A green protocol for one-pot three-component synthesis of α-amino phosphonates catalyzed by succinic acid

Article abstract of DOI:10.1007/s11164-013-1081-8

A simple, efficient, and general method has been developed for the one-pot, three-component synthesis of α-amino phosphonates from a condensation reaction of trialkyl phosphite, aldehydes, and amines in the presence of a catalytic amount of succinic acid (8.5 mol %) (for the first time) under solvent-free conditions. The advantages of this protocol are excellent yields, short reaction time, mild reaction conditions, higher availability, low costs, more environmentally friendly, lack of need for column chromatography and simple work-up procedure. Graphical Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s11164-013-1081-8

Res Chem Intermed
DOI 10.1007/s11164-013-1081-8
A green protocol for one-pot three-component synthesis
of a-amino phosphonates catalyzed by succinic acid
•
Nourallah Hazeri Malek Taher Maghsoodlou
•
•
Sayyed Mostafa Habibi-Khorassani Jasem Aboonajmi
•
•
Mojtaba Lashkari Seyed Sajad Sajadikhah
Received: 10 December 2012 / Accepted: 23 January 2013
Ó Springer Science+Business Media Dordrecht 2013
Abstract A simple, efficient, and general method has been developed for the one-pot,
three-component synthesis of a-amino phosphonates from a condensation reaction of
trialkyl phosphite, aldehydes, and amines in the presence of a catalytic amount of
succinic acid (8.5 mol %) (for the first time) under solvent-free conditions. The
advantages of this protocol are excellent yields, short reaction time, mild reaction
conditions, higher availability, low costs, more environmentally friendly, lack of need
for column chromatography and simple work-up procedure.
Keywords a-amino phosphonate Á Succinic acid Á Trialkyl phosphite Á Amine Á
Aldehyde
Introduction
Organophosphorus compounds have found a wide range of applications in the
industrial, agricultural, and medicinal chemistry fields, owing to their biological and
physical properties as well as their utility as synthetic intermediates [1, 2]. In recent
years, a-amino phosphonates have received attention as structural analogs of the
corresponding a-amino acids. The activities of a-amino phosphonates, such as HIV
protease [3], enzyme inhibitors [4], antibiotics [5], peptide mimics [6], herbicide,
insecticides and fungicides [7, 8], antithrombotic agents [9], antimicrobial agents [10],
and inhibitors of UDP-galactopyranose mutase [11], are reported in the literature. As a
result, a number of methods have been developed for the synthesis of a-amino
phosphonates [12]. Of these, the nucleophilic addition of phosphites to imines,
catalyzed by a base or an acid, is the most convenient [13–16]. However, these methods
N. Hazeri (&) Á M. T. Maghsoodlou Á S. M. Habibi-Khorassani Á
J. Aboonajmi Á M. Lashkari Á S. S. Sajadikhah
Department of Chemistry, Faculty of Science, University of Sistan & Baluchestan,
P. O. Box 98135-674, Zahedan, Iran
e-mail: n_hazeri@yahoo.com; nhazeri@chem.usb.ac.ir
123

N. Hazeri et al.
are not devoid of limitation as many imines are hygroscopic and are not sufficiently
stable for isolation. In the other words, these reactions cannot be processed in a one-pot
reaction involving a carbonyl compound, an amine and a trialkyl phosphite, because the
existing amines and water during imine formation can decompose or deactivate the
Lewis acid. This drawback has been overcome by some recent methods using metal
triflates [M(OTf)n, M = Li, Mg, Al, Cu, Ce] [17], InCl3 [18], TaCl5–SiO2 [19],
CF3CO2H [20], In(OTf)3 [21], magnesium perchlorate [22], PhNMe3Cl [23],
H3PW12O40 [24], Amberlyst-15 [26], Amberlite-IR 120 [26], sulfamic acid [27],
TiO2 [28], oxalic acid [29], boric acid [30], Yttria-zirconia [31], SbCl3/Al2O3 [32],
CoCl2.6H2O [33], microwave-assisted [34], and ionic liquid [35]. However, most of
these methods have drawbacks, such as toxic catalysts, environmental pollution caused
by using an organic solvent, expensive catalyst, difficulty of preparation, unavailable
reagents, prolonged reaction times, unsatisfactory yields, and harsh reaction conditions.
