A simple method for preparation of ZnO nanoparticles as a highly efficient nanocatalyst for N-formylation of primary and secondary amines under solvent-free condition

Article abstract of DOI:10.1080/15533174.2012.741180

A convenient reaction between alky, aryl, and heteroalkyl amines and formic acid as a formylating agent in the presence of catalytic amount of mechanochemically synthesized zinc oxide nanoparticles under solvent-free condition for the synthesis of corresponding N-formyl derivatives is described. Copyright Taylor and Francis Group, LLC.

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A Simple Method for Preparation of ZnO Nanoparticles
as a Highly Efficient Nanocatalyst for N-Formylation
of Primary and Secondary Amines under Solvent-Free
Condition
Heshmatollah Alinezhad a b & Fatemeh Salehian a
a Faculty of Chemistry, University of Mazandaran, Babolsar, I. R. Iran
b Nano and Biotechnology Research Group, University of Mazandaran, Babolsar, I. R. Iran
Accepted author version posted online: 12 Dec 2012.Published online: 07 Mar 2013.
To cite this article: Heshmatollah Alinezhad & Fatemeh Salehian (2013) A Simple Method for Preparation of ZnO Nanoparticles
as a Highly Efficient Nanocatalyst for N-Formylation of Primary and Secondary Amines under Solvent-Free Condition, Synthesis
and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:5, 532-538, DOI: 10.1080/15533174.2012.741180
To link to this article: http://dx.doi.org/10.1080/15533174.2012.741180
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:532–538, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.741180
A Simple Method for Preparation of ZnO Nanoparticles as a
Highly Efficient Nanocatalyst for N-Formylation of Primary
and Secondary Amines under Solvent-Free Condition
Heshmatollah Alinezhad1,2 and Fatemeh Salehian1
1Faculty of Chemistry, University of Mazandaran, Babolsar, I. R. Iran
2Nano and Biotechnology Research Group, University of Mazandaran, Babolsar, I. R. Iran
and sizes.[5–8] However, most of these methods involve a strictly
A convenient reaction between alky, aryl, and heteroalkyl
amines and formic acid as a formylating agent in the presence
of catalytic amount of mechanochemically synthesized zinc oxide
nanoparticles under solvent-free condition for the synthesis of cor-
responding N-formyl derivatives is described.
controlled synthesis environment, expensive equipment and
complicated procedures.
Mechanochemical processing is a novel method for the pro-
duction of nanosized materials, where separated nanoparticles
can be prepared. The method has been widely applied to synthe-
size a large variety of nanoparticles, including ZnS, CdS, ZnO,
LiMn2O4, SiO2, and CeO2.[9–12] Milling of precursor powders
leads to the formation of a nanoscale composite structure of the
starting materials that react during milling or subsequent heat
treatment to form a mixture of separated nanocrystals of the
desired phase.
Keywords amines, formic acid, N-formylation, solvent-free, ZnO
nanoparticles
INTRODUCTION
Designing of new specific catalysts and exploring their cat-
alytic activity has caused profound effects in optimizing the
efficiency of a wide range of organic synthesis. Development
of such catalysts has resulted in more economical and envi-
ronmentally friendly chemistry through replacing nonselective,
unstable, or toxic catalysts.[1] Surface of metal oxides exhibit
both Lewis acid and Lewis base characters. This is character-
istic of many metal oxides, especially TiO2, Al2O3, and ZnO,
and they are excellent adsorbents for a wide variety of organic
compounds and increase reactivity of the reactants.[2]
Nanoscale oxide particles are gaining increasing technical
importance for classic areas of application such as catalysts,
passive electronic components, or ceramic materials.[3,4] Metal
oxide nanoparticles are also widely used in industrial applica-
tions as catalysts, ceramic, pigments, and so on. Zinc oxide
nanoparticles are certainly some of the most interesting multi-
functional of metal oxides, because they have surface properties
that suggest that a very rich organic chemistry may occur there.
