[3+2] Cycloaddition reactions of arylallenes with C-(N-arylcarbamoyl)- and C,C-bis(methoxycarbonyl)nitrones and subsequent rearrangements

Article abstract of DOI:10.1016/j.tetlet.2014.04.107

The first example of 1,3-dipolar cycloaddition reactions of nitrones with arylallenes is described. C-Carbamoylnitrones react with the C1C2 double bond of arylallenes affording the corresponding 4-methyleneisoxazolidines in good yields. N-Aryl-C,C-bis(met

Full text of DOI:10.1016/j.tetlet.2014.04.107

Accepted Manuscript
[3+2] Cycloaddition reactions of arylallenes with C-(N-arylcarbamoyl)- and
C,C-bis(methoxycarbonyl)nitrones and subsequent rearrangements
Julia Malinina, Tung Q. Tran, Alexander V. Stepakov, Vladislav V. Gurzhiy,
Galina L. Starova, Rafael R. Kostikov, Alexander P. Molchanov
PII:
S0040-4039(14)00744-8
DOI:
http://dx.doi.org/10.1016/j.tetlet.2014.04.107
TETL 44569
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
6 February 2014
15 April 2014
30 April 2014
Please cite this article as: Malinina, J., Tran, T.Q., Stepakov, A.V., Gurzhiy, V.V., Starova, G.L., Kostikov, R.R.,
Molchanov, A.P., [3+2] Cycloaddition reactions of arylallenes with C-(N-arylcarbamoyl)- and C,C-
bis(methoxycarbonyl)nitrones and subsequent rearrangements, Tetrahedron Letters (2014), doi: http://dx.doi.org/
10.1016/j.tetlet.2014.04.107
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Graphical Abstract
[3+2] Cycloaddition reactions of arylallenes with C-(N-arylcarbamoyl)- and C,C-
bis(methoxycarbonyl)nitrones and subsequent rearrangements
Julia Malinina, Tung Q. Tran, Alexander V. Stepakov, Vladislav V. Gurzhiy, Galina L. Starova,
Rafael R. Kostikov, Alexander P. Molchanov
R
O
N
Ar
O
O
H
O
NHAr1
C
N
R
Ar1HN
Ar
R1
H
O
O
N
Ar
O
O
R1
R1
E
Ar
E
E
N
+
E
+
Ar
E
E
N
N
H
H
E= CO2Me
E
E
R1
1

[3+2] Cycloaddition reactions of arylallenes with C-(N-arylcarba-
moyl)- and C,C-bis(methoxycarbonyl)nitrones and subsequent
rearrangements
Julia Malinina,a Tung Q. Tran,b Alexander V. Stepakov,a Vladislav V. Gurzhiy,a Galina L. Starova,a
Rafael R. Kostikov,a Alexander P. Molchanova*
a Chemistry Department, Saint-Petersburg State University, Universitetsky prosp. 26, Saint Petersburg 198504, Russian Federation
bSchool of Chemical Engineering, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi, Viet Nam
______________________________________________________________________________________
Abstract ─ The first example of 1,3-dipolar cycloaddition reactions of nitrones with arylallenes is described.
C-Carbamoylnitrones react with the C1–C2 double bond of arylallenes affording the corresponding 4-
methyleneisoxazolidines in good yields. N-Aryl-C,C-bis(methoxycarbonyl)nitrones usually gave rearranged
products: mixtures of 4,5-dihydro-4-oxo-1H-benzo[b]azepine-2,2(3H)dicarboxylates and 4-oxo-1,5-
diarylpyrrolidine-2,2-dicarboxylates.
Keywords: allenes; nitrones; isoxazolidines; 1,3-dipolar cycloaddition; stereochemistry.
The 1,3-dipolar cycloaddition reaction is a very important method and is utilized for the synthesis
of heterocycles from simple starting materials. Amongst various 1,3-dipoles, nitrones are highly
attractive due to the extensive applications of the corresponding cycloadducts.1 While the cycload-
dition reactions of nitrones with alkenes and alkynes is well established for the formation of isox-
azolidines or isoxazolines, often with a high degree of stereochemical control, only a few examples
of the 1,3-dipolar cycloaddition of nitrones and allenes have been reported.2 Usually, in this reac-
tion, allenes possessing electron-withdrawing groups (COOR, CN, SO2Ph) were used.3 In these
cases, the regiochemistry is characterized by the new bond formation between the nitrone oxygen
atom and the central carbon of the allene with the nitrone carbon atom bonding to the α-carbon. Di-
arylnitrones react with both double bonds of 1,1-dimethylallene or vinylideneadamantane.4 Howev-
er, reactions of arylallenes with nitrones have not been studied as yet. Earlier, we investigated the
reactions of C-carbamoyl- and C,C-bis(methoxycarbonyl)nitrones with methylene- or vinylidene-
cyclopropanes and 1,3-diarylprop-2-enones.5 It was shown in cycloaddition reactions that these ni-
trones were more selective and reactive than diarylnitrones. Besides, the presence of additional
functional groups in the nitrone moiety makes the obtained products more useful for synthetic de-
sign.
Initially, we investigated the reaction of substituted arylallenes 1a–c with N-aryl-C-(phenylcarba-
moyl)nitrones 2a,b and N-methyl-C-(phenylcarbamoyl)nitrone 2c. The reactions of arylallenes 1a–c
* Corresponding author. Fax: 7-812-4286939; e-mail: a.molchanov@spbu.ru
2

