Synthesis of novel 5-phenylimidazo[1,2-c]quinazolin-3-amine derivatives via Groebke-Blackburn-Bienayme multicomponent reaction

Article abstract of DOI:10.1007/s00706-014-1204-y

We have developed an efficient and environmentally benign one-pot procedure for synthesis of novel N-alkyl-2-aryl-5-phenylimidazo[1,2-c]quinazolin-3-amine derivatives by use of the Groebke-Blackburn-Bienayme multicomponent reaction. The title compounds we

Full text of DOI:10.1007/s00706-014-1204-y

Monatsh Chem
DOI 10.1007/s00706-014-1204-y
ORIGINAL PAPER
Synthesis of novel 5-phenylimidazo[1,2-c]quinazolin-3-amine
derivatives via Groebke–Blackburn–Bienaym e´ multicomponent
reaction
Tahmineh Akbarzadeh
Mohammad Mahdavi
•
Abolfath Ebrahimi
Alireza Foroumadi
•
Mina Saeedi
Abbas Shafiee
•
•
•
Received: 17 February 2014 / Accepted: 14 March 2014
Ó Springer-Verlag Wien 2014
Abstract We have developed an efficient and environ-
mentally benign one-pot procedure for synthesis of novel
N-alkyl-2-aryl-5-phenylimidazo[1,2-c]quinazolin-3-amine
derivatives by use of the Groebke–Blackburn–Bienayme´
multicomponent reaction. The title compounds were syn-
thesized in good yields from 2-phenylquinazolin-4-amine,
aromatic aldehydes, and isocyanides in the presence of
ammonium chloride under solvent-free conditions.
et al. [3] have reported they are also useful for preparation
of psychopharmaceuticals, for example anticonvulsants,
anxiolytics, hypnotics, antipsychotics, and antiemetics, for
improving cognitive function of the brains of mammals, or
as benzodiazepine antagonists. Imidazo[1,2-c]quinazolines
synthesized by Chern et al. [4] were useful as active
ingredients for treatment of hypertension. Their antioxidant
activity acts as a potent inhibitor of lipid peroxidation [5].
Literature survey shows that 6-arylbenzimidazo[1,2-
c]quinazolines act as inhibitors of LPS-induced TNF-alpha
secretion [6]. Therefore, new synthetic methods for syn-
thesis of imidazo[1,2-c]quinazolines need active study.
In recent years there has been much interest in the use of
solvent-free conditions. Because there is no reaction medium
to collect, purify, and recycle, they result in reduced pollu-
tion, low cost, and simplicity in process and handling, which
are very important in industry [7]. Sequential solvent-free
reactions are possible in high-yielding systems [8]. In recent
years, solvent-free conditions for synthesis of heterocyclic
compounds have become increasingly significant and are
regarded as important and useful synthetic methods [9].
To the best of our knowledge, there is no report of the
synthesis of N-alkyl-2-aryl-5-phenylimidazo[1,2-c]quina-
zolines. Herein, in the context of our interest in designing
new heterocyclic structures [10–12], we wish to report a
green procedure for synthesis of novel imidazo[1,2-
c]quinazolines 6 by use of the Groebke–Blackburn–Bien-
aym e´ multicomponent reaction under solvent-free
conditions (Scheme 1).
Keywords Groebke–Blackburn–Bienaym e´ ꢀ
Isocyanides ꢀ Multicomponent reactions ꢀ
Phenylimidazo[1,2-c]quinazolines
Introduction
Fused imidazo[1,2-c]quinazoline heterocycles are of
interest to medicinal chemists because of their wide variety
of pharmacological and biological properties. In this
regard, versatile strategies for obtaining new structures are
of great interest to synthetic chemists [1]. Some imi-
dazo[1,2-c]quinazolines synthesized by Bourguignon et al.
