Traceless solid-phase synthesis of 3-substituted isoxazoles and 3-substituted 5-iodoisoxazolines using polystyrene-supported vinyl selenide

Article abstract of DOI:10.1055/s-2006-942436

A novel facile procedure for the traceless solid-phase synthesis of 3-substituted isoxazoles and 3-substituted 5-iodoisoxazolines in good yields and with excellent purities using polymer-supported vinyl selenide is described. The polymeric reagent can be

Full text of DOI:10.1055/s-2006-942436

PAPER
2293
Traceless Solid-Phase Synthesis of 3-Substituted Isoxazoles and 3-Substituted
5-Iodoisoxazolines Using Polystyrene-Supported Vinyl Selenide
Traceless Soli
h
o
hesis of 3-Su
u
bstitutedIso
-
xazoles
R
and 3-Substituted
i
5-Iodoisoxa
S
zoline
s
heng,*a Qin Xin,a Xiao-Ling Liu,a Wu-Kang Sun,a Rui Guo,a Xian Huanga,b
a
Institutes of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, 330027, P. R. of China
Fax +86(791)8517500; E-mail: shengsr@jxnu.edu.cn
b
Department of Chemistry, Zhejiang University, Hangzhou, 310028, P. R. of China
Received 21 February 2006; revised 20 March 2006
reagent.7 In continuation of our interest in solid-phase or-
ganoselenium chemistry, we wish to describe another
simple and efficient traceless solid-phase synthetic ap-
proach to 3-substituted isoxazoles and 3-substituted 5-io-
doisoxazolines based on a novel polystyrene-supported
vinyl selenide (Scheme 1).
Abstract: A novel facile procedure for the traceless solid-phase
synthesis of 3-substituted isoxazoles and 3-substituted 5-iodoisox-
azolines in good yields and with excellent purities using polymer-
supported vinyl selenide is described. The polymeric reagent can be
regenerated and reused as an environmentally benign reagent.
Key words: solid-phase organic synthesis, polymer-supported vi-
nyl selenide, isoxazole, isoxazoline
CH2=CH2
THF, r.t.
t-BuOK
SeBr
SeCH2CH2Br
SeCH=CH2
THF, r.t.
Polymer-supported reagents have attracted growing inter-
est because they have provided attractive and practical
methods for combinatorial chemistry and solid-phase or-
ganic synthesis (SPOS) in recent years.1 Synthesis on a
polymer support shows a number of advantages compared
to solution chemistry. The most salient is the possibility to
apply an excess of reagents and remove them without in-
volving time-consuming separation techniques. Now, the
synthesis of highly diverse organic molecule libraries us-
ing SPOS methodology is recognized as a valuable tool
for the acceleration of drug discovery. Isoxazole and isox-
azoline moieties, which are typically prepared by the 1,3-
dipolar cycloaddition of a nitrile oxide to alkynes and alk-
enes, represent two classes of unique pharmacophores that
are observed in many therapeutic agents and are versatile
intermediates for the synthesis of complex natural prod-
ucts.2 It is therefore not surprising that these compounds
have been both widely studied and used, in particular in
combinatorial synthesis and some methods for their prep-
aration have been transferred to the solid-phase in recent
years.3 Since the first organoselenium resin4 used in SPOS
with the combined advantage of decreased volatility and
simplification of product work-up was reported in 1976,
several research groups5 including ours6 have developed
selenium-based approaches for SPOS. More recently, we
reported 3-substituted-5-iodomethyl isoxazolines, isox-
azoline-containing 1,2-di-heterocyclic substituted com-
pounds using a polystyrene-supported allyl selenide
1
2
3
Scheme 1
Treatment of polymer-supported b-bromoethyl selenide
26e easily prepared from polystyrene-bound selenenyl
bromide 15a with t-BuOK in THF at room temperature af-
forded the vinyl selenide resin 3 (Scheme 1), which was
evidenced by its FT-IR spectrum with the complete disap-
pearance of the C–Br (572 cm–1) absorption and the ab-
sence of bromine from the elemental analysis. According
to the classical method, resin 3 was allowed to react with
nitrile oxides generated in situ from oximes and NCS in
the presence of triethylamine to form the isoxazoline resin
4, which exhibited a weaker C=N stretching band at
1606–1620 cm–1. As expected, the newly loaded resins
when treated with excess 30% hydrogen peroxide at room
temperature resulted in the facile oxidation of the selenide
to the corresponding selenoxide. A syn-elimination of the
selenoxide resulted in the release of 3-substituted isox-
azoles 5 (Scheme 2) in good yields and with excellent pu-
rities in excess of 95% (Table 1). The residual resin 6,
polystyrene-supported phenylseleninic acid, was obtained
as a by-product, whose IR data were identical to the pre-
viously reported data.8 The polystyrene-supported phe-
nylseleninic acid could be converted to resin 1 and
recycled by treatment with potassium iodide and sodium
thiosulfate6c,9 followed by bromine.6a For example, 3-phe-
Se
R1CH=NOH/CHCl3
H2O2
SeOOH
+
SeCH=CH2
O
THF, r.t.
