C-C coupling between trinitrothiophenes and triaminobenzenes: Zwitterionic intermediates and new all-conjugated structures

Article abstract of DOI:10.1039/c6ob00243a

The reactions of 1,3,5-triaminobenzene derivatives with 2,3,4-trinitrothiophene and 2-bromo-3,4,5-trinitrothiophene gave new all-conjugated compounds bearing both an electron-withdrawing and an electron-donor moiety on the same unit. The reactions with 2,3,4-trinitrothiophene offered evidence, by NMR spectroscopy at low temperature, of the formation of new labile Wheland-Meisenheimer intermediates whereas at room temperature stable unexpected products derived from the attack of the nucleophile at C-4 with replacement of the nitro group were isolated. Their formation caused, in turn, the obtainment of a salt between 1-nitroso-2,4,6-triaminobenzenes and 2,4-dinitrothiophen-3-ol. The reactions with 2-bromo-3,4,5-trinitrothiophene produced in good yields the S_NAr substitution product with the displacement of the bromide. All the new coupling products obtained are of applicative interest, considering the increasing concern for highly conjugated π-systems in solar energy conversion or optoelectronic devices.

Full text of DOI:10.1039/c6ob00243a

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C–C Coupling between trinitrothiophenes and triaminobenzenes:
zwitterionic intermediates and new all‐conjugated structures
C. Boga,a* G. Micheletti,a S. Cino,a S. Fazzini,a L. Forlani,a N. Zannaa and D. Spinellib
Received 00th January 20xx,
Accepted 00th January 20xx
The reactions of 1,3,5‐triaminobenzene derivatives with 2,3,4‐trinitrothiophene and 2‐bromo‐3,4,5‐trinitrothiophene gave
new all‐conjugated compounds bearing both an electron‐withdrawing and an electron‐donor moiety on the same unit. The
reactions with 2,3,4‐trinitrothiophene offered evidence, by NMR spectroscopy at low temperature, of formation of new
labile Wheland‐Meisenheimer intermediates whereas at room temperature stable unexpected products derived from the
attack of the nucleophile at C‐4 with replacement of the nitro group were isolated. Their formation caused, in turn, the
obtainment of the salt between 1‐nitroso‐2,4,6‐triaminobenzenes and 2,4‐dinitrothiophen‐3‐ol. The reactions with 2‐
bromo‐3,4,5‐trinitrothiophene produced in good yields the SNAr substitution product with displacement of the bromide.
All the new coupling products obtained are of applicative interest, considering the increasing concern for highly
conjugated ‐systems in solar energy conversion or optoelectronic devices.
DOI: 10.1039/x0xx00000x
www.rsc.org/
Introduction
This situation appears evident in the case of the reactions
Heteroaromatics with electron‐donor and ‐acceptor between two partners with opposite electronic requirements
architectures are receiving growing interest in diverse and very activated, used in the same amount to yield an
applicative fields such as solar energy conversion1 and intermediate which is at the same time a σ‐cationic complex
optoelectronic devices,2 with particular attention to (Wheland intermediate, on the electron rich reagent) and a σ‐
thiophene‐based structures. An easy synthetic route to such a anionic one (Meisenheimer intermediate, on the electron poor
kind of compounds might be the C–C coupling between reagent).
We
called
these
intermediates
aromatic electron‐poor and electron‐rich partners through Wheland/Meisenheimer (WM) complexes5 (Scheme 1).
SEAr/SNAr reactions,3 that are long since among our main
research interests.4 It must be remarked that the so‐called
EDN
+
H
nucleophilic and electrophilic aromatic substitutions represent
taxonomic definitions useful for didactic uses, in fact when
there is a nucleophilic reagent, there shall be an electrophilic
reagent as partner (often called ‘substrate’). So, the
conventional classification is poorly significant; for example, in
nucleophilic aromatic substitution (SNAr) the electron‐poor
partner is considered the substrate, probably because the
nucleophilic reagent is often used in excess and the same
considerations are valid for the SEAr reaction.
+
_
H
EWD
EDN
EWD
EWD = electron-withdrawing groups
EDN = electron-donor groups
Wheland-Meisenheimer
complex (WM)
Scheme 1. Aromatic substitution between neutral aromatic
reagents.
In principle, the mechanism of both aromatic substitution
reactions is in the same coordinate/energy path. When heterocycles bearing electron‐withdrawing groups
Consequently, the parameters affecting SNAr reactions are the (mainly nitro groups) are mixed with strongly nucleophilic
same influencing SEAr reactions, by inverting the sign (or the reagents such as sym‐triaminobenzene derivatives, the C–C
electron density) of the charge on the involved reaction coupling can occur under mild conditions and almost
centers.
quantitatively as in the case recently reported about their
reaction with a series of chloro‐nitrobenzofurazans.7 When
1,3,5‐(N‐piperidinyl)‐, 1,3,5‐(N‐morpholinyl)‐, and 1,3,5‐(N‐
pyrrolidinyl)‐benzene were mixed with super‐electrophiles8
a. Department of Industrial Chemistry ‘Toso Montanari’ ALMA MATER STUDIORUM
‐ Università di Bologna Viale del Risorgimento, 4 40136 Bologna, Italy. E mail:
carla.boga@unibo.it
such as 4,6‐dinitrobenzofuroxan
(
DNBF
)
and 4,6‐
b. . Department of Chemistry ‘G. Ciamician’ ALMA MATER STUDIORUM ‐ Università
di Bologna Via Selmi 2, 4 40126 Bologna, Italy. E mail: carla.boga@unibo.it
† Footnotes relaꢀng to the ꢀtle and/or authors should appear here.
Electronic Supplementary Information (ESI) available: Copies of the 1H, 13C NMR
and mass spectra of new compounds, g‐COSY and g‐HSQC of WMa and WMc. See
DOI: 10.1039/x0xx00000x
dinitrotetrazolopyridine
Wheland/Meisenheimer
obtained.5,6
(
(
DNTP
)
the first evidence for
complex formation was
WM
)
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Later, the first examples of WM intermediates derived from anionic complexes (with anionic nucleophiles)ViehwaAvrteiclebOenleinne
aromatic pentatomic heterocycles as nucleophiles were reported.4b
DOI: 10.1039/C6OB00243A
obtained by the coupling between 2‐amino‐1,3‐thiazole Obviously, when the electrophile bears a powerful leaving
derivatives and DNBF 9a
moreover, the reaction of 2,4‐ group X (e.g. the bromide in 1), the isolation of a σ‐complex is
;
