Synthesis of new tetrahydro-1,5-benzodiazepin-3-yl-2-phenylacetamides via isocyanide-based multicomponent reactions

Article abstract of DOI:10.1002/jhet.1041

New tetrahydro-1H-1,5-benzodiazepin-2-phenylacetamides were synthesized in good yields by a four-component reaction of benzylidene Meldrum's acid, benzene-1,2-diamines, isocyanides, and water in CH₂Cl₂ at room temperature.

Full text of DOI:10.1002/jhet.1041

January 2013
Synthesis of New Tetrahydro-1,5-benzodiazepin-3-yl-2-
phenylacetamides via Isocyanide-Based Multicomponent
Reactions
175
*
Ali Mohammad Astaraki and Ayoob Bazgir
Department of Chemistry, Islamic Azad University, Doroud Branch, Doroud, Iran
*
E-mail: a_bazgir@iau-doroud.ac.ir
Received April 12, 2011
DOI 10.1002/jhet.1041
View this article online at wileyonlinelibrary.com.
New tetrahydro-1H-1,5-benzodiazepin-2-phenylacetamides were synthesized in good yields by a four-
component reaction of benzylidene Meldrum’s acid, benzene-1,2-diamines, isocyanides, and water in
CH2Cl2 at room temperature.
J. Heterocyclic Chem., 50, 175 (2013).
INTRODUCTION
of heterocyclic compounds [24–28], herein, we report an
efficient isocyanide-based four-component method for the
preparation of new tetrahydro-1H-1,5-benzodiazepin-2-
phenylacetamides. These compounds have closely related ring
systems such as triflubazam, clobazam, and 1,5-benzodiaze-
pines, which have a broad spectrum of biological activities.
Benzodiazepine derivatives have been known to display
a wide range of pharmacological activities as anticonvul-
sant, antianxiety, analgesic, sedative, antidepressive,
hypnotic agents [1], as well as anti-inflammatory agents
[2]. Among the 1,5-benzodiazepines, the 1,5-benzodiaze-
pine-2-ones such as telenzepine [3], triflubazam [4], and
clobazam [5] (Fig. 1), are clinically used as anxiolytic or
antisecretory agents. Further, compound I have been
investigated as cholecystokinin-B receptor antagonist [6]
(Fig. 1). Two recently published patents indicate that
2,3,4,5-tetrahydro-1H-1,5-benzodiazepine derivatives
carrying carboxamide substituents are potentially important
as a therapeutic and prophylactic agent for diabetes, diabetic
nephropathy, or glomerulosclerosis [7].
Multicomponent reactions (MCRs) have been frequently
used by synthetic chemists as a facile means to generate
molecular diversity from bifunctional substrates that react
sequentially in an intramolecular fashion [8,9]. In recent
years, isocyanide-based multicomponent condensation
reactions (IMCRs) by virtue of their synthetic potential,
their inherent atom efficiency, convergent nature, ease of
implementation, and the generation of molecular diversity,
have attracted much attention because of the advantages
that they offer to the field of combinatorial chemistry
[10,11]. Similarly, IMCRs have emerged as valuable tools
for the preparation of structurally diverse chemical libraries
of drug-like heterocyclic compounds [12–16]. In this con-
text, benzodiazepine derivatives show interesting features
that make them attractive for use in IMCRs [17–23].
RESULTS AND DISCUSSION
We found that a mixture of benzylidene Meldrum’s acid 1,
benzene-1,2-diamines 2, isocyanides 3, and water in CH2Cl2 at
room temperature, afforded corresponding 2,4-dioxo-2,x3,4,5-
tetrahydro-1H-1,5-benzodiazepin-3-yl-2-phenylacetamides 4 in
good yields for 24 h. The results are summarized in Table 1.
The good yield and purity of products and simplicity of
the present procedure makes it an interesting, convenient,
and acceptable one-pot method for the preparation of tetra-
hydro-1H-1,5-benzodiazepin-2-phenylacetamides. In addi-
tion, the workup of these very clean reactions involves
only a filtration and simple washing step with EtOH.
Because of the importance of ferrocenyl heterocyclic
compounds [29,30], we used ferrocenecarboxaldehyde 5
in the reaction. This made it possible to synthesize new fer-
rocenyl benzodiazepine 6 (Scheme 1).
