Structure and temperature controlled synthesis of novel thiazolidin-4-one derivatives bearing an azasugar

Article abstract of DOI:10.1016/j.tetasy.2013.03.006

Novel thiazolidin-4-one linked pseudo-aza-disaccharides and thiazolidin-4-ones containing C-pseudo-aza-nucleosides were synthesized via a one-pot three component reaction. The former was synthesized stereoselectively by the tandem Staudinger/aza-Wittig/cyclization reaction of azasugar aldehyde 1, an azidosugar, and mercaptoacetic acid. The reaction was structure and temperature controlled, and could be performed stereospecifically under 40 C. It was the first report of a stereospecific synthesis of thiazolidin-4-one linked derivatives. However, these derivatives were synthesized with low stereoselectivity by involving the condensation reaction of azasugar aldehyde 1, aniline, and mercaptoacetic acid.

Full text of DOI:10.1016/j.tetasy.2013.03.006

Tetrahedron: Asymmetry 24 (2013) 457–463
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Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Structure and temperature controlled synthesis of novel thiazolidin-4-one
derivatives bearing an azasugar
⇑
Hua Chen, Sinan Wei, Hongbo Zhang, Xiaoliu Li
Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 24 January 2013
Accepted 7 March 2013
Novel thiazolidin-4-one linked pseudo-aza-disaccharides and thiazolidin-4-ones containing C-pseudo-
aza-nucleosides were synthesized via a one-pot three component reaction. The former was synthesized
stereoselectively by the tandem Staudinger/aza-Wittig/cyclization reaction of azasugar aldehyde 1, an
azidosugar, and mercaptoacetic acid. The reaction was structure and temperature controlled, and could
be performed stereospecifically under 40 °C. It was the first report of a stereospecific synthesis of thiaz-
olidin-4-one linked derivatives. However, these derivatives were synthesized with low stereoselectivity
by involving the condensation reaction of azasugar aldehyde 1, aniline, and mercaptoacetic acid.
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
moiety,13 we herein report a structure and temperature controlled
synthesis of thiazolidin-4-one derivatives containing an azasugar.
The thiazolidin-4-one ring is a core substructure in various
synthetic pharmaceuticals, which is associated with diverse bio-
logical activities such as antibacterial, anti-fungal, anti-cancer,
antiviral, anti-inflammatory and analgesic, and calcium antagonis-
tic.1,2 Recently, thiazolidin-4-one linked pseudodisaccharides and
thiazolidin-4-one containing C-pseudonucleosides have been dem-
onstrated to possess strong immunostimulatory activities.3,4 Gen-
erally, thiazolidin-4-one derivatives have been synthesized in
two ways; one is the one-pot three component condensation from
an amine, a carbonyl compound, and a mercaptoacetic acid via an
intermediate imine,5–8 and the other is the tandem Staudinger9/
aza-Wittig10/cyclization reaction employing an azide compound
instead of amine (Scheme 1).3,11 However, both protocols were
carried out with almost no stereoselectivity and commonly affor-
ded a pair of the stereoisomers. To the best of our knowledge,
the only example of stereospecific formation of the thiazolidin-4-
one ring was found in the synthesis of thiazolidin-4-one fused
bicyclic azasugar analogues.12 In a continuation of our studies on
Novel thiazolidin-4-one linked pseudo-aza-disaccharides were
first synthesized stereospecifically by the Staudinger/aza-Wittig/
cyclization reaction starting from azasugar aldehyde 1, azidosugar
2a–d, and mercaptoacetic acid. In addition, thiazolidin-4-one con-
taining C-pseudo-aza-nucleosides were synthesized from azasugar
aldehyde 1, aniline 2e–f, and mercaptoacetic acid.
2. Results and discussion
According to the reported procedures,14 the requisite azasugar
aldehyde 1 and the azido azasugar 2c can be readily prepared from
D
-mannose, while azidosugars 2a and 2b can be synthesized from
-glucose and -ribose, respectively. As shown in Scheme 2, the
D
D
azido azasugar 2d was synthesized from N-TFA-protected azido
azasugar 5 via the deprotection of the TFA and Bz groups, followed
by N-Boc protection.
Based on our previous report,3the synthesis of thiazolidin-4-one
linked pseudo-aza-disaccharides 3a and 3a0 was carried out by the
tandem Staudinger/aza-Wittig reaction of azasugar aldehyde 1 and
bioactive thiazolidin-4-one derivatives containing
a
sugar
O
O
R
H2N
N3
R
R
S
S
HSCH2COOH
N
R
R
CHO
+
OH
*
*
NH
N
R
R
R
R
Scheme 1. The one-pot three component reactions for the synthesis of thiazolidin-4-one.
⇑
Corresponding author. Tel./fax: +86 312 5971116.
E-mail address: lixl@hbu.cn (X. Li).
0957-4166/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetasy.2013.03.006

458
H. Chen et al. / Tetrahedron: Asymmetry 24 (2013) 457–463
O
CF3
H
N
Boc
N
N
N3
BzO
N3
Ref [14]
ii
i
N3
D-mannose
O
O
HO
O
HO
O
O
O
5
6
2d
Scheme 2. The synthesis of the six-membered azasugar azide 2d. Reagents and conditions: (i) K2CO3, MeOH, 40 °C, 3 h, 95%; (ii) Boc2O, Et3N, DCM, MeOH, 2 h, 80%.
azidosugar 2a stirring with triphenylphosphine (Ph3P) to generate
the imine intermediate via an iminophosphorane, followed by
in situ condensation with mercaptoacetic acid, as shown in
Scheme 3. Temperature had a significant effect on both the reac-
tion yield and the reaction stereoselectivity as shown in Table 1.
