, 60.69, 56.67, 54.03, 29.43, 29.12, 9.55, 9.50.
performed on the E. Merck Kieselgel 60 F-254 plates using the
N-Butyl-D-glucosamine (3). 1H NMR (500 MHz, D2O) d 5.16 (1H,
following eluent system (v/v) 1 : 1 petroleum ether – AcOEt and d, J ¼ 3.5 Hz), 4.67 (1H, d, J ¼ 10.5 Hz), 3.80 (6H, m), 3.69 (2H,
visualized by treatment with an acidic solution of 10% H2SO4 ddd, J ¼ 30.5, 11.5, 5.0 Hz), 2.22 (4H, m), 1.55 (4H, m), 0.86
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Table 3 Chemical shifts (ppm) of the carbon atoms in the 13C NMR spectra of tetra-O-acyl-N-acyl-D-glucosamine derivativesa
Sugar moiety
C-1 C-2
Acyl groups
C-3
C-4
C-5
C-6
N-acyl
O-acyl
5
6
7
90.44 51.30 70.40 67.20 69.96 61.43 169.76 (C]O)
172.44; 173.23; 171.24; 171.66 (C]O);
36.02; 36.00; 35.86; 35.85 (–COCH2–);
18.40; 18.36; 18.30; 18.24 (CH2CH2–);
13.60; 13.56; 13.50; 13.50 (–CH3)
171.17; 170.64; 169.48; 169.27 (C]O);
20.81; 20.67; 20.62; 20.53 (–CH3)
22.99 (CH3)
92.64 52.62 72.88 67.98 72.62 61.75 172.98 (C]O)
38.56 (–COCH2)
19.00 (–CH2CH2)
13.49 (–CH3)
a
b
90.41 50.94 70.43 67.30 69.74 61.39 172.03 (C]O)
175.05; 173.97; 172.83; 172.49 (C]O);
27.33; 27.22; 27.18 (COCH2); 8.91; 8.82;
8.78 (CH3)
38.19 (COCH2)
18.79 (–CH2CH2)
13.36 (–CH3)
92.51 52.48 72.42 67.68 72.85 61.50 172.91 (C]O)
174.48; 172.87; 172.63 (C]O); 27.41;
27.31; 27.28 (COCH2); 8.87; 8.75; 8.54
(CH3)
38.41 (COCH2)
18.90 (–CH2CH2)
18.38 (–CH3)
90.60 51.21 70.62 67.34 69.88 61.45 169.80 (C]O)
22.99 (COCH3)
8
9
172.09; 172.55; 174.06; 175.25 (C]O);
27.57; 27.49; 27.36; 27.31 (CH2CO); 9.14;
9.05; 8.95; 8.91 (CH3CH2)
174.44; 173.48; 173.22; 171.66 (C]O);
36.00; 35.99; 35.86; 35.85 (COCH2); 18.40;
18.32; 18.29; 18.23 (CH2); 13.58; 13.55;
13.49 (CH3)
171.66; 173.23; 173.49; 173.77 (C]O);
35.85; 35.86; 35.99; 36.01 (COCH2); 18,
24; 18.29; 18.33; 18.41 (CH2); 13.42; 13.5;
13.55; 13.58 (CH3)
170.63; 169.99; 169.75; 169.49; 169.44;
169.28; 168.60 (C]O); 20.94; 20.73;
20.69; 20.61; 20.57; 20.36 (CH3)
a
b
a
90.46 51.21 70.44 67.21 69.98 61.45 171.21 (C]O)
29.47 (COCH2)
9.49 (CH3)