R1
N
NCS, Et3N, r.t.
O
R1
N
3
4
5
6
Scheme 2
SYNTHESIS 2006, No. 14, pp 2293–2296
x
x.
x
x
.
2
0
0
6
Advanced online publication: 26.06.2006
DOI: 10.1055/s-2006-942436; Art ID: F02506SS
© Georg Thieme Verlag Stuttgart · New York

2294
S.-R. Sheng et al.
PAPER
nyl isoxazole (5a) was obtained in 85% yield under the Table 2 Yields and Purities of 3-Substituted 5-Iodoisoxazolines 7
same reaction conditions using the recovered selenenyl
Entry R1
Products Yield (%)a Purity (%)b
bromide resin 1 (second run), and in 80% yield after being
recycled for a second time (i.e. third run). It was shown
that recycling the resin two to three times led to a gradual
deterioration of the resin 1.
1
2
3
4
5
6
7
Ph
7a
7b
7c
85
84
78
82
80
82
80
>95
>95
>95
>95
>95
>95
>95
p-MeC6H4
p-NO2C6H4
p-ClC6H4
n-Pr
Table 1 Yields and Purities of 3-Substituted Isoxazoles 5
7d
7j
Entry
R1
Products Yield (%)a Purity (%)b
1
2
Ph
5a
5b
5c
5d
5e
5f
88
87
80
82
83
83
84
85
84
78
>95
>95
>95
>95
>95
>95
>95
>95
>95
>95
Ph
7ac
7ad
p-MeC6H4
p-NO2C6H4
p-ClC6H4
m-ClC6H4
2,6-Cl2C6H3
p-FC6H4
2-furyl
Ph
3
a Overall yields based on polymer-supported selenium bromide 1
(1.18 mmol Br/g).
4
b Determined by 1H NMR spectroscopy of the crude cleavage product.
c With the third regenerated resin 1.
5
d With the fourth regenerated resin 1.
6
7
5g
5h
5i
in the corresponding solution-phase synthesis. Moreover,
the polymeric reagent can be regenerated and reused as an
environmentally benign reagent.
8
9
PhCH2CH2
n-Pr
Mps were uncorrected. 1H NMR (400 MHz) and 13C NMR (100
MHz) spectra were recorded on a Bruker Avance (400 MHz) spec-
trometer, using CDCl3 as the solvent and TMS as internal standard.
MS (EI, 70 eV) were recorded on a HP5989B mass spectrometer.
FT-IR spectra were taken on a Perkin-Elmer SP One FT-IR spectro-
photometer. Microanalyses were performed with a PE 2400 ele-
mental analyzer. Polystyrene (H 1000, 100–200 mesh, cross-linked
with 1% divinylbenzene) for the preparation of polystyrene-sup-
ported selenium bromide and other starting materials were pur-
chased from commercial suppliers and used without further
purification. DMF was distilled from CaH2 and THF was distilled
from Na/benzophenone immediately prior to use. Selenyl bromide
was prepared according to a known procedure.5a
10
5j
a Overall yields based on polymer-supported selenium bromide 1
(1.18 mmol Br/g).
b Determined from the 1H NMR spectrum of the crude cleavage prod-
uct.