dipyrrolidinyl‐1,3‐thiazole with DNBF or DNTP offered the first a very hard goal: the σ‐anionic complexes formation, in such
X‐ray diffraction analyses of WM complexes (Scheme 2).9b
kind of substrates, is ‘only’ an hypothesis, but when X = H, it is
expected to isolate moderately stable σ‐complexes, because of
the low ability of the hydride to act as a leaving group:
actually, in this case there is a lot of evidences of the presence
in the reaction mixtures of σ‐complexes as well as of their
isolation.
O2N
O
N
N
O
S
N
O2N
H
X
N
O
+
N
O
Y
O2N
H
It has been reported14a that 3‐bromo‐3,4,5‐trinitrothiophene
S
NO2
H
X
X = NHR, Y = H
X = Y =
(1) reacts with aromatic amines giving, depending on the
N
Y
DNBF
experimental conditions, either displacement of the nitro
group in position 4 or of both this group and the bromine
atom. Also thiophenols replace simultaneously these groups
whereas benzenesulfinic acid displaces the bromine and the
nitro group in position 5. Only a few papers have appeared so
far on the reactivity of 14b,14,11b and no reactions with carbon
N
WM
Scheme 2. WM intermediates from DNBF and 2‐aminothiazole
derivatives
nucleophiles, thus, the behavior of
derivatives is far from predictable.
1 with triaminobenzene
Pentatomic heterocycles such as thiophene, furan, and
pyrroles are known as
‐excessive (electron‐rich) substrates
Rarer still are the reports on 2,3,4‐trinitrothiophene (
2): its
able to react with electron‐poor reagents (electrophiles). This
point of view was so diffuse that in 1968 J. Miller10 stated that
these heteroaromatics are not prone to give SNAr reactions
even if at that time some authors11 had given strong evidence
about the ability of nitrothiophenes to react with electron‐rich
reagents.
chemical properties have been scarcely11b,15b investigated and
no reaction were reported, except the formation of a
complex with naphthalene.15a
Moreover, in planning the present study, we considered that
the possible new coupling products that will be obtained bear
simultaneously an electron‐rich and an electron‐poor moiety;
contrarily to the most known thiophene‐based structures,
‐
Actually, the introduction of one or more strong electron‐
withdrawing groups in thiophenes makes these compounds
more and more prone to interact with electron‐rich reagents;
this fact represents a general characteristic of pentatomic
heterocyclic compounds (thiophene, selenophene, and
furane). We think that the ability of nitrothiophenes to fast
react with nucleophiles depends from two factors:4b a) ‘the
low resonance stabilization energy of thiophene with respect
to benzene, which causes a lower loss of stabilization energy
on going from starting products to transition states’11d b) the
geometry of the thiophene ring with ‘the internal angles along
the ring carbon atoms (ca. 111–112°) very similar to the figure
corresponding to sp3‐hybridazed carbon atoms’ ‘implies a
lower energy, with respect to benzene, for the formation of
the transition state’.
those expected to be obtained from the trinitrothiophenes
and possess the thiophene moiety as electron‐withdrawing
1
2
part, giving structures that might be of interest in several
applied fields.1,2,16
Results and discussion
The reactions between 2‐bromo‐3,4,5‐trinitrothiophene (
and tris(N,N‐dialkylamino)benzene derivatives 3a and 3b
carried out in acetonitrile with the reactants in equimolar
ratio, gave compounds 4a and 4b, derived from the
substitution reaction at the carbon bearing the bromine atom,
in 61 and 55% yield (Scheme 3).
1)
,
The above hypothesis is confirmed by comparing the results
observed
bromobenzene,
in
piperidinodebromination
2‐bromo‐5‐nitrothiophene,
of
4‐nitro‐
2‐bromo‐5‐
nitroselenophene, and 2‐bromo‐5‐nitrofuran. As matter of fact
their reactivities largely increase as their aromaticities
decrease (a relationship between their logarithmic reactivity
and Bird aromaticity indexes has been observed).12
Going on with this investigation, now we are looking for
gaining information on SNAr/SEAr reactions between thiophene
derivatives activated by nitro groups, as 2‐bromo‐3,4,5‐
trinitrothiophene (1) and 2,3,4‐trinitrothiophene (2), and sym‐
triaminobenzenes, ‘strongly’ activated nucleophilic reagents at
the neutral carbon atom. In nitrothiophene series, several
Scheme
trinitrothiophene (
3.
Reactions
between
2‐bromo‐3,4,5‐
1) and nucleophiles 3a–d.
Under the above conditions, the formed hydrobromic acid
reacts with
examples of formation of
 neutral (with naphthalene) and σ
3
giving the relevant salt: the finding that
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compounds 4a and 4b have been obtained in yield higher than of signals in the region typical of the diagnostic signals of WM
View Article Online
DOI: 10.1039/C6OB00243A
50% can be considered an indication of an only partial complexes.5,6,9
salification of the bases present in the mixture.
When the reactions of Scheme 3 were carried out in equimolar broad singlets with the same integration value appeared at
ratio of reagents and in the presence of basic alumina to avoid 5.48, 5.36, 4.98, and 4.95 ppm. Direct proton to carbon
the formation of salts between HBr and the starting correlation (Figure SI‐51) obtained at 70 °C showed that the
nucleophiles (or reaction products), 4a and 4b were obtained two signals at = 4.95 and 4.98 ppm are connected directly to
in 82% and 65% yield, respectively. In contrast, the reaction carbon atoms resonating at = 55.3 and 39.3 ppm,
between and 3c afforded a complex reaction mixture.
respectively, a clear evidence for the sp3 hybridization of these
To extend this behaviour to other nucleophilic benzenes, we carbon atoms (C‐5 and C‐6, spectra S52 and S53). The two
carried out the reaction between 1,3,5‐trimethoxybenzene hydrogen atoms which resonate at = 5.48 and 5.36 ppm are
3d) and : the reaction appears slower that those with 3a‐c connected to two carbon atoms at = 91.8 and 87.4 ppm,
and the compound 4d was obtained in 47% yield.
chemical shift values typical for the sp2‐hybridized CH carbon
Blatt and coworkers11b and, later, some of us4b,14 reported that atoms of 1,3,5‐triaminobenzene derivatives.5,6 The two distinct
the reactions of with anionic or neutral nucleophiles yielded hydrogen (and carbon) signals are due to the presence of an
In particular, immediately after the mixing of 2 and 3a, four