[
2] act as coronary smooth muscle relaxants, and Hansen
Electronic supplementary material The online version of this
article (doi:10.1007/s00706-014-1204-y) contains supplementary
material, which is available to authorized users.
T. Akbarzadeh ꢀ A. Ebrahimi
Department of Medicinal Chemistry, Faculty of Pharmacy,
Tehran University of Medicinal Sciences, 14176 Tehran, Iran
M. Saeedi ꢀ M. Mahdavi ꢀ A. Foroumadi ꢀ A. Shafiee (&)
Department of Medicinal Chemistry, Faculty of Pharmacy,
Pharmaceutical Sciences Research Center, Tehran University of
Medicinal Sciences, 14176 Tehran, Iran
Results and discussion
We have developed a method for synthesis of novel imi-
e-mail: shafieea@tums.ac.ir
dazo[1,2-c]quinazolines
6
based on the Groebke–
123

T. Akbarzadeh et al.
Scheme 1
CN
ArCHO
R N C
N
Ph
+
N
Ph
CN
4
Solvent-free
KOH, 150°C
5
+
N
N
Solvent-free
NH Cl, 150°C
NH2
NHR
4
NH2
N
1
2
Ar
3
6
Table 1 Optimization of the reaction conditions
Entry Solvent Conditions Additive
Blackburn–Bienaym e´ three-component reaction of hetero-
aromatic amidines, aldehydes, and isocyanides for
synthesis of fused 3-aminoimidazoles [13–15]. In their
work, heteroaromatic amidines, for example 2-aminopyri-
dine or pyrimidine, were reacted with isocyanides and
aldehydes in the presence of a catalytic amount of protic
acids. This led to reports of the use of different hetero-
amidines and catalysts [16–20].
a
Time/h Yield/%
1
2
PhCH
PhCH
3
3
Reflux
Reflux
–
24
24
Trace
10
4
NH Cl
(
1 mmol)
3
4
5
6
CH
3
CN
Reflux
Reflux
Reflux
Reflux
–
–
–
24
24
24
24
Trace
5
EtOH
MeOH
MeOH
30
During our investigations, we found that 2-phenylqui-
nazolin-4-amine (3) [21] is a very good substrate with
excellent performance in cyclization reactions. It is worth
mentioning that 3 can easily be prepared by a green pro-
cedure, by reaction of benzonitrile (1) and
NH Cl
4
42
(
1 mmol)
7
8
Solvent-
free
150 °C
150 °C
–
5
2
45
83
Solvent-
free
4
NH Cl
(1 mmol)
2
-aminobenzonitrile (2) in the presence of KOH under
solvent-free conditions at 150 °C (Scheme 1).
In a preliminary study, reaction of 3 (1 mmol), 2-fluo-
robenzaldehyde (1 mmol), and tert-butyl isocyanide
Conducted with 2-phenylquinazolin-4-amine (1 mmol), 2-fluoro-
benzaldehyde (1 mmol), and tert-butyl isocyanide (1 mmol)
a
Yield of isolated product
(
1 mmol) was selected as model reaction; the substrates
were reacted in different solvents and in the absence of
solvent. Because the solvent can be of crucial importance
in organic reactions, such solvents as toluene, methanol,
ethanol, and acetonitrile were used either at room tem-
perature or under reflux. Some results are summarized in
Table 1. However, examination of solvents revealed that
they suppressed or did not improve the cyclization reaction,
and formation of the desired product, N-tert-butyl-2-(2-
fluorophenyl)-5-phenylimidazo[1,2-c]quinazolin-3-amine
Table 2 Synthesis of 5-phenylimidazo[1,2-c]quinazolin-3-amines 6
(
Scheme 1)
a
Entry
Ar
R
Product
Yield/%
1
3
4
6
5
6
7
8
a
2-F-C H
6
4
tert-Butyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
tert-Butyl
tert-Butyl
tert-Butyl
tert-Butyl
6a
6b
6c
6d
6e
6f
83
75
82
58
88
71
83
77
4-Cl-C
6 4
H
4-Pyridinyl
4-NO
4-F-C
4-NO
2
-C
6
H
4
4
(
Table 2, 6a) did not occur. Surprisingly, when the model
reaction was conducted under solvent-free conditions, the
starting materials were consumed (according to TLC) in
H
6 4
2
-C
6
H
4-MeO-C
6
H
4
6g
6h
5
h, and the expected product 6a was obtained in 45 %
yield.