92.66 52.87 73.14 67.44 72.35 61.46 171.22 (C]O)
29.69 (COCH2)
9.63 (CH3)
10
11
12
90.52 52.84 70.19 67.04 69.42 61.53 167.39 (C]O)
134.44 (CH)
131.17 (C)
89.80 53.53 70.53 68.36 72.66 61.56 123.71 (CH)
90.43 52.90 70.29 66.84 69.21 61.39 167.31 (C]O)
134.37 (CH)
b
a
174.00; 173.37; 173.08; 172.83172.74;
172.03 (C]O); 27.48; 27.29; 27.27; 27.20
(COCH2); 20.93; 15.18; 14.12; 8.91; 8.85;
8.78; 8.54; 8.45 (CH3)
173.21; 172.50; 172.20; 171.95; 171.93;
171.82; 171.19; 171.08 (C]O); 35.95;
35.88; 35.85; 35.74; 35.66; 29.67 (COCH2);
18.28; 18.21; 18.19; 18.11; 18.07; 17.96;
17.90 (CH2); 14.17; 13.61; 13.59; 13.57;
13.52; 13.42; 13.21; 13.12 (CH3)
132.12 (C)
b
a
89.72 53.60 68.16 65.75 72.83 60.29 123.58 (CH)
90.33 52.97 70.30 66.82 69.10 60.38 167.33 (C]O)
134.39 (CH)
131.26 (C)
b
89.67 53.71 70.20 68.13 72.80 61.43 123.59 (CH)
13
14
90.61 51.00 70.61 67.56 69.66 61.53 171.55 (C]O)
170.57; 169.99; 169.02; 168.57 (C]O);
22.87; 20.79; 20.58; 20.56 (CH3)
175.18; 174.05; 173.55; 172.55 (C]O);
27.52; 27.47; 27.34; 27.30 (COCH2); 9.08;
9.04; 8.97; 8.90 (CH3)
20.44 (CH3)
90.60 51.09 70.61 67.32 69.88 61.47 172.08 (C]O)
29.49 (COCH2)
9.57 (CH3)
15
18
90.44 51.25 70.40 67.26 70.00 61.48 174.48 (C]O)
173.27; 172.73; 171.71; 171.24 (C]O);
38.38; 36.06; 36.02; 35.91 (COCH2); 18.89;
18.44; 18.33; 18.28 (–CH2CH2); 13.63;
13.60; 13.58; 13.56 (–CH3)
18.28 (–COCH2)
35.89 (–CH2CH2)
13.55 (–CH3)
92.31 52.92 67.86 72.43 72.84 61.66 18.12 (CH3); 46.95 (CH); 128.36 (2C; CH); 169.25; 169.42; 170.61; 170.94 (C]O);
128.59 (CH); 129.0 (CH); 129.18 (CH);
130.05 (2C, CH); 131.15 (CH); 132.63
(CH); 137.32 (C); 138.03 (C); 141.34 (C);
173.67 (C]O); 196.43 (C]O).
20.44; 20.52; 20.65; 20.71 (CH3)
a
NMR experimental conditions: 125 MHz, CDCl3.
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(6H, m). 13C NMR (125 MHz, D2O) d 177.82, 177.59, 95.04, 90.93, acetone (200 mL). Then 12.5 mL of aq. HCl (5 M) was added.
75.98, 73.87, 71.61, 70.61, 70.22, 70.00, 60.82, 60.67, 56.62, Aer 30 min, diethyl ether was added to the reaction mixture
54.03, 38.03, 37.63, 19.01, 12.69.
