Synthesis and [3 + 2]-cycloaddition reactions of superelectrophilic (dimethylaminophenyl)benzofulvene derivatives

Full text of DOI:10.1134/S1070428015030318

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2015, Vol. 51, No. 3, pp. 449–451. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © Yu.P. Semenyuk, P.G. Morozov, M.E. Kletskii, O.N. Burov, A.S. Cheprasov, S.V. Kurbatov, 2015, published in Zhurnal
Organicheskoi Khimii, 2015, Vol. 51, No. 3, pp. 462–464.
SHORT
COMMUNICATIONS
Dedicated to Full Member of the Russian Academy of Sciences
V.I. Minkin on his 80th anniversary
Synthesis and [3+2]-Cycloaddition Reactions
of Superelectrophilic (Dimethylaminophenyl)benzofulvene
Derivatives
a
a
a
a
Yu. P. Semenyuk , P. G. Morozov , M. E. Kletskii , O. N. Burov ,
b, c
a
A. S. Cheprasov , and S. V. Kurbatov
a
Southern Federal University, ul. Zorge 7, Rostov-on-Don, 344090 Russia
e-mail: tavunova@mail.ru
b
Research Institute of Physical and Organic Chemistry, Southern Federal University,
pr. Stachki 194/2, Rostov-on-Don, 344090, Russia
c
Southern Scientific Center, Russian Academy of Sciences,
ul. Chekhova 41, Rostov-on-Don, 344006 Russia
Received October 6, 2014
DOI: 10.1134/S1070428015030318
Chloro-substituted dinitrobenzofuroxan 1 and dini-
trobenzofurazan 2 possess super-electrophilic prop-
erties [1, 2] which make them capable of forming
highly stable dipolar spirocycles [3, 4] and intramolec-
ular contact charge-transfer π-complexes [5], as well as
of reacting with weak neutral carbon-centered nucleo-
philes, e.g., π-excessive nitrogen heterocycles (pyr-
roles, indoles, indolizines) [6–8]. We report here the
reaction of super-electrophiles 1 and 2 with π-exces-
sive benzofulfene 3 whose chemical properties have
not been studied at all [according to the Chemical
Abstracts data (SciFinder)].
Mixing equimolar amounts of benzofulvene 3 and
chloro derivative 1 or 2 in chloroform at room tem-
perature resulted in fast formation of deeply colored
(blue–green) biaryls 4 and 5, respectively, in high
yields (Scheme 1). Presumably, this S Ar–S Ar reac-
tion is mediated by dipolar Meisenheimer–Wheland
σ-adduct A [6]. The presence in a single molecule of
both donor and acceptor fragments in combination
with a conjugated bond system gives rise to intramo-
lecular charge transfer. According to DFT B3LYP/
6-31G(d) calculations, the charge transfer from the
benzofulvene fragment to nitrobenzoxadiazole amounts
N
E
Scheme 1.
NO2
NO2
N
O N
N
NO2
2
O N
2
H
O
O
N
Y
Y
Y
CHCl3
Cl
O
+
O N
2
Cl
NMe2
NMe2
NMe
2
1
, 2
3
A
4, 5
1
, 4, Y = N→O; 2, 5, Y = N.
4
49

4
50
SEMENYUK et al.
Scheme 2.
CH2
N
H
N
COOH
+
CH O
2
Me
–CO , –H O
2 2
Me
CH2
6
7
8
Me
Me
Me
N
N
N
NO2
N
N
O
N
O N
2
O N
2
O N
2
O
O
5
+
8
+
N
N
N
NMe2
NMe2
NMe2
B
9
10
to 0.26 ē for molecule 4 and 0.27 ē for 5, which may
be related to more planar structure of the latter. The
dihedral angle between the benzofulvene and dinitro-
benzoxadiazole planes is 45 and 38° for molecules 4
and 5, respectively. This may be due to the lack of
N-oxide oxygen atom in 5.