Therefore, it is necessary to further develop an efficient one-pot multi-component
synthesis of a-amino phosphonates which is devoid of these problems.
It is well known that homogeneous catalysts have gained increasing attraction in
recent years due to their operational simplicity, low cost, ease of preparation and
handling, stability, lack of toxicity, and economic and environmental advantages.
One of these homogeneous catalysts is succinic acid (c4-dicarboxylic acid). Succinic
acid, c4-dicarboxylic acid, a common metabolite in plants, animals and microor-
ganisms, has been used widely in the agricultural, food and pharmaceutical
industries [36]. This acid holds good industrial applications and is used in industries
such as resins, polymer, paints, cosmetics and inks, etc. [38–40]. To date, the
economically renewable resources used in succinic acid production reported are
cheese whey [40–43], cane molasses [44, 45], Jerusalem artichoke [46], wheat flour
[47], wood hydrolysate [48, 49, 50], and corn straw hydrolysate [51]. As part of our
continuing interest in developing methods for the synthesis of a-amino phospho-
nates [52–56], here we report a green, simple and efficient protocol for the synthesis
of a-amino phosphonates through one-pot three-component reactions of aldehydes,
amines, and trialkyl phosphite using catalytic amounts of succinic acid (8.5 mol %)
under solvent-free conditions at room temperature (Scheme 1).
Results and discussion
Succinic acid is a readily available, low cost reagent, which can be conveniently
handled, and removed from the reaction mixture. Thus, its remarkable catalytic
R2
R1
H
P
OR3
P
N
O
H
N
Succinic acid (8.5 mol%)
Solvent-free, rt
O
+
+
R1
H
R2
H
R3O
OR3
OR3
R3O
2
1
3
4a-af
Scheme 1 Synthesis of a-amino phosphonates 4a–af
123

Synthesis of a-amino phosphonates catalyzed by succinic acid
activities together with its operational simplicity make it the most suitable catalyst
for the synthesis of a-amino phosphonates. First, in order to optimize the reaction
conditions, the reaction of benzaldehyde (1 mmol), aniline (1 mmol), and trimethyl
phosphite (1 mmol) was carried out using different quantities of succinic acid under
different conditions at room temperature. As can be seen in Table 1, maximum yield
was obtained with 8.5 mol % of the catalyst under solvent-free conditions. Poor
yield (41 %) was obtained when the reaction was carried out in the absence of
succinic acid at room temperature under solvent-free conditions for 24 h. We have
also studied the effect of various solvents on the model reaction. The various
solvents screened were EtOAc, EtOH, MeOH, THF, CHCl3, Et2O, acetone, CH2Cl2,
and MeCN. Due to the growing concern for the influence of the organic solvent on
the environment as well as on the human body, organic reactions without the use of
conventional organic solvents have attracted the attention of synthetic organic
chemists. It is observed that the solvent-free conditions gave an excellent yield of
product and the shortest reaction time than in the presence of solvents. Development
of solvent-free organic reactions is thus gaining prominence.
Thus, several reactions of different aldehydes, amines, and trialkyl phosphite
were examined in the presence of succinic acid as a catalyst under solvent-free
conditions at room temperature (Table 2). In all cases, the one-pot, three-component
reaction proceeded smoothly to afford the corresponding a-amino phosphonates in
good to excellent yields. As shown in Table 2, the reaction of anilines with a variety
of aromatic aldehydes containing electron-deficient and/or electron-releasing groups
and trimethyl/triethylphosphite proceeded to afford a-amino phosphonates in good
Table 1 Optimization reaction conditions for the reaction of benzaldehyde (1 mmol), aniline (1 mmol),
and trimethyl phosphite (1 mmol) at room temperature in the presence of succinic acid
Entry
Catalyst (mol %)
Solvent
Time (min)
Yielda (%)
1
4
–
30
15
5
93
97
98
98
98
98
79
65
76
70
67
69
70
82
69
41
2
6
–
3
8.5
17
25
35
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
–
–
4
–
5
5
–
5
6
–
5
7
EtOAc
EtOH
MeOH
THF
CHCl3
Et2O
Acetone
CH2Cl2
MeCN
–
20
30
20
25
28
35
25
15
30
24 h
8
9
10
11
12
13
14
15
16
a
Yield refers to the pure isolated products
123

N. Hazeri et al.
to excellent yields. On the basis of experimental results, the rates of all reactions in
the presence of triethyl phosphite were reduced in comparison with trimethyl
phosphite under constant conditions.