Because the efficiency of ammonium chloride in iso-
cyanide-based multicomponent reactions has been proved
10, 22–24], the model reaction was conducted in the
3,4,5-tri-MeO-C
6 2
H
Yield of isolated product
[
presence of NH Cl. It was found that use of ammonium
4
mass for C H FN . The mass spectrum contained a
26 23 4
chloride (1 mmol) is essential to obtain the corresponding
strong peak at m/z = 354 which is related to elimination of
tert-butyl. Another peak was observed at m/z = 334,
resulting from the loss of Ph. The strongest peak was
observed at m/z = 205, related to formation of the 2-phe-
nylquinazolinium ion. After confirmation of the structure
of 6a, and using the optimized conditions, we next set out
to investigate the scope of the reaction. For this purpose,
product 6a in good yield and shorter reaction time (83 %,
2
h).
Compound 6a furnished well-defined H NMR and
1
13
C
NMR spectra. The structure was also confirmed by analysis
of the mass spectroscopy fragmentation pattern. The peak
at m/z = 410.19 was in accordance with the calculated
1
23

Synthesis of novel 5-phenylimidazo[1,2-c]quinazolin-3-amine derivatives
Scheme 2
Cl
N
N
Ph
N
Ph
H
δ+
R N C
5
N
Ph
H N
3
O
+
N
N
N
[4+1] cycloaddition
δ+
NHR
Ar
H
N
NH2
4
H N H
Ar
6
3
3
Ar
Cl
7
different aromatic aldehydes and isocyanides were reacted
with 2-phenylquinazolin-4-amine 3 in the presence of
ammonium chloride; the corresponding compounds 6 were
obtained in good yields (Table 2). The results showed that
the reaction is compatible with different benzaldehydes
including those with electron-donating and electron-with-
drawing substituents at different positions.
mass spectrometer operating at an ionization potential of
70 eV. Elemental analysis was performed with an Ele-
mentar Analysensystem VarioEL in CHNS mode.
General procedure for synthesis
of 5-phenylimidazo[1,2-c]quinazolin-3-amine
derivatives 6
The sequence of reactions used for preparation of imi-
dazo[1,2-c]quinazolines 6 is depicted in Scheme 2. The
reaction begins by formation of iminium ion 7 by con-
densation of the 2-phenylquinazolin-4-amine 3 and
A mixture of 0.26 g 2-phenylquinazolin-4-amine 3 (1 mmol),
aromatic aldehyde 4 (1 mmol), isocyanide 5 (1.2 mmol), and
ammonium chloride (1 mmol) was stirred at 150 °C for
2–3 h. After completion of the reaction (checked by TLC) the
mixture was cooled to room temperature and the residue was
purified by column chromatography using silicagel and
petroleum ether–ethyl acetate (5:1) as eluent.
aromatic aldehydes 4, probably catalyzed by NH Cl.
4
Nonconcerted [4 ? 1] cycloaddition between 7 and iso-
cyanide 5 then leads to formation of the product 6 [13–15].