The synthesis was studied first at room temperature, but no prod-
uct was formed after 12 h. However, when the reaction was carried
out at 40 °C, the reaction proceeded stereospecifically and afforded
a single product 3a in a good yield of 70%. When the temperature
was increased to 60 °C, the reaction produced the corresponding
diastereomeric thiazolidin-4-one derivatives 3a (more polar and
a majority) and 3a0 (less polar and a minority) with a high stereo-
selective ratio of 10:1. As the temperature increased to 80 °C, the
ratio of 3a and 3a0 decreased to 6:1 with a total yield of 57%, and
the reaction provided the diastereomeric products in a total yield
of 48% with an isomeric ratio of 6:1 when the reaction was carried
out at 120 °C.
Under the same conditions as described in Table 1 entry 2, the
one pot reaction of azasugar aldehyde 1 and other azido sugars
2b–d was carried out at 40 °C and stereospecifically afforded the
single stereoisomers 3b–d in good yields of 66–72%, respectively
(Scheme 4). To the best of our knowledge, this is the first example
of the stereospecific synthesis of thiazolidin-4-one derivatives by a
one-pot three component reaction.
Mechanically, the stereochemistry in constructing thiazolidin-
4-one depends on the nucleophilic condensation of imine (C@N)
and HSCH2COOH. In order to investigate the main structural effects
on the reaction selectivity, we carried out the reaction using aza-
sugar aldehyde 1 with aniline 2e and 4-chloro aniline 2f instead
of the azido sugars at 40 °C (Scheme 5). However, both reactions
afforded the diastereomeric products of the thiazolidin-4-one con-
taining C-pseudo-aza-nucleosides 3e–f (more polar and a majority)
and 3e0–f0 (less polar and a minority) in a ratio of 2:1, and so exhib-
ited low stereoselectivity. Considering the previous results3 in
which the synthesis of the thiazolidin-4-one linked pseudodisac-
Table 1
Exploratory studies of the tandem reaction using 1 and 2aa
b
c
Entry
Temp (°C)
Ratio of 3a:3a0
Total yield of 3a and 3a0
d
1
2
3
4
5
6
rt
40
60
—
—
1:0
10:1
6:1
70%
65%
57%
50%
48%
80
100
120
6:1
6:1
a
The ratio of reactants: 1:2a:Ph3P:HSCH2COOH = 1:1:1.1:2. Compounds 1a, Ph3P,
and 2a were first stirred for 30 min in toluene, then mercaptoacetic acid was added
and stirred for another 12 h until the starting materials disappeared by TLC.
b
Determined by 1H NMR.
Isolated yield.
No products were detected after 12 h.
c
d
charides by the tandem reaction from a sugar aldehyde with
azidosugars 2a or 2b proceeded with very low stereoselectivity,
we postulate that the highly stereoselective synthesis shown in
Scheme 3 would be likely due to the synergistic hindrance effects
of the two sugar groups and the N-Boc group.
Thus, the bulky chiral sugars might cause a dominant attack of
the sulfur atom onto the imine from one side and generate one iso-
mer as the predominant product at 40 °C. As the reaction temper-
ature increased, the molecular movement was accelerated,
lowering the reaction stereoselectivity. In the cases of 2e and 2f,
the planar phenyl group diminished the hindrance effect, which
led to a nearly equal attack of the sulfur atom from both sides of
the imine and afforded the diastereomers with low
stereoselectivity.
The further deprotection of 3 could effectively produce the cor-
responding products 4 in good yields. The structures of the new
compounds were determined according to analyses of their 1H
13
NMR, C NMR, and HR ESI MS spectra. The structure of 4e0 was
confirmed by single-crystal X-ray analysis (Fig. 1),15 in which the
5
1
4
O
S
2
*
Boc
3
N
Boc
N
N
O
O
OMe
O
OMe
Ref [14]
N3
D-mannose
+
H
O
O
O
O
O
O
O
O
3a
1
2a
(R)-major isomer
(S)-minor isomer
3a'
O
S
O
S
H
N
(R)
H
N
N
O
(S) N
H
O
OMe
OMe
H
+
HO
HO
OH
OH
HO
HO
OH
OH
4a
4a'
Scheme 3.

H. Chen et al. / Tetrahedron: Asymmetry 24 (2013) 457–463
459
O
O
S
Boc
N
S
Boc
O
+
(R)
H
N
(R)
N
N
N
ii
i
Sugar1
Sugar1
2b-d
N3
Sugar2
H
H
O
O
O
O
HO
OH
4b-d
1
3b-d
Boc
Boc
OMe
N
N
O
Sugar1:
O
HO
HO
BzO
OBz
O
O
O
OBz
d
c
b
H
N
H
N
OMe
OH
O
Sugar2:
OH
HO
HO
OH
OH
OH
d
c
b
Scheme 4. The stereospecific synthesis of thiazolidin-4-one linked pseudo-aza-disaccharides. Reagents and conditions: (i) PPh3, HSCH2COOH, 12 h, 66–72%; (ii) for 4c–d: 90%
CF3COOH/H2O, 1 h, 80%; for 4b: (a) MeOH/MeONa, 1 h, (b) 90% CF3COOH/H2O, 1 h, 50%.
O
S
Boc
N
Boc
N
O
*
N
i
H
+
H2N
R
R
O
O
O
O
2e-f
1
3e-f and 3e'-f'
O
O
S
S
H
(R)
H
N
(S)
N
N
N
ii
H
H
+
R
R
HO
OH
HO
OH
4e-f
4e'-f'
H
Cl
R=
e
f
Scheme 5. The synthesis of the thiazolidin-4-one containing C-pseudo-aza-nucleo-
sides. Reagents and conditions: (i) HSCH2COOH, DCC, DMAP, 12 h, total yields 62–
70%; (ii) 90% CF3COOH/H2O, 1 h, 85–90%.
Figure 1. X-ray crystallographic structure of 4e0.
Table 2
The 1H NMR signal (d = ppm) of H-2 in compounds 4
3. Conclusion
Compounds
4a
4b
4c
4d
4e
4f
In conclusion, novel thiazolidin-4-one linked pseudo-aza-disac-
charides 4a–d were synthesized stereoselectively by a Staudinger/
aza-Wittig/cyclization reaction. The reaction stereoselectivity
could be controlled by the structure of the reactants (N-Boc
protected azasuger aldehyde and azido sugars), while temperature
also had a significant impact on the reaction. The present findings
may provide an important reference for the asymmetry synthesis
of thiazolidin-4-ones. The examination of the immunostimulat-
ing activity of these compounds is currently underway in our
laboratory.
dH-2 (R form)
dH-2 (S form)
5.26
5.38 4a0
5.23
5.04
5.03
5.32
5.49 4e0
5.48
5.50 4f0
new generated chiral carbon (C-2) had the (S)-configuration.