We have also prepared four new analogs of these compounds in excellent yields
(Table 2, entries 30–33). These new compounds were characterized by elemental
1
analyses, IR, H, 13C, 31P NMR, and mass spectroscopies.
To show the merit of the present work in comparison with reported results in the
literature, we compared the results of succinic acid with the other catalysts for the
synthesis of compounds 4a. As shown in Table 3, succinic acid can act as more
effective catalyst with respect to reaction times and yields of products.
A plausible mechanism is shown in scheme 2. It is believed to involve the
formation of activated imine A by the addition of aldehyde and amine. Then
phosphite is added to the C=N bond of imine A to give phosphonium intermediate
B. This phosphonium intermediate undergoes reaction with water to give the
a-aminophosphonates 4 and ethanol [30, 57–60].
Experimental
Melting points and IR spectra were measured on an Electrothermal 9100 apparatus
1
and a JASCO FT/IR-460 plus spectrometer, respectively. The H, 13C, and 31P
NMR spectra were obtained on Bruker DRX-400 Avance instruments with CDCl3
as a solvent. Elemental analyses were performed using a Heraeus CHN-O-Rapid
analyzer. Mass spectra were recorded on an Agilent Technology (HP) spectrometer
operating at an ionization potential of 70 eV. All reagents and solvents obtained
from Fluka and Merck were used without further purification.
General procedure for the synthesis of a-amino phosphonates 4a–af
The mixture of aldehyde (1 mmol), amine (1 mmol), and succinic acid (8.5 mol %,
0.010 g) were stirred for a few minutes. Then trimethyl/triethyl phosphite (1 mmol)
was added, and the reaction mixture was stirred at room temperature for the
appropriate time as indicated in Table 2. The progress of reactions was monitored
by TLC (ethyl acetate/n-hexane, 1/4). After completion of the reaction, the reaction
mixture was washed with water (3 9 10 mL). The catalyst is solvable in water and
was removed from the reaction mixture. The crude product was washed with the
mixture of n-hexane/Et2O (5/2) to give pure products.
Compound 4ad: white solid, mp. 111–113 °C; IR (KBr) t: 3,360 (NH), 3,253
(br, OH), 1,269 (P=O); 1H NMR (CDCl3, 400 MHz) d: 3.52, 3.78 (2d, 6H,
JHP = 10.8 Hz, P(OMe)2), 3.88 (s, 3H, OMe), 4.74 (d, 1H, JHP = 24.0 Hz, P–C–H),
4.71, 5.82 (2br, 2H, NH, OH), 6.64 (d, 2H, JHH = 8.0, HAr), 6.74 (t, 1H,