=



1

(
1

1
both bromo and nitro substitution. In the present case, also asymmetric carbon center on the thiophene moiety and a “C‐2
carrying out the reactions with two or more equivalents of center” (sp3 carbon) of the triaminobenzene moiety that
tris(amino)benzene only the product
4 of monosubstitution makes diastereotopic the two carbon atoms C‐8 and C‐10 (and
was isolated: the replacement of the bromine atom is surely also the hydrogen atoms H‐8 and H‐10, Scheme 5) and thus
1
the main process even if in the reaction mixtures there are, in anisochronous signals in both the H and 13C NMR spectra
some cases, low amount of starting materials and traces of appear.
unidentified compounds.
We like to remember that this observation represents the first
It is known3,17 that the attack of a nucleophile on a non‐ evidence of formation of a chiral center on a sp3‐hybridized CH
substituted carbon is a process faster than the attack on a carbon in a nucleophilic reaction involving a thiophene
carbon bearing a leaving group (exerting steric/electronic derivative.
repulsions towards the electron‐rich entering reagent).
The reaction between 2 and 3c also evidenced the presence of
Therefore, one can expect that σ covalent complexes may be the zwitterionic intermediate (WMc) in the NMR spectrum at –
more easily observed in the absence of leaving groups, also 70 °C, whose structure was ascertained by both direct proton
because the departure of H– is a difficult process and the to carbon and carbon to carbon correlation experiments (Fig.s
formed σ complex can only return‐back to starting materials, SI‐55–SI‐57). When the temperature was slowly increased the
as depicted in Scheme 4 (pathway A).
signals related to WMa and WMc gradually broadened until to
disappear at about –30 °C (a subsequent lowering of the
O2N
NO2
NO2
O2N
k1H
+ Nu
temperature did not give return‐back to the WM signals).
_
X
NR2
k-1H
NO2
S
+
NO2
S
Nu
X
R2N
X = Br (1), H (2)
O2N
H
slow
X = H, pathway A
NR2
NO2
NR2
k-1Br
S
k1Br
O2N
H
NO2
Path. A
5a-c
+
O2N
NO2
O2N
NO2
O2N
H5
NO2
NO2
S
R2N
NR2
Path. B
fast
k2
-Br–
_
_
3a-c
2
R2N
X
Nu
S
NO2
S
H6
NO2
NO2
S
+
Nu
NR2 = N-piperidinyl (a)
NR2 = N-morpholinyl (b)
NR2 = N-pyrrolidinyl (c)
H10
R2N
+
NR2
H8 WMa-c
X = Br, pathway B
Scheme 4. Reaction pathways for the trinitrothiophene
derivatives/nucleophile interactions
Scheme 5. Formation of intermediates WMa‐c and products
5a–c.
In Scheme 4 k1H>k1Br, while k2, concerning the departure of the
leaving group, represents (in our experimental conditions) a
fast step.
It is noteworthy that among other compounds formed during
the mixing of the reagents at –70 °C, whose signals remained
almost unchanged until +25 °C, we were able to isolate and
Turning attention to 2,3,4‐trinitrothiophene (
2
), the inspection
by variable temperature H NMR spectroscopy (from –70°C to
+25°C) of the reaction mixtures obtained by mixing at 70 °C
equimolar amounts of and 3a (or 3c) in CD2Cl2 showed that
1
identify compounds 5a and 5c
No evidence of WMb was obtained from the reaction carried
out in CD2Cl2 at –70 °C between and 3b; only peaks of
.

2
2
this reaction is complicated by the presence of several
starting reagents and traces of 5b were present in the
spectrum until about 0 °C whereas at 25 °C the spectrum
products. Among them, WMa and WMc complexes (Scheme 5)
1
were identified owing the presence, in the H NMR spectrum,
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became more complex and the signals of 5b gradually possibilities (
Journal Name
A
‐
C
in Figure 1) about the position of the proton
View Article Online
DOI: 10.1039/C6OB00243A
increased as those of the starting reagents disappeared.
Compounds 5a arise from a de‐nitro‐substitution reaction in
position 3 of the thiophene ring. They have been obtained in
yield no higher than 45% and their structure was attributed by
means of NMR data (NOESY‐1D) and comparison with 13C NMR
on the cationic part of the salt 6.