with nitrones 2a,b occurred at room temperature with high regio- and stereoselectivity and in good
yields (Table 1), whereas the reaction between phenylallene 1a and N-methylnitrone 2c took place
at 80 °C. Separation of the crude mixtures on silica gel gave pure samples of isoxazolidines 3a–g
(yields of 63–88%) and 4a–f (yields of 3–8%). Carrying out the reaction in toluene at 110 °C for 35
hours did not lead to a change in the ratio of products 3 and 4. Neither regioisomeric products nor
products of nitrone addition to the C2-C3 double bond were observed. The compositions and struc-
tures of the products 3a–g and 4a–f were established by elemental and spectral analysis. The rela-
tive configurations of the products were established from 1Н-1Н NOESY spectra for compounds 3d
and 4d (see the Supplementary data). The substituents at the С3 and С5 atoms were cis-orientated for
major diastereomers 3a–g. The structure of compound 3c was unambiguously confirmed by X-ray
diffraction analysis (Figure 1).6
Table 1 Reactions of allenes 1a–c with nitrones 2a–c
R1
R1
R2
O
R1
N
H
O
N
R2
CH2Cl2
O
H
O
O
+
+
O
C
NHPh
N
R2
PhHN
PhHN
H
H
1a-c
4a-f
3a-g
2a-c
Entry
R1
R2
Time
Yield (%)a
1
2
3
4
H (1a)
H (1a)
Cl (1b)
Cl (1b)
Ph (2a)
4-MeC6H4 (2b)
Ph (2a)
3 d
6 d
3 d
3 d
80 (3a)
88 (3b)
88 (3c)
78 (3d)
8 (4a)
3 (4b)
8 (4c)
7 (4d)
4-MeC6H4 (2b)
5
6
7
Me (1c)
Me (1c)
H (1a)
Ph (2a)
4-MeC6H4 (2b)
Me (2c)
2 d
2 d
3 h
81 (3e)
63 (3f)
71 (3g)b
8 (4e)
7 (4f)

a Isolated yield, CH2Cl2, 20 C.
b Isolated yield, benzene, 80 C.
3

C3
C4
C6
C5
N1
C2
C1
C22
C23
C21
N2
O1
C18
C7
C20
C19
C8
C9
O2
C11
C12
C10
C13
C14
C17
C15
Cl1
C16
Figure 1. ORTEP representation of 3c.
The high regio- and stereoselectivity of the cycloaddition is in agreement with the concerted reac-
tion mechanism. The transition state (TS) formed during the cycloaddition should be polarized as
shown in Figure 2. The nitrone oxygen atom has high electron density and interacts with C1 of the
allene having a positive charge in TS. The starting nitrone has a more stable cis-configuration with
respect to the oxygen atom and carbamoyl group. At the same time, a more stable s-transoid-
orientation of the substituents along the Ph–C1–O–N chain is realized. Therefore, in the TS the ini-
tial cis-configuration of the starting nitrone explains the preferred formation of the cis-orientated
phenyl and carbamoyl groups in major adducts 3.
+
R
N
H
-
O
CONHPh
H
-
+
H
Ph
H
cis
Figure 2. The proposed TS for the reaction of allenes 1 with nitrones 2.
Next we performed the reaction N-arylallenes 1a–c with N-methyl-C,C-bis(methoxycarbonyl)-
nitrone 5. In these cases, after heating the reaction mixture in toluene for 100-200 hours, adducts of
the C1–C2 double bond 4-methyleneisoxazolidines 6a–c, and the C2–C3 bond, 5-benzylideneisoxa-
zolines 7a–c, were obtained (Table 2). Rearrangement products, pyrrolidinones 8a–c, were also iso-
lated.3a The structure of isoxazolidine 6a was established from HSQC and HMBC spectral data. In
the HMBC spectrum, cycloadduct 6a exhibited an interaction between the protons of the methylene
group with carbons C3 and C5 of the isoxazolidine ring. The (E)-configuration of the double bond
of cycloadducts 7a–c was determined from the NOESY 1H-1H spectrum of compound 7b based on
the presence of a cross-peak between the methylene protons of the isoxasolidine ring and the ortho-
protons of the aromatic ring. The structures of products 8a–c were established on the basis of spec-
tral data and the NOESY and HMBC spectra of compound 8b (see the Supplementary data).
4

Table 2
Reactions of allenes 1a–c and nitrone 5
R
R
+
R
Me
O
+
N
+
MeO2C
MeO2C
C
MeO2C
MeO2C
O
MeO2C CO2Me
MeO2C
MeO2C
O
N
N
N
R
Me
Me
Me
7a-c
1a-c
5
6a-c
8a-c
Entry
R
Time (h)
184b
91
Yield (%)a
16 (7a)
15 (7b)
9 (7c)
1
2
3
H
9 (6a)
23 (6b)
19 (6c)
16 (8a)
11 (8b)
15 (8c)
Cl
Me
108
a) Isolated yield, reaction occurred in toluene, 110 C.
b)
In benzene, 80 C.
The reactions of phenylallene 1a with N-aryl-С,С-bis(methoxycarbonyl)nitrones 9a–c were per-
formed at 60 °С in benzene over 20–25 hours. Complex mixtures of products were separated on
silica. The compositions and structures of the products 10a–c, 11a–c and 12a–c were established
from elemental and spectral analysis.7 The structures of compounds 10c and 11c were confirmed
additionally by X-ray diffraction analysis (Figures 3 and 4).8
Table 3
Reactions of allene 1a and nitrones 9a-c.
O
R1
Ph
O
Ph
O
MeO2C
MeO2C
R1
R1
Ph
benzene
60 о
O
N
+
+
N
Ph
CO2Me
CO2Me
C
+
С
CO2Me
CO2Me
N
N
MeO2C
CO2Me
H
H
R1
1a
9a-c
10a-c
11a-c
12a-c
Entry
R1
H
Yield (%)a
Ratio of 10:11:12b
2:1:1
1
2
3
47 (10a)
49 (10b)
50 (10с)
16 (11a)
17 (11b)
9 (11c)
7 (12a)
Cl
7 (12b)
2:1:0.7
Me
11 (12c)
2:1:1
a Isolated yield.
b Ratio determined from the by 1H NMR spectra of the crude reaction mixture.
5

c
C4
C3
C5
O1
C8
C2
C6
C1
C7
C9
O2
C20
C11
O3
C12
C19
C18
C10
N1
C15
O4
C13
C21
C16
C17
C14
O5
Figure 3. ORTEP representation of compound 10c.
C14
O5
C20
C10
C8
C11
C15
C19
C18
C12
C13
C9
C21
C7
C6
C4
C16
N1
O2
C17
C1
O3
C2
O4
O1
C3
C5
Figure 4. ORTEP representation of compound 11c.
Primary adducts of phenylallene with nitrones were not detected in this reaction because they
easily undergo cascade transformations. It was shown earlier that benzazepinones and pyrrolidi-
nones were obtained in the reactions of N,C-diphenylnitrone with substituted cyano- or (arylsul-
fonyl)allene as a result of thermal rearrangement of 5-methyleneisoxazolidines.3b,c Apparently,
cleavage of the N-O bond of the isoxazolidine ring is enhanced markedly by groups which are able
to stabilize the carbon radical center. In our case, the primary adducts of nitrones with the allenic
C2=C3 bond, 13, and C1=C2 bond, 14 (5-methyleneisoxazolidines), undergo homolytic cleavage of
the N–O bond and to give the resonance-stabilized biradicals 15 and 16, respectively. Both biradi-
cals contain two fragments: an oxacinnamyl radical (in 15) or an oxaallyl radical (in 16) and an ary-
laminyl radical. However, the electron-withdrawing effect of the carbonyl groups diminishes the
activity of the N-radical centers in arylaminyl radicals and the C-radical center at the ortho-position
of the aromatic ring may be more active, and we observe C–C coupling with formation benzazepi-
nones 10 and 11. Analogous transformations were observed in the reactions of nitrones with methy-
lenecyclopropanes.9
6