JHH = 8.0 Hz, HAr), 6.90 (d, 1H, JHH = 8.0 Hz, HAr), 6.98 (d, 1H, JHH = 8.0 Hz,
HAr), 7.02 (s, 1H, HAr), 7.14 (t, 2H, JHH = 8.0 Hz, HAr); 13C NMR (CDCl3, 100 MHz)
d: 53.8, 53.9 (2d, JCP = 7.0 Hz, P(OMe)2), 55.4 (d, JCP = 153.0 Hz, P–CH), 55.9
(s, OMe), 110.2 (d, JCP = 5.0 Hz, CAr), 113.9 (s, CAr), 114.7 (d, JCP = 3.0 Hz, CAr),
118.5 (s, CAr), 120.9 (d, JCP = 7.0 Hz, CAr), 127.1 (d, JCP = 3.0 Hz, CAr), 129.2
123

Synthesis of a-amino phosphonates catalyzed by succinic acid
Table 2 Preparation of a-amino phosphonates 4a–af
Entry
R1
R2
R3
Product
Time (min)
Yielda(%)
Ref.b
1
2
Ph
Ph
Me
Et
4a
4b
4c
5
20
17
38
12
4
98
97
90
85
90
94
90
88
88
98
95
90
96
95
90
85
88
91
95
95
92
95
95
89
90
95
93
92
85
80
77
70
[22]
[28]
[23]
[26]
[51]
[53]
[51]
[29]
[28]
[30]
[32]
[54]
[29]
[28]
[52]
[29]
[29]
[26]
[54]
[53]
[32]
[26]
[26]
[21]
[22]
[34]
[34]
[20]
[34]
c
Ph
Ph
3
4-NO2–C6H4
4-NO2–C6H4
2,4-di-Cl–C6H3
2,4-di-OMe-C6H3
2,4-di-OMe–C6H3
4-Cl–C6H4
Ph
Me
Et
4
Ph
4d
4e
5
Ph
Me
Me
Et
6
Ph
4f
7
Ph
4g
4h
4i
30
4
8
Ph
Me
Et
9
4-Cl–C6H4
Ph
35
40
65
10
8
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
a
4-OMe–C6H4
4-OMe–C6H4
2,4-di-OMe–C6H3
2-Cl–C6H4
Ph
Me
Et
4j
Ph
4k
4l
4-OMe-C6H4
Ph
Me
Me
Et
4m
4n
4o
4p
4q
4r
2-Cl–C6H4
Ph
14
20
90
6
2,5-di-OMe–C6H3
4-CN–C6H4
Ph
Ph
Me
Me
Me
Et
Ph
4-OMe-C6H4
Ph
4-F–C6H4
30
2
2,5-di-OMe–C6H3
2-Me–C6H4
3-OMe–C6H4
3-Cl–C6H4
4-Cl-C6H4
Ph
Me
Me
Me
Me
Me
Et
4 s
4t
2
Ph
4u
4v
4w
4x
4y
4z
25
6
Ph
4-NMe2–C6H4
3-NO2–C6H4
4-NO2–C6H4
Ph
Ph
2
3-NO2–C6H4
4-NO2–C6H4
4-Cl–C6H4
4-OMe–C6H4
4-OMe–C6H4
4-Me–C6H4
Ph
50
20
7
Me
Me
Me
Me
Me
Me
Me
Me
4-NO2–C6H4
4-OMe–C6H4
Ph
4aa
4ab
4ac
4ad
4ae
4af
14
35
16
40
35
45
4-OH-3-OMe–C6H3
4-OH-3-OMe–C6H3
2,4-di-OMe–C6H3
4-Me–C6H4
2-CN–C6H4
c
c
Yields refer to the pure isolated products
b
All known products have been reported previously in the literature and were characterized by com-
parison of IR and NMR spectra with authentic samples
c
The new compounds synthesized in this work
(s, CAr), 145.7 (d, JCP = 3.0 Hz, CAr), 146.2 (d, JCP = 14.0 Hz, CAr), 147.1 (d,
JCP = 2.0 Hz, CAr); 31P NMR (CDCl3, 162 MHz) d: 25.27; MS (EI, 70 eV) m/z (%):
337 (M?, 6), 267 (54), 228 (100), 93 (8); Anal. calcd for C16H20NO5P: C, 56.97; H,
5.98; N, 4.15; found C, 57.09; H, 5.80; N, 4.30.
123

N. Hazeri et al.
Table 3 Comparison of succinic acid with previously reported catalyst for the synthesis of a-amino
phosphonate 4a
Entry
Catalyst
Conditions
Time
Yield (%)
Ref.
