New reaction of pyridinium ylide with 2,4,6-trinitrofluorobenzene leading to stable heptatrienide moiety

Article abstract of DOI:10.1002/hc.20315

A new reaction of pyridinium ylide (4) with 2,4,6-trinitrofluorobenzene leading to stable negatively charged heptatriene moiety (6) is described. This reaction proceeds via a new route of decomposition of intermediate σ;-complex (5) occurring with the for

Full text of DOI:10.1002/hc.20315

Heteroatom Chemistry
Volume 18, Number 4, 2007
N
ew Reaction of Pyridinium Ylide With
2
,4,6-Trinitrofluorobenzene Leading to Stable
Heptatrienide Moiety
Yuri G. Gololobov, Olesya A. Linchenko, Pavel V. Petrovskii,
Victor N. Khrustalev, and Irina A. Garbuzova
A.N. Nesmeyanov Institute of Organo-Element Compounds, Russian Academy of Science, 119991
M-334, Vavilov Str., 28, Moscow, Russia
Received 27 May 2006
It would be very interesting to expand the scope
ABSTRACT: A new reaction of pyridinium ylide
of the reaction to other types of zwitterions and other
(
4) with 2,4,6-trinitrofluorobenzene leading to sta-
electron-deficient fluoroarenes. In this work, we re-
port on a new reaction for other type of carbanions,
that is, pyridinium ylide derived from malonic ester
ble negatively charged heptatriene moiety (6) is de-
scribed. This reaction proceeds via a new route of
decomposition of intermediate σ-complex (5) oc-
curring with the formation of ethylfluoroformate.
ꢀ
C
4
4
with 2,4,6-trinitrofluorobenzene (TNFB) leading to
stable heptatrienide moiety 6.
2007 Wiley Periodicals, Inc. Heteroatom Chem 18:421–
24, 2007; Published online in Wiley InterScience
(
www.interscience.wiley.com). DOI 10.1002/hc.20315
RESULTS AND DISCUSSION
Nucleophilicity of pyridinium ylide 4 is just below
the nucleophilicity of zwitterion 2. This follows from
our observation that pyridinium ylide 4 reacts with
DNFB very slowly. We will discuss in details the
results of the latter reaction in the follow-up pub-
lication. Simultaneously, ylide 4 reacts with TNFB
INTRODUCTION
In a previous publication [1], we have described
an unusual aromatic nucleophilic substitution re-
action. Phosphorus-containing zwitterion 1 bearing
ethoxy and cyano groups at the carbanion center
forms, upon reaction with 2,4-dinitrofluorobenzene
in CDCl at room temperature very smoothly with
3
(DNFB), the first example of P-zwitterions 3 with a
the quantitative formation of an almost black pow-
der. The formation of ethylfluoroformate was estab-
negatively charged heptatriene moiety. This reaction
proceeds via a new route of decomposition of the
intermediate σ-complex 2 occurring with the forma-
tion of ethylfluoroformate (Scheme 1).
19
lished by the F NMR spectroscopy of the reaction
mixture. Most likely, similar to Scheme 1, at the first
stage of the reaction (Scheme 2), σ-complex 5 was
formed. At the second stage, the rupture of the weak
C C bond between the α-C atom and the C(O)OEt
moiety took place because the presence of second
C(O)OEt group and positively charged nitrogen
weakens the C C(O)OEt bond in the σ-complex 5.
The latter yielded ethylfluoroformate and a new type
of zwitterion (6).
Correspondence to: Yuri G. Gololobov; e-mail: Yugol
ineos.ac.ru.
@
Contract grant sponsor: Russian Foundation for Basic
Research.
Contract grant number: Project No. 04-03-32489.
ꢀ
c 2007 Wiley Periodicals, Inc.
421