c
O
N
+
N
H
O
R2N
–O
–O
R2N
NR2
NO2
NR2
NO2
H
+
O2N
signals of the starting reagent 2; attempts to obtain structure
O2N
S
S
NR2
NR2
by single crystal X ray diffraction of compound 5a gave no
satisfactory refinement of data but confirmed the position of
the triaminobenzene moiety between the two nitro groups.
It is noteworthy that after each experiment carried out in the
A
B
H
O
+ O
N
H
N
+
–O
–O
R2N
NR2
NMR spectroscopy tube between
2
and 3a
–c
we noted the
NO2
R2N
NR2
NO2
1
presence of a precipitate. This solid was separated and its H
NMR signals matched with those of minor signals observed in
the spectra of the reaction mixture recorded at different
temperatures; likely, due to its scarce solubility in CD2Cl2, this
compound seemed to be a minor constituent in the reaction
mixture.
O2N
O2N
S
S
NR2
NR2
D
C
Figure 1. Possible structures of salts 6a–c.
After isolation by filtration, the unexpected structure
6 was
Structure
piperidine moiety.
equilibrium with A 19
similarly to what indicated by Effenberger18 in a paper in which
compounds 6a were prepared from 3a
and N2O4. In the 1H
NMR spectra of salts 6a , two signals related to protons
bound to aromatic ring are recorded, indicating structure as
the probable one, owing the symmetry of the two protons of
the aromatic ring in and . In our opinion, more probable of
structure is that depicted as , in which the proton bound to
A
shows the proton on a nitrogen atom of the
is a Wheland complex which may be in
presents the protonated nitroso group,
first supposed for this solid on the basis of ESI+ and ESI– mass
spectra, and later it was confirmed by NMR spectral data and
B
.
C
by isolation and characterization of its neutral constituents
and (Scheme 6). NMR data of the free bases, i.e. 1‐nitroso‐
2,4,6‐(N,N‐dialkylamino)benzene derivatives 7a , obtained by
treatment of 6a with methanolic solution of KOH, agree with
literature data18 whereas 2,4‐dinitrothiophen‐3‐ol (
) obtained
7
8

c
c
–
c

c

c
A
8
by treatment of 8‐salt with HCl solution, has never been
reported so far.
Moreover, the mixing of equimolar amounts of compound 7b
B
C
A
D
the nitrogen atom is involved in a hydrogen bond between the
piperidinyl nitrogen and the oxygen atom of the nitroso group.
1
and
8
directly into the NMR spectroscopy tube produced H
NMR signals of the triaminobenzene moiety matching with
It has to be noted that compounds 6a
yields much higher than those of the corresponding 5a
unexpected formation of salts 6a might be tentatively

c
have been obtained in
those of 6b
.

c; the

c
NR2
explained by the pathways depicted in Scheme 7.
O
–O
NO2
NR2 = piperidinyl
NR2 = morpholinyl b
NR2 = pyrrolidinyl c
a
R2N
N
H+
2HNO2
H2NO2
–
H2NO2+ + NO2
NO+ + H2O
O2N
+
S
NR2
6a-c
NO2– + H2O
HNO2
HNO2 + OH–
NO+ + OH–
KOH/MeOH
R2N
R2N
NR2
O–K+
NO2
O2N
O
SEAr
NO+
H+
NR2
+
R2N
N
+
NR2
+
S
8-salt
R2N
O2N
NR2
O2N
R2N
NO
OH
7a-c
3a-c
7a-c
filtration
O2N
NO2
SNAr
–
NO2
+
NO2
OH–
OH
+
HCl
NO2
8 (70%)
NO2
S
8-salt
S
7a (70%)
7b (97%)
7c (97%)
2
8
S
7a-c + 8
6a-c
Scheme 7. Proposed reaction pathway to explain the
formation of compounds 6a
Nitrous acid, derived from the reaction between
Scheme 6. Isolation of compounds 7ac and 8.
–c.
On the base of our previous paper19 on the interaction
between triaminobenzenes and proton, there are three main
2
and 3a–c to
give 5a–c, can decompose, in the absence of water (reactions
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were carried out in dichloromethane or in acetonitrile) into Experimental Details.
View Article Online
DOI: 10.1039/C6OB00243A
The 1H and 13C NMR spectra were recorded at 300, 400, or 600
MHz (1H NMR) and 75.46, 100.56, or 150.80 MHz (13C NMR),
respectively. J values are given in Hz. Signal multiplicities were
established by DEPT‐135 experiments. Chemical shifts were
nitrosonium and hydroxide ions through the self‐protonation
process depicted in Scheme 7 (top). The two naked ions thus
formed can attack triaminobenzene and trinitrobenzene by
SEAr and SNAr, respectively.

(ppm) with reference to the solvent [for 1H and
The reaction produces, besides 7a–c and
8, a further amount
measured in
13C NMR, respectively: = 5.30 ppm and 54.2 ppm for
CD2Cl2= 7.26 ppm and 77.0 ppm for CDCl3; = 2.50 ppm and
39.50 ppm for (CD3)2SO;  = 3,31 ppm and 49.2 ppm for
CD3OD; = 1.96 ppm and 118.1 ppm for CD3CN]. The variable–
of nitrous acid that, in turn, can decompose promoting the
formation of a further amount of 7a–c and
8, like in an

autocatalytic cycle.
Compounds 7a–c and
experimentally confirmed by adding 7a to a CD3CN solution of
. On the basis of the all above findings, we hypothesized that
the more plausible structure for might be that reported in
8 can form the salts 6a–c, as