I
Se
O
CH3I, NaI
+
SeCH3
DMF, 75 °C
O
R1
R1
N
N
4
7
8
Scheme 3
Polystyrene-Supported Vinyl Selenide 3
THF (10 mL) saturated with anhyd ethane was added to the polysty-
rene-bound selenenyl bromide 1 (1.0 g, 1.18 mmol). The deep-red
coloration of the polymer disappeared instantly and the mixture was
stirred at r.t. for 5 min. After removal of the solvent, the yellow resin
2 containing 1.14 mmol of Br was obtained and then swelled in THF
(5 mL). A solution of t-BuOK (1.50 mmol) in THF (10 mL) was
added under a N2 atmosphere. The mixture was stirred at r.t. for 5 h
and then filtered. The polymer was washed successively with H2O,
THF, MeOH, and CH2Cl2 (2 × 5 mL of each) and then dried under
vacuum to afford resin 3.
Another cleavage protocol for traceless cleavage of resin
4 employs methyl iodide and sodium iodide in DMF,7b
and we applied this to isoxazoline resin 4 (Scheme 3). It
was shown that 3-substituted 5-iodoisoxazolines 7 could
be obtained in moderate to good yields with good purity
(Table 2). It should be noted that the regenerated polysty-
rene-supported methyl selenide 8 could be easily convert-
ed into polystyrene-supported selenium bromide 1 by
treatment with bromine.5a To show the reactivity of the re-
generated polymeric reagent, the conversion of polysty-
rene-supported selenium bromide 1 into 3-phenyl 5-
iodoisoxazoline (7a) was repeated four times. The purity
of 7a (Table 2, entry 7), remained almost the same as the
originally prepared selenium bromide resin but with a
slight decrease in yield.
FT-IR (KBr): 3059, 2934, 1578, 1478, 1436, 1170, 1022, 736, 690,
471 cm–1.
3-Substituted Isoxazoles 5; General Procedure
To a stirred solution of NCS (4 mmol) in anhyd CHCl3 (5 mL) was
added aldoxime (4 mmol) under a N2 atmosphere at r.t. in one por-
tion. Resin 3 (1.0 mmol) was added after chlorination was complete
(ca. 20 min), then Et3N (4.5 mmol) in CHCl3 (2 mL) was added
dropwise over ca. 10 min. The mixture was stirred at r.t. for 12 h and
then filtered, the polymer was filtered and washed successively with
THF, MeOH, H2O, and CH2Cl2 (2 × 5 mL of each) to funish a yel-
low resin 4. The washed resin 4 was pre-swollen with THF (15 mL),
then treated with 30% H2O2 (1.0 mL, 11.6 mmol) and stirred at r.t.
for 30 min. The residual resin was filtered off and washed with Et2O
(4 × 3 mL). The filtrate was treated with a sat. solution of NaHCO3
In conclusion, an efficient and convenient method for the
traceless solid-phase synthesis of 3-substituted isoxazoles
and 3-substituted 5-iodoisoxazolines in good yields and
purities employing a selenium-based traceless linker strat-
egy has been developed. Simple work-up procedure re-
places the time-consuming isolation and purification steps
Synthesis 2006, No. 14, 2293–2296 © Thieme Stuttgart · New York

PAPER
Traceless Solid-Phase Synthesis of 3-Substituted Isoxazoles and 3-Substituted 5-Iodoisoxazolines
2295
and extracted with Et2O (2 × 20 mL). The organic layer was washed
with H2O (20 mL), dried over anhyd MgSO4, and concentrated to
afford 5a–k.
IR (film): 3128, 2958, 2927, 1616, 1556, 1514, 1459, 1438, 1387,
1365, 1125, 1014, 872, 780 cm–1.
1H NMR: d = 8.43 (d, J = 1.6 Hz, 1 H), 7.57 (dd, J = 1.8, 0.8 Hz, 1
H), 7.28 (dd, J = 3.5, 0.8 Hz, 1 H), 6.62 (d, J = 1.6 Hz, 1 H), 6.54
(dd, J = 3.5, 1.8 Hz, 1 H).
13C NMR: d = 160.9, 146.9, 146.6, 135.0, 128.3, 125.5, 102.2.
EIMS: m/z (%) = 135 (M+, 49.2), 86 (59.7), 84 (100), 78 (52.1), 52
(53.9), 51 (50.1), 43 (40.8).
3-Phenylisoxazole (5a)10
Colorless oil.
IR (film): 3034, 2927, 1552, 1609, 1458, 1437, 1396, 1124, 1099,
1028, 946, 763 cm–1.