Therefore, its diastereomer 4e should have an (R)-configuration
at C-2. In our previous studies,3,11 we have found an important cor-
relation between the stereochemistry of C-2, the molecular polar-
ity and the chemical shift of H-2. Based on the crystallographic
structure of 4e0 and with the comparison of the chemical shifts
of H-2 summarized in Table 2, the structures of 4a, 4a0, 4f and 4f0
could be tentatively determined. Thus, similar to the observations
in the cases of 4e and 4e0, compounds 4a and 4f have more polarity
and higher up-field chemical shifts of H-2 than those of their iso-
mers 4a0 and 4f0 (Table 2), implying that their C-2s in 4a and 4f
have an (R)-configuration. Accordingly, compounds 4b–d and 3a–
f should have an (R)-configuration, and compounds 3a0, 3e0–f0
should possess an (S)-configuration at C-2.
4. Experimental section
4.1. General methods
Melting points were measured on an SGW X-4 micro melting
point apparatus. Optical rotations were determined on an SGW-1

460
H. Chen et al. / Tetrahedron: Asymmetry 24 (2013) 457–463
automatic polarimeter. 1H NMR and 13C NMR spectra were
measured on a Brucker advance II 600 FT-NMR spectrometer using
tetramethylsilane (Me4Si) as the internal standard. High-resolution
mass spectra (HRMS) were carried out on a FTICR-MS (Ionspec 7.0
T) mass spectrometer with electrospray ionization (ESI). X-ray
crystallographic measurements were made on a Bruker SMART
CCD diffractometer. Thin-layer chromatography (TLC) was per-
formed on precoated plates (Qingdao GF254) with detection by
UV light or with phosphomolybdic acid in EtOH–H2O followed by
heating. Column chromatography was performed using SiO2 gel
(Qingdao 300–400 mesh).
washed successively with water (50 mL ꢀ 2) and saturated brine
(50 mL ꢀ 2), dried over anhydrous magnesium sulfate and concen-
trated under reduced pressure to give a crude product, which was
purified using column chromatography (petroleum ether:ethyl
acetate V/V 4:1) to afford 3a. Under the same conditions, com-
pounds 3b–d were obtained.
4.4.1. (3aS,4R,6aR)-tert-Butyl 4-((R)-3-(((3aR,4R,6R,6aR)-6-
methoxy-2,2-dimethyl-tetrahyd-rofuro[3,4-d][1,3]dioxol-4-
yl)methyl)-4-oxothiazolidin-2-yl)-2,2-dimethyldihydro-3aH-
[1,3]dioxolo[4,5-c]pyrrole-5(4H)-carboxylate 3a
Pale yellow syrup, yield 49%; 1H NMR (600 MHz, CDCl3) dH:
1.25–1.45 (21H, m, 7CH3), 3.16 (1H, dd, J = 13.8 Hz, 4.8 Hz,
CH2), 3.28 (3H, s, –OCH3), 3.55–3.69 (3H, m, CH2, CH), 3.95 (1H,
d, J = 12.6 Hz, CH), 4.07 (1H, dd, J = 13.8 Hz, 10.8 Hz, CH), 4.34
(1H, d, J = 3.0 Hz, CH), 4.49 (1H, d, J = 6.0 Hz, CH), 4.51–4.61
(2H, m, CH2), 4.66–4.69 (1H, m, CH), 4.79 (1H, t, J = 5.4 Hz, CH),
4.97 (1H, s, CH), 5.28 (1H, s, CH); 13C NMR (125 MHz, CDCl3)
dC: 24.7, 26.2, 27.1, 28.5, 31.9, 46.7, 53.7, 55.5, 60.9, 66.2, 79.0,
79.9, 80.7, 81.3, 81.9, 82.8, 85.4, 110.1, 112.6, 153.5, 171.2; HRMS
4.2. Synthesis of compound 6
Compound 5 (5.7 g, 13.3 mmol) was dissolved in 270 mL of
anhydrous MeOH, after which anhydrous K2CO3 (5 equiv) was
added. After continued stirring for 3 h at 40 °C under a nitrogen
atmosphere, the mixture was neutralized with dilute HCl and con-
centrated and extracted with (100 mL ꢀ 3) of ethyl acetate. The or-
ganic layer was dried over anhydrous magnesium sulfate and
concentrated under reduced pressure to give a crude product,
which was purified using column chromatography (petroleum
ether:ethyl acetate V/V 4:1) to furnish compound 6.
(ESI): Calcd for
553.2187.
C
24H38N2O9SNa ([M+Na]+): 553.2195. Found:
4.4.2. (3aS,4R,6aR)-tert-Butyl 4-((S)-3-(((3aR,4R,6R,6aR)-6-
methoxy-2,2-dimethyl-tetrahydr-ofuro[3,4-d][1,3]dioxol-4-
yl)methyl)-4-oxothiazolidin-2-yl)-2,2-dimethyldihydro-3aH-
[1,3]dioxolo[4,5-c]pyrrole-5(4H)-carboxylate 3a0
4.2.1. (3aR,6S,7R,7aS)-6-(Azidomethyl)-2,2-dimethylhexahydro-
[1,3]dioxolo[4,5-c]pyridin-7-ol 6
White solid, yield 95%, mp 143.0–144.0 °C, ½a D25
¼ þ32:6 (c 1.0,
ꢁ
CHCl3); 1H NMR (600 MHz, CDCl3) dH: 1.38 (3H, s, CH3), 1.52 (3H, s,
CH3), 2.72 (1H, dd, J = 12.6 Hz, 4.8 Hz, CH), 3.08, 3.20 (2H, CH2),
3.43, 3.56 (2H, CH2), 3.92 (1H, t, J = 2.4 Hz, CH), 4.22 (1H, q,
J = 2.4 Hz, CH), 4.28–4.31 (1H, m, CH); 13C NMR (125 MHz, CDCl3)
dC: 26.1, 28.0, 47.9, 52.7, 54.6, 70.8, 76.3, 77.2, 109.4; HRMS
(ESI): Calcd for C9H17N4O3 ([M+H]+): 229.1304. Found: 229.1301.