temperature NMR spectra and 2D low‐temperature spectra (g‐
COSY and g‐HSQC) were recorded on a 400 MHz spectrometer.
ESI‐MS and HR‐ESI‐MS spectra were recorded using Waters 2Q
4000 and Xevo instrument, respectively. Chromatographic
purifications were carried out on columns of silica gel (0.037‐
0.063 mm) or aluminium oxide, activated, basic, Brockmann I,
standard grade ca. 150 mesh at medium pressure. In the
8
8
Schemes 6 and 7, even if, since we were not able to obtain
crystals suitable for X‐Ray diffraction analysis, other isomeric
structures cannot be completely ruled out.
In the whole, the occurrence of these reactions might be the
possible reason of both, the low yields found for compound
Supporting Information are provided copies of the 1H NMR, 13
NMR and mass spectra of all new compounds and for the
known compounds whose NMR and mass data were never or
only partially reported; crude salts 6a
without purification to obtain neutral components 7a
1,3,5‐Trimethoxybenzene (3d) is commercially available, 1,3,5‐
tris(N,N‐dialkylamino)benzenes 3a were prepared as
described previously,5 as well as bromotrinitrothiophene (
).11b Given that NMR spectra of
and trinitrothiophene ( and
C
5ac and the high yields of the recovered salts 6ac.
Conclusions
–
c
have been treated
In conclusion, the present study reports the first examples of
reactions between trinitrothiophene derivatives and sym‐
triaminobenzene derivatives 3a–c, strongly activated aromatic
neutral carbon nucleophiles. The structure of the coupling
–
c
and
8.
–
c
1)
product obtained using 2‐bromo‐3,4,5‐trinitrothiophene (1) as
2
1
electrophile revealed that only the de‐bromination
substitution reaction occurs and no evidence of de‐
nitrosubstitution reactions was obtained.
2
have been never reported so far, we report them below (we
notice that 13C NMR spectra show some signals as triplet, likely
due to carbon‐nitrogen coupling).20 2‐Bromo‐3,4,5‐
trinitrothiophene (1): 13C NMR (150.8 MHz, CDCl3, 25 °C):
 =
A
very peculiar reactivity was observed when 2,3,4‐
trinitrothiophene ( ) was reacted with 3a : the latter showed
2
c
140.1 (br.s, C), 136.8 (br.s, C), 136.2 (t, JC‐N = 15.0 Hz, C), 121.5
ppm (C). 2,3,4‐Trinitrothiophene (2). 1H NMR (600 MHz, CDCl3,
the ability to attack, in a fast step, the unsubstituted carbon
atom (C‐5) of the thiophene ring and offered the first evidence
of WM complexes in thiophene series and also the first
example with an electrophilic partner belonging to the class of
aromatic monocyclic pentatomic heterocycles. The attack at
the C‐5 carbon atom of the electrophile competes with the
attack on the carbon bearing the nitro group in position 3 of
the thiophene ring that produces new compounds with the
triaminobenzene moiety bound at the C‐3 carbon atom; the
consequent nitro group departure eliminates the possibility to
return‐back to the starting materials while the only possibility
for WM is the return to the starting reagents.
25 °C):
  =
= 8.57 ppm; 13C NMR (150.8 MHz, CDCl3, 25 °C):
142.3 (t, JC‐N = 13.2 Hz, C), 137.8 (br.s, C), 135.8 (t, JC‐N = 14.8
Hz, C), 129.9 ppm (CH).
Compounds 7a‐c were described previously18 and their data
agree with those reported;18 their H NMR data have been
1
reported only partially and below their H NMR, 13C NMR and
1
mass data are reported.
Preparation of compounds 4a,b,d. General procedure. 2‐
Bromo‐3,4,5‐trinitrothiophene (
added to an equimolar amount of 1,3,5‐tris(N,N‐
dialkylamino)benzene 3a 3b, or 3c (or of trimethoxybenzene
1) (0.030 g, 0.1 mmol) was
,
The reaction is complicated by other processes, one of them is
the formation of a salt that, after neutralization, provided 1‐
nitroso‐2,4,6‐triaminobenzene derivatives and the hitherto
unknown 2,4‐dinitrothiophen‐3‐ol. Therefore, present findings
can be considered a new method to synthesize 1‐nitroso‐2,4,6‐
3d) dissolved in CH3CN (5 mL). Immediately after mixing, the
colour of the reaction mixture turned to red or blue. The
progress of the reaction, magnetically stirred, was monitored
by TLC and 1H NMR analysis. The product was purified by flash
chromatography on silica gel (petroleum light/Et2O 8/2 v/v for
4a, n‐hexane/ethyl acetate 4/6 for 4b and 4d). The reactions
were carried out also in the presence of basic alumina; that
was filtered off after disappearance of starting material on
TLC, products were then quickly purified as above described.
The yields reported below are referred to the first procedure
with equimolar amount of reagents.
triaminobenzenes and, even more interestingly, the CC
coupling products 4a,b,d and 5a–c herein reported gives
access to new highly conjugated structures, bearing both
electron‐poor and electron‐rich moieties, of possible interest
in applied chemistry.
1,1',1''‐[2‐(3,4,5‐Trinitro‐2‐thienyl)benzene‐1,3,5‐
triyl]tripiperidine (4a): blue‐violet solid, 33 mg (61%) mp > 300
Experimental
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Organic & Biomolecular Chemistry
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1
°C (dec.); H NMR (600 MHz, CDCl3, 25 °C): δ = 6.36 (s, 2 H, 1,1',1''‐[2‐(2,4‐Dinitro‐3‐thienyl)benzene‐1,3,5‐
aromatics), 3.32 (t, J = 4.78 Hz, 4 H, NCH2), 2.80
NCH2), 1.74 1.62 (m, 6 H), 1.62
(m, 4 H). 13C NMR (150.8 MHz, CDCl3, 25 °C): δ = 154.9 (C), H, CH arom.), 3.24 (t, J = 5.7 Hz, 4 H, NCH2), 2.70
154.8 (C), 144.6 (C), 137.0 (C), 136.0 (C), 134.4 (C), 107.6 (C), NCH2), 1.78 1.66 (m, 4 H, NCH2CH2), 1.66 1.57 (m, 2 H,
1.29 ppm (m, 12 H, NCH2CH2 and
View Article Online
1

2.66 (m, 8 H, triyl]tripiperidine (5a): dark blue solid, 1D8O.7I:m10g.10(2395/%C6).OBH00N2M43RA


1.53 (m, 8 H), 1.53–1.43 ppm (400 MHz, CDCl3, 25 °C): δ = 8.22 (s, 1 H, CH thioph), 6.41 (s, 2
2.56 (m, 8 H,