We have not established an exact mechanism for the for-
mation of products 4; however, a reasonable possibility is
shown in Scheme 2. The formation of product 4 can be ra-
tionalized by initial formation of 1,5-benzodiazepine 7 via
condensation of 1 and 2. Intermediate 8 was produced by
Michael-type addition reaction of an isocyanide 3 to 7,
followed by nucleophilic attack of a H2O molecule on the nitri-
lium moiety to produce compound 9. Finally, tautomerization
Because of the biological activity of 2,3,4,5-tetrahydro-
1H-1,5-benzodiazepine [7], and our interest in synthesis
© 2013 HeteroCorporation

176
A. M. Astaraki and A. Bazgir
Vol 50
Scheme 1
8430 mass spectrometer operating at an ionization potential of
70 eV. 1H NMR spectra were recorded on a BRUKER DRX-
300 AVANCE spectrometer at 300.13. IR spectra were recorded
using a Shimadzu IR-470 apparatus. Elemental analyses were
performed using a Heracus CHN-O-Rapid analyzer.
Because of the very low solubility of products 4 and 6, we
were unable to obtain the 13C-NMR spectrum.
Typical procedure for the preparation of tetrahydro-1H-
1,5-benzodiazepin-2-phenylacetamides (4). A mixture of
benzylidene Meldrum’s acid (1 mmol), benzene-1,2-diamines
(1 mmol), isocyanides (1 mmol) and H2O (0.5 mL) in CH2Cl2
(4 mL) was stirred for 24 h at room temperature. After
completion of the reaction (TLC; ethyl acetate/n-hexane, 1/1),
the reaction mixture was filtered and the precipitate washed
with EtOH (5 mL) to afford the pure product.
N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-tetrahydro-1H-1,5-
benzodiazepin-3-yl)-2-phenylacetamide (4a). White powder
(82%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3331, 3283, 3065,
1700, 1649, 1606. 1H NMR (300 MHz, DMSO-d6): dH 0.99–1.74
(10H, m, 5CH2 of cyclohexyl), 3.35 (1H, bs, CH-N, overlap with
solvent), 3.74 (1H, d, J = 10.4 Hz, CH), 4.33 (1H, d, J = 10.4 Hz,
CH), 7.11–7.39 (9H, m, Ar-H), 8.03 (1H, bs, NH-cyclohexyl),
10.29 (1H, s, NH), 10.49(1H, s, NH). MS (EI, 70 eV) m/z: 391
(M+). Anal. Calcd for C23H25N3O3: C, 70.57; H, 6.44; N, 10.73.
Found: C, 70.48; H, 6.38; N, 10.65.
Figure 1. Important biologically active 1,5-benzodiazepines.
of 9 produces the tetrahydro-1H-1,5-benzodiazepin-2-phenyla-
cetamides 4 (Scheme 2) [23]. Compounds 4 and 6 are stable
1
solids whose structures were established by IR, H NMR
spectroscopy, and elemental analysis.
In conclusion, we have described an efficient four-component
method for the synthesis of new tetrahydro-1,5-benzodiazepin-
2-phenylacetamides using readily available starting materials.
The products are of potential synthetic and pharmacological
interest. Prominent among the advantages of this new method
are operational simplicity, good yields, and easy work-up
procedures employed.
EXPERIMENTAL
2-(4-Chlorophenyl)-N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-
tetrahydro-1H-1,5-benzodiazepin-3-yl) acetamide (4b).
White powder (80%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3319,
Melting points were measured on an Electrothermal 9100
apparatus. Mass spectra were recorded on a FINNIGAN-MAT
1
3216, 3074, 1699, 1646, 1602. H NMR (300 MHz, DMSO-d6):
d
H 0.98–1.65 (10H, m, 5CH2 of cyclohexyl), 3.36 (1H, bs, CH-N,
Table 1
overlap with solvent), 3.71 (1H, d, J = 11.3 Hz, CH), 4.35 (1H, d,
J = 11.3 Hz, CH), 7.10–7.42 (8H, m, Ar-H), 8.08 (1H, d, J = 7.1
Hz, NH-cyclohexyl), 10.34 (1H, s, NH), 10.53 (1H, s, NH). MS
Synthesis of 1,5-benzodiazepin 4.