and stirring for 1 hour. The residue was collected by suction
N,N-Phthaloyl-D-glucosamine (4). 1H NMR (500 MHz, D2O) d 7.67 ltration, washed with the cold diethyl ether and dried in vacuo
1
(4H, m), 7.52 (4H, d, 2.5 Hz), 5.39 (1H, d, 3 Hz), 4.87 (1H, d, 8.5 to give the product 17 (20.2 g, 91.3%). H NMR (500 MHz, d6-
Hz), 3.87–3.62 (8H, m), 3.43 (2H, m), 3.22 (2H, dd, J ¼ 10, 9 Hz). DMSO) d 8.85 (3H, s), 5.91 (1H, d, J ¼ 8.5 Hz), 5.37 (1H, t, J ¼
13C NMR (125 MHz, D2O) d 174.18, 133.92, 130.83, 128.8, 92.79, 9.5 Hz), 4.92 (1H, t, J ¼ 9.5 Hz), 4.17 (1H, dd, J ¼ 12.0, 4.0 Hz),
89.19, 76.23, 72.05, 71.66, 69.77, 69.66, 60.55, 60.42, 56.82, 54.38. 3.99 (2H, m), 3.54 (1H, t, J ¼ 9.5 Hz), 2.17–1.97 (12H, s). 13C NMR
General procedure for synthesis of N-acyl-1,3,4,6-tetra-O- (125 MHz, d6-DMSO) d 169.89, 169.70, 169.25, 168.56, 90.07,
acyl-D-glucosamine derivatives (5–12). A round-bottomed ask 71.58, 70.32, 67.82, 61.23, 52.14, 20.88, 20.79, 20.41, 20.27.
equipped with a three-way stopcock was heated under reduced
Synthesis of N-(2-(3-benzoylphenyl)propanoyl)-1,3,4,6-tetra-
pressure and then cooled room temperature under a nitrogen O-acetyl-2-deoxy-2-amino- b-D-glucopyranose (18). A 6.0 g (16.2
atmosphere. N-acyl glucosamine (4.52 mmol), pyridine (10 mL) mmol) sample of 17 was dissolved in CH2Cl2 (80 mL). Then 80
and anhydride acid (27.12 mmol) were replaced in the ask. The mL of Na2CO3 solution (1 M) was added. Aer 30 min, the
mixture was stirred at room temperature for 10 h. The cold mixture was extracted with CH2Cl2. The organic layer was
water was then added and the resulting solution was extracted washed with water, dried over anhydrous MgSO4 and concen-
with ethyl acetate. The organic layer was washed with saturated trated under reduced pressure to give 1,3,4,6-tetra-O-acetyl-b-D-
ꢁ
NaHCO3 aqueous solution, brine, dried over MgSO4 and glucosamine as a white solid (5.1 g, 92.8%). Mp (138 C).
concentrated in vacuo to provide the desired products.
A round-bottomed ask equipped with a three-way stopcock
General procedure for synthesis of penta-acyl-D-glucosamine was heated under reduced pressure and then cooled room
derivatives (13–15). Using the same procedure as described for temperature under a nitrogen atmosphere. Ketoprofen (1.0 g,
compounds 5–12, with replacement of N-acyl glucosamine by 3.9 mmol) in dry DMF (15 mL) and DCC (1.22 g, 5.8 mmol) were
Glu$HCl.
placed in the ask and the mixture was stirred at 0 ꢁC. Into the
ask was added 1,3,4,6-tetra-O-acetylglucosamine (0.5 g,
1.5 mmol) in dry DMF via a syringe. The whole was stirred at
0 C for 4 h and stirring was continued at room temperature
overnight. The mixture was diluted by ethyl acetate and then the
Procedure for the synthesis of glucosamine conjugated with
ketoprofen
ꢁ
Synthesis of N-((p-methoxyphenyl)methyliden)-1,3,4,6-tetra- solid was ltered off. Ethyl acetate layer was washed with water,
O-acetyl-2-deoxy-2-amino-b-D-glucopyranose (16). Into a round- dried over anhydrous MgSO4 and concentrated under reduced
bottomed ask were introduced 20.0
g
of GlcN$HCl pressure. The pure product 18 was recrystallized in diethyl ether
(92.76 mmol) and 100 mL of NaOH solution (1 M). Aer cooling as a white solid (0.44 g, 51.5%).