102.0 (CH), 54.0 (NCH2), 48.6 (NCH2), 25.7(NCH2CH2), 25.6 NCH2CH2), 1.42

(NCH2CH2), 24.2 (NCH2CH2CH2), 24.1 ppm (NCH2CH2CH2). ESI NCH2CH2CH2). 13C NMR (100.56 MHz, CDCl3, 25 °C): δ = 154.2
MS (ES+) m/z: 545 (M+ + 1), 567 (M+ + Na), 583 (M+ + K); (C), 154.0 (C), 146.6 (C), 145.6 (C), 133.5 (C), 127.3 (CH), 111.7
elemental analysis calcd (%) for C25H32N6O6S: C 55.13, H 5.92, (C), 103.0 (CH), 53.6 (NCH2), 49.5 (NCH2), 26.4 (2 sign.
N 15.43. Found: C 55.21, H 5.94, N 15.45.
4,4',4''‐[2‐(3,4,5‐Trinitro‐2‐thienyl)benzene‐1,3,5‐
overlapped, NCH2CH2), 25.9 (CH2), 24.3 ppm (NCH2CH2CH2). ESI
MS (ES+) m/z: 500 (M+ + 1), 522 (M+ + Na), 538 (M+ + K);
triyl]trimorpholine (4b): purple solid, 30.3 mg (55%), mp 200 elemental analysis calcd (%) for C25H33N5O4S: C 60.10, H 6.66,
1
°C (dec.); H NMR (600 MHz, CDCl3, 25 °C): δ = 6.43 (s, 2 H, N 14.02. Found: C 60.19, H 6.68, N 14.05. X‐ray diffraction
aromatics), 3.87 (t, J = 4.9 Hz, 4 H, OCH2), 3.70 (t, J = 4.9 Hz, 8 analysis of
a single crystal of 5a showed that the
H, OCH2), 3.31 (t, J = 4.9 Hz, 4 H, NCH2), 2.85‐2.79 ppm (m, 8 H, triaminobenzene moiety is bound at the C‐3 of the thiophene
NCH2). 13C NMR (150.8 MHz, CDCl3, 25 °C): δ = 154.9 (C), 153.5 ring but, unfortunately, due to the symmetry of the cell, the
(C), 143.1 (C), 137.0 (C), 136.6 (C), 134.8 (C), 108.7 (C), 102.4 resolution of the structure was not satisfactory for the
(CH), 66.51 (OCH2), 66.45 (OCH2), 52.6 (NCH2), 47.5 ppm requirements for the deposit in CCDC.
(NCH2). ESI MS (ES+) m/z: 573 (M+ + Na), 589 (M+ + K); 4,4',4''‐[2‐(2,4‐Dinitro‐3‐thienyl)benzene‐1,3,5‐
elemental analysis calcd (%) for C22H26N6O9S: C 48.00, H 4.76, triyl]trimorpholine (5b): dark purple solid, 21.2 mg (28%). H
1
N 15.27. Found: C 48.12, H 4.78, N 15.30.
NMR (400 MHz, CDCl3, 25 °C): δ = 8.27 (s, 1 H, CH thioph), 6.46
(4d): (s, 2 H, arom), 3.88 (t, J = 4.9 Hz, 4 H, OCH2), 3.53 3.47 (m, 8 H,
2.65 ppm (m, 8 H,
2,3,4‐Trinitro‐5‐(2,4,6‐trimethoxyphenyl)thiophene

orange solid, 18.1 mg (47%). 1H NMR (600 MHz, CD3CN, 25 °C): OCH2), 3.27 (t, J = 4.9 Hz, 4 H, NCH2), 2.72

δ = 6.35 (s, 2 H, aromatics), 3.92 (s, 3H, OCH3), 3.84 ppm (s, 6 NCH2). 13C NMR (150.8 MHz, CDCl3, 25 °C): δ = 153.5 (C), 152.6
1
H, OCH3). H NMR (600 MHz, CDCl3, 25 °C): δ = 6.18 (s, 2 H, (C), 146.5 (C), 146.1 (C), 132.1 (C), 127.5 (CH), 113.0 (C), 103.1
aromatics), 3.89 (s, 3H, OCH3), 3.81 ppm (s, 6 H, OCH3). 13C (CH), 67.0 (OCH2), 66.7 (OCH2), 52.4 (NCH2), 48.4 ppm (NCH2).
NMR (150.8 MHz, CDCl3, 25 °C): δ (selected) = 165.0 (C), 158.8 ESI MS (ES+): 506 (M+ + H), 528 (M+ + Na); elemental analysis
(C), 152.1 (C), 150.3 (C), 140.5 (C), 97.7 (C), 91.0 (CH), 55.9 calcd (%) for C22H27N5O7S: C 52.27, H 5.38, N 13.85. Found: C
(OCH3), 55.7 ppm (OCH3). ESI‐MS (ES+) m/z: 386 (M+ + 1), 408 52.33, H 5.39, N 13.81.
(M+ + Na); elemental analysis calcd (%) for C13H11N3O9S: C 1,1',1''‐[2‐(2,4‐Dinitro‐3‐thienyl)benzene‐1,3,5‐
1
40.52, H 2.88, N 10.91. Found: C 40.41, H 2.89, N 10.88.
triyl]tripyrrolidine (5c): dark brown solid, 30.2 mg (44%). H
Preparation of compounds 5a–c and 6a
–
c. General NMR (600 MHz, CDCl3, 25 °C): δ = 8.10 (s, 1 H, CH thioph), 5.94
(s, 2 H, arom), 3.34 (t, J = 6.6 Hz, 4 H, NCH2), 2.83 2.78 (m, 4 H,
2.72 (m, 4 H, NCH2), 2.01 1.97 (m, 4 H, NCH2CH2),
1.65 ppm (m, 8 H, NCH2CH2); H NMR (400 MHz, CD2Cl2,
70 °C): = 8.13 (s, 1 H), 5.76 (s, 2 H), 3.25 (br.t, J = 6.11 Hz, 4
H), 2.73 2.55 (m, 8 H), 1.90 (br.t, J = 6.11 Hz, 4 H), 1.70 1.53
were isolated by filtration from the above reaction mixture. ppm (m, 8 H); 1H NMR (400 MHz, CD3CN, 25 °C): δ = 8.35 (s, 1
Compounds 5a were also obtained carrying out the reaction H), 5.96 (s, 2 H), 3.33 (t, J = 6.7 Hz, 4 H), 2.82 2.75 (m, 4 H),
in a larger scale: to a magnetically stirred solution of 1,3,5‐ 2.75‐2.67 (m, 4 H), 2.05 2.00 (m, 4 H), 1.75 1.63 ppm (m, 8
tris(dialkylamino)benzene (0.15 mmol) in CH2Cl2 or CH3CN (10 H). 13C NMR: (150.8 MHz, CD2Cl2, 25 °C):  = 151.6 (C), 150.5
mL), an equimolar amount of 2,3,4‐trinitrothiophene ( ) was (C), 148.2 (C), 145.9 (C), 136.8 (C), 128.0 (CH), 104.1 (C), 95.6
procedure.