Scheme 2
Product 4
Ar
R′
Yield (%)a
a
C6H5
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
2,6-(Me)2C6H3
2,6-(Me)2C6H3
2,6-(Me)2C6H3
82
80
76
79
77
73
81
82
77
74
79
b
c
d
e
f
g
h
i
4-Cl-C6H4
2-Cl-C6H4
4-Me-C6H4
4-Br-C6H4
3-Br-C6H4
3-NO2-C6H4
3-MeO-C6H4
C6H5
j
k
4-Cl-C6H4
3-MeO-C6H4
aIsolated yields.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

January 2013
Synthesis of New Tetrahydro-1,5-benzodiazepin-3-yl-2-phenylacetamides
177
via Isocyanide-Based Multicomponent Reactions
(EI, 70 eV) m/z: 425 (M+). Anal. Calcd for C23H24ClN3O3: C,
64.86; H, 5.68; N, 9.87. Found: C, 64.74; H, 5.59; N, 9.96.
2-(2-Chlorophenyl)-N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-
tetrahydro-1H-1,5-benzodiazepin-3-yl) acetamide (4c).
White powder (76%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3346,
(M+). Anal. Calcd for C24H27N3O4: C, 68.39; H, 6.46; N, 9.97.
Found: C, 68.28; H, 6.38; N, 10.09.
N-(2,6-dimethylphenyl)-2-(2,4-dioxo-2,3,4,5-tetrahydro-
1H-1,5-benzodiazepin-3-yl)-2-phenylacetamide (4i). White
powder (77%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3450,
1
1
3265, 3080, 1701, 1651, 1605. H NMR (300 MHz, DMSO-d6):
3256, 3064, 1702, 1656, 1601. H NMR (300 MHz, DMSO-d6):
dH 1.08–1.69 (10H, m, 5CH2 of cyclohexyl), 3.47 (1H, bs, CH-N,
d
H 1.88 (6H, s, 2CH3), 3.84 (1H, d, J = 10.8 Hz, CH), 4.64 (1H, d,
overlap with solvent), 3.95 (1H, d, J = 11.2 Hz, CH), 4.72 (1H, d,
J = 11.2 Hz, CH), 7.14–7.37 (8H, m, Ar-H), 7.57 (1H, d, J = 8.1
Hz, NH-cyclohexyl), 10.31 (1H, s, NH), 10.62 (1H, s, NH). MS
(EI, 70 eV) m/z: 425 (M+). Anal. Calcd for C23H24ClN3O3: C,
64.86; H, 5.68; N, 9.87. Found: C, 64.94; H, 5.48; N, 9.80.
N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-tetrahydro-1H-1,5-
benzodiazepin-3-yl)-2-(4-methylphenyl) acetamide (4d). White
powder (79%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3324, 3214,
3075, 1699, 1647, 1603. 1H NMR (300 MHz, DMSO-d6):
dH 0.94–1.65 (10H, m, 5CH2 of cyclohexyl), 2.20 (3H, s,
CH3), 3.36 (1H, bs, CH-N, overlap with solvent), 3.69 (1H,
d, J = 11.3 Hz, CH), 4.28 (1H, d, J = 11.2 Hz, CH), 6.97–7.27
(8H, m, Ar-H), 7.99 (1H, d, J = 7.8 Hz, NH-cyclohexyl), 10.26
(1H, s, NH), 10.48 (1H, s, NH). MS (EI, 70 eV) m/z: 405
(M+). Anal. Calcd for C24H27N3O3: C, 71.09; H, 6.71; N, 10.36.
Found: C, 70.99; H, 6.79; N, 10.45.
2-(4-Bromophenyl)-N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-
tetrahydro-1H-1,5-benzodiazepin-3-yl)acetamide (4e). White
powder (77%); mp >270ꢀC. ir (KBr) (nmax/cmÀ1): 3315, 3214,
3071, 1699, 1647, 1603. 1H NMR (300 MHz, DMSO-d6): dH
0.99–1.66 (10H, m, 5CH2 of cyclohexyl), 3.33 (1H, bs, CH-N,
overlap with solvent), 3.73 (1H, d, J = 8.8 Hz, CH), 4.35 (1H,
d, J = 8.8 Hz, CH), 6.95–7.49 (8H, m, Ar-H), 8.03 (1H, bs,
NH-cyclohexyl), 10.28 (1H, s, NH), 10.47 (1H, s, NH). MS (EI, 70
eV) m/z: 471 (M+), 469 (M+). Anal. Calcd for C23H24BrN3O3: C,
58.73; H, 5.14; N, 8.93. Found: C, 58.81; H, 5.21; N, 8.82.