N-tert-Butyl-2-(2-fluorophenyl)-5-phenylimidazo[1,2-c]-
Conclusion
quinazolin-3-amine (6a, C H FN )
2
6
23
4
1
Yellow crystals; m.p.: 164–166 °C; H NMR (500 MHz,
CDCl ): d = 8.66 (d, J = 6.8 Hz, 1H, H ), 8.00 (d,
We report a convenient, green method for preparation of N-
alkyl-2-aryl-5-phenylimidazo[1,2-c]quinazoline-3-amine
derivatives by three-component reaction of 2-phenylqui-
nazolin-4-amine, aromatic aldehydes, and isocyanides in
the presence of ammonium chloride under solvent-free
conditions. The main advantages of the procedure include
preparation of new compounds in the absence of expensive
catalyst and solvent, good yields, and product diversity. It
is worth mentioning that better yields of products and
shorter reaction times were obtained under solvent-free
conditions than when a variety of different solvents were
used. Use of solvent-free conditions is vital for environ-
mental reasons, among other advantages.
3
7
J = 7.4 Hz, 2H, H , H
0
0
), 7.81–7.79 (m, 2H, H , H ),
9
1
6
8
7
.70–7.53 (m, 5H, Ph), 7.37–7.30 (m, 2H, H3
J = 6.8 Hz, 1H, H4 ), 2.75 (d, J = 6.0 Hz, 1H, NH), 0.60
s, 9H, tert-butyl) ppm; C NMR (125 MHz, CDCl3):
d = 159.3 (d, JC–F = 244.1 Hz), 147.2, 141.3, 140.3,
, H5 ), 7.18 (t,
0 0
0
13
(
134.4, 133.9, 131.5, 129.5, 129.4, 129.3, 129.2, 127.8,
127.6, 127.5, 127.0, 124.2, 122.2 (d, JC–F = 31.0 Hz),
121.8, 118.0, 115.2 (d, JC–F = 22.7 Hz), 55.2, 28.5 ppm;
IR (KBr): mꢀ = 3,394, 3,237, 2,968, 2,863, 1,614, 1,595,
-1
,553 cm ; MS (70 eV): m/z = 410.19 (M ).
?
1
2-(4-Chlorophenyl)-N-cyclohexyl-5-phenylimidazo[1,2-c]-
quinazolin-3-amine (6b, C H ClN )
2
8
25
4
1
Yellow crystals; m.p.: 259–261 °C; H NMR (500 MHz,
CDCl ): d = 8.66 (d, J = 7.6 Hz, 1H, H ), 8.28 (d,
Experimental
3
7
J = 8.5 Hz, 2H, H2
0
, H6
0
), 7.97 (d, J = 8.3 Hz, 1H, H10),
7
.77–7.76 (m, 2H, H , H ), 7.70–7.63 (m, 5H, Ph), 7.41 (d,
8
All chemicals were purchased from Merck and Sigma–
Aldrich and used without further purification. Melting
9
J = 8.5 Hz, 2H, H3
0
, H5
0
), 2.42 (s, 1H, NH), 2.30–2.26 (m,
1
3
H, NCH), 1.39–0.62 (m, 10H, cyclohexyl) ppm; C NMR
1
points were taken on a Kofler hot-stage apparatus. H and
1
1
3
(125 MHz, CDCl ): d = 145.1, 141.2, 140.3, 134.9, 130.6,
C NMR spectra were recorded on a Bruker FT-500, with
3
1
1
2
30.1, 129.5, 129.3, 129.2, 128.6, 128.5, 128.3, 128.2,
27.8, 127.5, 125.4, 125.3, 122.0, 56.3, 31.9, 29.0,
8.2 ppm; IR (KBr): mꢀ = 3,415, 3,231, 3,131, 2,924,
TMS as internal standard. IR spectra were obtained on a
Nicolet Magna FTIR 550 spectrophotometer in KBr. Mass
spectra were determined on an Agilent Technology (HP)
123

T. Akbarzadeh et al.
-
,614, 1,565 cm ; MS (70 eV): m/z = 454.17 (M ? 2),
1
?
1
128.7, 128.4, 128.1, 128.0, 127.6, 127.1, 122.9, 122.0,
118.0, 56.8, 28.9 ppm; IR (KBr): mꢀ = 3,390, 2,967, 1,599,
?
52.18 (M ).