422 Gololobov et al.
NO2
CN
i-Pr PCH C
CN
(
DNFB)
i-Pr PCH C
3
2
3
2
NO2
F
C(O)OEt
1
O=C
2
OEt
NO2
CN
i-Pr PCH C
3
2
NO2
-FC(O)OEt
3
SCHEME 1
Physico-chemical methods confirmed the com-
position of compound 6. The structure of zwitte-
rion 6 was established by X-ray diffraction. UV/V
is spectroscopy in acetone showed λmax = 419 nm
tances within the C11 C12 C13 C14 C15 moiety
˚
(1.369(3)–1.384(3) A) are significantly shorter than
˚
the C10 C11 (1.433(3) A) and C10 C15 (1.437(3)
˚
˚
A) linkages, and the C1 C7 bond length (1.441(3)
(
ε = 18,300) and 535 nm (ε = 24,300). The IR spec-
A) is substantially shorter than the corresponding
−1
trum showed an intense band at 1643 cm (COOEt).
This suggests a high degree of interaction between
the C(O)OEt group and the negative charge. The IR
˚
C
sp2
C
sp2 (1.488 A) bond length. Furthermore, the
ortho-NO groups in the 2,4,6-trinitrophenyl sub-
2
stituent turn away from the phenyl ring plane (the
−
1
spectrum also contained intense bands at 1264 cm
dihedral angles between the planes of the ortho-
−1
(
para-NO
2
) and 1322 cm (ortho-NO
2
), which could
◦
◦
NO
2
groups and phenyl ring are 35.2 and 44.1 ),
be the result of the formation of a system of conju-
while the para-NO
plane (the corresponding dihedral angle is 2.6 ).
The N3 C13 distances (1.452(2) A) are shorter than
2
group is almost coplanar to this
1
gated bonds. In the H NMR spectra, the ring protons
◦
of zwitterion 6 were shifted upfield in comparison to
the aromatic protons of TNFB (8.67 and 9.18 ppm,
correspondingly) due to the negatively charged hep-
tatriene fragment. The X-ray diffraction study of 6
has also confirmed its zwitterionic nature (Fig. 1,
Table 1).
˚
˚
the N2 C11 (1.469(2) A) and N4 C15 (1.477(2)
˚
A) linkages. The bond length distribution within
the 2,4,6-trinitrophenyl fragment clearly indicates a
considerable contribution of the quinoid resonance
form.
Thus, the data obtained unequivocally point out
to a bipolar character of molecule 6; the negative
charge is delocalized over the fragment that includes
the C(1) C(10) bond, the C11 C12 C13 C14 C15
The molecule consists of a central carbon atom
bonded to three planar substituents. The sub-
stituents are oriented in a “propeller-like” fashion.
˚
The C1 C10 bond length (1.415(2) A) has an inter-
˚
mediate value between the Csp2
˚
Car (1.470 A) and
moiety, and para-NO group, whereas the positive
2
C
sp2
C
sp2 (1.350 A) bond lengths. Moreover, the dis-
charge is localized on the N1 nitrogen atom.
OEt
NO2
O C
C(O)OEt
(
TNFB)
N
C
N C
NO2
C(O)OEt
F
O C
OEt
4
NO2
5
OEt
OEt
NO2
NO2
NO2
O C
C O
C
N
C
NO2
N
NO2
-FC(O)OEt
6
NO2
2
SCHEME 2
Heteroatom Chemistry DOI 10.1002/hc