1H NMR: d = 8.46 (d, J = 1.7 Hz, 1 H), 7.85–7.82 (m, 2 H), 7.56–
7.26 (m, 3 H), 6.67 (d, J = 1.7 Hz, 1 H).
Anal. Calcd for C7H5NO2: C, 66.22; H, 3.73; N, 10.37. Found: C,
66.16; H, 3.70; N, 10.32.
3-(p-Methylphenyl)isoxazole (5b)
3-(2-Phenylethyl)isoxazole (5i)13
Colorless oil.
Colorless solid; mp 54–55 °C (Lit.11 55–56 °C).
IR (KBr): 3033, 2925, 1614, 1553, 1524, 1381, 1126, 1098, 908,
824, 776, 733 cm–1.
1H NMR: d = 8.45 (d, J = 1.6 Hz, 1 H), 7.75 (d, J = 8.1 Hz, 2 H),
7.28 (d, J = 8.1 Hz, 2 H), 6.66 (d, J = 1.6 Hz, 1 H), 2.31 (s, 3 H).
IR (film): 3125, 2926, 1614, 1600, 1555, 1521, 1475, 1425, 1248,
1095, 1025, 1102, 909, 746 cm–1.
1H NMR: d = 8.01 (d, J = 1.6 Hz, 1 H), 7.26–7.20 (m, 2 H), 7.15–
7.01 (m, 3 H), 5.92 (d, J = 1.6 Hz, 1 H), 2.90–2.85 (m, 4 H).
3-(p-Nitrophenyl)isoxazole (5c)
3-(Propyl)isoxazole (5j)13
Colorless oil.
Pale-yellow solid; mp 170–171 °C (Lit.10 169–171 °C).
IR (KBr): 3006, 2961, 1612, 1587, 1554, 1522, 1464, 1385, 1290,
1225, 1177, 1126, 1098, 1028, 880, 836, 777, 609 cm–1.
1H NMR: d = 8.66 (d, J = 1.8 Hz, 1 H), 8.21 (d, J = 8.7 Hz, 2 H),
7.34 (d, J = 8.6 Hz, 2 H), 6.94 (d, J = 1.8 Hz, 1 H).
IR (film): 3120, 2925, 1604, 1475, 1425, 1248, 1096, 1025, 1105,
910, 745 cm–1.
1H NMR: d = 8.39 (dt, J = 1.6, 0.6 Hz, 1 H), 6.22 (d, J = 1.5 Hz, 1
H), 2.65 (t, J = 7.0 Hz, 2 H), 2.12–1.40 (m, 2 H), 0.99 (t, J = 7.0 Hz,
3 H).
3-(p-Chlorophenyl)isoxazole (5d)
Colorless solid; mp 69–70 °C (Lit.12 69–71 °C).
3-Substituted 5-Iodoisoxazolines 7; General Procedure
To a suspension of the swollen resin 4 (1.0 g) in anhyd DMF (10
mL) was added NaI (1.0 g) and CH3I (1.0 mL) under N2. The mix-
ture was stirred at 75–80 °C for 24 h and then cooled to r.t. The mix-
ture was filtered and the resin was washed with CH2Cl2 (10 × 3
mL). The filtrate was washed successively with a sat. solution of
NaHCO3 (30 mL), a sat. solution of Na2S2O3 (30 mL), H2O (10 × 3
mL), dried over anhyd MgSO4, and concentrated to afford product
7a–e.
IR (KBr): 3129, 2926, 1648, 1606, 1547, 1502, 1429, 1371, 1275,
1121, 1111, 1098, 1013, 946, 886, 834, 784 cm–1.
1H NMR: d = 8.47 (d, J = 1.7 Hz, 1 H), 7.77 (d, J = 8.7 Hz, 2 H),
7.35 (d, J = 8.7 Hz, 2 H), 6.64 (d, J = 1.7 Hz, 1 H).
3-(m-Chlorophenyl)isoxazole (5e)10
Colorless oil.
IR (film): 3129, 2926, 1645, 1602, 1546, 1502, 1429, 1370, 1276,
1121, 1112, 1097, 1015, 945, 885, 836, 784 cm–1.
1H NMR: d = 8.12 (d, J = 1.8 Hz, 1 H), 7.37–7.26 (m, 4 H), 6.35 (d,
J = 1.8 Hz, 1 H).