Compounds 5a
chromatography on silica gel column of the final reaction 1.77
mixture between and (or 3b 3c) derived from experiments
carried out in the NMR spectroscopy tube. Compounds 6a

c
and 6a

c
were first isolated by NCH2), 2.78


1

2
3
,



c



c



2
added. Immediately after mixing, the reaction mixture became (CH), 52.1 (NCH2), 48.3 (NCH2), 26.3 (NCH2CH2), 25.7 ppm
dark red or violet. The solution was stirred for 1 hour (using 3a (NCH2CH2). ESI MS (ES+) m/z: 458 (M+ + 1), 480 (M+ + Na), 496
or 3c) and 12 hours (for 3b) and the progress of the reaction (M+ + K); elemental analysis calcd (%) for C22H27N5O4S: C 57.75,
was monitored by TLC and 1H NMR analysis. During the H 5.95, N 15.31. Found: C 57.72, H 5.96, N 15.28.
reaction time a solid was formed and then separated from the 1‐(2‐Nitroso‐3,5‐dipiperidin‐1‐ylphenyl)piperidin‐1‐ium 2,4‐
reaction mixture by filtration. Compounds 5a
solids) were purified by flash chromatography on silica gel NMR (400 MHz, CDCl3, 25 °C):
(eluent:dichloromethane/n‐hexane, in different ratio J = 1.9 Hz, 1 H, arom), 5.24 (d, J = 1.9 Hz, 1 H, arom), 3.62
depending on the polarity of the different products) of the (m, 4 H, NCH2), 3.53 3.47 (m, 4 H, NCH2), 3.37 3.19 (m, 4 H,
concentrated mother liquor. The solid precipitated were NCH2), 1.88 1.56 ppm (m, 18 H, NCH2CH2 and NCH2CH2CH2).
compounds 6a = 162.0 (C), 160.8 (C),
; in some cases precipitation was favored by 13C NMR (100.56 MHz, CDCl3, 25 °C):
addition of diethyl ether to the reaction mixture. Crude 157.2 (C), 151.0 (C), 141.0 (C), 140.6 (C), 134.6 (CH), 124.5 (C),
compounds 6a were subjected to treatment for obtaining 87.4 (CH), 86.5 (CH), 51.2 (NCH2), 50.8 (NCH2), 49.5 (NCH2),
c (very dark dinitrothiophen‐3‐olate (
6a): dark red solid, 49.1 mg (60%). 1H

= 8.31 (s, 1 H, thioph), 5.36 (d,
3.56





c


c
neutral components without purification (see below).
26.18 (NCH2CH2), 25.8 (NCH2CH2), 25.5 (NCH2CH2), 24.1
(NCH2CH2CH2), 24.0 (NCH2CH2CH2), 23.8 ppm (NCH2CH2CH2).
6 | J. Name., 2012, 00, 1‐3
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HRMS (ES+) m/z: (M+) calcd for C21H33N4O 357.2649 found 25.6 (NCH2CH2), 24.5 (NCH2CH2CH2), 24.4 ppm (NCH2CH2CH2).
View Article Online
DOI: 10.1039/C6OB00243A
+
+
357.2650; ESI MS (ES+) m/z: 357 (M+); ESI MS (ES‐) m/z: 189 HRMS (ES ) m/z: (M ) calcd for C21H33N4O 357.2649 found
(M
4‐(3,5‐Dimorpholin‐4‐yl‐2‐nitrosophenyl)morpholin‐4‐ium
2,4‐dinitrothiophen‐3‐olate
(65%). 1H NMR (400 MHz, DMSO‐d6, 25 °C):
thioph), 5.77 (br.s, 1 H, arom), 5.66 (br.s., 1 H, arom), 4.4 Hz, 4 H, OCH2), 3.43 (t, J = 4.4 Hz, 4 H, NCH2), 3.25 (t, J = 4.4
.
357.2651; ESI MS (ES+) m/z: 357 (M+ + 1), 379 (M+ + Na).
4,4',4''‐(2‐Nitrosobenzene‐1,3,5‐triyl)trimorpholine
(7b):18
(
6b): dark red solid, 53.8 mg green solid, 17.5 mg (97%). 1H NMR (400 MHz, CDCl3, 25 °C):


= 8.71 (s, 1 H, = 5.60 (s, 2 H, arom), 3.94 (t, J = 4.4 Hz, 8 H, OCH2), 3.82 (t, J =
3.85
3.62


3.67 (m, 4 H, OCH2), 3.74
3.49 (m, 4 H, NCH2), 3.44


3.64 (m, 12 H, OCH2 and NCH2), Hz, 8 H, NCH2). 13C NMR (100.56 MHz, CDCl3, 25 °C):

3.30 ppm (m, 4 H, OCH2). 13C‐ (selected) = 157.5 (C), 149.0 (C), 89.5 (CH), 66.7 (OCH2), 66.4
NMR (100.56 MHz, DMSO‐d6 , 25 °C):