1
2
3
4
5
6
7
8
9
10
Oxalic acid
Boric acid
Solvent-free/50 °C
Solvent-free/rt
CH2Cl2/rt
2 h
98
98
94
97
95
95
99
96
92
98
[29]
15 min
\15 min
35 min
15 min
45 min
2 h
[30]
H3PW12O40
PPA–SiO2
[24]
Solvent-free/80 °C
Solvent-free/100 °C
Solvent-free/80 °C
MeCN/60 °C
[53]
Al(H2PO4)3
NaHSO4–SiO2
Yttria–zirconia
CoCl2.6H2O
Amberlyst-15
Succinc acid
[52]
[55]
[31]
Solvent-free/rt
15 min
25 min
5 min
[33]
MeCN/rt
[26]
Solvent-free/rt
This work
P(OR3)3
H
N
3
O
R1
succinic acid
H
R2
R2
N
+
R1
H
-H2O
A
2
1
H2O
OH
R3O
R3O P
R3O
R3O
O R3
R1
O
P
N
R1
R2
N
R2
-R3OH
H
H
B
4
Scheme 2 Plausible mechanism for the synthesis of a-amino phosphonates 4a–af
Compound 4ae: white solid, mp. 104–107 °C; IR (KBr) t: 3,365 (NH), 3,260 (br,
OH), 1,265 (P=O); 1H NMR (CDCl3, 400 MHz) d: 2.22 (s, 3H, ArMe), 3.53, 3.79 (2d,
6H, JHP = 10.4 Hz, P(OMe)2), 3.88 (s, 3H, OMe), 4.71 (d, 1H, JHP = 22.4 Hz, P–C–
H), 4.50, 5.75 (2br, 2H, NH, OH), 6.55 (d, 2H, JHH = 8.0, HAr), 6.90 (d, 1H,
JHH = 8.0 Hz, HAr), 6.95 (d, 2H, JHH = 8.0 Hz, HAr), 6.96 (s, 1H, HAr), 7.02 (s, 1H,
HAr); 13C NMR (CDCl3, 100 MHz) d: 20.4 (s, ArMe), 53.8 (d, JCP = 6.0 Hz,
2P(OMe)2), 55.7 (d, JCP = 142.0 Hz, P–CH), 55.9 (s, OMe), 110.2 (d, JCP = 5.0 Hz,
CAr), 114.0 (s, CAr), 114.6 (d, JCP = 2.0 Hz, CAr), 120.9 (d, JCP = 6.0 Hz, CAr),
127.2 (d, JCP = 3.0 Hz, CAr), 127.8 (s, CAr), 129.7 (s, CAr), 143.8 (d, JCP = 15.0 Hz,
CAr), 145.6 (d, JCP = 3.0 Hz, CAr), 147.0 (d, JCP = 2.0 Hz, CAr); 31P NMR (CDCl3,
162 MHz) d: 25.41; MS (EI, 70 eV) m/z (%): 351 (M?, 8), 242 (100), 234 (17); Anal.
calcd for C17H22NO5P: C, 58.12; H, 6.31; N, 3.99; found C, 58.25; H, 6.45; N, 4.06.
123

Synthesis of a-amino phosphonates catalyzed by succinic acid
Compound 4af: white solid, mp. 88–90 °C; IR (KBr) t: 3,383 (NH), 2,211 (CN),
1
1,246 (P=O); H NMR (CDCl3, 400 MHz) d: 3.61, 3.81 (2d, 6H, JHP = 10.4 Hz,
P(OMe)2), 3.79, 3.94 (2 s, 6H, 2OMe), 5.35 (dd, 1H, JHP = 23.6 Hz,
JHH = 8.8 Hz, P–C-H), 5.60 (t, 1H, JHH = 8.0 Hz, NH), 6.50 (d, 1H, JHH = 6.4,
HAr), 6.51 (s, 1H, HAr), 6.64 (d, 1H, JHH = 8.4 Hz, HAr), 6.70 (t, 1H,
JHH = 8.0 Hz, HAr), 7.29–7.38 (m, 3H, HAr); 13C NMR (CDCl3, 100 MHz) d:
48.5 (d, JCP = 157.0 Hz, P–CH), 53.8 (d, JCP = 7.0 Hz, P(OMe)2), 55.3, 55.8 (2 s,
2OMe), 97.2 (s, CAr), 98.7 (d, JCP = 1.0 Hz, CAr), 105.0 (d, JCP = 3.0 Hz, CAr),
111.8 (s, CN), 115.1 (d, JCP = 1.0 Hz, CAr), 117.4 (s, CAr), 117.7 (s, CAr), 129.1 (d,
JCP = 5.0 Hz, CAr), 132.7 (s, CAr), 134.2 (s, CAr), 149.6 (d, JCP = 13.0 Hz, CAr),
158.0 (d, JCP = 6.0 Hz, CAr), 160.9 (d, JCP = 3.0 Hz, CAr); 31P NMR (CDCl3,
162 MHz) d: 24.08; MS (EI, 70 eV) m/z (%): 376 (M?, 2); Anal. calcd for
C18H21N2O5P: C, 57.45; H, 5.62; N, 7.44; found C, 57.53; H, 5.75; N, 7.33.
Acknowledgments We gratefully acknowledge financial support from the Research Council of the
University of Sistan and Baluchestan.