Reaction of Pyridinium Ylide With 2,4,6-Trinitrofluorobenzene 423
TABLE 1 Crystal Data and Structure Refinement for 6
Molecular formula
Molecular weight
Temperature
C15H12N O
376.29
100.0(2) K
4
8
˚
Wavelength
0.71073 A
Crystal system
Space group
Unit cell dimensions
Monoclinic
C2/c
˚
˚
a= 24.360(2) A
b= 7.4337(7) A
˚
c= 17.9945(17) A
◦
β = 106.088(5)
3
˚
Volume
3130.9(5) A
Z
8
3
Density (calculated)
Absorption coefficient
F(0 0 0)
1.597 mg/m
0.132 mm
1552
−
1
3
Crystal size
θ range for data collection
Index ranges
0.30 × 0.24 × 0.04 mm
◦ ◦
1.74 to 26.08
−30 ≤ h ≤ 30, −9 ≤
k ≤ 9, −22 ≤ l ≤ 22
13,875
Reflections collected
FIGURE 1 Molecular structure of 6 along with the atom la-
Independent reflections
Completeness to θ = 26.08
Absorption correction
3055 [R(int) = 0.0426]
beling scheme.
◦
98.4%
Semiempirical
from equivalents
0.996 and 0.965
In our article [1], we reported the first exam-
ple of nucleophilic aromatic substitution reactions
of fluorine atom in a highly electron-deficient arene
by 1,3-zwitterion 1, giving stable heptatriene moiety
Maximum and minimum
transmission
Refinement method
Full-matrix least-squares
2
on F
3
with conjugated anion. In this article, we describe
Data/restraints/parameters
3055/0/244
2
the second example of this type that gives the similar
heptatriene moiety 6. This allows us to suggest that
we have actually discovered a new type of transfor-
mation for σ-complexes that leads to the heptatrienic
systems. This expands our knowledge of the proper-
ties of σ-complexes and enables us to synthesize new
perspective synthones.
Goodness-of-fit on F
1.011
Final R indices [for 2369
reflections with I > 2σ(I )]
R indices (all data)
R = 0.0396,
1
wR = 0.0888
2
R = 0.0571,
1
wR = 0.0980
2
−3
˚
Largest difference peak and hole 0.262 and −0.261 eA
black powder was filtered off. Yield: 148 mg (99.3%);
◦
1
mp: 112–115 C. The H NMR spectra matched that
EXPERIMENTAL
of compound 6 (see below). The crude product was
The NMR spectra were recorded on a Bruker spec-
crystallized twice (CH
127–128 C. Calcd. for C15
N, 14.89. Found: C, 47.85; H, 3.11; N, 14.89. H
3
CN and ether mixture); mp
: C, 47.87; H, 3.19;
1
◦
trometers Avance AMX-400 ( H 400.1 MHz) and
H
12
N
4
O
8
13
1
Avance AMX-600 ( C 150.9 MHz), δ (ppm), mul-
tiplicity, number of protons, reference of protons,
J/Hz. The IR spectra were recorded on a Nico-
3
NMR (CDCl ): 1.22 (t, 3H, CH CH O, JHH = 7.2);
3
3
2
3
4.11 (q, 2H, CH
3
CH
2
3
O,
J
HH = 7.2); 7.70 (m, 2 H,
−
1
let IR-Fourier-spectrometer Magna-IR-750 (ν/ cm ).
UV/Vis spectra were recorded on a Carl Zeiss spec-
trometer Specord M-40 (nm) (acetone). The reac-
H
m
); 8.04 (t, 1H, H
p
, JHpHm = 7.2); 8.27 (d, 2H, H
o
,
3
13
JHoHm = 7.2), 8.67 (s, 2H, CH-C(NO )). C NMR
2
(CDCl
3
): 14.2 (CH
3
CH
2
O); 60.3 (CH
3
CH O); 98.2
2
tions were carried out under dry N
2
.
(C1Ar); 125.5, 127.0, 130.4 (CHPy); 137.5 (C
40.0 (CH ); 144.6 (C -NO ); 146.1(C C1Ar), 163.1
CO). IR (KBr): 1264 cm (para-NO ), 1322 (ortho-
NO ), 1643 (C(O)OMe).
P
-NO );
2
1
(
m
o
2
−
1
2
1
-(Ethoxycarbonylpyridiniomethylidene)-2,4,6-
trinitrocyclohexadienide 6
2
To the mixture of TNFB (92 mg, 0.4 mmol) and 4 (95
mg, 0.4 mmol), CDCl (0.5 mL) was added. The reac-
tion mixture was left for a week. The F NMR spec-
X-Ray Crystal Structure Determination
3
19
Data were collected on a Bruker three-circle
diffractometer equipped with a SMART 1K CCD
tra contained one signal at −16.47 ppm (FC(O)OEt)
[1]. Ether was added, and the resulting crystalline
detector MoK radiation, graphite monochromator,
α
Heteroatom Chemistry DOI 10.1002/hc