Pale yellow syrup, yield 8%; 1H NMR (600 MHz, CDCl3) dH: 1.30–
1.46 (21H, m, 7CH3), 3.07–3.77 (7H, m, 2CH2, –OCH3), 3.91, 4.17
(1H, d, J = 12.6 Hz, CH), 3.96–4.08 (1H, m, CH), 4.26–4.36 (1H, m,
CH), 4.44 (1H, d, J = 6.0 Hz, CH), 4.63–4.68 (3H, CH2, CH), 4.86–
4.89 (1H, m, CH), 4.96, 5.13 (1H, CH), 4.98 (1H, s, CH); 13C NMR
(125 MHz, CDCl3) dC: 24.9, 25.0, 26.5, 28.3, 31.9, 46.5, 55.9, 63.9,
65.2, 79.9, 80.5, 80.6, 82.4, 82.8, 85.8, 110.7, 112.6, 155.1, 170.5;
HRMS (ESI): Calcd for C24H38N2O9SNa ([M+Na]+): 553.2195. Found:
553.2198.
4.3. Synthesis of compound 2d
A mixture of compound 6 (2.9 g, 12.7 mmol), Boc2O (2 equiv),
and TEA (3 equiv) in anhydrous MeOH (100 mL) was stirred at
room temperature for 2 h under a nitrogen atmosphere, then con-
centrated under reduced pressure to give a crude product, which
was purified using column chromatography (petroleum ether:-
ethyl acetate V/V 10:1) to give 2d.
4.4.3. (2R,3R,4S,5R,6S)-2-(((R)-2-((3aS,4R,6aR)-5-(tert-Butoxy
carbonyl)-2,2-dimethyltetrahydro-3aH-[1,3]dioxolo[4,5-c]pyrr-
ol-4-yl)-4-oxothiazolidin-3-yl)methyl)-6-methoxytetra hydro-
2H-pyran-3,4,5-triyl tribenzoate 3b
Pale yellow syrup, yield 72%; 1H NMR (600 MHz, CDCl3) dH:
1.25–1.62 (15H, 5CH3), 3.47–3.77 (8H, m, 2CH2, –OCH3, CH), 3.96,
4.08 (1H, CH), 4.46–4.57 (2H, m, CH2), 4.62–4.65 (1H, m, CH),
4.78–4.80 (1H, m, CH), 5.07–5.29 (3H, 3CH), 5.41–5.48 (1H, m,
CH), 6.10–6.17 (1H, m, CH), 7.28–8.00 (15H, ArH); 13C NMR
(125 MHz, CDCl3) dC: 24.9, 26.7, 28.2, 28.4, 29.7, 31.7, 45.0, 55.6,
61.4, 65.6, 70.1, 70.7, 71.9, 79.2, 80.2, 81.1, 96.6, 96.9, 111.8,
128.2, 128.4, 128.5, 128.9, 129.1, 129.2, 129.6, 129.9, 131.9,
132.0, 133.0, 133.2, 153.6, 154.1, 165.4, 165.7, 171.1, 171.5; HRMS
(ESI): Calcd for C43H48N2O13SNa ([M+Na]+): 855.2774. Found:
855.2771.
4.3.1. (3aR,6S,7R,7aS)-tert-Butyl 6-(azidomethyl)-7-hydroxy-2,2-
di methyltetrahydro-[1,3]dioxolo[4,5-c]pyridine-5(6H)-carbox-
ylate 2d
White solid, yield 80%, mp 100.1–102.0 °C, ½a D25
¼ þ28:4 (c 1.0,
ꢁ
CHCl3); 1H NMR (600 MHz, CDCl3) dH: 1.32 (3H, s, CH3), 1.38–1.48
(12H, m, 4 CH3), 3.24, 3.37 (1H, d, J = 14.4 Hz, CH), 3.54–3.70 (2H,
m, CH2), 4.01–4.34 (5H, CH2, 3CH); 13C NMR (125 MHz, CDCl3)
dC: 24.2, 26.4, 28.3, 40.9, 42.2, 49.3, 49.7, 51.0, 51.8, 66.0, 66.8,
72.5, 72.6, 73.6, 73.7, 80.2, 80.4, 109.4; HRMS (ESI): Calcd for
C
14H24N4O5Na ([M+Na]+): 351.1644. Found: 351.1638.
4.4.4. (3aS,4S,6aR)-tert-Butyl 4-(((R)-2-((3aS,4R,6aR)-5-(tert-
butoxycarbonyl)-2,2-dimethyltetrahydro-3aH-[1,3]dioxolo [4,5-
c]pyrrol-4-yl)-4-oxothiazolidin-3-yl)methyl)-2,2-dimethyl
dihydro-3aH-[1,3]dioxolo[4,5-c]pyrrole-5(4H)-carboxylate 3c
Pale yellow syrup, yield 70%; 1H NMR (600 MHz, CDCl3) dH:
1.29–1.53 (30H, 10CH3), 3.10, 3.40 (2H, CH2), 3.47–3.91 (5H,
2CH2, CH), 4.04–4.09 (1H, m, CH), 4.27–4.31 (1H, m, CH), 4.38–
4.80 (5H, m, CH), 5.11, 5.24, 5.33 (1H, CH); 13C NMR (125 MHz,
CDCl3) dC: 24.6, 25.6, 27.6, 28.3, 31.7, 41.9, 50.7, 53.7, 60.3, 65.5,
79.6, 80.6, 81.2, 81.8, 112.1, 112.3, 153.6, 154.3, 171.5; HRMS
4.4. General procedure for the synthesis of compounds 3a–d
and 3a0
Azidosugar 2a (1.0 g, 3.7 mmol), Ph3P (1.1 equiv), and azasugar
aldehyde 1 (1.0 equiv) were dissolved in 200 mL of anhydrous tol-
uene, and the mixture was stirred in 40 °C for 30 min under a
nitrogen atmosphere. Next, mercapto acetic acid (2.0 equiv) was
added. After continued stirring for 12 h at 40 °C (80 °C for 3a and
3a0), the mixture was neutralized with aqueous NaHCO3 and ex-
tracted with (100 mL ꢀ 3) of ethyl acetate; the organic layer was
(ESI): Calcd for
622.2775.