J = 10.8 Hz, CH) 6.96–7.55 (12H, m, Ar-H). 9.40 (1H, s, NH),
10.16 (1H, s, NH), 10.63 (1H, s, NH). MS (EI, 70 eV) m/z: 413
(M+). Anal. Calcd for C25H23N3O3: C, 72.62; H, 5.61; N, 10.16.
Found: C, 72.79; H, 5.55; N, 10.23.
2-(4-Chlorophenyl)-N-(2,6-dimethylphenyl)-2-(2,4-dioxo-
2,3,4,5-tetrahydro-1H-1,5-benzodiazepin-3-yl)acetamide (4j).
White powder (73%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3450,
3300, 3290, 1699, 1662, 1600. 1H NMR (300 MHz, DMSO-d6): dH
1.94 (6H, s, 2CH3), 3.81 (1H, d, J = 12.9 Hz, CH), 4.65 (1H, d,
J = 12.9 Hz, CH) 6.97–7.54 (11H, m, Ar-H). 9.65 (1H, s, NH),
10.39 (1H, s, NH), 10.67 (1H, s, NH). MS (EI, 70 eV) m/z: 447
(M+). Anal. Calcd for C25H22ClN3O3: C, 67.04; H, 4.95; N,
9.38. Found: C, 67.14; H, 4.87; N, 9.31.
2-(3-Methoxyphenyl)-N-(2,6-dimethylphenyl)-2-(2,4-dioxo-
2,3,4,5-tetrahydro-1H-1,5-benzodiazepin-3-yl)acetamide (4k).
White powder (79%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3291,
3228, 3078, 1700, 1656. 1H NMR (300 MHz, DMSO-d6): dH
1.92 (6H, s, 2CH3), 3.77 (3H, s, OCH3), 3.85 (1H, d, J = 11.2
Hz, CH), 4.62 (1H, d, J = 11.2 Hz, CH), 6.76–7.20 (11H, m,
Ar-H), 9.40 (1H, s, NH), 10.17 (1H, s, NH), 10.42 (1H, s, NH).
MS (EI, 70 eV) m/z: 443 (M+). Anal. Calcd for C26H25N3O4: C,
70.41; H, 5.68; N, 9.47. Found: C, 70.30; H, 5.61; N, 9.55.
N-cyclohexyl-2-ferocenyl-2-(2,4-dioxo-2,3,4,5-tetrahydro-
1H-1,5-benzodiazepin-3-yl)acetamide (6a). Light yellow
(75%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3460, 3300, 3074,
1
1700, 1655, 1603. H NMR (300 MHz, DMSO-d6): dH 1.19–1.83
2-(3-Bromophenyl)-N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-
tetrahydro-1H-1,5-benzodiazepin-3-yl) acetamide (4f). White
powder (73%); mp >270ꢀC. ir (KBr) (nmax/cmÀ1): 3317, 3185,
3069, 1700, 1648, 1601. 1H NMR (300 MHz, DMSO-d6): dH
1.14–1.65 (10H, m, 5CH2 of cyclohexyl), 3.38 (1H, bs, CH-N,
overlap with solvent), 3.71 (1H, d, J = 9.6 Hz, CH), 4.32 (1H, d,
J = 9.6 Hz, CH), 7.20–7.48 (8H, m, Ar-H), 8.10 (1H, bs,
NH-cyclohexyl), 10.37 (1H, s, NH), 10.55 (1H, s, NH). MS (EI, 70
eV) m/z: 471 (M+), 469 (M+). Anal. Calcd for C23H24BrN3O3: C,
58.73; H, 5.14; N, 8.93. Found: C, 58.60; H, 5.07; N, 8.81.