424 Gololobov et al.
◦
˚
TABLE 2 Bond Lengths (A) and Angles ( ) for 6
O(1) C(7)
O(2) C(7)
1.224(2)
1.346(2)
N(4) C(15)
C(1) C(10)
1.477(2)
1.415(2)
O(2) C(8)
O(3) N(2)
1.451(2)
1.230(2)
C(1) C(7)
C(2) C(3)
1.441(3)
1.375(3)
O(4) N(2)
O(5) N(3)
1.228(2)
1.232(2)
C(3) C(4)
C(4) C(5)
1.386(3)
1.385(3)
O(6) N(3)
O(7) N(4)
1.226(2)
1.234(2)
C(5) C(6)
C(8) C(9)
1.369(3)
1.497(3)
O(8) N(4)
N(1) C(2)
1.216(2)
1.349(2)
C(10) C(11)
C(10) C(15)
1.433(3)
1.437(3)
N(1) C(6)
N(1) C(1)
1.363(2)
1.433(2)
C(11) C(12)
C(12) C(13)
1.378(3)
1.375(3)
N(2) C(11)
N(3) C(13)
1.469(2)
1.452(2)
C(13) C(14)
C(14) C(15)
1.384(3)
1.369(3)
C(7) O(2) C(8)
C(2) N(1) C(6)
C(2) N(1) C(1)
C(6) N(1) C(1)
O(4) N(2) O(3)
O(4) N(2) C(11)
O(3) N(2) C(11)
O(6) N(3) O(5)
O(6) N(3) C(13)
O(5) N(3) C(13)
O(8) N(4) O(7)
O(8) N(4) C(15)
O(7) N(4) C(15)
C(10) C(1) N(1)
C(10) C(1) C(7)
N(1) C(1) C(7)
N(1) C(2) C(3)
C(2) C(3) C(4)
C(5) C(4) C(3)
C(6) C(5) C(4)
116.71(14)
119.85(15)
121.43(16)
118.72(15)
123.84(17)
117.44(16)
118.65(15)
123.66(16)
118.41(16)
117.93(16)
124.47(17)
117.61(16)
117.81(16)
119.98(16)
125.52(16)
114.47(15)
121.01(18)
119.41(18)
119.21(18)
119.51(18)
N(1) C(6) C(5)
O(1) C(7) O(2)
O(1) C(7) C(1)
O(2) C(7) C(1)
O(2) C(8) C(9)
C(1) C(10) C(11)
C(1) C(10) C(15)
C(11) C(10) C(15)
C(12) C(11) C(10)
C(12) C(11) N(2)
C(10) C(11) N(2)
C(13) C(12) C(11)
C(12) C(13) C(14)
C(12) C(13) N(3)
C(14) C(13) N(3)
C(15) C(14) C(13)
C(14) C(15) C(10)
C(14) C(15) N(4)
C(10) C(15) N(4)
120.86(17)
122.48(17)
125.49(17)
111.96(15)
106.91(15)
126.31(17)
121.92(17)
111.76(16)
124.08(18)
113.27(16)
122.33(16)
119.25(18)
121.30(17)
119.03(18)
119.67(17)
118.21(18)
125.22(18)
113.52(17)
120.80(16)
◦
φ and ω scan modes (θmax = 26 ), and corrected for
ACKNOWLEDGMENTS
Lorentz and polarization effects and for absorption
3]. The structure was determined by direct methods
and refined by a full-matrix least-squares technique
on F with anisotropic displacement parameters for
We thank Dr. Mikhail Gololobov for advice and help-
ful discussion.
[
2
all nonhydrogen atoms. The hydrogen atoms were
placed in calculated positions and refined in riding
mode with fixed thermal parameters. All calculations
were carried out using the SHELXTL PLUS pro-
gram (PC Version 5.10) [4]. Crystallographic data
for 6 have been deposited with the Cambridge Crys-
tallographic Data Center. CCDC No. 609224. Copies
of this information may be obtained free of charge
from the Director, CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK (Fax: +44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk or www.ccdc.cam.ac.uk).
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2] Gololobov, Yu.; Linchenko, O. A.; Petrovskii, P. V.;
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2
005, 54(10) 2471.
3] Sheldrick, G. M. SADABS, V 2.01, Bruker/Siemens
Area Detector Absorption Correction Program;
Bruker AXS Inc.: Madison, WI, 1998.
4] Sheldrick, G. M. SHELXTL, V 5.10, Bruker AXS Inc.:
Madison, WI, 1998.
Heteroatom Chemistry DOI 10.1002/hc