3-Phenyl-5-iodoisoxazoline (7a)
Colorless oil.
IR (film): 3056, 2954, 2887, 1625, 1500, 1435, 1108, 1040, 892,
690, 540 cm–1.
1H NMR: d = 7.65–7.63 (m, 2 H), 7.44–7.42 (m, 3 H), 5.03 (t,
J = 7.1 Hz, 1 H), 3.50 (d, J = 7.1 Hz, 2 H).
13C NMR: d = 155.4, 132.2, 128.7, 128.0, 124.9, 81.2, 41.5.
EIMS: m/z (%) = 273 (M+).
3-(2,6-Dichlorophenyl)isoxazole (5f)
Colorless solid; mp 59–60 °C (Lit.10 59–60 °C).
IR (KBr): 3132, 2926, 1645, 1605, 1547, 1500, 1429, 1373, 1276,
1124, 1112, 1095, 1016, 945, 887, 840, 784 cm–1.
1H NMR: d = 8.55 (d, J = 1.9 Hz, 1 H), 7.38–7.29 (m, 3 H), 6.46 (d,
J = 1.9 Hz, 1 H).
Anal. Calcd for C9H8INO: C, 39.59; H, 2.95; N, 5.13. Found: C,
39.66; H, 3.02; N, 5.18.
3-(p-Fluorophenyl)isoxazole (5g)
Colorless solid; mp 35–36 °C.
3-(p-Methylphenyl)-5-iodoisoxazoline (7b)
IR (KBr): 3030, 2929, 1607, 1557, 1520, 1494, 1434, 1379, 1236,
1159, 1125, 1098, 885, 842, 777 cm–1.
1H NMR: d = 8.38 (d, J = 1.6 Hz, 1 H), 7.77 (d, J = 8.1 Hz, 2 H),
7.12 (d, J = 8.0 Hz, 2 H), 6.66 (d, J = 1.6 Hz, 1 H).
White solid; mp 84–85 °C.
IR (film): 3052, 2958, 2927, 1630, 1599, 1495, 1377, 1105, 1098,
898, 818, 691 cm–1.
1H NMR: d = 7.57 (d, J = 8.0 Hz, 2 H), 7.23 (d, J = 8.0 Hz, 2 H),
4.98 (t, J = 7.2 Hz, 1 H), 3.50 (d, J = 7.2 Hz, 2 H), 2.38 (s, 3 H).
13C NMR: d = 166.1, 162.2, 134.1, 128.3, 121.0, 114.7, 102.2.
EIMS: m/z (%) = 163 (M+, 100), 108 (48.3), 107 (61.7), 95 (80.7),
75 (52.1), 57 (49.9), 43 (41.8).
13C NMR: d = 155.8, 140.7, 129.7, 126.8, 126.5, 80.8, 41.7, 21.5.
EIMS: m/z (%) = 287 (M+).
Anal. Calcd for C9H6NFO: C, 66.26; H, 3.71; N, 8.59. Found: C,
66.22; H, 3.65; N, 8.53.
Anal. Calcd for C10H10INO: C, 41.84; H, 3.51; N, 4.88. Found: C,
41.92; H, 3.63; N, 4.95.
3-(2-Furyl)isoxazole (5h)
Colorless oil.
3-(p-Nitrophenyl)-5-iodoisoxazoline (7c)
White solid; mp 93–94 °C.
Synthesis 2006, No. 14, 2293–2296 © Thieme Stuttgart · New York

2296
S.-R. Sheng et al.
PAPER
York, 2001. (d) Nicolaou, K. C.; Hanko, R.; Hartwig, H.
Handbook of Combinatorial Chemistry; Wiley-VCH:
Weinheim, 2002. (e) Dolle, R. E. J. Comb. Chem. 2002, 4,
369.
IR (film): 3052, 2960, 2930, 1632, 1600, 1495, 1106, 1098, 895,
825, 613, 543 cm–1.
1H NMR: d = 7.67 (d, J = 8.4 Hz, 2 H), 7.46 (d, J = 8.4 Hz, 2 H),
5.01 (t, J = 7.4 Hz, 1 H), 3.53 (d, J = 7.4 Hz, 2 H).
(2) (a) Koiowski, A. P. Acc. Chem. Res. 1984, 17, 410.
(b) Baraldi, P. G.; Barco, A.; Benneti, S.; Olllini, G. P.;
Simoni, D. Synthesis 1987, 857. (c) Dominguez, E.; Ibeus,
E.; Matrinez de Margorta, E.; Palacious, J. K.; San Marka, E.
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P.; Vitafinzi, P. Isoxazoles in the Chemistry of Heterocylic
Compounds, Vol. 1, Part I; Taylor, E. C., Ed.; Wiley
Interscience: New York, 1991, 1–46. (f) Pruitt, J. R.; Pinto,
D. J.; Estrella, M. J.; Bostrom, L. L.; Knabb, R. M.; Wong,
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2000, 10, 685.
(3) (a) Franzen, R. G. J. Comb. Chem. 2000, 2, 195.
(b) Dörwald, F. Z. Organic Synthesis on Solid Phase; Wiley-
VCH: Weinheim, 2002, Chap. 15.
(4) Michels, R.; Kato, M.; Heitz, W. Makromol. Chem. 1976,
177, 2311.
(5) (a) Nicolaou, K. C.; Pastor, J.; Barluenga, S.; Winssinger, N.
Chem. Commun. 1998, 1947. (b)Ruhland, T.; Andersen, K.;
Pedersen, H. J. Org. Chem. 1998, 63, 9204. (c) Uehlin, L.;
Wirth, T. Org. Lett. 2001, 3, 2931. (d) Fujita, K.-I.;
Hashimoto, S.; Oishi, A.; Taguchi, Y. Tetrahedron Lett.
2003, 44, 3793. (e) Berlin, S.; Ericsson, C.; Engman, L. J.
Org. Chem. 2003, 68, 8386. (f) Cohen, R. J.; Fox, D. L.;
Salvatore, R. N. J. Org. Chem. 2004, 69, 4265.
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2094. (e) Sheng, S.-R.; Liu, X.-L.; Wang, X.-C.; Xin, Q.;
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Xu, W. M. Tetrahedron 2004, 60, 9963.
13C NMR: d = 155.2, 136.2, 128.8, 127.8, 127.5, 80.6, 40.8.
EIMS: m/z (%) = 307 (M+).
Anal. Calcd for C9H7ClINO: C, 35.15; H, 2.29; N, 4.55. Found: C,
35.18; H, 2.37; N, 4.59.
3-(p-Chlorophenyl)-5-iodoisoxazoline (7d)
Pale-yellow solid; mp 124–125 °C.
IR (film): 3050, 2962, 2931, 1631, 1598, 1511, 1495, 1340, 1320,
1098, 905, 828, 752, 690 cm–1.
1H NMR: d = 8.21 (d, J = 8.2 Hz, 2 H), 7.81 (d, J = 8.2 Hz, 2 H),
4.96 (t, J = 7.3 Hz, 1 H), 3.51 (d, J = 7.3 Hz, 2 H).
13C NMR: d = 154.2, 135.2, 127.5, 126.2, 124.1, 81.8, 40.8.
EIMS: m/z (%) = 318 (M+).
Anal. Calcd for C9H7IN2O3: C, 33.99; H, 2.22; N, 8.81. Found: C,
34.08; H, 2.34; N, 8.92.
3-(Propyl)-5-iodoisoxazole (7j)
Colorless oil.
IR (film): 2965, 1618, 1600, 1495, 1378, 1100, 904, 750, 690 cm–1.
1H NMR: d = 4.98 (t, J = 7.1 Hz, 1 H), 3.50 (d, J = 7.1 Hz, 2 H),
2.65 (t, J = 7.0 Hz, 2 H), 2.12–1.40 (m, 2 H), 0.99 (t, J = 7.0 Hz, 3
H).
13C NMR: d = 155.0, 81.8, 40.8, 39.8, 20.1, 13.6.
EIMS: m/z (%) = 239 (M+).
Anal. Calcd for C6H10INO: C, 30.15; H, 4.22; N, 5.86. Found: C,
30.24; H, 4.31; N, 5.94.
(7) (a) Huang, X.; Xu, W. M. Org. Lett. 2003, 5, 4649. (b) Xu,
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1075.
Acknowledgment
We gratefully acknowledge financial support from the National Na-
tural Science Foundation of China (No.20562005) and NSF of Ji-
angxi Province (No.0420017).
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