(10H, m, 5CH2 of cyclohexyl), 3.56 (1H, bs, CH-N), 3.94–4.18
(11H, m, CHfer and 2CH), 7.08–7.18 (4H, m, Ar-H). 8.10 (1H, d,
J = 7.6 Hz, NH), 10.38 (1H, s, NH), 10.40 (1H, s, NH). MS (EI,
70 eV) m/z: 499 (M+). Anal. Calcd for C27H29 Fe N3O3: C, 64.94;
H, 5.85; N, 8.41. Found: C, 64.81; H, 5.76; N, 8.49.
N-(2,6-dimethylphenyl)-2-ferocenyl-2-(2,4-dioxo-2,3,4,5-
tetrahydro-1H-1,5-benzodiazepin-3-yl)acetamide (6b). White
powder (67%); mp 228–235ꢀC. ir (KBr) (nmax/cmÀ1): 3450,
1
3300, 3261, 1680, 1662, 1600. H NMR (300 MHz, DMSO-d6):
dH 2.19 (6H, s, 2CH3), 4.22–4.80 (11H, m, CHfer and 2CH),
6.53–7.31 (7H, m, Ar-H). 9.09 (1H, s, NH), 9.20 (1H, s, NH),
9.65 (1H, s, NH). MS (EI, 70 eV) m/z: 521 (M+). Anal. Calcd for
C29H27 Fe N3O3: C, 66.80; H, 5.22; N, 8.06. Found: C, 66.89; H,
5.28; N, 7.99.
N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-tetrahydro-1H-1,5-
benzodiazepin-3-yl)-2-(3-nitrophenyl) acetamide (4g). White
powder (81%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3316, 3216,
1
3069 (NH), 1700, 1646, 1605. H NMR (300 MHz, DMSO-d6):
dH 0.94–1.76 (10H, m, 5CH2 of cyclohexyl), 3.36 (1H, bs, CH-N,
overlap with solvent), 3.79 (1H, d, J = 11.3 Hz, CH), 4.52 (1H, d,
J = 11.3 Hz, CH), 7.08-8.21 (7H, m, Ar-H), 8.05 (1H, d, J = 8 Hz,
NH-cyclohexyl), 8.18–8.21 (2H, m, Ar-H), 10.38 (1H s, NH), 10.60
(1H, s, NH). MS (EI, 70 eV) m/z: 436 (M+). Anal. Calcd for
C23H24N4O5: C, 63.29; H, 5.54; N, 12.84. Found: C, 63.36; H, 5.62;
N, 12.75.
Acknowledgments. We gratefully acknowledge the financial
support from the Research Council of Islamic Azad University,
Doroud Branch.
N-cyclohexyl-2-(2,4-dioxo-2,3,4,5-tetrahydro-1H-1,5-
benzodiazepin-3-yl)-2-(3-methoxyphenyl) acetamide (4h). White
powder (82%); mp >260ꢀC. ir (KBr) (nmax/cmÀ1): 3361, 3260,
3060, 1690, 1677, 1605. 1H NMR (300 MHz, DMSO-d6): dH
1.15–1.65 (10H, m, 5CH2 of cyclohexyl), 3.38 (1H, bs, CH-N,
overlap with solvent), 3.67 (4H, bs, OCH3 and CH), 4.29 (1H, bs,
CH), 6.77–7.21 (8H, m, Ar-H), 8.03 (1H, bs, NH-cyclohexyl),
10.30 (1H, s, NH), 10.49 (1H, s, NH). MS (EI, 70 eV) m/z: 421
REFERENCES AND NOTES
[1] (a) Schutz, H. Benzodiazepines; Springer: Heidelberg, 1982;
(b) Landquist, J. K. In Comprehensive Heterocyclic Chemistry; Katritzky,
A. R., Rees, C. W., Eds.; Pergamon: Oxford, 1984; Vol.1, p 166.
[2] De Baun, J. R.; Pallos, F. M.; Baker, D. R. U.S. Pat.
3,978,227, 1976; Chem Abstr 1977, 86, 5498d.
[3] Eltze, M.; Gonne, S.; Riedel, R.; Schlotke, B.; Schudt, C.;
Simon, W. A. Eur J Pharmacol 1985, 112, 211.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

178
A. M. Astaraki and A. Bazgir
Vol 50
[4] Nicholson, A. N.; Stone, B. M.; Clarke, C. H. Br J Clin Phar-
macol 1977, 4, 567.
[5] Kruse, H. Drug Dev Res 1982, 2, 145.
