KF/Al2O3: Solid-supported reagent used in 1,3-dipolar cycloaddition reaction of nitrile oxide

Article abstract of DOI:10.1080/00397911.2011.558665

The stereoselective synthesis of 2-isoxazolidine through 1,3-dipolar cycloaddition reaction of nitrile oxide, which is in situ generation from aldoxime in the presence of N-bromosuccinamide and solid-supported reagent KF/Al2^O3 at room temperature, is reported. KF/Al2^O3 is sufficiently basic such that it can replace organic bases such as Et ³N used in typical procedures and it catalyses the reaction to enhance the rate of the reaction.

Full text of DOI:10.1080/00397911.2011.558665

This article was downloaded by: [University of Hong Kong Libraries]
On: 23 September 2013, At: 10:10
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
KF/Al2O3: Solid-Supported Reagent Used
in 1,3-Dipolar Cycloaddition Reaction of
Nitrile Oxide
Monalisa Boruah a & Dilip Konwar b
a Department of Chemistry, Indian Institute of Technology, New
Delhi, India
b Synthetic Organic Chemistry Division, North East Institute of
Science and Technology, Jorhat, India
Accepted author version posted online: 03 Apr 2012.Published
online: 18 Jul 2012.
To cite this article: Monalisa Boruah & Dilip Konwar (2012) KF/Al2O3: Solid-Supported Reagent
Used in 1,3-Dipolar Cycloaddition Reaction of Nitrile Oxide, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 42:22, 3261-3268,
DOI: 10.1080/00397911.2011.558665
To link to this article: http://dx.doi.org/10.1080/00397911.2011.558665
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,

systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Synthetic Communications1, 42: 3261–3268, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.558665
KF/Al2O3: SOLID-SUPPORTED REAGENT USED IN
1,3-DIPOLAR CYCLOADDITION REACTION OF NITRILE
OXIDE
Monalisa Boruah1 and Dilip Konwar2
1Department of Chemistry, Indian Institute of Technology, New Delhi, India
2Synthetic Organic Chemistry Division, North East Institute of Science and
Technology, Jorhat, India
GRAPHICAL ABSTRACT
Abstract The stereoselective synthesis of 2-isoxazolidine through 1,3-dipolar cycloaddition
reaction of nitrile oxide, which is in situ generation from aldoxime in the presence of
N-bromosuccinamide and solid-supported reagent KF/Al2O3 at room temperature, is
reported. KF/Al2O3 is sufficiently basic such that it can replace organic bases such as
Et3N used in typical procedures and it catalyses the reaction to enhance the rate of the
reaction.
Keywords 1,3-Dipolar cycloaddition reaction; KF=Al2O3; NBS; nitrile oxide; solid-
supported reagent
INTRODUCTION
1,3-Dipolar cycloaddition[1] reaction is an important synthetic methodology
for the construction of five-membered heterocyclic rings. Nitrile oxide is known to
be one of the most reactive 1,3-dipoles. The cycloaddition reactions of nitrile oxides
to alkene dipolarophiles have been extensively used for the preparation of substi-
tuted 2-isoxazolines, which are versatile intermediates for the synthesis of a wide var-
iety of natural products[1] and are important pharmacophores in medicinal
chemistry.[2] 2-Isoxazolines are found in a number of pharmaceutically active com-
pounds such as antifungal,[2a] antibacterial,[2b] anti-HIV,[2c] caspase inhibitory,[2d]
antimuscarinic,[2e] anti-inflammatory,[2f] anticancer,[2g] and antidepressant[2h] com-
pounds. In a typical method, nitrile oxide is generated by dehydrohalogenation of
hydroximoyl chloride using Et3N,[3] and it can be assumed that the tertiary amino
group is compatible with the CNO group. It was reported that hydroximoyl chloride
Received December 1, 2010.
Address correspondence to Monalisa Boruah, Department of Chemistry, Indian Institute of
Technology, Delhi, Hauz Khas, Delhi 16, India. E-mail: lisadergaon@yahoo.co.in
3261

3262
M. BORUAH AND D. KONWAR
forms rather stable quaternary salts with tertiary amines, especially pyridine.[4]
Moreover, triethylamine was added to the reaction mixture slowly to reduce the
extent to which the nitrile oxide dimerizes to the corresponding furoxan,[5] and this
time of addition was optimized to maximized the extent of conversion. In such a
case, replacing the organic bases by solid-supported reagent KF=Al2O3 may over-
come this difficulty and enhance the rate of the reaction. Moreover, it possesses a
lot of advantages, such as solid-phase synthesis, and excess support-bound reagent
can be used and removed by filtration, avoiding cumbersome aqueous workup
and decreasing solvent waste.
In recent years, development of ecofriendly processes using safer reagents has
received renewed attention in the field of synthetic organic chemistry. The applica-
tions of solid-supported reagents such as KF=Al2O3 in organic synthesis are in
demand.[6] Solid-supported reagents possess a number of the advantages of both sol-
ution and solid-phase chemistry, so that they are widely used in a variety of reac-
tions. An important application of KF=Al2O3 in a number of organic reactions is
as a replacement of organic bases because of its strongly basic nature.[7] Its use in
1,3-dipolar cycloaddition has been less explored.[8]
Our efforts to develop newer methods for the synthesis of heterocyclic
compounds,[9] through 1,3-dipolar cycloaddition reactions encouraged us to develop
an improved and efficient method for the synthesis of 2-isoxazolines under the
solid-supported reagent KF=Al2O3. Here we use KF=Al2O3 as a replacement for
organic base Et3N for the in situ generation of nitrile oxide by dehalogenation of
hydroximoyl bromide in the cycloaddition reaction. In this procedure, the
solid-supported reagent KF=Al2O3 may be conveniently utilized because (i) the
strong basisity of KF=Al2O3 derives from the generation of KOH in the initial prep-
aration of the solid-supported material by reaction of KF with the alumina
(Scheme 1).[10] So, the CNO group of the nitrile oxide is unaffected during the
Scheme 1. 1,3-Dipolar cycloaddition reaction of nitrile oxide in the presence of solid-supported reagent
KF=Al2O3.

KF/Al2O3: SOLID-SUPPORTED REAGENT
3263
cycloaddition reaction. On the other hand, Et3N is also attacked by N-bromosucci-
nimide (NBS); it is preferable to add the NBS to the oxime prior to the introduction
of the amine. Moreover, olefins with electron-withdrawing groups undergo polymer-
ization under highly basic conditions more readily than cycloaddition reaction.
Therefore, all the reported methods used weak organic base for generation of nitrile
oxide. (ii) It is believed that the solid support binds the substrate to its surface[11]
and catalyzes the reaction to enhance the rate of the reaction by blocking the
dimerization of dipoles and polymerization of dipolarophile. (iii) It is easy to weigh
accurately, and excess amount does not affect the reaction. (iv) It avoids the cumber-
some aqueous workup and decreases the solvent handling issue. To the best of our
knowledge, this reagent has not utilized so far in the in situ generation of nitrile
oxide.
Initially, we investigated this one-flask procedure[12] by using styrene as
dipolarophile and KF=Al2O3 instead of an organic base to direct formation of 2-iso-
xazolines from hydroxymoyl bromide of corresponding aldoximes. p-Methoxy-
benzaldoxime (1a, 0.25 mmol) was first treated with an equimolar amount of NBS
in dichloromethane at room temperature, and after 30 min aldoxime was completely
brominated. Then solid-supported reagent KF=Al2O3 (2 g, 40% KF in alumina) and
styrene (0.28 mmol) were added simultaneously and stirred at room temperature for
a further 0.5–1 h. During the reaction, the produced side product (i.e., succinamide)
was trapped by KF=Al2O3 and settled down in the reaction mixture. After com-
pletion of the reaction, the reaction mixture was diluted and the side product was
removed by filtration through ciliate. Evaporation of the solution in vacuuo gave
almost pure cycloaddition product 2-isoxazolidine (3a) with excellent yield
(Scheme 1).
The reaction was investigated with different solvent conditions. Dichloro-
methane was established as good for all. We also used biphasic and homogeneous
mixed solvent systems, but no significant result appeared during this investigation.
Only the use of a catalytic amount of water enhanced the rate of the reaction.
Further investigation of the feasibility of using solid-supported reagent
KF=Al2O3 in this reaction under solvent-free condition continued. p-Methoxy-
benzaldoxime was treated with an equimolar amount of NBS in dichloromethane
at room temperature. After stirring was continued for 1–2 h to confirm the com-
pletion of reaction, the reaction mixture was diluted with diethyl ether and washed
with water and brine. The desire product hydroximoyl bromide was isolated from
side product succinamide, followed by KF=Al2O3 and styrene. The reaction mixture
was finely mixed and mechanically stirred with extra Al2O3 for 2–3 h. The cyclo-
addition product was extracted the reaction mixture by adding diethyl ether with
65% yield.
For comparison purpose, the in situ generation of nitrile oxide and the
cycloaddition reaction were investigated by using KOH as a base instead of
KF=Al2O3. In this investigation, the reaction did not provide the desired cyclo-
addition product. We thought that the presence of a strong inorganic base affected
the hydroximoyl chloride and prevented the formation of nitrile oxide in the reaction
mixture. On the other hand, the used of weak inorganic bases steered the reaction
toward another type of addition reaction=polymerization rather than the 1,3-dipolar
cycloaddition reaction. In contrast, KOH, generated initially from KF=Al2O3, reacts

3264
M. BORUAH AND D. KONWAR
in mild reaction conditions. Moreover, it is believed that the hydroximoyl bromide is
bound with solid-supported reagent in reaction conditions and enhances the rate of
reaction as compared to the other typical procedure.
To explore the scope of the reaction, we investigated the reaction with varieties
of aliphatic, aromatic, and heteroaromatic aldoxime. Generally, aliphatic hydroxi-
moyl chlorides=bromides are known to be less stable than aromatic derivatives.
We thought that isolation and purification of aliphatic hydroximoyl bromide should
be avoided because of undesired decomposition. Therefore, in this procedure, we
directly applied KF=Al2O3 and styrene as dipolarophile for generation of nitrile
oxide and then performed cycloaddition reaction in the same reaction mixture
without any separation and purification of hydroximoyl bromide. The side product
succinimide, which was produced along with the hydroximoyl bromide in the bro-
mination step, was immediately trapped by the solid-supported reagent and settled,
and then the hydroximoyl bromide was free in the reaction mixture. It was observed
that the rapid cycloaddition gave very good yield as compared to the other typical
procedure.
A variety of aromatic, aliphatic, and heteroaromatic aldoximes (1a–l) were suc-
cessfully converted into the corresponding nitrile oxides, which were trapped with
styrene as cycloadduct (3a–l, Table 1). Yields of cycloadducts were satisfactory for
the three-step transformation including bromination of aldoxime by NBS, nitrile
oxide generation, and cycloaddition to styrene. Regardless of the kinds of starting
aldoximes, yields of styrene cycloaddition are comparable, indicating the wide syn-
thetic versatility of this nitrile oxide preparation method from a verity of aldoximes.
However, use of excess amount of KF=Al2O3 was not relatively effective in the reac-
tion. On the other hand, excess amount of NBS did not lead to overbromination.
We also investigated the 1,3-dipolar cycloaddition reaction of the nitrile oxide
generated from 1a in the presence of solid-supported reagent KF=Al2O3, outlined in
Table 2. Nitrile oxide cycloaddition to terminal alkenes proceeded regioselectively to
Table 1. 1,3-Dipolar cycloaddition reaction of nitrile oxide derived from aldoxime 1a–l with styrene in the
presence of KF=Al2O3
Entry
R of aldoxime
Time (h)
Producta
Yield (%)b
1
2
p-MeOC6H4
p-MeC6H4
p-NO2C6H4
p-OHC6H4
o-OHC6H4
p-BrC6H4
0.5
0.5
1.5
1
3a
3b
3c
3d
3e
3f
96
98
88
85
81
91
88
85
80
75
77
80
3
4
5
1
6
0.5
0.5
1.5
3
7
p-ClC6H4
=
C6H5CH CH
3g
3h
3i
8
9
C6H5CH2
n-Pr
i-Pr
10
11
12
3.5
3.5
2
3j
3k
3l
4-Py
aProducts have been identified from their respective spectral (IR,1H NMR,13C NMR, mass, GC), physi-
cal data and comparison with authentic samples.
bYields mentioned are the isolated yield, determined by GC and based on reactant.

KF/Al2O3: SOLID-SUPPORTED REAGENT
3265
Table 2. 1,3-Dipolar cycloaddition reaction of nitrile oxide derived from aldoxime 1a with different
dipolarophiles in the presence of KF=Al2O3
Entry
a
Dipolarophile
2-Isoxazoline
Time (h)
2
Yield (%)
90
Methyl acrylate
b
c
Methyl vinyl sulfonate
Allyl alcohol
1
65
92
96
3.5
0.5
d
N-Phenyl maleimide
e
f
Acrylonitrile
3.5
3
55
45
Methyl crotonate
40
80
g
Dimethyl maleate
2.5
give 5-subsituted 2-isoxazolines as single products (entries a–e, Table 2). On the
other hand, the reaction with 1,2-disubsituted internal alkenes [e.g., methyl crotonate
(entry f)] leads to a mixture of regioisomers 4 and 5 in an approximately 1:1 ratio.
It is believed that the substrate hydroxymoyl bromide and styrene were bound
with the surface of the solid-supported reagent and then generated nitrile oxide and
then cycloaddition immediately without formation of any dimers or polymers.
Moreover, in this one-pot reaction, succinamide was produced as a major side pro-
duct in the bromination step of aldoxime in the reaction mixture, but the further
steps of the method, such a generation of nitrile oxide and then cycloaddition with

3266
M. BORUAH AND D. KONWAR
dipolarophile, were performed without removing the side product from the reaction
mixture. This side product was bound with the solid-supported reagent and sepa-
rated from the reaction mixture under reaction conditions. Skipping this separation
step must be a greater advantage because the undesired side product did not isolate
in between the reaction, and the resulting hydroximoyl bromide is not stable
enough to be isolated.
In conclusion, we have provided an improved and efficient one-pot synthesis of
2-isoxazoline through 1,3-dipolar cycloaddition reaction of nitrile oxide in the pres-
ence of solid-supported reagent KF=Al2O3. In this process, a single cycloadduct is
isolated from the reaction mixture by filtration, and avoiding the water workup
enhanced the percentage of yield of the pure form as compared to reported methods.
EXPERIMENTAL
Melting points were determined on a Buchi melting-point B-540 apparatus and
are uncorrected. Column chromatography was performed using silica gel (60–120
mesh). Thin-layer chromatography (TLC) was performed on EM reagents
0.25-mm silica 60-F plates. Infared (IR) spectra were obtained on a Perkin-Elmer
1
system 2000 FT=IR spectrophotometer. Data for H NMR and 13C NMR spectra
were recorded on a Bruker Avance DPX 300-MHz spectrometer. Chemical shifts
were reported in parts per million (ppm) downfield from tetramethylsilane (TMS)
1
with solvent resonance as the internal standard. Data for H NMR are reported
as chemical shifts (d ppm), multiplicity (s, singlet; d, doublet; t, triplet; q, quartet;
m, multiplet), coupling constant (Hz), and integration. Data for 13C NMR were
reported as chemical shifts. Conversion and stereochemistry was determined by
gas chromatography. Commercially available reagents were used directly.
Typical Experimental Procedure for Nitrile Cycloaddition in the
Presence of KF/Al2O3
p-Methoxyphenyl aldoxime (1a, 0.25 mmol) was added to a stirred solution of
NBS (0.28 mmol) in dichloromethane and vigorously stirred for 30 to 45 min. The
reaction was monitored by thin-layer chromatography (TLC). After bromination
of the aldoxime (1a) to hydroximoyl bromide (2a), KF=Al2O3 (2 g, 40% by weight)
and styrene (0.28 mmol) were added and the reaction mixture was stirred for a
further 2 h. The solid mass was filtered through cilite from the reaction mixture.
CH2Cl2 was evaporated in vacuum, and residue was dissolved in EtOAc (20 mL).
The organic layer was washed with water (10 mL ꢀ 3), dried over anhydrous sodium
sulfate, concentrated under reduced pressure, and purified by silica-gel column chro-
matography to give 3-(p-methoxyphenyl)-5-phenyl-2-isoxazoline (3a) in 96% yield.
Analytical Data
3-(p-Methoxyphenyl)-5-phenyl-2-isoxazoline (3a). Colorless plates; mp
1
103–105 ꢁC; H NMR (CDCl3) d 3.35 (1H, dd, Jgem ¼ 16.7 Hz and J4–5 ¼ 8.2 Hz,
one of H-4), 3.76 (1 H, dd, Jgem ¼ 16.7 Hz and J4–5 ¼ 10.9 Hz, the other of H-4),
3.84 (3H, s, MeO), 5.71 (1H, dd, J5–4 ¼ 10.9 and 8.2 Hz, H-5), 6.93 (2H, dd,

KF/Al2O3: SOLID-SUPPORTED REAGENT
3267
J ¼ 8.9 and 1.2 Hz, Ar), 7.29–7.41 (5H, m, Ph), and 7.63 (2H, dd, J ¼ 8.9 and 1.2 Hz,
Ar); 13C NMR (CDCl3) d 43.44 (C-4), 55.35 (MeO), 82.29 (C-5), 114.14, 122.04,
125.87, 128.14, 128.27, 128.72, 141.09 (Ph and Ar), 155.66 (C-3), and 161.09 (Ar);
MS (m=z): 254 (Mþ1, base peak), 253 (73, Mþ), 221 (13), 207 (12), 154 (17), 147
(40), 136 (20), and 73 (24). Anal. found: C, 75.78; H, 6.03; N, 5.46. Calculated for
C16H15NO2: C, 75.87; H, 5.96; N, 5.53.
3-Benzyl-5-phenyl-2-isoxazoline (3i). Colorless oil; IR (neat) 3040, 2920,
1
1610, 1500, 1460, 1430, 1080, 1040, 760, and 700 cmꢂ1; H NMR (CDCl3) d 2.75
(1H, dd, Jgem ¼ 17.1 Hz and J4–5 ¼ 8.4 Hz, one of H-4), 3.18 (1H, dd, Jgem ¼ 17.1 Hz
and J4–5 ¼ 10.9 Hz, the other of H-4), 3.64 (1H, d, Jgem ¼ 14.8 Hz, one of PhCH2),
3.71 (1H, d, Jgem ¼ 14.8 Hz, the other of PhCH2), 5.47 (1H, dd, J5–4 ¼ 8.4 and
10.9 Hz, H-5), and 7.20–7.30 (10H, m, Ph); 13C NMR (CDCl3) d 33.91 (PhCH2),
44.27 (C-4), 81.61 (C-5), 125.56, 126.92, 127.82, 128.44, 128.64, 135.47, 140.84 (each
Ph), and 157.23 (C-3); MS m=z (rel. intensity, %) 238 (Mþ1, base peak), 107 (6), 91
(16), and 77 (4). Anal. found: C, 80.67; H, 6.41; N, 5.85. Calcd. for C16H15NO: C,
80.98; H, 6.37; N, 5.90.
5-Phenyl-3-propyl-2-isoxazoline (3j). Light yellow oil; 1H NMR (CDCl3) d
0.97 (3H, t, J ¼ 7.5 Hz, CH3 of n-Pr), 1.62 (2H, tt, J ¼ 7.5 and 7.5 Hz, CH2 of n-Pr),
2.36 (2H, t, J ¼ 7.5 Hz, CH2 of n-Pr), 2.89 (1H, dd, Jgem ¼ 16.9 Hz and J4–5 ¼ 8.2 Hz,
one of H-4), 3.35 (1H, dd, Jgem ¼ 16.9 Hz and J4–5 ¼ 10.9 Hz, the other of H-4), 5.54
(1H, dd, J5–4 ¼ 10.9 and 8.2 Hz, H-5), 7.29–7.38 (5H, m, Ph); 13C NMR (CDCl3) d
13.71, 19.76, 29.57 (each n-Pr), 45.30 (C-4), 81.16 (C-5), 125.67, 127.94, 128.63,
141.37 (each Ph), and 158.34 (C-3); MS m=z (rel. intensity, %) 189 (Mþ1, 55), 161
(21), 117 (18), 104 (base peak), 91 (17), and 77 (20). Anal. found: C, 75.89; H,
8.00; N, 7.39. Calcd. for C12H15NO: C, 76.16; H, 7.99; N, 7.40.
5-Phenyl-3-isopropyl-2-isoxazoline (3k). Light yellow oil; 1H NMR
(CDCl3) d 1.18 (3H, d, J ¼ 7.0 Hz, one of Me), 1.19 (3H, d, J ¼ 7.0 Hz, the other
of Me), 2.75 (1H, sep, J ¼ 7.0 Hz, Me2CH), 2.94 (1H, dd, Jgem ¼ 16.9 Hz and J4–5
¼
8.2 Hz, one of H-4), 3.63 (1H, dd, Jgem ¼ 16.9 Hz and J4–5 ¼ 10.9 Hz, the other of
H-4), 5.53 (1H, dd, J5–4 ¼ 10.9 and 8.2 Hz, H-5), and 7.27–7.38 (5H, m, Ph); 13C
NMR (CDCl3) d 20.08, 20.09, 27.89 (each i-Pr), 43.24 (C-4), 81.24 (C-5), 125.67,
127.93, 128.62, 141.39 (each Ph), and 162.98 (C-3); MS m=z (rel. intensity, %) 189
(Mþ1, 58), 117 (18), 104 (base peak), and 77 (21). Anal. found: C, 75.91; H, 7.98;
N, 7.45. Calcd. for C12H15NO: C, 76.16; H, 7.99; N. 7.40.
5-Phenyl-3-(4-pyridyl)-2-isoxazoline (3l). Colorless plates from CH2Cl2–
hexane; mp 67–698ꢁ C; IR (KBr) 3000, 2200, 1590, 1400, 1350, 900, 810, 720, and
1
690 cmꢂ1; H NMR (CDCl3) d 3.32 (1H, dd, Jgem ¼ 16.7 Hz and J4–5 ¼ 8.5 Hz, one
of H-4), 3.76 (1H, dd, Jgem ¼ 16.7 Hz and J4–5 ¼ 11.1 Hz, the other of H-4), 5.81
(1H, dd, J5–4 ¼ 11.1 and 8.5 Hz, H-5), 7.32–7.42 (5H, m, Ph), 7.54 (2H, dd, J ¼ 4.5
and 1.7 Hz, Ar), and 8.68 (2H, dd, J ¼ 4.5 and 1.7 Hz, Ar); 13C NMR (CDCl3) d
42.11 (C-4), 83.46 (C-5), 120.88, 125.81, 128.52, 128.88, 136.77, 140.19, 150.46 (Ph
and Ar), and 154.59 (C-3); MS m=z (rel. intensity, %) 224 (Mþ1, 58) and 104 (base
peak). Anal. found: C, 74.98; H, 5.42; N, 12.44. Calcd. for C14H12N2O: C, 74.98;
H, 5.39; N, 12.49.

3268
M. BORUAH AND D. KONWAR
ACKNOWLEDGMENTS
We gratefully acknowledge the Department of Science and Technology, New
Delhi, for the financial support to carry out the work. Also the author thanks the
director, North East Institute of Science and Technology, Jorhat, Assam, and Indian
Institute of Technology, Delhi.
REFERENCES
1. (a) Padwa, A. (Ed.). 1,3-Dipolar Cycloaddition Chemistry; Wiley-Interscience: New York,
1984; (b) Torssell, K. B. G. Nitrile Oxides, Nitrones, and Nitronate in Organic Synthesis;
VCH: New York, 1988; (c) Christi, M.; Huisgen, R. Chem. Ber. 1973; 106, 3345.
2. (a) Kaur, H.; Kumar, S.; Renu M.; Sangal, S. K. Acta Cienc. Indica Chem. 1999, 25, 49;
(b) Chung, Y. J.; Kim, D. H.; Choi, K. Y.; Kim, B. H. Kor. J. Med. Chem. 1995, 5, 141; (c)
,
Dighade, S. R.; Patil, S. D.; Chincholkar, M. M.; Dighade, N. R. Asian J. Chem. 2003 15,
450; (d) Kim, E. E. K.; Park, M. J.; Park, T. K.; Moon, K. Y. Chem. Abstr. 2001, 134,
262851j; (e) Amici, M. D.; Conti, P.; Vistoli, G.; Corea, G.; Ottolino, G.; Micheli, C.
D. Med. Chem. Res. 2001, 10, 615; (f) Khan, M. S. Y.; Bawa, S. Indian J. Chem. 2001,
1207; (g) Simoni, D.; Manfredini, S.; Tibrizi, M. A.; Bazzanini, R.; Guarinini, M.;
Ferroni, R.; Traniello, F.; Nastruzzi, C. G.; Gambari, R. Top. Mol. Organ. Eng. 1991,
119; (h) Gil, J. I. A.; Fermandez, G. E. J.; Alcazar, V. M. J. Chem. Abstr. 2002, 134,
201298z.
3. Grundmann, C.; Frommeld, H.-D. J. Org. Chem. 1966, 546.
4. (a) Wieland, H.; Hochtlen, A. Ann. 1933, 505, 237; (b) Quillico, A.; Gaudiano, G.; Ricca,
A. Gazz. Chim, Ital. 1957, 638; (c) Grundmann, C.; Mini, V.; Dean, J. M.; Frommeld,
H.-D. Ann. 1933, 191.
5. Lu, T.-J.; Yang, J.-F.; Shue, L.-J. J. Org. Chem. 1995, 60, 7701.
6. Blass, B. E. Tetrahedron 2002, 9301.
7. (a) Yamawaki, J.; Ando, T.; Hanafusa, T. Chem. Lett. 1981, 1143; (b) Fraile, J. M.;
Garcia, J. I.; Matoral, J. A.; Figueras, F. Tetrahedron Lett. 1996, 5995; (c) Yadav, V.
K.; Kapoor, K. K. Tetrahedron 1996, 3659; (d) Kabalka, G. W.; Wang, L.; Namboodiri,
V.; Pagni, R. M. Tetrahedron Lett. 2000, 5151.
8. (a) Berree, F.; Marchand, E.; Morel, G. Tetrahedron Lett. 1992, 6155; (b) Bougrin, K.;
Soufiaoui, M.; Loupy, A.; Jacquault, P. New J. Chem. 1995, 213.
9. Boruah, M.; Konwar, D.; Sarmah, S. D. Tetrahedron Lett. 2007, 4535.
10. Weinstock, L. M.; Stevenson, J. M.; Tomellini, R. B.; Reinhold, D. F. Tetrahedron Lett.
1986, 3845.
11. Texier-Boullet, F.; Villemin, D.; Ricard, M.; Moison, H.; Foucaud, A. Tetrahedron 1985,
41, 159.
12. Kanemasa, S.; Matsuda, H.; Kamimura, A.; Kakinami, T.; Tetrahedron 2000, 1057.