So far, a variety of techniques have been applied to the prepara-
tion of nanocrystalline ZnO with different particle morphologies
Formamides are important intermediates in the synthesis of
pharmaceutically valuable compounds,[13] fungicides and her-
bicides,[14] formamidines,[15] isocyanides,[16] and can be used as
a catalyst in some reactions such as allylation[17] and hydrosi-
lylation[18] of carbonyl compounds. A number of methods have
been reported for the formylation of amines. Some of the formy-
lation reagents are chloral,[19] activated formic acid using DCC
or EDCI,[20] formic acid esters,[21] ammonium format,[22] Lewis
acids,[23] solid-supported reagents,[24] aq. 85% formic acid using
ZnO,[25] aq. formic acid in protic ionic liquid,[26] indium-formic
acid[27] and formic acid at 80◦C.[28] Many of these methods
have disadvantages such as expensive and toxic reagents and
catalysts, long reaction times, high temperature, side products
formation, tedious work-up procedure, and difficult accessibility
to reagents. Thus, a mild, convenient, high-yield, experimental
simplicity and effectiveness procedure using inexpensive cata-
lyst would be valuable.
ZnO under solvent-free conditions have proved to be useful
to chemists due to the reaction rate enhancement, selectivity,
easier work-up, and recyclability of the supports.[25]
As the part of our research, we are trying to synthesize and
use nanoparticles having catalytic activities, which are eco-
nomic for large-scale preparation. Here we describe the use
of ZnO nanoparticles (NAP-ZnO) as a simple and efficient het-
erogeneous eco-friendly catalyst for N-formylation of different
amines (Scheme 1).
Received 2 November 2011; accepted 15 October 2012.
The authors are thankful to the Research Council of University of
Mazandaran for the partial support of this work.
Address correspondence to Heshmatollah Alinezhad, Faculty of
Chemistry, University of Mazandaran, Babolsar, I. R. Iran. E-mail:
heshmat@umz.ac.ir
532

NAP-ZNO FOR N-FORMYLATION OF AMINES
533
SCH. 1. N-Formylation of amines with formic acid catalyzed by ZnO-nanoparticles.
EXPERIMENTAL
Materials were purchased from Merck, Germany. The reac-
tions were monitored by TLC using silica gel plates and the
products were purified by flash column chromatography on sil-
ica gel (Merck, 230–400 mesh, Germany) and were identified
by comparison of their spectra (1H NMR, 13C NMR, IR) and
physical data with those of the authentic samples. Nuclear mag-
netic resonance spectra were recorded on a Bruker DRX-400
AVANCE spectrometer (Germany) in CDCl3 or DMSO as sol-
vent. Melting points were determined using an Electrothermal
Thermo Scientific IA9200 apparatus (USA). Mass spectra were
obtained on an Agilent technologies instrument (USA) and IR
spectra were determined on a Shimadzu instrument (Kyoto,
Japan). Powder X-ray diffraction data were obtained using a
Shimadzu XD-D1 diffractometer (Kyoto, Japan) using Cu Ka
radiation (λ = 1.5418 Å). The transmission electron micro-
graphs (TEM) were obtained with a Philips CM10 microscope
(The Netherlands).
FIG. 1. X-ray diffraction pattern of ZnO nanoparticles.
ray diffraction pattern of the mechanochemically synthesized
zinc oxide is shown in Figure 1. The diffraction angle and inten-
sity of the characteristic peaks of the samples is well consistent
with that of the standard JCPDS card No. 36–1451. The value of
15.8 nm was calculated from XRD data for average particle size
of this crystalline ZnO using Scherrer’s equation.[30] Figure 2
shows a typical TEM micrograph of the ZnO nanoparticles. It
can be observed that the particles are almost 10–20 nm, which
is in good agreement with XRD crystal sizes.
Preparation of ZnO Nanoparticles
To prepare nanosized particles of zinc oxide,[29] we used the
method of mechanochemical synthesis from salt systems. Zinc
acetate [Zn(CH3CO2)2.2H2O] and oxalic acid [H2C2O4.2H2O]
were used as the main raw materials. Zinc acetate was dried at
120◦C in air for 24 h prior to use. In a typical synthesis, starting
materials [Zn(CH3COO)2.2H2O and H2C2O4.2H2O] were put
in an agate mortar with molar ratio of 2:3 and mixed and milled
for 45 min at room temperature. The white powders (precursor)
were calcined at 450◦C in air in a porcelain crucible for 30 min
to prepare the ZnO nanoparticles. The results obtained from
XRD pattern and TEM micrograph of the ZnO nanoparticles
show that the mean particle size is 15 nm.
Encouraged with the initial success in the N-formylation re-
action, we carried out formylation of aniline (1 mmol) with aq.
General Procedure
To a mixture of aq. 98% formic acid (3 mmol, 0.11 mL)
and ZnO nanoparticles (2 mol%, 0.0016 g) was added an amine
(1 mmol). The reaction mixture was heated in an oil bath at
70◦C with continuous stirring. The progress of the reaction was
monitored by TLC. After completion of the reaction, CH2Cl2
or EtOAc was added to the cooled reaction mixture, and then
filtered to remove the ZnO nanoparticles. The organic solvent
was washed with H2O (2×10 mL) and a saturated solution of
NaHCO3 and dried over anhydrous Na2SO4. After removal of
the solvent, the pure product was obtained. This was further
purified by recrystallization with suitable solvent (Table 1).
RESULTS AND DISCUSSION
In this study, we prepared nanosized ZnO catalyst[29] and used
it successfully in the synthesis of N-formylation of amines. X-
FIG. 2. TEM micrograph of synthesis ZnO nanoparticle.

534
H. ALINEZHAD AND F. SALEHIAN
TABLE 1
N-Formylation of amines with formic acid catalyzed by ZnO-nanoparticlesa
Entry
1
Substrate
Time (min)
7
Product
Yield (%)b
98
Ref
[25]
2
3
6
3
95
94
[31]
[24]
4
5
25
6
92
94
[32]
[33]
6
35
93
[25]
7
8
30
15
95
94
[31]
[34]
9
30
25
98
95
[25]
[25]
10
11
12
40
42
96
96
[25]
[35]
13
60
89
[36]
(Continued on next page)

NAP-ZNO FOR N-FORMYLATION OF AMINES
535
TABLE 1
N-Formylation of amines with formic acid catalyzed by ZnO-nanoparticlesa (Continued)
Entry
14
Substrate
Time (min)
45
Product
Yield (%)b
93
Ref
[37]
15
20
95
[24]
16
17
360
90
81
98
[24]
[38]
18
15
92
[39]
19
20
21
22
23
30
20
90
91
93
93
85
[40]
[31]
[25]
[39]
[25]
20
30
360
24
25
26
-
-
No reaction
No reaction
-
-
-
-
6
97
[41]
aReaction conditions: formic acid (3 mmol, 0.11 mL), amine (1 mmol), and ZnO nanoparticles (2 mol%, 0.0016 g) at 70◦C.
bYields refer to isolated pure products.
98% formic acid (3 mmol) under solvent-free condition. In the sults were obtained in the presence of NAP-ZnO (2 mol%) after
process of optimization of this reaction, we explored different 7 min. In continuation, we optimized the catalyst amount. With
amount of NAP-ZnO and formic acid with various solvents at inclusion of 1 mol% of NAP-ZnO the reaction took longer time.
different temperatures. In the absence of the catalyst, formamide Using more than 2 mol% of NAP-ZnO (5, 7, and 10 mol%)
was obtained in trace amount after 2 h at 70◦C, while good re- has less effect on the yield and time of the reaction. Thus, we

536
H. ALINEZHAD AND F. SALEHIAN
TABLE 2
Comparison nano-ZnO with other catalysts for N-formylation of amines
Nano-ZnO
Other catalysts
Entry
1
Amine
Time (min)
Yield (%)
95
Time (min)
20
Yield (%)
92a
Time (min)
30
Yield (%)
98b
6
2
15
94
25
93a
-
-
3
4
20
30
95
98
150
50
85c
93a
90
90b
92c
330
aZnO.[23]
bZnCl2.[25]
cSodium formate.[39]
found that 2 mol% of NAP-ZnO could effectively catalyze the 11, and 13) exhibit a decrease of reaction time when compared
reaction for synthesis of the desired product. Then, the effect with the corresponding 3 or 4-substituted anilines, which may
of temperature was studied by carrying out the model reaction be ascribed to the steric hindrance for the unidirectional entry
in the presence of NAP-ZnO (2 mol%) at room temperature, of reacting species (Table 1, entries 3, 5, and 8).
50◦C, and 70◦C. It was observed that the best yield obtained
O-Formylation of benzylalcohol and phenol under this reac-
at 70◦C. Also we investigated the effect of different solvents tion condition was not successful (Table 1, entries 24 and 25).
(CH2Cl2 and CH3CN) on the reaction, the results showed the Also, the formylation of amines occurred selectively in the pres-
reaction needed longer time (90 and 150 min, respectively) ence of hydroxyl group (Table 1, entries 9–11). Therefore, the
than solventless condition, therefore the solvent free condi- described catalytic formylating system is chemoselective.
tion was selected. Finally, we surveyed the different amount
Heterocyclic amines are easily formylated to the correspond-
of formic acid (1, 2, and 3 mmol) in the reaction and the best ing formamides in high to excellent yields (Table 1, entries 21
reaction time and yield was obtained using 3 mmol of formic and 22).
acid.
When o-phenylenediamine was used, instead of N-
Aliphatic and aromatic primary and secondary amines formylation, cyclization occurred to give benzimidazole as a
(1 mmol) converted to their N-formyl derivatives in an easy product (Table 1, entry 26).
route in the presence of NAP-ZnO (2 mol%) in formic acid
In order to show the advantages and the drawbacks of nano-
ZnO for the N-formylation of amines, we have compared the re-
(3 mmol) at 70◦C under solvent free condition (Table 1).
To widen the scope, we subjected a series of other aro- sults with some of those reported with other catalysts in Table 2.
matic amine derivatives having electron-donating as well as The results clearly signify the usefulness of the present cata-
electron-withdrawing substituents to obtain the corresponding lyst for the synthesis of formamides. Although, Hosseini and
formamides with excellent yields under the optimized reaction coworkers[25] described formylation of amines with 50 mol%
conditions. Previously, the N-formylation of anilines having ZnO, but, in comparison of our method, it is evident that, the
electron-withdrawing groups was found to be difficult.[31] When catalytic activity of the nano-ZnO is much greater than that of
anilines are substituted at the 4-position with electron-donating the bulk-ZnO.
(ED) groups, higher reaction rates are observed than the one
Furthermore, NAP-ZnO can also be recovered by filtration.
bearing electron-withdrawing (EW) groups at that position (Ta- It was washed with distilled water and dichloromethane, dried
ble 1, entries 2, 3, 6, 7, and 9). On the other hand, in the N- for 2 h under vacuum and reused as a catalyst in the formylation
formylation reaction of amines using NAP-ZnO, 2-substituted reaction. The NAP-ZnO recycled for four runs without loss of
anilines with either EW or ED groups (Table 1, entries 4, 10, its activity.

NAP-ZNO FOR N-FORMYLATION OF AMINES
537
CONCLUSION
(CH2), 115.5 (C, trans), 115.7 (C, cis), 121.2 (CH),
123.1 (CH, trans), 123.3 (CH, cis), 130.9 (CH, trans),
131.9 (CH, cis), 134.3 (CH, trans), 134.6 (CH, cis),
140.5 (C), 159.5 (C O, ester, trans), 161.3 (C O, es-
ter, cis), 168.0 (C O, formyl).
In conclusion, we have shown that the synthesized NAP-ZnO
catalyze the N-formylation of amines with formic acid in high
to excellent yields and in short duration. Our protocol avoids
the use of expensive reagents and the reaction performed un-
der solvent free condition serves as an efficient method. We
believe that the present methodology could be an important ad-
dition to the existing methodologies. The NAP-ZnO was well
characterized by transmission electron microscopy (TEM) and
powder X-ray diffraction (powder XRD). The advantages of the
present method are (a) the ease of preparation of NAP-ZnO;
(b) using NAP-ZnO as a reusable, nontoxic, and inexpen-
sive heterogeneous nanocatalyst; (c) mild reaction conditions;
(d) easy and clean work-up; (e) more convenient and envi-
ronmentally benign; (f) high to excellent product yields and
(g) excellent chemoselectivity.
N-(4-methoxyphenyl) ethylformamide (entry 17): Light yellow
viscous oil. IR (KBr): 3390, 2938, 1658, 1112, cm–1.
1H NMR (400 MHz, CDCl3): 19: 81 (cis/trans), δ 8.4
(brd, 1H), 8.15 (s, 0.81H, cis), 8.15 (d, 0.19H, trans),
7.14 (d, 2H, J = 6.4, Ar-H), 7.14 (d, 2H, J = 6.8, Ar-H),
6.8 (d, 2H, J = 6.4, Ar-H), 6.2 (brd, 1H), 3.8 (s, 3H),
3.51 (dd, 2H, J = 6.4, 6.8 Hz, trans), 3.40 (dd, 0.5H,
J = 6.4, 6.8 Hz, cis), 2.77 (t, 2H, J = 6.8 Hz, trans),
2.74 (t, 0.44H, J = 6.8 Hz, cis). 13C NMR (400 MHz,
CDCl3): δ = 34.6 (CH2, trans), 36.86 (CH2, cis), 39.4
(CH2, trans), 43.29 (CH2, cis), 55.29 (CH3, trans), 55.31
(CH3, cis), 114.14 (CH, trans), 114.28 (CH, cis), 128.24
(C), 129.71 (CH, trans), 129.84 (CH, cis), 130.37 (C),
161.11 (C O, trans), 164.42 (C O, cis).
The physical and spectral data (mp, IR, H NMR, and 13C
NMR) of selected products 5, 10, 11, and 17 are given subse-
quently.
1
3-methoxyformanilide (entry 5): Light yellow viscous oil. IR
1
(KBr): 3110, 2890, 1660, 1570, 1140 cm–1. H NMR
(400 MHz, CDCl3): 50:50 (cis/trans), δ 8.71 (d, 1H, J =
11.6 Hz, cis), 8.38 (s, 1H, trans), 8.13 (brd, 1H, cis), 7.41
(brd, 1H, trans), 6.63–6.76 (m, 4H, Ar-H), 7.01–7.32 (m,
4H, Ar-H), 3.85 (s, 6H). 13C NMR (400 MHz, CDCl3):
δ = 55.35 (CH3, trans), 55.41 (CH3, cis), 104.98 (CH,
trans), 105.85 (CH, cis), 110.42 (CH, trans), 110.59
(CH, cis), 110.95 (CH, trans), 111.99 (CH, cis), 129.82
(CH, trans), 130.64 (CH, cis), 137.89 (C, trans), 138.05
(C, cis), 158.96 (C O, trans), 160.17 (C, trans), 160.71
(C, cis), 162.42 (C O, cis).
REFERENCES
1. (a) Singh, R.; Kissling, M.R.; Letellier, A.M.; Nolan, P.S. J. Org. Chem.
2004, 69, 209. (b) Anastas, P.T.; Bartlett, L.B.; Kirchhof, M.M.; Williamson,
C.T. Catal. Today 2000, 55, 11.
2. Tanabe, K. Solid Acids and Bases; Academic Press, New York, 1970.
3. Feldmann, C.; Jungk, H. Angew. Chem. Int. Ed. 2001, 40, 359.
4. Wang, Y.; Ma, C.; Sun, X.; Li, H. Inorg. Chem. Commun. 2002, 5, 751.
5. Palkar, V.R. Nanostruct. Mater. 1999, 11, 369.
6. Park, H.K.; Kim, D.K.; Kim, C.H. J. Am. Ceram. Soc. 1997, 80, 743.
7. Kodas, T.T. Adv. Mater. 1989, 6, 180.
8. Zhang, B.P.; Binh, N.T.; Wakatsuki, K.; Segawa, Y.; Yamada,Y.; Usami, N.;
Kawasaki, M.; Koinuma, H. J. Phys. Chem. B 2004, 108, 10899.
9. Li, F.; Yu, X.; Pan, H.; Wang, M.; Xin, X. Solid State Sci. 2000, 2,
767.
10. Soiron, S.; Rougier, A.; Aymard, L.; Tarascon, J. J. Power Sources 2001,
97/98, 402.
Ethyl 3-formamidobenzoate (entry 10): White powder, m.p
=
73–76◦C. IR (KBr): 3318, 3012, 1687, 1612, 1483,
1098 cm–1. 1H NMR (400 MHz, DMSO): 19:81
(cis/trans), δ 10.45 (s, 1H), 8.85 (d, 0.19H, J = 11.2 Hz,
cis), 8.32 (s, 0.81H, trans), 8.25 (s, 1H, Ar-H), 7.46–7.82
(m, 3H, Ar-H), 4.31 (q, 2H, J = 7.2 Hz), 1.31 (t, 3H,
J = 7.2 Hz). 13CNMR (400 MHz, DMSO): δ = 14.61
(CH3), 61.30 (CH2, cis), 61.36 (CH2, trans), 118.4 (CH,
cis), 119.98 (CH, trans), 122.0 (CH, cis), 124.0 (CH,
trans), 124.6 (CH, cis), 124.7 (CH, trans), 129.8 (CH,
cis), 130.3 (CH, trans), 130.96 (C, cis), 131.5 (C, trans),
139.0 (C, cis), 139.3 (C, trans), 160.4 (C O, ester, cis),
163.0 (C O, ester, trans), 165.8 (C O, formyl, cis),
165.9 (C O, formyl, trans).
11. Yang, H.; Hu, Y.; Tang, A.; Jin, S.; Qiu, G. J. Alloys Compd. 2004, 363,
271.
12. (a) Jackson, A.; Meth-Cohn, O. J. Chem. Soc. Chem. Commun. 1995, 1319.
(b) Kobayashi, K.; Nagato, S.; Kawakita, M.; Morikawa, O.; Konishi, H.
Chem. Lett. 1995, 575. (c) Kakehi, A.; Ito, S.; Hayashi, S.; Fujii, T. Bull.
Chem. Soc. Jpn. 1995, 68, 3573. (d) Lohray, B.B.; Baskaran, S.; Rao, B.S.;
Reddy, B.Y.; Rao, I.N. Tetrahedron Lett. 1999, 40, 4855.
13. Tsuzuki, T.; McCormick, P.G. Scripta Mater. 2001, 44, 1731.
14. Chen, B.C.; Bednarz, M.S.; Zhao, R.; Sundeen, J.E.; Chen, P.; Shen, Z.;
Skoumbourdis, A.P.; Barrish, J.C. Tetrahedron Lett. 2000, 41, 5453.
15. Han, Y.; Cai, L. Tetrahedron Lett. 1997, 38, 5423.
16. Effenberger, F.; Eichhorn, J. Tetrahedron: Asymmetry 1997, 8, 469.
17. Kobayashi, S.; Nishio, K. J. Org. Chem. 1994, 59, 6620.
18. Kobayashi, S.; Yasuda, M.; Hachiya, I. Chem. Lett. 1996, 407.
19. (a) Waki, M.; Meienhofer, J. J. Org. Chem. 1977, 42, 2019. (b) Chen, F.M.
F.; Benoiton, N.L. Synthesis 1979, 709.
20. (a) Yale, H.L. J. Org. Chem. 1971, 36, 3238. (b) Kisfaludy, L.; Laszlo, O.
Synthesis 1987, 510. (c) Duezek, W.; Deutsch, J.; Vieth, S.; Niclas, H.J.
Synthesis 1996, 37.
21. Blicke, F.F.; Lu, C.J. J. Am. Chem. Soc. 1952, 74, 3933.
22. Reddy, P.G.; Kumar, G.D. K.; Baskaran, S. Tetrahedron Lett. 2000, 41,
9149.
Ethyl 2-formamidobenzoate (entry 11): Creme powder, m.p
61–64◦C. IR (KBr): 3281, 2996, 1693, 1591, 1526,
=
1082 cm–1. 1H NMR (400 MHz, CDCl3): 22:78
(cis/trans), δ 11.05 (brd, 0.22H, cis), 10.51 (brs, 0.78H,
trans), 8.96 (d, 0.22H, J = 11.2 Hz, cis), 8.71 (d, 0.78H,
J = 8.4 Hz, trans), 8.52 (m, 1H, Ar-H), 7.13–8.06 (m,
3H, Ar-H), 4.39 (q, 2H, J = 7.2), 1.43 (t, 3H, J = 7.2).
13CNMR (400 MHz, CDCl3): δ = 14.17 (CH3), 61.52

538
H. ALINEZHAD AND F. SALEHIAN
23. (a) Desai, B.; Danks, T.N.; Wagner, G. Tetrahedron Lett. 2005, 46, 955. 32. Ikawa, T.; Barder, T.E.; Biscoe, M.R.; Buchwald, S.L. J. Am. Chem. Soc.
(b) Das, B.; Krishnaiah, M.; Balasubramanyam, P.; Veeranjaneyulu, B.;
Nandankumar, D. Tetrahedron Lett. 2008, 49, 2225.
24. Chandra Shekhar, A.; Ravi Kumar, A.; Sathaiah, G.; Luke Paul, V.; Sridhar,
M.; Shanthan Rao, P. Tetrahedron Lett. 2009, 50, 7099.
2007, 129, 13001.
33. Kavalek, J.; Sterba, V. Collect. Czech. Chem. Commun. 1975, 40, 1924.
34. Tumma, H.; Nagaraju, N.; Reddy, K.V. J. Mol. Catal. A. 2009, 310, 121.
35. Connolly, T.J.; Durst, T. Can. J. Chem. 1997, 75, 536.
36. Cai, L.; Han, Y.; Ren, S.; Huang, L. Tetrahedron 2000, 56, 8253.
25. Hosseini-Sarvari, M.; Sharghi, H. J. Org. Chem. 2006, 71, 6652.
26. Akbari, J.; Hekmati, M.; Sheykhan, M.; Heydari, A. ARKIVOC 2009, 123. 37. Jung, S.H.; Ahn, J.H.; Park, S.K.; Choi, J.K. Bull. Korean Chem. Soc. 2002,
27. Kim, J.G.; Jang, D.O. Synlett 2010, 1231. 23, 149.
28. Rahman, M.; Kundu, D.; Hajra, A.; Majee, A. Tetrahedron Lett. 2010, 51, 38. Saito, I.; Takami, M.; Matsuura, T. Bull. Chem. Soc. Japan 1975, 48,
2896.
2865.
29. Shen, L.; Bao, N.; Yanagisawa, K.; Domen, K.; Gupta, A.; Grimes, C.A.
39. Hill, D.R.; Hasiao, C.N.; Kurukulasuriya, R.; Wittenberger, S. Org. Lett.
2002, 4, 111.
Nanotechnology 2006, 17, 5117.
30. Cullity, B.D. Elements of X-ray Diffraction, vol. 1; Addison-Wesley, 40. Sawa, Y.; Kato, T.; Masuda, T.; Hori, M.; Fujimura, H. Yakugaku Zasshi,
Boston, 1978.
1975, 95, 251.
31. Pratap, T.V.; Baskaran, S. Tetrahedron Lett. 2001, 42, 1983.
41. Alinezhad, H.; Salehian, F.; Biparva, P. Syn. Commun. 2012, 42, 102.