[19] De Silva, R. A.; Santra, S.; Andreana, P. R. Org Lett 2008, 10,
4541.
[20] Zohreh, N.; Alizadeh, A.; Bijanzadeh, H. R.; Zhu, L.-G. J
Comb Chem 2010, 12, 497.
[21] Shaabani, A.; Maleki, A.; Hajishaabanha, F.; Mofakham, H.;
Seyyedhamzeh, M.; Mahyari, M.; Weng Ng, S. J Comb Chem 2010,
12, 186.
[22] Shaabani, A.; Maleki, A.; Mofakham, H. J Comb Chem 2008,
10, 595.
[23] Shaabani, A.; Rezayan, A. H.; Keshipour, S.; Sarvary, A.;
Weng Ng, S. Org Lett 2009, 11, 3342.
[24] Ghahremanzadeh, R.; Sayyafi, M.; Ahadi, S.; Bazgir, A. J
Comb Chem 2009, 11, 393.
[25] Jadidi, K.; Ghahremanzadeh, R.; Bazgir, A. J Comb Chem
2009, 11, 341.
[26] Ghahremanzadeh, R.; Imani Shakibaei, G.; Ahadi, S.; Bazgir,
A. J Comb Chem 2010, 12 191.
[27] Ahadi, S.; Ghahremanzadeh, R.; Mirzaei, P.; Bazgir, A.
Tetrahedron 2009, 65, 9316.
[28] Akbarzadeh, R.; Mirzaei, P.; Bazgir, A. J Organomet Chem
2010, 695, 2320.
[29] Kelly, P. N.; Prêtre, A.; Devoy, S.; O’Rielly, I.; Devery, R.;
Goel, A.; Gallagher, J. F.; Lough, A. J.; Kenny, P. T. M. J Organomet
Chem 2007, 692, 1327.
[6] Ursini, A.; Capelli, A. M.; Carr, R. A. E.; Cassara, P.; Corsi,
M.; Curcuruto, O.; Curotto, G.; Cin, M. D.; Davalli, S.; Donati, D.; Feriani,
A.; Finch, H.; Finizia, G.; Gaviraghi, G.; Marien, M.; Pentassuglia, G.; Polinelli,
S.; Ratti, E.; Reggiani, A.; Tarzia, G.; Tedesco, G.; Tranquillini, M. E.; Trist,
D. G.; Van Amsterdam, F. T. M. J Med Chem 2000, 43, 3596.
[7] (a) Ohtake, Y.,Fukaya, Y. E. E. Pat. 1,820,799 A1, 2007; (b)
Finch, H.; Shah, P.; Carr, R. A. E. U.S. Pat. 5,585,376, 1996.
[8] Dömling, A.,Ugi, I. Angew Chem Int Ed Engl 2000, 39, 3168.
[9] Dömling, A. Chem Rev 2006, 106, 17.
[10] Ugi, I.; Werner, B.; Dömling, A. Molecules 2003, 8, 53.
[11] Hulme, C.; Gore, V. Curr Med Chem 2003, 10, 51.
[12] Shaabani, A.; Maleki, A.; Mofakham, H.; Khavasi, H. R. J
Comb Chem 2008, 10, 323.
[13] Fujiwara, S.-I.; Asanuma, Y. Shin-Ike, T.; Kambe, N. J Org
Chem 2007, 72, 8087.
[14] Yavari, I.; Esnaashari, M. Synthesis 2005, 1049.
[15] Nair, V.; Vinod, A. U.; Abhilash, N.; Menon, R. S.; Santhi, V.;
Varma, R. L.; Viji, S.; Mathew, S.; Srinivas, R. Tetrahedron 2003, 59, 10279.
[16] Teimouri, M. B.; Mansouri, F. J Comb Chem 2008, 10, 507.
[17] Xu, Z.; Dietrich, J.; Shaw, Hulme C. Tetrahedron Lett 2010,
51, 4566.
[30] Anderson, C. E.; Donde, Y.; Yariv, D.; Christopher, J.;
Overman, L. E. J Org Chem 2005, 70, 648.
[18] Sañudo, M.; García-Valverde, M.; Marcaccini, S.; Delgado, J.
J.; Rojo, J.; Torroba, T. J Org Chem 2009, 74, 2189.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet