Reactions of 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes with C,N-diarylnitrones and nitrile oxides

Article abstract of DOI:10.1016/j.tetlet.2012.03.093

The reactions of unactivated bis(methylene)cyclopropanes with nitrones and nitrile oxides have been investigated. The 1,1-diaryl-2-isopropylidene-3- methylenecyclopropanes react with the C,N-diarylnitrones to give a mixture of 2,2-dimethyl-1,6-diaryl-3-(diarylmethylene)piperidin-4-ones and 5-methyl-1-aryl-1-(arylamino)-4-(diarylmethylene)hex-5-en-3-ones. 2,3-Dihydro-3-methylenepyridin-4(1H)-ones are obtained by reaction of 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes with nitrile oxides.

Full text of DOI:10.1016/j.tetlet.2012.03.093

Tetrahedron Letters 53 (2012) 3411–3415
Contents lists available at SciVerse ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Reactions of 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes
with C,N-diarylnitrones and nitrile oxides
Alexander V. Stepakov a, , Anna G. Larina a, Vitaly M. Boitsov b, Alexander P. Molchanov a,
⇑
Vladislav V. Gurzhiy a, Galina L. Starova a
a Chemistry Department, Saint-Petersburg State University, Universitetsky Prosp. 26, St-Petersburg 198504, Russian Federation
b Saint-Petersburg Academic University, Nanotechnology Research and Education Centre RAS, Khlopin Str. 8/3, St-Petersburg 194021, Russian Federation
a r t i c l e i n f o
a b s t r a c t
Article history:
The reactions of unactivated bis(methylene)cyclopropanes with nitrones and nitrile oxides have been
investigated. The 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes react with the C,N-diarylnitro-
nes to give a mixture of 2,2-dimethyl-1,6-diaryl-3-(diarylmethylene)piperidin-4-ones and 5-methyl-1-
aryl-1-(arylamino)-4-(diarylmethylene)hex-5-en-3-ones. 2,3-Dihydro-3-methylenepyridin-4(1H)-ones
are obtained by reaction of 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes with nitrile oxides.
Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved.
Received 20 January 2012
Revised 12 March 2012
Accepted 22 March 2012
Available online 29 March 2012
Keywords:
2-Isopropylidene-3-
methylenecyclopropanes
Nitrones
Nitrile oxides
3-Methylenepiperidin-4-ones
2,3-Dihydro-3-methylenepyridin-4(1H)-
ones,1,3-dipolar cycloaddition
1,3-Dipolar cycloaddition reactions have long been recognized
as important for the synthesis of heterocyclic rings.1 Nitrones
and nitrile oxides are remarkably versatile building blocks in
organic synthesis, and are known to take part in 1,3-dipolar cyclo-
addition reactions with a wide range of dipolarophiles. Cycloaddi-
tions of nitrones and nitrile oxides to alkenes are well established
reactions in which isoxazolidines and isoxazolines are formed,
often with a high degree of stereochemical control.2 These cycload-
ducts have attracted considerable attention due to the potential
biological activities of isoxazolines and isoxazolidines.1a,b Isoxaz-
olidines and isoxazolines have also been used as precursors to
reported the first example of the Yb(OTf)3-catalyzed formal [3+3]
cycloadditions of methylenecyclopropane-dicarboxylates with
C,N-diarylnitrones with the formation of substituted 1,2-oxazines
in good yields.7 The chemistry of methylenecyclopropanes has
been explored extensively. Novel intramolecular rearrangements
and also cycloaddition reactions with compounds containing
carbon–carbon or carbon–heteroatom multiple bonds, such as
imines, aldehydes, ketones, and
a,b-unsaturated ketones and
aldehydes, have been studied.2b,d,8 However, reactions of bis(meth-
ylene)cyclopropanes with nitrones and nitrile oxides have not been
studied. In continuation of our earlier work,9 we have studied the
reactions of non-activated bis(methylene)cyclopropanes with
nitrones and nitrile oxides. The choice of bis(methylene)cyclopro-
panes 1 as dipolarophiles in this process appeared particularly
interesting in order to expand the synthetic utility of this
methodology.
c-amino alcohols through the reductive cleavage of the N–O bond,
and are potential precursors for the synthesis of natural products
such as alkaloids and b-lactam antibiotics.2a The groups of Brandi
and de Meijere have systematically studied 1,3-dipolar cycloaddi-
tion reactions of methylenecyclopropanes with nitrones and nitrile
oxides that afford the exocyclic [3+2] adducts in good yields.3,4
Rearrangements of 5-spirocyclopropaneisoxazolines and 5-spiro-
cyclopropaneisoxazolidines have shown potential for the synthesis
of functionalized pyridones (Brandi–Guarna reaction)5 which are
precursors for the synthesis of natural alkaloids.6 Recently, Wang
The starting 1,1-diaryl-2-isopropylidene-3-methylenecyclopro-
panes 1a–d are easily accessible via thermolysis of the correspond-
ing
1-(2-methylpropenylidene)-2,2-diarylcyclopropanes.10
In
earlier studies we investigated the reaction of the C,N-diarylnitrone
2a with bis(methylene)cyclopropane 1a. Heating of 1a and nitrone
2a (1.5 equiv) in benzene (80 °C, 40 h) led to a mixture of com-
pounds 4a and 5a in 13% and 18% yields, respectively (Table 1, en-
try 1). 5-spiroisoxazolidine 3 could not be isolated because
⇑
Corresponding author. Fax: +7 812 4286939.
E-mail address: alstepakov@yandex.ru (A.V. Stepakov).
0040-4039/$ - see front matter Crown Copyright Ó 2012 Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.03.093

3412
A. V. Stepakov et al. / Tetrahedron Letters 53 (2012) 3411–3415
Table 1
Reactions of bis(methylene)cyclopropanes 1a–d with nitrones 2a–c
Ar2
Ar1
O
N
Ar1
O
Ar1
Ar1
Ar1
Ar1
Ar1
N
O
Ph
Ar1
2a, b
Ar2
Ar2
Ph
Me
+
Me
Me
Me
Me
benzene,
Ar2
N
80 °C, 40 h
Me
O
HN
Me
Ph
Ph
4a-g
5a-g
1a-d
3
Entry
Ar1
Ar2
Yield of 4a (%)
Yield of 5a (%)
1b
2c
3d
4e
5f
Ph (1a)
Ph (1a)
Ph (2a)
4-ClC6H4 (2b)
Ph (2a)
4-ClC6H4 (2b)
4-ClC6H4 (2b)
Ph (2a)
4-ClC6H4 (2b)
CONHPh (2c)
13 (4a)
17 (4b)
16 (4c)
19 (4d)
11 (4e)
6 (4f)h
8 (4g)j
—
18 (5a)
27 (5b)
13 (5c)
18 (5d)
19 (5e)
43 (5f)
41 (5g)
—
4-MeC6H4 (1b)
4-MeC6H4 (1b)
4-ClC6H4 (1c)
4-MeOC6H4 (1d)
4-MeOC6H4 (1d)
Ph (1a)
6g
7i
8k
a
b
c
d
e
f
Isolated yield.
21% of starting material 1a was recovered.
19% of starting material 1a was recovered.
23% of starting material 1b was recovered.
21% of starting material 1b was recovered.
24% of starting material 1c was recovered.
19% of starting material 1d was recovered.
Spectral yield.
22% of starting material 1d was recovered.
Spectral yield.
Mixture of unidentified products.
g
h
i
j
k
rearrangement occurs smoothly under the reaction conditions to
give the products 4a and 5a. In the 1H NMR spectrum of the crude
reaction mixture the signals due to proposed intermediate 3 were
not found. The reaction products were isolated by preparative thin
layer chromatography on silica. The compositions and structures of
the products were established by elemental and spectral analy-
ses.11 The structures of compounds 4a and 5a were confirmed by
X-ray diffraction analysis (Figs. 1 and 2).12,13 Running the reaction
in benzene at 20 °C for 56 h did not lead to the formation of 4 and
5. The 1H NMR spectra of the crude reaction mixture contained
only signals due to the starting bis(methylene)cyclopropane and
nitrone. A similar reaction occurred on the treatment of bis(meth-
Figure 2. ORTEP representation of 5a.
ylene)cyclopropane 1a with nitrone 2b to give a mixture of com-
pounds 4b and 5b in 17% and 27% yields, respectively (Table 1,
entry 2). The reactions of bis(methylene)cyclopropanes 1b,c and
nitrones 2a,b proceed in an analogous manner: mixtures of
bis(methylene)cyclopropanes 1b and 1c, respectively, and nitrones
2a or 2b in benzene afforded, on heating (80 °C, 40 h), mixtures of
the corresponding products 4 and 5 (Table 1, entries 3–5). More-
over, increasing the electron density of the aryl functionalities in
bis(methylene)cyclopropane 1d by introducing two electron-
donating methoxy groups led to the formation of ketones 5f and
5g (41–43%) as the major products (Table 1, entries 6 and 7). Sig-
Figure 1. ORTEP representation of 4a.

A. V. Stepakov et al. / Tetrahedron Letters 53 (2012) 3411–3415
3413
Ar1
Ar1
Ar1
Ar1
Me
Me
Me
Me
2a,b
1a-d
O
O
Ar2
Ar2
N
N
Ph
3
Ph
6
O
Ar1
O
Me
O
Me
Ar1
Ar1
ring closure
Me
ring closure
Me
4a-g
Ar1
Me
Me
Ar2
N
Ar2
N
Ar2
N
Ar1
Ar1
Ph
7b
Ph
7a
Ph
8
not found
H-transfer
5a-g
Scheme 1. Proposed reaction mechanism for the formation of compounds 4 and 5.
Table 2
Reactions of bis(methylene)cyclopropanes 1a–d with nitrile oxides 10a–c
HO
N
Ar1
O
Ar1
Ar1
Ar1
Ar1
Cl
Ar3
9a, b
Ar1
Ar3
Me
Me
Et3N, benzene,
Me
Me
60 °C, 14 h
O
N
N
H
Ar3
Me
Me
10
1a-d
11a-e
Entry
Ar1
Ar3
Yield of 11a,b (%)
1
2
3
4
5
6
Ph (1a)
4-ClC6H4 (9b)
Ph (9a)
Ph (9a)
Ph (9a)
4-ClC6H4 (9b)
EtO2C (9c)
28 (11a)c
32 (11b)d
15 (11c)e
22 (11d)f
25 (11e)g
4-MeC6H4 (1b)
4-ClC6H4 (1c)
4-MeOC6H4 (1d)
4-MeOC6H4 (1d)
Ph (1a)
h
—
a
b
c
Isolated yield.
3,4-(Ar3)2furoxanes—dimers of the corresponding nitrile oxides—were isolated from the reaction mixtures in all cases.
35% of starting material 1a was recovered.
d
e
f
29% of starting material 1b was recovered.
37% of starting material 1c was recovered.
41% of starting material 1d was recovered.
38% of starting material 1d was recovered.
g
h
Mixture of unidentified products.
nals for the corresponding piperidin-4-ones 4f,g were detected in
the 1H NMR spectra of the reaction mixtures (spectral yields
6–8%), but it was impossible to separate them as individual com-
pounds. Increasing the nitrone concentration in the reaction
mixture (up to 2.0–2.5 equiv) and the reaction time (up to 56 h)
did not lead to significant increases in the yields of the products
4 and 5. At the same time, increased amounts of unidentified prod-
ucts were observed in these cases which made product separation
difficult. The reaction of bis(methylene)cyclopropane 1a with
amidonitrone 2c gave a mixture of unidentified products (Table
1, entry 8).
spiroisoxazolidines 3. The rearrangement of 3 starts with the
homolytic cleavage of the N–O bond to afford the diradical 6
which, instantaneously, undergoes a cyclopropane ring-opening
to form the highly reactive diradical intermediate 7 (Scheme 1).14
Diradical 7a/7b eventually cyclizes onto the pyridone moiety 4a–
g or produces open-chain aminoketones 5a–g through hydrogen
transfer. It is important to note that formation of the regioisomeric
pyridones 8 was not observed in the reactions of bis(methy-
lene)cyclopropanes 1a–d with nitrones 2a,b. This is possibly the
result of steric hindrance in the transition state 7a.
Next, the reactions of bis(methylene)cyclopropanes 1a–d with
nitrile oxides (generated from hydroximoyl chlorides 9a,b) were
investigated. Nitrile oxides are more reactive than nitrones in
The addition of nitrones 2 to the bis(methylene)cyclopropanes 1
occurs at the unsubstituted double bond with the formation of

3414
A. V. Stepakov et al. / Tetrahedron Letters 53 (2012) 3411–3415
Ar1
Ar1
Ar1
Ar1
Me
Me
Me
Me
9a,b
Et3N
1a-d
O
O
Ar3
Ar3
N
N
10
12
O
Ar1
O
Me
O
Me
Ar1
ring
closure
ring
Ar1
Me
closure
Me
11a-e
Ar1
Me
Me
Ar3
N
Ar3
N
Ar3
N
H
Ar1
Ar1
13a
13b
14
not found
H-transfer
open-chain products
were not found
Scheme 2. Proposed reaction mechanism for the formation of 11.
OMe
Cl
MeO
OMe
Cl
a
Me
O
HN
O
MeO
Me
Me
5g
15
Scheme 3. Conditions and yield: (a) glacial AcOH, reflux, 72 h, 36%.
1,3-dipolar cycloadditions toward unactivated alkenes.1a–c,2a On
the other hand, they are also much less stable, mainly due to their
facile dimerization to give furoxans.2a Benzonitrile oxide (gener-
ated in situ from the corresponding hydroximoyl chloride 9a in
the presence of Et3N)2a was treated with 1b in benzene at 60 °C
to give a 32% yield of the dihydropyridinone 11b (Table 1, entry
2). A threefold excess of hydroximoyl chloride 9a was used for
the reaction because the dimerization of nitrile oxides is strongly
preferred if rather unreactive dipolarophiles such as bis(methy-
lene)cyclopropanes 1 are used. The yield of 11b was not more than
10% if equimolar amounts of the reagents were used. Running the
reaction in benzene at 20 °C for 24 h and using a threefold excess of
hydroximoyl chloride 9a gave the product 11b in pure form (less
than 13%), together with extensive formation of 3,4-diphenylfuro-
xan. 5-spiroisoxazoline 10 could not be isolated because rearrange-
ment occurred smoothly under the reaction conditions. In the 1H
NMR spectrum of the crude reaction mixture the signals of 10 were
not observed. A similar reaction occurred on the treatment of
bis(methylene)cyclopropanes 1a,c,d with nitrile oxides generated
from 9a,b giving dihydropyridinones 11a,c–e in 15–28% yields
(Table 2, entries 1, 3–5). The reaction products were isolated by
preparative thin layer chromatography on silica. The composition
and structures of the products were established by elemental and
spectral analyses.15 The 1H NMR spectra of compounds 11a–e
exhibited a signal for the olefinic proton at the C(5) atom at d
5.4, a signal for the NH group at d 5.5, and signals for methyl groups
at the C(2) atom at d 1.1 and d 2.2. The shift of one methyl group
signal to a higher field (d 1.1) was due to the shielding effect in-
duced by the aromatic ring of the diarylmethylene fragment. The
13C NMR spectra of compounds 11a–e exhibited signals for the
CO groups at d 188, and signals for the methyl groups (N-CMe2)
at d 25 and d 28 (see Supplementary data). The reaction of
bis(methylene)cyclopropane 1a with nitrile oxide generated from
hydroximoyl chloride 9c gave a mixture of unidentified products
(Table 2, entry 6). 3,4-(Ar3)2Furoxanes—the dimers of the corre-
sponding nitrile oxides—were isolated from the reaction mixtures
in all cases. The rearrangement includes the cleavage of both the
N–O bond of the isoxazoline ring (intermediate 12) and the C–C
bond of the cyclopropane ring to form a highly reactive diradical
intermediate 13a/b which cyclizes into the pyridone ring. The
formation of regioisomeric pyridones 14 and open-chain enami-
nones2b,f,3a was not observed during the reactions of bis(methy-
lene)cyclopropanes 1a–d with nitrile oxides (Scheme 2).
Diene 5g could be transformed into indene 15 in 36% yield by
heating in glacial acetic acid (Scheme 3). Running the reaction in
concentrated sulfuric acid leads to polymerization. It should be
noted that the synthesis of novel indene derivatives may be of
interest due to the many biologically active natural products and
pharmaceutically important compounds which contain an indene
fragment.16 Indene derivatives are also used as ligands in
organometallics and as functional materials.17
In conclusion, the first examples of the reactions of nitrones and
nitrile oxides with non-activated bis(methylene)cyclopropanes
have been described. The nitrones react with 1,1-diaryl-2-isopro-

A. V. Stepakov et al. / Tetrahedron Letters 53 (2012) 3411–3415
3415
Barile, I.; De Sarlo, F.; Brandi, A. Tetrahedron Lett. 1999, 40, 6657; (e) Ferrara, M.;
Cordero, F. M.; Goti, A.; Brandi, A.; Estieu, K.; Paugam, R.; Ollivier, J.; Salaün, J.
Eur. J. Org. Chem. 1999, 2725; (f) Cordero, F. M.; Pisaneschi, F.; Goti, A.; Ollivier,
J.; Salaün, J.; Brandi, A. J. Am. Chem. Soc. 2000, 122, 8075.
pylidene-3-methylenecyclopropanes to give mixtures of 2,2-
dimethyl-1,6-diaryl-3-(diarylmethylene)piperidin-4-ones and
5-methyl-1-aryl-1-(arylamino)-4-(diarylmethylene)hex-5-en-3-ones
in moderate yields. 2,3-Dihydro-2,2-dimethyl-6-aryl-3-(diarylm-
ethylene)pyridin-4(1H)-ones were obtained by the reaction of ni-
trile oxides with bis(methylene)cyclopropanes. The initially
formed products of the 1,3-dipolar cycloaddition of nitrones and
nitrile oxides to the unsubstituted double bonds of bis(methy-
lene)cyclopropanes were not observed due to their smooth
rearrangement under the reaction conditions.
5. Hassner, A.; Namboothiri, I. Organic Syntheses Based on Name Reactions, third
ed.; Elsevier, 2012.
6. (a) Brandi, A.; Garro, S.; Guarna, A.; Goti, A.; Cordero, F.; De Sarlo, F. J. Org. Chem.
1988, 53, 2430; (b) Cordero, F. M.; Brandi, A.; Querci, C.; Goti, A.; De Sarlo, F.;
Guarna, A. J. Org. Chem. 1990, 55, 1762; (c) Cordero, F. M.; Cicchi, S.; Goti, A.;
Brandi, A. Tetrahedron Lett. 1994, 35, 949; (d) Cicchi, S.; Goti, A.; Brandi, A. J. Org.
Chem. 1995, 60, 4743; (e) Brandi, A.; Cordero, F. M.; Goti, A.; Guarna, A.
Tetrahedron Lett. 1992, 33, 6697; (f) Cordero, F. M.; Anichini, B.; Goti, A.; Brandi,
A. Tetrahedron 1993, 49, 9867.
7. Hu, B.; Zhu, J.; Xing, S.; Fang, J.; Du, D.; Wang, Z. Chem. Eur. J. 2009, 15, 324.
8. (a) Hu, B.; Jiang, L.; Ren, J.; Wang, Z. Eur. J. Org. Chem. 2010, 1358; (b) Lu, B.-L.;
Shi, M. Eur. J. Org. Chem. 2011, 243.
Acknowledgements
9. (a) Stepakov, A. V.; Larina, A. G.; Molchanov, A. P.; Stepakova, L. V.; Starova, G.
L.; Kostikov, R. R. Russ. J. Org. Chem. 2007, 43, 41; (b) Stepakov, A. V.; Larina, A.
G.; Radina, O. V.; Boitsov, V. M.; Molchanov, A. P. Chem. Heterocycl. Compd.
2008, 44, 430; (c) Stepakov, A. V.; Larina, A. G.; Radina, O. V.; Molchanov, A. P.;
Kostikov, R. R. Vestnik SPbGU. 2009, Ser. 4, 1, 110.; (d) Larina, A. G.; Stepakov, A.
V.; Boitsov, V. M.; Molchanov, A. P.; Gurzhiy, V. V.; Starova, G. L.; Lykholay, A. N.
Tetrahedron Lett. 2011, 52, 5777; (e) Tran, T. Q.; Diev, V. V.; Molchanov, A. P.
Tetrahedron 2011, 67, 2391; (f) Diev, V. V.; Stetsenko, O. N.; Tran, T. Q.; Kopf, J.;
Kostikov, R. R.; Molchanov, A. P. J. Org. Chem. 2008, 73, 2396; (g) Diev, V. V.;
Tran, T. Q.; Molchanov, A. P. Eur. J. Org. Chem. 2009, 525; (h) Molchanov, A. P.;
Tran, T. Q.; Kostikov, R. R. Russ. J. Org. Chem. 2011, 47, 269.
10. Hendrick, M. E.; Hardie, J. A.; Jones, M., Jr. J. Org. Chem. 1971, 36, 3061.
11. 1H NMR data for 4a: dH (300 MHz, CDCl3) 0.90 (s, 3H, Me), 1.44 (s, 3H, Me), 2.93
(dd, 1H, J = 14.5 and 4.4 Hz), 3.25 (dd, 1H, J = 14.5 and 10.2 Hz), 5.07 (dd, 1H,
J = 10.2 and 3.6 Hz), 7.03–7.31 (m, 20H, Aryl). 13C NMR: dc (75 MHz, CDCl3) 25.0
(Me), 31.0 (Me), 52.2 (CH2), 61.1 (CH), 64.0 (C), 125.7 (CH), 127.4 (CH), 127.6
(2CH), 127.9 (2CH), 128.3 (2CH), 128.5 (4CH), 128.7 (2CH), 128.9 (2CH), 129.0
(2CH), 132.0 (2CH), 142.2 (2C), 142.6 (C), 144.5 (C), 145.9 (C), 147.4 (C), 206.7
(CO). 1H NMR data for 5a: dH (300 MHz, CDCl3) 1.67 (s, 3H, Me), 2.70–2.86 (m,
2H, CH2), 4.68 (dd, 1H, J = 8.0 and 5.1 Hz, CH), 4.78 (s, 1H, @CH2), 5.05 (s, 1H,
@CH2), 6.50 (d, 2H, J = 8.0 Hz, Aryl), 6.69 (t, 1H, J = 7.3 Hz, Aryl), 7.08–7.24 (m,
17H, Aryl), NH-signal is not be seen. 13C NMR: dc (75 MHz, CDCl3) 23.3 (Me),
51.5 (CH2), 55.1 (CH), 114.2 (2CH), 118.1 (CH), 119.9 (CH2), 126.7 (2CH), 127.5
(CH), 128.4 (2CH), 128.5 (CH), 129.02 (2CH), 129.04 (2CH), 129.1 (CH), 129.4
(2CH), 130.2 (2CH), 130.5 (2CH), 141.6 (C), 141.8 (C), 143.1 (C), 143.2 (C), 143.9
(C), 145.5 (C), 147.4 (C), 206.0 (CO).
12. Crystallographic data for the structure 4a have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publication number
CCDC 846709. Copies of these data can be obtained on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (email: deposit@ccdc.cam.ac.uk).
13. Crystallographic data for the structure 5a have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publication number
CCDC 846710. Copies of these data can be obtained on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (email: deposit@ccdc.cam.ac.uk)
14. Ochoa, E.; Mann, M.; Sperling, D.; Fabian, J. Eur. J. Org. Chem. 2001, 4223.
15. 1H NMR data for 11a: dH (300 MHz, CDCl3) 1.10 (s, 3H, Me), 2.21 (s, 3H, Me),
5.34 (s, 1H, @CH), 5.56 (s, 1H, NH), 7.28–7.42 (m, 12H, Aryl), 7.53 (d, 2H,
J = 8.0 Hz). 13C NMR: dc (75 MHz, CDCl3) 25.3 (Me), 28.1 (Me), 72.1 (C), 101.0
(CH), 121.5 (CH), 128.0 (2CH), 128.6 (CH), 128.8 (2CH), 129.0 (2CH), 129.7
(2CH), 132.7 (C), 134.0 (C), 137.4 (C), 138.4 (C), 144.3 (C), 148.2 (C), 154.8 (C),
187.5 (CO).
We are grateful to Dr. Sergey Vyazmin and Dr. Elena Grinenko
for recording IR spectra.
Supplementary data
Supplementary data (experimental procedures, characteriza-
tion data, and copies of NMR spectra) associated with this article
can be found, in the online version, at http://dx.doi.org/10.1016/
j.tetlet.2012.03.093. These data include MOL files and InChiKeys
of the most important compounds described in this article.
References and notes
1. (a) Tufariello, J. J In Padwa, A., Ed.; 1,3-Dipolar Cycloaddition Chemistry; Wiley:
New York, NY, 1984; Vol. 2, pp 83–168; (b) Jones, R. C. F.; Martin, J. In Synthetic
Applications of 1,3-Dipolar Cycloaddition Chemistry Toward Heterocycles and
Natural Products; Padwa, A., Pearson, W. H., Eds.; Wiley: New York, 2002; pp 1–
81; (c) Gothelf, K. V.; Kanemasa, S. In Cycloaddition Reactions in Organic
Synthesis; Kobayashi, S., Jørgensen, K. A., Eds.; Wiley-VCH: Weinheim
(Germany), 2002; pp 211–280; (d) Maas, G. In The Chemistry of Heterocyclic
Compounds; Padwa, A., Pearson, W., Eds.; Wiley: New York, 2002; Vol. 59, pp
539–621.
2. (a) Torsell, K. B. G. Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis;
Weinheim, Germany: VCH, 1988; (b) Brandi, A.; Cicchi, S.; Cordero, F. M.; Goti,
A. Chem. Rev. 2003, 103, 1213; (c) Brandi, A.; Goti, A. Chem. Rev. 1998, 98, 589;
(d) Pellissier, H. Tetrahedron 2010, 66, 8341; (e) Cordero, F. M.; De Sarlo, F.;
Brandi, A. Monatsh. Chem. 2004, 135, 649; (f) Brandi, A.; Cordero, F. M.; De Sarlo,
F.; Goti, A.; Guarna, A. Synlett 1993, 1.
3. (a) Goti, A.; Cordero, F. M.; Brandi, A. Top. Curr. Chem. 1996, 178, 1; (b) de
Meijere, A.; Kozhushkov, S. I.; Hadjiarapoglou, L. P. Top. Curr. Chem. 2000, 207,
149; (c) Revuelta, J.; Cicchi, S.; de Meijere, A.; Brandi, A. Eur. J. Org. Chem. 2008,
1085; (d) Cardona, F.; Goti, A.; Brandi, A. Eur. J. Org. Chem. 2007, 1551; (e)
Marradi, M.; Brandi, A.; Magull, J.; Schill, H.; de Meijere, A. Eur. J. Org. Chem.
2006, 5485; (f) Brandi, A.; Cardona, F.; Cicchi, S.; Cordero, F. M.; Goti, A. Chem.
Eur. J. 2009, 15, 7808; (g) Revuelta, J.; Cicchi, S.; Goti, A.; Brandi, A. Synthesis
2007, 485; (h) Marradi, M.; Brandi, A.; de Meijere, A. Synlett 2006, 1125.
4. (a) de Meijere, A.; von Seebach, M.; Kozhushkov, S. I.; Boese, R.; Bläser, D.;
Cicchi, S.; Dimoulas, T.; Brandi, A. Eur. J. Org. Chem. 2001, 3789; (b) Zorn, C.;
Goti, A.; Brandi, A.; Johnsen, K.; Noltemeyer, M.; Kozhushkov, S. I.; de Meijere,
A. J. Org. Chem. 1999, 64, 755; (c) Zorn, C.; Goti, A.; Brandi, A.; Johnsen, K.;
Kozhushkov, S. I.; de Meijere, A. Chem. Commun. 1998, 903; (d) Cordero, F. M.;
16. Huffman, J. W.; Padgett, L. W. Curr. Med. Chem. 2005, 12, 1395.
17. (a) Wang, B. Q. Coord. Chem. Rev. 2006, 250, 242; (b) Alt, H. G.; Koppl, A. Chem.
Rev. 2000, 100, 1205; (c) Zargarian, D. Coord. Chem. Rev. 2002, 233–234, 157; (d)
Barber, J.; Rakitin, O. A.; Ros, M. B.; Torroba, T. Angew. Chem., Int. Ed. 1998, 37,
296.