Ph
O*
Ph
N
O
H
R1
Ph
*
H-shift
C-C
O
MeO2C
MeO2C
10
MeO2C
MeO2C
*
N
N
CO2Me
CO2Me
*
C-N
R1
R1
12
15
+ 9a-c
1a
13
O
Ph
Ph
H
O
R1
*
CO2Me
H-shift
CO2Me
CO2Me
C-C
Ph
11
O
CO2Me
*
CO2Me
CO2Me
*N
N
N
*
R1
16
R1
14
Scheme 1. Proposed reaction mechanism for the formation of compounds 10, 11 and 12.
In conclusion, the first examples of the reactions of nitrones with non-activated arylallenes have
been described. C-Carbamoyl nitrones react with arylallenes to give 4-methyleneisoxazolidines
with high stereoselectivity. N-Methyl-C,C-bis(methoxycarbonyl)nitrone reacts in a nonselective
manner with both double bonds of arylallenes, giving 4- and 5-methyleneisoxazolidines. N-Aryl-
C,C-bis(methoxycarbonyl)nitrones also undergo nonselective reactions with С1=С2 bond and
С2=С3 bond, but with formation of only regioisomers of 5-methyleneisoxazolidines, which are un-
stable under the reaction conditions and undergo the rearrangement into benzazepinones and pyrro-
lidinones
Acknowledgements
We gratefully acknowledge the financial support from the Russian Foundation for Basic Research
(Project No 12-03-01008-a). We are also grateful to the X-ray Diffraction Centre, the Centre for
Magnetic Resonance and the Centre for Chemical Analysis and Material of Saint-Petersburg State
University.
Supplementary data
Supplementary data (experimental procedures, characterization data, and copies of NMR spectra) associated
with this article can be found, in the online version
References and notes
7