4
-
1
,516, 1,466, 1,336 cm ; MS (70 eV): m/z = 437.19
1
N-Cyclohexyl-5-phenyl-2-(pyridine-4-yl)imidazo[1,2-c]-
?
M ).
(
quinazolin-3-amine (6c, C H N )
2
7 25 5
1
Yellow crystals; m.p.: 204–206 °C; H NMR (500 MHz,
CDCl ): d = 8.68–8.63 (m, 3H, H , H5 , H ), 8.28–8.25
N-tert-Butyl-2-(4-methoxyphenyl)-5-phenylimidazo[1,2-c]-
0
0
quinazolin-3-amine (6g, C H N O)
27 26 4
3
3
7
1
(
m, 2H, H2
0
, H6
0
), 7.96 (d, J = 7.6 Hz, 1H, H ), 7.77–7.74
10
Yellow crystals; m.p.: 163–165 °C; H NMR (500 MHz,
CDCl ): d = 8.71 (d, J = 8.0 Hz, 1H, H ), 8.18–7.95 (m,
(
m, 2H, H , H ), 7.70–7.65 (m, 5H, Ph), 2.53 (d,
8
9
3
7
J = 4.1 Hz, 1H, NH), 2.35–2.30 (m, 1H, NCH),
1
3H, H , H , H ), 7.78 (d, J = 7.0, 2H, H
10
0
, H6
0
), 7.68–7.61
8
9
2
3
1
.44–0.61 (m, 10H, cyclohexyl) ppm;
C
NMR
(m, 5H, Ph), 6.95 (d, J = 7.0 Hz, 2H, H3
0
, H5
0
), 3.84 (s, 3H,
3
1
(
125 MHz, CDCl ): d = 148.5, 145.7, 141.9, 141.0,
OCH ), 2.41 (s, 1H, NH), 0.53 (s, 9H, tert-butyl) ppm;
3
C
3
1
1
2
1
40.2, 134.0, 131.9, 130.3, 129.7, 128.8, 128.5, 128.0,
27.9, 127.6, 121.9, 121.1, 118.3, 57.6, 32.2, 24.9,
4.1 ppm; IR (KBr): mꢀ = 3,379, 3,128, 2,928, 2,852,
NMR (125 MHz, CDCl ): d = 158.7, 146.4, 143.6, 143.5,
3
141.1, 141.0, 140.5, 135.0, 129.9, 129.3, 128.4, 128.3,
127.6, 127.4, 126.7, 124.6, 122.0, 113.0, 55.9, 54.7,
28.9 ppm; IR (KBr): mꢀ = 3,380, 2,960, 2,837, 1,613,
-
1
,712, 1,598, 1,572 cm ; MS (70 eV): m/z = 419.21.
-
1
?
1
,567, 1,506 cm ; MS (70 eV): m/z = 422.21 (M ).
N-Cyclohexyl-2-(4-nitrophenyl)-5-phenylimidazo[1,2-c]-
quinazolin-3-amine (6d, C H N O )
2
N-tert-Butyl-5-phenyl-2-(3,4,5-trimethoxyphenyl)-
8 25 5 2
1
Yellow crystals; m.p.: 260–261 °C; H NMR (500 MHz,
CDCl ): d = 8.66 (dd, J = 8.3, 1.7 Hz, 1H, H ), 8.54 (d,
imidazo[1,2-c]quinazolin-3-amine (6h, C H N O )
2
9 30 4 3
1
Yellow crystals; m.p.: 208–210 °C; H NMR (500 MHz,
CDCl ): d = 8.74 (d, J = 7.5 Hz, 1H, H ), 7.97 (d,
3
7
J = 9.0 Hz, 2H, H3
0
, H5
0
), 8.29 (d, J = 9.0 Hz, 2H, H2 ,
0
3
7
H6
0
), 7.98 (dd, J = 8.3, 1.4 Hz, 1H, H ), 7.78–7.76 (m,
10
J = 7.5 Hz, 1H, H ), 7.80–7.78 (m, 2H, H , H ),
10 8 9
2
H, H , H ), 7.73–7.66 (m, 5H, Ph), 2.53 (d, J = 5.1 Hz,
8
7.67–7.60 (m, 7H, ArH), 3.99 (s, 6H, OCH ), 3.91 (s,
3
9
1
H, NH), 2.34–2.33 (m, 1H, NCH), 1.60–0.88 (m, 10 H,
3
3H, OCH ), 2.42 (s, 1H, NH), 0.59 (s, 9H, tert-butyl) ppm;
3
13
1
cyclohexyl) ppm;
C
NMR (125 MHz, CDCl3):
C NMR (125 MHz, CDCl ): d = 152.9, 152.0, 146.6,
3
d = 145.9, 145.6, 141.0, 140.3, 140.2, 134.0, 130.4,
141.4, 141.1, 139.2, 137.9, 135.4, 130.5, 130.1, 129.0,
128.7, 128.3, 128.0, 127.2, 125.5, 122.7, 105.9, 61.0, 56.6,
56.3, 29.4 ppm; IR (KBr): mꢀ = 3,357, 2,964, 1,605, 1,589,
1
30.3, 129.8, 128.6, 128.3, 128.1, 127.9, 127.7, 127.3,
1
23.1, 122.0, 118.2, 57.6, 32.2, 24.9, 24.1 ppm; IR (KBr):
-
1
;
-1
?
mꢀ = 3,376, 3,119, 2,926, 2,853, 1,596, 1,569, 1,336 cm
MS (70 eV): m/z = 463.20.
1,500, 1,460 cm ; MS (70 eV): m/z = 482.23 (M ).
Acknowledgments We gratefully acknowledge partial financial
support from Tehran University of Medicinal Sciences Research
Council.
N-tert-Butyl-2-(4-fluorophenyl)-5-phenylimidazo[1,2-c]-
quinazolin-3-amine (6e, C H FN )
4
2
6
23
1
Yellow crystals; m.p.: 165–167 °C; H NMR (500 MHz,
DMSO-d ): d = 8.49 (d, J = 6.6 Hz, 1H, H ), 7.95–7.71
6
7
References
(
m, 6H, ArH), 7.58–7.33 (m, 6H, ArH), 3.12 (bs, 1H, NH),
1
.34 (s, 9H, tert-butyl) ppm; C NMR (125 MHz, DMSO-
3
0
1
. Cardellini M, Franchetti P, Grifantini M, Martelli S, Petrelli F
1975) Farmaco Sci 30:536
d6): d = 159.5 (d, JC–F = 245.5 Hz), 147.4, 140.3 (d,
JC–F = 45.0 Hz), 134.5, 132.3, 130.0, 129.7, 128.4, 128.2
(
2. Bourguignon JJ, Wermuth CG, Renaud de la Faverie JF, Thollon
C, Lombet A (1992) Preparation of imidazo[1,2-c]quinazolinones
as smooth muscle relaxants. US Patent 5,128,338, Jul 7, 1992.
Chem Abstr 116:21068
(
d, JC–F = 23.5 Hz), 127.9, 127.5, 127.3, 124.7, 124.5,
22.7 (d, JC–F = 13.4 Hz), 121.8, 118.1, 115.6 (d,
JC–F = 21.5 Hz), 54.8, 28.7 ppm; IR (KBr): mꢀ = 3,421,
1
3
. Hansen HC, Kristiansen M (1995) Imidazoquinazoline com-
pounds and their use. US Patent 5,371,080, Dec 6, 1994. Chem
Abstr 122:105917
-
1
2
,975, 1,654, 1,597, 1,557, 1,488 cm ; MS (70 eV):
m/z = 410.19.
4
. Chern JW, Lu GY, Lai YJ, Yen MH, Tao PL (1996) 3-Substituted
methyl-2,3-dihydroimidazo[1,2-c]quinazoline derivatives, their
preparation, and their use for treatment of hypertension and
dysuria. US Patent 5,512,677, Apr 30, 1996; (1994). Chem Abstr
N-tert-Butyl-2-(4-nitrophenyl)-5-phenylimidazo[1,2-c]-
quinazolin-3-amine (6f, C H N O )
2
6 23 5 2
1
Yellow crystals; m.p.: 264–265 °C; H NMR (500 MHz,
1
21:222010
CDCl ): d = 8.67 (d, J = 6.3 Hz, 1H, H ), 8.54 (d,
3
7
5. Dom a´ ny G, Gizur T, Gere A, Tak a´ cs-Nov a´ k K, Farsang G,
Ferenczy GG, T a´ rk a´ nyi G, Demeter M (1998) Eur J Med Chem
J = 7.4 Hz, 2H, H3
0
, H5
0
), 8.27 (d, J = 7.4 Hz, 2H, H2
0
,
3
3:181
H6
0
), 7.98 (d, J = 7.4 Hz, 1H, H ), 7.78–7.76 (m, 2H, H ,
10 8
6
. Galarce GD, Foncea RE, Edwards AM, Pessoa-Mahana H, Pes-
soa-Mahana CD, Ebensperger RA (2008) Biol Res 41:43
7. Tanaka K, Toda F (2000) Chem Rev 100:1025
H ), 7.72–7.66 (m, 5H, Ph), 2.52 (s, 1H, NH), 0.53 (s, 9H,
9
1
3
tert-butyl) ppm; C NMR (125 MHz, CDCl ): d = 146.2,
3
1
46.1, 141.9, 141.0, 140.6, 136.0, 134.7, 130.3, 129.9,
8. Cave GWV, Raston CL, Scott JL (2001) Chem Commun 21:2159
1
23

Synthesis of novel 5-phenylimidazo[1,2-c]quinazolin-3-amine derivatives
9
. Martins MAP, Frizzo CP, Moreira DN, Buriol L, Machado P
2009) Chem Rev 109:4140
18. Adib M, Mahdavi M, Noghani MA, Mirzaei P (2007) Tetrahe-
dron Lett 48:7263
(
1
1
1
0. Mahdavi M, Asadi M, Saeedi M, Ebrahimi M, Rasouli MA,
Ranjbar PR, Foroumadi A, Shafiee A (2012) Synthesis 44:3649
1. Mahdavi M, Asadi M, Saeedi M, Rezaei Z, Moghbel H, Forou-
madi A, Shafiee A (2012) Synlett 23:2521
2. Khoobi M, Alipour M, Zarei S, Jafarpour F, Shafiee A (2012)
Chem Commun 48:2985
3. Groebke K, Weber L, Mehlin F (1998) Synlett 661
4. Blackburn C, Guan B, Fleming P, Shiosaki K, Tsai S (1998)
Tetrahedron Lett 39:3635
19. Rostamnia S, Lamei K, Mohammadquli M, Sheykhan M, Heydari
A (2012) Tetrahedron Lett 53:5257
20. Maiti B, Chanda K, Selvaraju M, Tseng CC, Sun CM (2013) ACS
Comb Sci 15:291
21. Smyrl NR, Smithwick RW (1982) J Heterocycl Chem 19:493
22. Shaabani A, Rezazadeh F, Soleimani E (2008) Monatsh Chem
139:931
23. Bonne D, Dekhane M, Zhu J (2004) Org Lett 6:4771
24. Bonne D, Dekhane M, Zhu J (2005) Org Lett 7:5285
1
1
1
5. Bienaym e´ H, Bouzid K (1998) Angew Chem Int Ed 37:2234
16. Sharma A, Li H (2011) Synlett 1407
17. Rousseau AL, Matlaba P, Parkinson CJ (2007) Tetrahedron Lett
4
8:4079
123