References
1. K.A. Schug, W. Lindner, Chem. Rev. 105, 67 (2005)
2. K. Moonen, I. Laureyn, C.V. Stevens, Chem. Rev. 104, 6177 (2004)
3. A. Peyman, W. Stahl, K. Wagner, D. Ruppert, K.H. Budt, Bioorg. Med. Chem. Lett. 4, 2601 (1994)
4. M.C. Allen, W. Fuhrer, B. Tuck, R. Wade, J.M. Wood, J. Med. Chem. 32, 1652 (1989)
5. F.R. Atherton, C.H. Hassal, R.W. Lambert, J. Med. Chem. 29, 29 (1986)
6. P. Kafarski, B. Leczak, Phosphorus Sulfur Silicon Relat. Elem. 63, 193 (1991)
7. L. Maier, Phosphorus Sulfur Silicon Relat. Elem. 53, 43 (1990)
8. L. Maier, H. Sporri, Phosphorus Sulfur Silicon Relat. Elem. 61, 69 (1991)
9. J.H. Meyer, P.A. Barlett, J.A. Chem, Soc. 120, 4600 (1998)
10. M.V.N. Reddy, B.S. Kumar, A. Balakrishna, C.S. Reddy, S.K. Nayak, C.D. Reddy, Arkivoc 15, 246
(2007)
11. W. Pan, C. Ansiaux, S.P. Vincent, Tetrahedron Lett. 48, 4353 (2007)
12. T. Yokomatsu, Y. Yoshida, S. Shibuya, J. Org. Chem. 59, 7930 (1994)
13. S. Laschat, H. Kunz, Synthesis 90 (1992)
14. H.J. Ha, G.S. Nam, Synth. Commun. 22, 1143 (1992)
15. J. Zon, Pol. J. Chem. 55, 643 (1981)
16. J. S. Yadav, B. V. S. Reddy, S. Raj, K. B. Reddy, A. R. Prasad, Synthesis 2277 (2001)
17. H. Firouzabadi, N. Iranpoor, S. Sobhani, Synthesis 2692 (2004)
18. C.B. Ranu, A. Hajra, U. Jana, Org. Lett. 1, 1141 (1999)
19. S. Chandrasekhar, S.J. Parkash, V. Jagadeshwar, C. Narsihmulu, Tetrahedron Lett. 42, 5561 (2001)
20. T. kiyama, M. Sanada, K. Fuchibe, Synlett. 1463 (2003)
21. R. Ghosh, S. Maiti, A. Chakraborty, D.A. Maiti, J. Mol. Catal. A: Chem. 210, 53 (2004)
22. S. Bhagat, A.K. Chakraborti, J. Org. Chem. 72, 1263 (2007)
23. A. Heydari, A. Arefi, Catal. Commun. 8, 1023 (2007)
24. A. Heydari, H. Hamidi, M. Pouayoubi, Catal. Comuun. 8, 1224 (2007)
25. M. Tajbakhsh, A. Heydari, H. Alinezhad, M. Ghanei, S. Khaksar, Synthesis 352 (2008)
26. A.K. Bhattacharya, K.C. Rana, Tetrahedron Lett. 49, 2598 (2008)
27. S.D. Mitragotri, D.M. Pore, U.V. Desai, P.P. Wadgaonkar, Catal. Commun. 9, 1822 (2008)
28. M.H. Sarvari, Tetrahedron 64, 5459 (2008)
29. S.M. Vahdat, R. Baharfar, M. Tajbakhsh, A. Heydari, S.M. Baghbaniane, S. Khaksar, Tetrahedron
Lett. 49, 6501 (2008)
30. Z. Karimi-Jaberi, M. Amiri, Heteroatom Chem. 21, 96 (2010)
31. S. Ramalingam, P. Kumar, Catal. Lett. 125, 315 (2008)
32. K.S. Ambica, S.C. Taneja, M.S. Hundal, K.K. Kapoor, Tetrahedron Lett. 49, 2208 (2008)
123