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1987, 28, 755; (b) Padwa, A.; Matzinger, M.; Tomioka, Y.; Venkatramanan, M. K. J. Org. Chem.
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dron 1997, 53, 9575.
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2012, 2054; (b) Stepakov, A. V.; Larina, A. G.; Boitsov, V. M.; Molchanov, A. P.; Gurzhiy, V. V.;
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Eur. J. Org. Chem. 2009, 525; (d) Tran, T. Q.; Diev, V. V.; Molchanov, A. P. Tetrahedron 2011, 67,
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G. L.; Lykholay, A. N. Tetrahedron Lett. 2011, 52, 5777; (g) Molchanov, A. P.; Tran, T. Q. Russ. J.
Org. Chem. (Engl. Ed.) 2012, 48, 1283. (h) Molchanov, A. P.; Tran, T. Q., Kostikov, R. R. Russ.
Chem. Bull. (Engl. Ed.) 2012, 61, 871; (i) Tran, T. Q.; Savinkov, R. S.; Diev, V. V.; Starova, G. L.;
Molchanov, A. P. Tetrahedron 2013, 69, 5173.
6. (3a) IR, ν, cm–1: 3344, 1690 s. δH (300 MHz,CDCl3): 4.90–4.94 (m, 1H), 4.97–5.01 (m, 1H), 5.53–
5.59 (m, 1H), 5.77–5.79 (m, 1H), 7.10–7.25 (m, 4H), 7.35–7.48 (m, 9H), 7.66 (d, 2H, J = 8.0 Hz),
9.12 (s, 1H). δc (75 MHz, CDCl3): 72.8 (CH), 82.6 (CH), 110.9 (CH2), 115.1 (CH), 119.8 (2 CH),
124.6 (2 CH), 128.5 (2 CH), 128.8 (2 CH), 129.0 (2 CH), 129.2 (2 CH), 130.0 (CH), 133.0
(CH),136.2 (C), 137.4 (C), 149.1 (C), 149.2 (C), 166.1 (CO). (4a): IR, ν, cm-1: 3348, 1690 s. δH (300
MHz, CDCl3): 4.70 (d, 1H, J = 1.5 Hz), 4.85 (d, 1H, J = 1.5 Hz), 5.67–5.71 (m, 1H), 5.68–5.72 (m,
1H), 7.08–7.19 (m, 4H), 7.30–7.43 (m, 9H), 7.64 (d, 2H, J = 8.0 Hz), 8.87 (s, 1H). δc (75 MHz,
CDCl3): 72.6 (CH), 82.7 (CH), 110.1 (CH2), 116.0 (2 CH), 119.8 (2 CH), 123.4 (2 CH), 124.7 (CH),
128.6 (2 CH), 128.7 (2 CH), 129.0 (2 CH), 129.1 (2 CH), 136.3 (C), 137.2 (C), 148.6 (C), 149.2 (C),
167.0 (CO). Crystallographic data for the structure 3c have been deposited with the Cambridge Crys-
tallographic Data Centre as supplementary publication number CCDC 930904. Copies of these data
can be obtained on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (email:
deposit@ccdc.cam.ac.uk).
7. (10c), ν, IR, cm–1: 3368. δH (300 MHz, CDCl3): 2.22 (s, 3H), 3.20 (d, 1H, J = 12.6 Hz), 3.37 (d, 1H, J
= 12.6 Hz), 3.75 (s, 3H), 3.85 (s, 3H), 4.50 (s, 1H), 4.81 (s, 1H), 6.89 (s, 1H), 6.95 (d, 1H, J = 7.3
Hz), 7.10 (dd, 1H, J = 8.7, 8.0 Hz), 7.20–7.35 (5H). δc (75 MHz, CDCl3): 20.8 (CH3), 43.0 (CH2),
53.2 (CH3), 53.5 (CH3), 63.6 (CH), 70.7 (C), 124.2 (CH), 127.1 (CH), 128.4 (2 CH), 129.1 (2 CH),
129.4 (CH), 131.4 (CH), 133.4 (C), 134.6 (C), 138.0 (C), 138.6 (C), 169.0 (CO), 169.1 (CO), 204.0
(CO). (11c): IR, cm-1: 3352. δH (300 MHz, CDCl3): 2.27 (s, 3H), 3.29 (d, 1H, J = 12.4 Hz), 3.50 (s,
3H), 3.51 (s, 3H), 4.46 (d, 1H, J = 12.4 Hz), 4.54 (s, 1H), 5.03 (s, 1H), 6.80 (d, 1H, J = 7.3 Hz), 6.92
(s, 1H), 6.98 (d, 1H, J = 8.0 Hz), 7.30–7.36 (3H), 7.83–7.89 (2H). δc (75 MHz, CDCl3): 20.6 (CH3),
46.9 (CH2), 52.7 (CH3), 53.3 (CH3), 61.1 (CH), 73.0 (C), 122.2 (CH), 126.4 (C), 128.1 (2 CH), 128.4
(2 CH), 128.5 (CH), 129.4 (CH), 132.8 (C), 133.4 (C), 134.9 (C), 140.3 (C), 168.5 (2 CO), 201.6
(CO). (12c): IR, cm-1: 3060. δH (300 MHz, CDCl3): 2.22 (s, 3H), 3.16 (d, 1H, J = 18.0 Hz), 3.22 (d,
1H, J = 18.0 Hz), 3.70 (s, 3H), 3.98 (s, 3H), 4.99 (s, 1H), 6.62 (d, 2H, J = 8.7 Hz), 6.98 (d, 2H, J =
8

8.0 Hz), 7.29–7.40 (m, 3H), 7.58 (d, 2H, J = 7.3 Hz). δc (75 MHz, CDCl3): 20.3 (CH3), 45.8 (CH2),
53.1 (CH3), 53.4 (CH3), 70.1 (C), 70.6 (CH), 116.4 (CH), 126.1 (2 CH), 128.2 (2 CH), 129.0 (2 CH),
129.3 (2 CH), 129.8 (C), 136.9 (C), 141.5 (C), 169.4 (CO), 169.7 (CO), 204.3 (CO).
8. Crystallographic data for structures 10c and 11c have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication numbers CCDC 930902 and CCDC 930903, re-
spectively. Copies of these data can be obtained on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK (email: deposit@ccdc.cam.ac.uk).
9. For selected examples, see: (a) Brandi, A; Cicchi, S.; Cordero, F. M.; Goti, A. Chem. Rev. 2003, 103,
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A. Chem. Rev. 1998, 98, 589; (d) Brandi, A.; Guarna, A.; Goti, A.; De Sarlo F. Tetrahedron Lett.
1986, 27, 1727; (e) Brandi, A.; Garro, S.; Guarna, A.; Goti, A.; Cordero, F.; De Sarlo, F. J. Org.
Chem. 1988, 53, 2430; (f) Cordero, F. M.; Goti, A.; De Sarlo, F.; Guarna, A.; Brandi, A.
Tetrahedron 1989, 45, 5917; (g) Brandi, A.; Dürüst, Y.; Cordero, F. M.; De Sarlo, F. J. Org. Chem.
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