N,N-Dimethyl-4-[(E)-1H-inden-1-ylidenemethyl]-
aniline (3). 4-(Dimethylamino)benzaldehyde, 0.745 g
(5 mmol), was added under stirring to a mixture of
0.58 g (5 mmol) of indene and 0.2 g (5 mmol) of
sodium hydroxide in 7 mL of ethanol. After 3 h, the
precipitate was filtered off, washed with ethanol, and
purified by silica gel chromatography using chloro-
We have studied [3+2]-cycloaddition reaction of
biaryl 5 with the simplest unstabilized azomethine
ylide generated in situ from sarcosine (6) and form-
aldehyde (7) according to conventional procedure. Di-
nitrobenzofurazan derivative 5 rather than dinitro-
benzofuroxan analog 4 was selected as substrate taking
into account the known effect of a bulky substituent in
position 7 of the benzofuroxan ring system [9], which
favors 1,3-N-oxide tautomerism and thus essentially
complicates product isolation and identification.
form as eluent. Yield 0.845 g (75%), yellow crystals,
1
mp 158–160°C. H NMR spectrum (CDCl ), δ, ppm:
3
3
8
3
7
5
.02 s [6H, N(CH ) ], 6.74 d (2H, 2-H, 6-H, J =
3 2
.9 Hz), 6.99 d (1H, 2′-H, J = 5.5 Hz), 7.13 d (1H,
′-H, J = 5.5 Hz) 7.17–7.22 m (2H, 5′-H, 6′-H), 7.28–
.38 m (1H, 4′-H), 7.43 s (1H, 1″-H), 7.58 d (2H, 3-H,
-H, J = 8.9 Hz), 7.65–7.74 m (1H, 7′-H). Found, %:
C 87.42; H 6.90; N 5.68. C H N. Calculated, %:
1
8
17
C 87.41; H 6.93; N 5.66.
Compounds 4 and 5 (general procedure). Com-
pound 3, 0.134 g (0.54 mmol), was added to a solution
of 0.27 mmol of benzofuroxan 1 [10] or benzofurazan
The cycloaddition process is likely to involve initial
formation of cycloadduct B (Scheme 2); however, we
failed to isolate it as pure substance. The reaction mix-
ture contained only nitrous acid elimination product 9
and oxidative aromatization product 10 which were
isolated in the pure state by column chromatography.
2
[11] in 5 mL of warm chloroform. The mixture was
kept for 24 h, and the precipitate was filtered off,
washed with chloroform, and dried in air.
(
E)-7-{1-[4-(Dimethylamino)benzylidene]-1H-
inden-3-yl}-4,6-dinitro-2,1,3-benzoxadiazole 1-oxide
4). Yield 0.096 g (76%), dark blue crystals, mp 202–
The relation between the spectral parameters of 5
and 10 and the empirical Brooker’s solvent parameters
(
1
χ and χ characterizes their polarity [12]. Compound
R
B
204°C. H NMR spectrum (DMSO-d ), δ, ppm: 3.05 s
6
1
0 showed a good correlation between the absorption
[
6H, N(CH ) ], 6.84 d (2H, 2′-H, 6′-H, J = 8.7 Hz),
3 2
maximum frequencies and χ . The corresponding cor-
7.06 d (1H, 4″-H, J = 7.5 Hz), 7.19 d.d (1H, 5″-H, J =
7.3, 7.5 Hz), 7.29 d.d (1H, 6″-H, J = 7.3, 7.4 Hz),
7.68 s (1H, 1′′′-H), 7.71 d (2H, 3′-H, 5′-H, J = 8.7 Hz),
7.95–8.03 m (2H, 2″-H, 7″-H), 9.06 s (1H, 5-H).
B
relation for compound 5 was somewhat worse, where-
as no correlation with χ was observed in both cases.