N. Hazeri et al.
33. Z. Karimi-Jaberi, H. Zare, M. Amiri, N. Sadeghi, Chin. Chem. Lett. 22, 559 (2011)
34. X.-J. Mu, M.-Y. Lei, J.-P. Zou, W. Zhang, Tetrahedron Lett. 47, 1125 (2006)
35. J.S. Yadav, B.V.S. Ready, P. Sreedhar, Green Chem. 4, 436 (2002)
36. J.G. Zeikus, M.K. Jain, P. Elankovan, Appl. Microbiol. Biotechnol. 51, 545 (1999)
37. M. K. Jain, R. Datta, J. G. Zeikus, Ellis Harwood Ltd. Chichester. 366 (1989)
38. M. V. Guettler, M. K. Jain, US Patent 5, 573, 931, 1996
39. G.N. Vermuri, M.A. Eiteman, E. Altman, Appl. Environ. Microbiol. 68, 1715 (2002)
40. N.S. Samuelov, R. Datta, M.K. Jain, J.G. Zeikus, Appl. Environ. Microbiol. 65, 2260 (1999)
41. P.C. Lee, W.G. Lee, S. Kwon, S.Y. Lee, H.N. Chang, Appl. Microbiol. Biotechnol. 54, 23 (2000)
42. P.C. Lee, S.Y. Lee, S.H. Hong, H.N. Chang, Bioprocess Biosyst. Eng. 26, 63 (2003)
43. C. Wan, Y. Li, A. Shahbazi, S. Xiu, Appl. Biochem. Biotechnol. 45, 111 (2008)
44. L. Agarwal, J. Isar, G.K. Meghwanshi, R.K. Saxena, J. Appl. Microbiol 100, 1348 (2006)
45. Y.P. Liu, P. Zheng, Z.H. Sun, N. Ye, J.J. Dong, L.L. Zhu, Bioresour. Technol. 99, 1736 (2008)
46. W. Ren, J.J. Dong, P. Zeng, Y. Ni, Z.H. Sun, Ind Microbiol Chin 38, 1 (2008)
47. C. Du, S.K.C. Lin, A. Koutinas, R. Wang, P. Dorado, C. Webb, Bioresour. Technol. 99, 8310 (2008)
48. P.C. Lee, S.Y. Lee, S.H. Hong, H.N. Chang, S.C. Park, Biotechnol. Lett. 25, 111 (2003)
49. D.Y. Kim, S.C. Yim, P.C. Lee, W.G. Lee, S.Y. Lee, H.N. Chang, Enzyme Microb. Technol. 35, 648
(2004)
50. D.B. Hodge, C. Andersson, K.A. Berglund, S.C. Park, Enzyme Microb. Technol. 44, 309 (2009)
51. P. Zheng, J.J. Dong, Z.H. Sun, Y. Ni, L. Fang, Bioresour. Technol. 100, 2425 (2009)
52. M.T. Maghsoodlou, S.M. Habibi-Khorassani, N. Hazeri, M. Rostamizadeh, S.S. Sajadikhah,
Z. Shahkarami, N. Maleki, Heteroatom Chem. 20, 316 (2009)
53. M.T. Maghsoodlou, S.M. Habibi-Khorassani, R. Heydari, N. Hazeri, S.S. Sajadikhah, M. Rostami-
zadeh, Chin. J. Chem. 28, 285 (2010)
54. M.T. Maghsoodlou, S.M. Habibi-Khorassani, R. Heydari, N. Hazeri, S.S. Sajadikhah, M. Rostami-
zadeh, L. Keishams, Turk. J. Chem. 34, 565 (2010)
55. M. Rostamizadeh, M.T. Maghsoodlou, N. Hazeri, S.M. Habibi-Khorassani, S.S. Sajadikhah,
N. Maleki, Z. Shahkarami, Lett. Org. Chem. 7, 542 (2010)
56. M.T. Maghsoodlou, R. Heydari, S.M. Habibi-Khorassani, N. Hazeri, S.S. Sajadikhah, M. Rostami-
zadeh, M. Lashkari, Synth. Commun. 42, 136 (2012)
57. A. Banik, S. Batta, D. Bandyopadhyay, B.K. Banik, Molecules 15, 8205 (2010)
58. J. Akbari, A. Heydari, Tetrahedron Lett. 50, 4236 (2009)
59. P.V. Shinde, A.H. Kategaonkar, B.B. Shingate, M.S. Shingare, Tetrahedron Lett. 52, 2889 (2011)
60. A.S. Paraskar, A. Sudalai, ARKIVOC 10, 183 (2006)
123