down to 0 ꢁC, 13.5 mL of p-anisaldehyde was added via dropwise
under stirring. The resulting mixture was maintained at 0 ꢁC for
1 h. The residue was collected by suction ltration, washed with
Conclusions
the cold water, the cold ethanol, diethyl ether and dried in vacuo We synthesized successfully ve novel tetra-O-acyl-N-acyl-D-
to give N-((p-methoxyphenyl)methyliden)-2-deoxy-2-amino-D- glucosamine derivatives 7, 9, 11, 12, 18 with a good yield. The
glucopyranose as a white solid (22.3 g, 80.87%).
most important inuence of a- and b-anomer ratio was related
A round-bottomed ask equipped with a three-way stopcock to acyl group at the amine (–NH2) position and at O-acyl group
was heated under reduced pressure and then cooled room of C-1 carbon position. Synthesis of substituent acyl groups
temperature under a nitrogen atmosphere. The above inter- containing longer carbon chain and the testing of biological
mediate (22.3 g, 75.03 mmol) and pyridine (120 mL) were placed activities of compounds 5–12 and 18 were planned.
in the ask. Aer cooling down to 0 ꢁC, acetic anhydride
(12.5 mL) was added under stirring via a syringe. The mixture
was stirred at 0 ꢁC during 2 h and stirring was continued at
Acknowledgements
room temperature overnight. The reaction was ended by adding We thank Prof. Dr Chu Pham Ngoc Son (President of Chemical
500 mL the water at 0 ꢁC. The residue was collected by suction Society of Ho Chi Minh City) for NMR spectra analysis.
ltration, washed with the cold water and dried in vacuo to give
16 as a white solid (28.7 g, 83.87%). 1H NMR (500 MHz, CDCl3) d
References
7.65 (2H, dd, J ¼ 7.0, 2.0 Hz), 6.92 (2H, dd, J ¼ 9.0, 2.0 Hz), 5.93
(1H, d, J ¼ 8 Hz), 5.43 (1H, t, 10 Hz), 5.14 (1H, t, J ¼ 10 Hz), 4.36
(1H, dd, J ¼ 12.5, 4.5 Hz), 4.12 (1H, dd, J ¼ 12.5, 2.5 Hz), 3.96
(1H, m), 3.84 (3H, s), 3.43 (1H, dd, J ¼ 10.0, 8.0 Hz), 2.13–1.88
(12H, s). 13C NMR (125 MHz, CDCl3) d 170.68, 169.89, 169.54,
168.76, 164.27, 130.27, 128.35, 114.09, 93.20, 73.30, 72.98,
72.81, 68.11, 61.87, 55.42, 20.81, 20.76, 20.68, 20.51.
1 V. Majithia and S. A. Geraci, Am. J. Med., 2007, 120, 936–939.
2 C. Turesson, W. M. O'Fallon, C. S. Crowson, S. E. Gabriel and
E. L. Matteson, Ann. Rheum. Dis., 2003, 62, 722–727.
3 J. A. A. A-Zubieta, H. K. Choi, M. Sadatsafavi, M. Etminan,
J. M. Esdaile and D. Lacaille, Arthritis Rheum., 2008, 59,
1690–1697.
Synthesis of 1,3,4,6-tetra-O-acetyl-b-D-glucosamine hydro-
chloride (17). A 28.0 g (60.0 mmol) sample of 16 was dissolved in
4 K. Nishimura, D. Sugiyama, Y. Kogata, G. Tsuji, T. Nakazawa,
S. Kawano, K. Saigo, A. Morinobu, M. Koshiba, K. M. Kuntz,
6244 | RSC Adv., 2014, 4, 6239–6245
This journal is © The Royal Society of Chemistry 2014

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Paper
RSC Advances
I. Kamae and S. Kumagai, Ann. Intern. Med., 2007, 146, 797– 15 U. Aich, C. T. Campbell, M. B. Jones, S. G. Sampathkumar
808. and K. J. Yarema, US Pat., 0144653 (A1), 2010
5 T. Towheed, L. Maxwell, T. P. Anastassiades, B. Shea, 16 S. Sampathkumar, M. B. Jones, M. A. Meledeo,
J. B. Houpt, V. Welch, M. C. Hochberg and G. A. Wells,
Glucosamine therapy for treating osteoarthritis; ed. C.