C
28H45N3O9SNa ([M+Na]+): 622.2774. Found:

H. Chen et al. / Tetrahedron: Asymmetry 24 (2013) 457–463
461
4.4.5. (3aR,6S,7R,7aS)-tert-Butyl 6-6-(((S)-2-((3aS,4R,6aR)-5-
(tert-butoxycarbonyl)-2,2-dimethyltetrahydro-3aH-[1,3]diox-
olo[4,5-c]pyrrol-4-yl)-4-oxothiazolidin-3-yl)methyl)-7-
hydroxy-2,2-dimethyltetrahydro-[1,3]dioxolo[4,5-c]pyridine-
5(6H)-carboxylate 3d
(ESI): Calcd for C21H27ClN2O5SNa ([M+Na])+: 477.1227. Found:
477.1225.
4.5.4. (3aS,4R,6aR)-tert-Butyl 4-((S)-3-(4-chlorophenyl)-4-
oxothiazolidin-2-yl)-2,2-dimethyl-dihydro-3aH-[1,3]dioxolo
[4,5-c]pyrrole-5(4H)-carboxylate 3f0
Pale yellow syrup, yield 66%; 1H NMR (600 MHz, CDCl3) dH:
1.31–1.51 (30H, 10CH3), 3.38 (2H, d, J = 9.6 Hz, CH2), 3.52–3.58
(2H, m, CH2), 3.62 (1H, d, J = 9.6 Hz, CH), 3.89–3.95 (3H, m, CH,
CH2), 4.10 (1H, d, J = 13.2 Hz, CH), 4.28 (1H, d, J = 7.8 Hz, CH),
4.46 (1H, dd, J = 7.8 Hz, 3.6 Hz, CH), 4.55 (1H, d, J = 13.2 Hz, CH),
4.67–4.74 (3H, m, 3CH), 5.04, 5.22 (1H, CH); 13C NMR (125 MHz,
CDCl3) dC: 24.0, 25.4, 26.1, 27.1, 28.2, 31.3, 41.8, 49.6, 51.8, 61.1,
63.8, 66.5, 72.7, 72.8, 78.9, 79.7, 80.9, 81.6, 109.2, 112.2, 154.2,
155.5, 173.5; HRMS (ESI): Calcd for C29H47N3O10SNa ([M+Na]+):
652.2879. Found: 652.2882.
Pale yellow syrup; yield 21%. 1H NMR (600 MHz, CDCl3) dH:
1.44–1.52 (15H, m, 5CH3), 3.03 (1H, dd, J = 12.6 Hz, 4.8 Hz, CH2),
3.63–3.67 (1H, m, CH2), 3.83 (1H, d, J = 14.4 Hz, CH2), 3.63–3.67,
3.83 (1H, m, CH2), 4.29–4.34 (1H, m, CH), 4.59 (1H, d, J = 5.4 Hz,
CH), 4.69 (1H, t, J = 5.4 Hz, CH), 5.74 (1H, s, CH), 7.39 (4H, s,
ArH); 13C NMR (125 MHz, CDCl3) dC: 25.0, 27.0, 27.7, 28.3, 33.1,
54.0, 60.4, 63.4, 68.4, 79.4, 80.6, 81.2, 112.4, 126.6, 129.2, 154.4,
170.7; HRMS (ESI): Calcd for
477.1227. Found: 477.1228.
C
21H27ClN2O5SNa ([M+Na]+):
4.5. General procedure for the synthesis of compounds 3e–f and
3e0–f0
4.6. General procedure for the synthesis of 4a, 4c–4f and 4a0,
4e0–4f0
Aniline 2e or chloroaniline 2f (1 mL) and sugar aldehyde 1
(1.2 equiv) were dissolved in 30 mL of anhydrous toluene. The mix-
ture was then stirred in 40 °C for 1 h under a nitrogen atmosphere.
Next, mercapto acetic acid (2.0 equiv), DCC (1.2 equiv), and DMAP
(0.2 equiv) were added. After continued stirring for 12 h, the mix-
ture was filtered and washed by ether, neutralized with aqueous
NaHCO3 and extracted with (60 mL ꢀ 3) of ethyl acetate. The or-
ganic layer was washed successively with water (30 mL ꢀ 2) and
saturated brine (20 mL ꢀ 2), dried over anhydrous magnesium sul-
fate, and concentrated under reduced pressure to give a crude
product, which was purified using column chromatography (petro-
leum ether:ethyl acetate V/V 6:1) to afford 3e–f and 3e0–f0.
Compound 3a (1.0 g, 1.8 mmol) was dissolved in 5 mL of 90%
trifluoroacetic acid aqueous solution. The mixture was then stirred
at rt for 1 h. After the reaction had finished, the solvent was re-
moved under reduced pressure to give a crude product, which
was purified using column chromatography (ethyl acetate:MeOH
V/V 5:1) to give 4a. According to the same procedure, compounds
4a0, 4c–4f, and 4e0–4f0 were obtained.
4.6.1. (R)-3-(((2R,3S,4R,5R)-3,4-Dihydroxy-5-methoxytetra hydro-
furan-2-yl)methyl)-2-methyl)-2-((2R,3S,4R)-3,4-di hydroxy-
pyrrolidin-2-yl)thiazolidin-4-one 4a
Yellow solid, yield 65%, mp 262.0 °C, ½a D25
¼ þ14:2 (c 1.0,
ꢁ
MeOH); 1H NMR (600 MHz, CD3OD) dH: 2.92 (1H, d, J = 12.0 Hz,
3.0 Hz, CH2), 3.10 (1H, dd, J = 12.0 Hz, 4.8 Hz, CH2), 3.38 (3H, s, –
OCH3), 3.53 (1H, dd, J = 15.0 Hz, 3.0 Hz, CH), 3.56 (1H, d,
J = 15.6 Hz, CH), 3.68 (1H, d, J = 16.2 Hz), 3.79 (1H, q, J = 3.0 Hz,
CH), 3.90 (1H, d, J = 4.2 Hz, CH), 4.01 (1H, dd, J = 14.4 Hz, 6.6 Hz,
CH), 4.05–4.08 (2H, m, CH2), 4.14–4.19 (2H, m, CH2), 4.75 (1H, s,
CH), 5.26 (1H, s, CH); 13C NMR (125 MHz, CD3OD) dC: 31.3, 46.2,
51.4, 54.5, 62.2, 64.6, 72.4, 72.7, 72.9, 74.8, 78.9, 108.8, 172.8;
HRMS (ESI): Calcd for C13H23N2O7S ([M+H]+), 351.1226. Found:
351.1231.
4.5.1. (3aS,4R,6aR)-tert-Butyl 2,2-dimethyl-4-((R)-4-oxo-3-
phenylthiazolidin-2-yl)dihydro-3aH-[1,3]dioxolo[4,5-c]pyrrole-
5(4H)-carboxylate 3e
Pale yellow syrup, yield 47%; 1H NMR (600 MHz, CDCl3) dH:
1.35–1.45 (15H, m, 5CH3), 2.52–2.63 (1H, m, CH2), 3.49–3.71 (2H,
m, CH2), 3.88 (1H, d, J = 16.2 Hz, CH2), 4.23 (1H, s, CH), 4.61–4.62
(1H, m, CH), 4.66–4.68 (1H, m, CH), 5.74, 5.92 (1H, CH), 7.31–
7.44 (5H, m, Ar); 13C NMR (125 MHz, CDCl3) dC: 25.1, 26.9, 28.3,
32.5, 53.9, 62.5, 66.3, 79.6, 80.2, 81.0, 112.0, 126.5, 126.9, 129.6,
136.9, 154.2, 170.5; HRMS (ESI): Calcd for
C21H28N2O5SNa
([M+Na]+): 443.1616. Found: 443.1620.
4.6.2. (S)-3-(((2R,3S,4R,5R)-3,4-Dihydroxy-5-methoxytetra
hydrofuran-2-yl)methyl)-2-methyl)-2-methyl)-2-((2R,3S,4R)-
3,4-dihydroxypyrrolidin-2-yl)thiazolidin-4-one 4a0
4.5.2. (3aS,4R,6aR)-tert-Butyl 2,2-dimethyl-4-((S)-4-oxo-3-
phenylthiazolidin-2-yl)dihydro-3aH-[1,3]dioxolo[4,5-c]pyrrole-
5(4H)-carboxylate 3e0
White solid, yield 62%, mp 260.0 °C, ½a D25
¼ ꢂ26:0 (c 1.0,
ꢁ
MeOH); 1H NMR (600 MHz, CD3OD) dH: 2.92 (1H, dd, J = 12.0 Hz,
2.4 Hz, CH2), 3.13 (1H, dd, J = 12.6 Hz, 4.8 Hz, CH2), 3.30 (3H, s, –
OCH3), 3.49 (1H, d, J = 15.0 Hz, CH), 3.71 (1H, dd, J = 13.8 Hz,
2.4 Hz, CH), 3.76 (1H, dd, J = 15.6 Hz, 1.8 Hz, CH), 3.84 (1H, dd,
J = 9.6 Hz, 4.8 Hz, CH), 3.89 (1H, d, J = 4.8 Hz, CH), 4.03 (1H, dd,
J = 7.2 Hz, 4.2 Hz, CH), 4.06–4.09 (2H, m, 2CH2), 4.11–4.14 (2H, m,
2CH2), 4.77 (1H, s, CH), 5.38 (1H, s, CH); 13C NMR (125 MHz,
CD3OD) dC: 31.6, 46.2, 51.8, 54.7, 60.1, 64.6, 71.8, 73.3, 74.5, 74.6,
80.9, 108.9, 172.7; HRMS (ESI): Calcd for C13H23N2O7S ([M+H]+),
351.1226. Found: 351.1228.
Pale yellow syrup, yield 23%; 1H NMR (600 MHz, CDCl3) dH:
1.35–1.45 (15H, m, 5CH3), 3.64–3.69 (1H, m, CH2), 3.75, 3.91 (1H,
d, J = 12 Hz, CH2), 3.78–3.83 (2H, m, CH2), 4.15, 4.29 (1H, CH),
4.75 (1H, d, J = 6 Hz, CH), 4.82–4.87 (1H, m, CH), 5.45, 5.76 (1H,
CH), 7.36–7.48 (5H, m, H-Ar); 13C NMR (125 MHz, CDCl3) dC:
24.9, 27.0, 28.3, 33.1, 53.3, 62.5, 68.9, 79.2, 80.2, 80.7, 112.3,
125.3, 127.2, 129.3, 154.1, 170.9; HRMS (ESI): Calcd for
C
21H28N2O5SNa ([M+Na]+): 443.1616. Found: 443.1621.
4.5.3. (3aS,4R,6aR)-tert-Butyl 4-((R)-3-(4-chlorophenyl)-4-
oxothiazolidin-2-yl)-2,2-dimethyl-dihydro-3aH-[1,3]dioxolo
[4,5-c]pyrrole-5(4H)-carboxylate 3f
4.6.3. (R)-2-((2R,3S,4R)-3,4-Dihydroxypyrrolidin-2-yl)-3-(((2S,
3S,4R)-3,4-dihydroxypyrrolidin-2-yl)methyl)thiazolidin-4-one
Pale yellow syrup, yield 41%; 1H NMR (600 MHz, CDCl3) dH:
1.32–1.37 (9H, m, 3CH3), 1.43 (6H, s, 2CH3), 3.61–3.65 (1H, m,
CH2), 3.75–3.80 (2H, m, CH2), 3.73–3.74, 3.90–3.92 (1H, m, CH2),
4.08, 4.23 (1H, CH), 4.69 (1H, d, J = 6.0 Hz, CH), 4.76–4.86 (1H, m,
CH), 5.42, 5.71 (1H, CH), 7.30–7.44 (4H, m, ArH); 13C NMR
(125 MHz, CDCl3) dC: 25.1, 27.0, 28.3, 66.2, 32.4, 53.8, 60.4, 63.3,
79.7, 80.1, 80.8, 112.2, 128.1, 129.8, 135.4, 154.2, 170.6; HRMS
4c
White solid, yield 80%, mp 110.1–111.3 °C, ½a D25
¼ þ31:1 (c 1.0,
ꢁ
H2O); 1H NMR (600 MHz, D2O) dH: 2.87, 3.04, 3.13 (4H, 2CH2), 3.41
(1H, dd, J = 13.2 Hz, 4.2 Hz, CH), 3.51 (1H, d, J = 16.2 Hz, CH), 3.58–
3.65(2H, m, CH2), 3.69 (1H, m, CH), 3.79 (1H, dd, J = 15.6 Hz, 3.6 Hz,
CH), 3.95 (1H, dd, J = 9.6 Hz, 4.2 Hz, CH), 4.07 (1H, d, J = 3.0 Hz, CH),
4.16–4.19 (2H, m, CH), 5.04 (1H, s, CH); 13C NMR (125 MHz, D2O)

462
H. Chen et al. / Tetrahedron: Asymmetry 24 (2013) 457–463
dC: 23.2, 31.4, 44.4, 50.4, 58.9, 61.6, 64.8, 68.8, 71.6, 72.5, 73.1,
175.5; HRMS (ESI): Calcd for C12H22N3O5S ([M+H]+), 320.1274.
Found: 320.1274.
4.7. Synthesis of compound 4b
To a solution of 3b (0.3 g, 0.4 mmol) in anhydrous MeOH (5 mL)
was added MeONa (2 equiv). The mixture was then stirred at room
temperature for 1 h under a nitrogen atmosphere. After the reac-
tion had finished and neutralized with cationic resin, the filtrate
was concentrated, then dissolved in 10 mL of 90% trifluoroacetic
acid aqueous solution, and stirred at room temperature for 1 h.
The solvent was removed under reduced pressure to give a crude
product, which was purified using column chromatography (ethyl
acetate:MeOH V/V 2:1) to give 4b.
4.6.4. (S)-2-((2R,3S,4R)-3,4-Dihydroxypyrrolidin-2-yl)-3-(((2S,3R,
4R,5R)-3,4,5-trihydroxypiperidin-2-yl)methyl)thiazolidin-4-one
4d
Pale yellow solid, yield 80%, mp 172.5–173.5 °C, ½a D25
¼ þ55:4 (c
ꢁ
1.0, H2O); 1H NMR (600 MHz, D2O) dH: 2.67 (1H, dd, J = 12.6 Hz,
10.8 Hz, CH), 2.84–2.92 (2H, m, CH2), 3.04 (1H, dd, J = 12.6 Hz,
4.2 Hz, CH), 3.28–3.31 (2H, m, CH2), 3.57 (1H, d, J = 16.8 Hz, CH),
3.63–3.65 (2H, m, 2CH), 3.67 (1H, dd, J = 16.2 Hz, 1.8 Hz, CH),
3.73 (1H, dd, J = 4.2 Hz, 0.6 Hz, CH), 3.89–3.93 (2H, m, CH2), 4.09
(1H, m, CH), 4.15 (1H, dd, J = 7.2 Hz, 4.8 Hz, CH), 5.02 (1H, t,
J = 4.8 Hz, CH); 13C NMR (125 MHz, D2O) dC: 31.8, 44.0, 44.2, 50.5,
50.9, 61.6, 64.8, 65.5, 68.9, 69.8, 72.7, 72.8, 174.7; HRMS (ESI):
Calcd for C13H24N3O6S ([M+H]+), 350.1385. Found: 350.1381.
4.7.1. (R)-2-((2R,3S,4R)-3,4-Dihydroxypyrrolidin-2-yl)-3-(((2R,3S,
4S, 5R,6S)-3,4,5-trihydroxy-6-methoxytetrahydro-2H-pyran-2-
yl)methyl)thiazolidin-4-one 4b
White solid, yield 50%, mp 106.2–108.3 °C, ½a D25
¼ þ123:0 (c 1.0,
ꢁ
CH3OH); 1H NMR (600 MHz, CD3OD) dH: 2.93, 3.12 (2H, CH2), 3.16
(1H, t, J = 9.6 Hz, CH), 3.41 (4H, m, –OCH3, CH), 3.53 (1H, dd,
J = 15.0 Hz, 2.4 Hz, CH), 3.58 (1H, d, J = 9.6 Hz, CH), 3.63 (1H, t,
J = 9.0 Hz, CH), 3.71 (1H, dd, J = 15.6 Hz, 1.8 Hz, CH), 3.79 (2H, m,
CH), 4.07 (1H, dd, J = 5.4 Hz, 3.6 Hz, CH), 4.14 (2H, m, CH), 4.67
(1H, d, J = 3.6 Hz, CH), 5.23 (1H, t, J = 3.6 Hz, CH); 13C NMR
(125 MHz, CD3OD) dC: 31.3, 43.8, 51.4, 54.5, 61.9, 64.5, 69.0, 71.7,
72.1, 72.3, 72.9, 73.2, 99.9, 173.3; HRMS (ESI): Calcd for
4.6.5. (R)-2-((2R,3S,4R)-3,4-Dihydroxypyrrolidin-2-yl)-3-phenyl-
thiazolidin-4-one 4e
Pale yellow solid, yield 87%, mp 160.0 °C, ½a D25
¼ þ115:1 (c 1.0,
ꢁ
MeOH); 1H NMR (600 MHz, CD3OD) dH: 2.68 (1H, dd, J = 12.0 Hz,
3.0 Hz, CH2), 2.95 (1H, dd, J = 11.4 Hz, 3.6 Hz, CH2), 3.29 (1H, d,
J = 3.6 Hz, CH), 3.55 (1H, d, J = 16.2 Hz, CH2), 3.78 (1H, d,
J = 15.6 Hz, CH2), 3.94 (1H, d, J = 4.2 Hz, CH), 4.12 (1H, t,
J = 5.4 Hz, CH), 5.32 (1H, s, CH), 7.22–7.38 (5H, m, ArH); 13C NMR
(125 MHz, CD3OD) dC: 32.1, 50.9, 63.5, 66.9, 72.5, 72.8, 126.9,
127.5, 128.9, 137.7, 172.0; HRMS (ESI): Calcd for C13H17N2O3S
([M+H]+): 281.0960. Found: 281.0967.
C
14H25N2O8S ([M+H]+), 381.1326. Found: 381.1323.
4.8. X-ray crystallographic measurement of a single crystal of
4e0
Single crystals of compound 4e0 were obtained by recrystalliza-
tion from a solution of EtOAc–MeOH and applied on a Bruker SMART
CCD diffractometer for analysis. The intensity data were collected on
a Bruker SMART CCD diffractometer with graphite-monochromated
4.6.6. (S)-2-((2R,3S,4R)-3,4-dihydroxypyrrolidin-2-yl)-3-phenyl-
thiazolidin-4-one 4e0
White solid, yield 85%, mp 160.0 °C, ½a D25
¼ ꢂ130:1 (c 1.0,
ꢁ
MeOH); 1H NMR (600 MHz, CD3OD) dH: 2.90 (1H, dd, J = 12.6 Hz,
1.8 Hz, CH2), 3.15 (1H, dd, J = 12.0 Hz, 4.2 Hz, CH2), 3.28 (1H, dd,
J = 7.8 Hz, 1.2 Hz, CH), 3.63 (1H, d, J = 15.6 Hz, CH2), 3.81 (1H, dd,
J = 7.8 Hz, 4.2 Hz, CH), 3.97 (1H, dd, J = 15.6 Hz, 1.8 Hz, CH2), 4.04
(1H, d, J = 1.8 Hz, CH), 5.49 (1H, s, CH), 7.25–7.39 (5H, m, ArH);
13C NMR (125 MHz, CD3OD) dC: 32.7, 52.2, 62.6, 67.2, 72.0, 74.9,
126.6, 127.6, 129.2, 137.2, 172.2; HRMS (ESI): HRMS (ESI): Calcd
for C13H17N2O3S ([M+H]+): 281.0960. Found: 281.0964.
Mo Ka radiation (k = 0.71073 Å) using the h/2x scan technique from
a single crystal of 0.36 ꢀ 0.11 ꢀ 0.11 mm, and a semi-empirical
absorption correction was applied for all complexes. The structure
was solved by direct methods and refined by full-matrix least-
squares on F2. The absolute structure parameter was 0.08 (7),
respectively. All non-hydrogen atoms were refined anisotropically.
Acknowledgements
4.6.7. (R)-3-(4-Chlorophenyl)-2-((2R,3S,4R)-3,4-dihydroxy pyrr-
Financial support from the National Natural Science Foundation
of China (NSFC) (20972039, 21172051), Research Fund for the Doc-
toral Program of Higher Education of China (20121301110004), the
Medicinal Joint Funds of the Natural Science Foundation of Hebei
Province and Shijiazhuang Pharmaceutical Group (CSPC) Founda-
tion (B2011201169, B2012201113), and the Natural Science Foun-
dations of Education Department of Hebei (ZH2011110, Y2011119)
is gratefully acknowledged.
olidin-2-yl)thiazolidin-4-one 4f
Pale yellow liquid, yield 90%, ½a D25
ꢁ
¼ þ64:1 (c 1.0, MeOH); 1H
NMR (600 MHz, CD3OD) dH: 2.84 (1H, dd, J = 12.0 Hz, 3.6 Hz,
CH2), 3.09 (1H, dd, J = 12.0 Hz, 4.2 Hz, CH2), 3.42 (1H, dd,
J = 6.6 Hz, 3.0 Hz, CH), 3.69 (1H, d, J = 15.6 Hz, CH2), 3.90 (1H, dd,
J = 16.2 Hz, 1.8 Hz, CH), 4.07 (1H, d, J = 3.6 Hz, CH2), 4.26 (1H, t,
J = 6.0 Hz, CH), 5.48 (1H, s, CH), 7.46–7.52 (4H, m, ArH); 13C NMR
(125 MHz, CD3OD) dC: 32.0, 51.1, 63.0, 66.6, 72.4, 72.9, 126.9,
127.8, 132.9, 136.4, 161.8, 171.9; HRMS (ESI): Calcd for
References
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13H16ClN2O3S ([M+H]+): 315.0570. Found: 315.0572.
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olidin-2-yl)thiazolidin-4-one 4f0
White solid, yield 88%, mp 155.0 °C, ½a D25
¼ ꢂ67:0 (c 1.0,
ꢁ
MeOH); 1H NMR (600 MHz, CD3OD) dH: 2.90 (1H, d, J = 12.0 Hz,
CH2), 3.15 (1H, dd, J = 12.6 Hz, 4.8 Hz, CH2), 3.27 (1H, d,
J = 7.8 Hz, CH), 3.64 (1H, d, J = 15.0 Hz, CH2), 3.83 (1H, q,
J = 4.8 Hz, CH), 3.96 (1H, d, J = 15.6 Hz, CH2), 4.06 (1H, s, CH), 5.50
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15. CCDC-911864 contains the supplementary crystallographic data for 4e0. These
data can be obtained free of charge from The Cambridge Crystallographic Data
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