R
The observed pattern indicated negative solvato-
chromism and high polarity of molecules 5 and 10 in
the ground state.
+
Found: m/z 494.1056 [M + Na] . C H N O . Calcu-
2
4
17
5
6
lated: M + Na 494.1071.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 3 2015

SYNTHESIS AND [3+2]-CYCLOADDITION REACTIONS
451
1
4
-{(E)-[3-(5,7-Dinitro-2,1,3-benzoxadiazol-4-yl)-
H-inden-1-ylidene]methyl}-N,N-dimethylaniline
5). Yield 0.095 g (78%), dark green crystals, mp 250–
(9700). H NMR spectrum (CDCl ), δ, ppm: 3.09 s
3
1
(
[6H, N(CH ) ], 4.35 s (3H, NCH ), 6.87 d (2H, 2′-H,
3
2
3
6′-H, J = 8.5 Hz), 7.06–7.20 m (2H, 4″-H, 5″-H), 7.30–
7.45 m (3H, 3′-H, 5′-H, 8-H), 7.45–7.57 m (3H, 6-H,
6″-H, 7″-H), 7.72 s (1H, 1′′′-H), 9.40 s (1H, 2″-H).
–
1
–1
2
52°C. UV spectrum, λmax, nm (ε, L mol cm ): in
acetonitrile: 443 (28300), 683 (10600); in acetone:
40 (27400), 668 (10200); in methylene chloride: 451
31400), 748 (14800); in chloroform: 448 (29400),
54 (14700); in 1,4-dioxane: 438 (28800), 672
13000); in toluene: 439 (26600), 701 (14300).
H NMR spectrum (acetone-d ), δ, ppm: 3.12 s [6H,
N(CH ) ], 6.90 d (2H, 2′-H, 6′-H, J = 9.0 Hz), 7.12 d
1H, 4″-H, J = 7.2 Hz), 7.23 d.d (1H, 5″-H, J = 7.2,
.5 Hz), 7.33 d.d (1H, 6″-H, J = 7.5, 7.7 Hz), 7.81 d
2H, 3′-H, 5′-H, J = 8.9 Hz), 7.97 d (1H, 7″-H, J =
.7 Hz), 8.00 s (1H, 1′′′-H), 8.07 s (1H, 2″-H), 9.20 s
+
4
Found: m/z 486.1536 [M + Na] . C H N O . Calcu-
2
7
21
5
3
(
lated: M + Na 486.1537.
1
7
The H NMR spectra were recorded on a Bruker
DPX-250 spectrometer (250 MHz). The electron ab-
sorption spectra were measured on a Varian Cary 50
(
1
6
–
5
3
2
spectrophotometer at 25°C (c = 4×10 M; cell path
length 1 cm).
(
7
This study was performed under financial support
by the Russian Scientific Foundation (project no. 14-
3-00103).
(
7
1
+
(
1H, 6-H). Found: m/z 478.1108 [M + Na] .
C H N O . Calculated: M + Na 478.1122.
2
4
17
5
5
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1
(
(
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1
(
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3
3
N(CH ) ], 4.21 t (2H, 8-H, J = 3.7 Hz), 4.41 t (2H,
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3
2
6
7
7
7
7
-H, J = 3.7 Hz), 6.72 d (2H, 2′-H, 6′-H, J = 8.9 Hz),
.03 d (1H, 4″-H, J = 7.3 Hz), 7.19 d.d (1H, 5″-H, J =
.3, 7.4 Hz), 7.27 d.d (1H, 6″-H, J = 7.3, 7.4 Hz),
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+
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9. Khmel’nitskii, L.I., Novikov, S.S., and Godoviko-
C H N O . Calculated: M + Na 488.1693.
2
7
23
5
3
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[
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in acetone: 375 (5100), 523 (2800), 689 (10100); in
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–1
–1
1
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(13800); in toluene: 375 (5800), 496 (2800), 734
1
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 3 2015