Musculoskeletal, John Wiley & Sons, New York, U.S.A,
2009, 4, pp. 3–10.
C. T. Campbell, S. S. Choi, K. Hida, P. Gomutputra,
A. Sheh, T. Gilmartin, S. R. Head and K. J. Yarema, ACS
Chem. Biol., 2006, 13, 1265–1275.
17 S. J. Warden, The Physician and Sports Medicine, 2010, 38,
132–138.
6 M. G. Buse, Am. J. Physiol., 2006, 290, E1–E8.
7 J. Cibere, J. A. Kopec, A. Thorne, J. Singer, J. Canvin, 18 S. Trelle, S. Reichenbach, S. Wandel, P. Hildebrand,
D. B. Robinson, J. Pope, P. Hong, E. Grant and
J. M. Esdaile, Arthritis Rheum., 2004, 51, 738–745.
B. Tschannen, P. M. Villiger, M. Egge and P. Juni, Br. Med.
J., 2011, 342, c7086.
8 F. Richy, O. Bruyere, O. Ethgen, M. Cucherat, Y. Henrotin 19 P. M. Kearney, C. Baigent, J. Godwin, H. Halls,
and J. Y. Reginster, Arch. Intern. Med., 2003, 163, 1514–1522.
9 I. Brockhausen, J. Carran, K. McEleney, M. Lehotay, X. Yang,
J. R. Emberson and C. Patrono, Br. Med. J., 2006, 332,
1302–1308.
L. Yin and T. Anastassiades, Carbohydr. Res., 2005, 340, 20 R. K. Uhrig, M. A. Picard, K. Beyreuther and M. Wiessler,
1997–2003. Carbohydr. Res., 2000, 325, 72–80.
10 K. Azuma, T. Osaki, T. Wakuda, T. Tsuka, T. Imagawa, 21 J. Borowiecka and A. Stanczak, Il Farmaco, 2001, 56, 257.
Y. Okamoto and S. Minami, Inammation, 2012, 35, 1462–1465. 22 Y. C. Zhang, Y. X. Li and H. S. C. Guan, Chem. Lett., 2005, (2),
11 N. Elmouelhi, U. Aich, V. D. P. Paruchuri, M. A. Meledeo,
C. T. Campbell, J. J. Wang, R. Srinivas, H. S. Khanna and 23 M. S. Macauley, G. E. Whitworth, A. W. Debowski, D. Chin
K. J. Yarema, J. Med. Chem., 2009, 52, 2515–2530. and D. J. Vocadlo, J. Biol. Chem., 2005, 280, 25313–25322.
12 M. W. Poustie, J. Carran, K. McEleney, S. J. Dixon, 24 T. Q. Ho, T. D. H. Nguyen, T. D. Nguyen, C. H. Dang and
179–182.
T. P. Anastassiades and S. M. Bernier, J. Pharmacol. Exp.
Ther., 2004, 311, 610–616.
13 J. M. Hermandez-Torres, S. T. Liew, J. Achkar and A. Wei,
Synthesis, 2002, 487–490.
C. H. Nguyen, Vietnam J. Chem., 2010, 48(4A), 676–682.
25 V. R. Krishnamurthy, A. Dougherty, M. Kamat, X. Song,
R. D. Cummings and E. L. Chaikof, Carbohydr. Res., 2010,
345, 1541–1547.
14 Y. Inouye, K. Onodra, S. Kitaoka and S. Hirano, J. Am. Chem. 26 Y. Chen, S. Luo, S. Hung, S. I. Chan and D. M. Tzou,
Soc., 1956, 78, 4722–4724.
Carbohydr. Res., 2005, 340, 723–729.
This journal is © The Royal Society of Chemistry 2014
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