= 161.6 (C), 160.7 (C), (OCH2), 52.1 (NCH2), 47.0 ppm (NCH2). HRMS (ES+) m/z: (M+)
156.4 (C), 150.8 (C), 141.9 (C), 140.8 (C), 137.1 (CH), 121.1 (C), calcd for C18H27N4O4 363.2027 found 363.2031; ESI MS (ES+)
89.0 (CH), 87.4 (CH), 66.0 (OCH2), 65.8 (OCH2), 49.6 (NCH2), m/z: 363 (M+ + 1), 385 (M+ + Na), 401 (M+ + K).
48.2 ppm (NCH2). HRMS (ES+) m/z: (M+) calcd for C18H27N4O4 1,1',1''‐(2‐Nitrosobenzene‐1,3,5‐triyl)tripyrrolidine
(7c):18
= 5.02
363.2027 found 363.2030; ESI MS (ES+) m/z: 363 (M+); ESI MS dark red solid 15.2 mg (97%). (400 MHz, CDCl3, 25 °C):

(ES‐) m/z: 189 (M).
(d, J = 2.1 Hz, 1 H, arom), 4.80 (d, J= 2.3 Hz, 1 H, arom),
1‐(2‐Nitroso‐3,5‐di(pyrrolidin‐1‐yl)phenyl)pyrrolidin‐1‐ium
3.75


3.61 (m, 4 H, NCH2), 3.44 (t, J = 6.6 Hz, 4 H, NCH2),
3.20 (m, 4 H, NCH2), 2.03 1.88 ppm (m, 12 H, NCH2CH2);
(selected) = 156.1 (C),
thioph), 5.00 (d, J = 2.3 Hz, 1 H, arom), 4.89 (d, J = 2.3 Hz, 1 H, 155.8 (C), 145.0 (C), 85.0 (CH), 83.6 (CH), 51.7 (br.s., NCH2),
arom), 3.83 3.20 (m, 12 H, NCH2), 2.10 1.95 ppm (m, 12 H, 51.02 (br.s., NCH2), 48.3 (NCH2), 25.8 (NCH2CH2), 25.6
NCH2CH2). 13C NMR (100.56 MHz, CD3CN , 25 °C):
2,4‐dinitrothiophen‐3‐olate
(41%); H NMR (400 MHz, CD3CN, 25 °C):
(
6c): dark red solid, 31.0 mg 3.39

1

= 8.39 (s, 1 H, 13C NMR (100.56 MHz, CDCl3, 25 °C):




= 163.7 (C), (NCH2CH2), 25.4 ppm (NCH2CH2). HRMS (ES+) m/z: (M+) calcd
162.8 (C), 159.2 (C), 154.3 (C), 151.6 (C), 149.8 (C), 144.9 (C), for C18H27N4O 315.2179 found 315.2182; ESI MS (ES+) m/z: 315
136.2 (CH), 87.2 (CH), 85.9 (CH), 51.8 (NCH2), 50.2 (NCH2), 50.1 (M+ + H), 337 (M+ + Na).
(NCH2), 25.8 (NCH2CH2), 25.4 (NCH2CH2), 25.3 ppm (NCH2CH2). 2,4‐Dinitrothiophene‐3‐ol (8): mustard‐color solid, 6.7 mg
HRMS (ES+) m/z: (M+) calcd for C18H27N4O 315.2179 found (70%) mp > 120 °C (dec.); 1H NMR (400 MHz, CD3OD, 25 °C):

=
315.2180; ESI MS (ES+) m/z: 315 (M+); ESI MS (ES‐) m/z: 189 = 8.77 ppm (s, 1 H). 13C NMR (100.56 MHz, CD3OD, 25 °C):

(M).
151.4 (C), 138.1 (C), 133.8 (CH), 130.0 ppm (C). HRMS (ES‐)
m/z: [M‐H]– calcd for C4HN2O5S 188.9612 found 188.9614.
Isolation of compounds 7a

c and 8. General procedure
2
A 3.9x10 M methanolic/KOH solution was added to an Formation and detection of Wheland‐Meisenheimer
equimolar amount (0.05 mmol) of the salt
6 dissolved in intermediates WMa and WMc.
methanol. After about 30 min a red solid precipitated; this A solution of 1,3,5‐triaminobenzene derivative (3a or 3c, 0.04
solid was collected by filtration and dried. NMR analysis mmol) was dissolved in CD2Cl2 (1 mL) and introduced in a NMR
indicated presence of a single product. The solid was treated spectroscopy tube that was inserted in the NMR probe. When
with an equimolar amount of 0.15 M aqueous hydrochloric the probe temperature reached 70°C, an equimolar amount
acid. After dilution with water and extraction with ethyl of 2,3,4‐trinitrothiophene (9.5 mg, 0.04 mmol) was added to
acetate, the organic layer was dried over anhydrous the solution, that became blue‐coloured, and the 1H NMR
magnesium sulfate, filtered and concentrated. and chemico‐ spectrum of the resulting solution was quickly recorded. The
physical data of the residue agreed with structure
mother liquor remained after treatment of with KOH/CH3OH temperatures until 25 °C. Immediately after the mixing, the
was concentrated and the 1H NMR of the residue revealed the spectrum at –70 °C showed the appearance of new signals,
presence of main product that was isolated by some of them ascribed to compound WM, also with the aid of
chromatography on basic alumina (eluent: g‐COSY and g‐HSQC experiments (see Supporting information).
dichloromethane/methanol, 9.5/0.5) and was identified as the On raising the temperature, signals belonging to WM gradually
neutral compound . Mixing equimolar amount of 7b and in broadened then disappeared at about 35 °C for WMa and
CD3CN gave signals of 6a. Moreover, the treatment of 30 °C for WMc; a return‐back from previous temperature did
compound 7a (or 7b) with one equivalent of picric acid not produced re‐appearance of signals of WM. In case of
produced 1H NMR signals of the triaminobenzene moiety reaction of with 3a, the 1H NMR spectrum recorded at
70 °C
similar to those of 6a (or 6b) (see spectra in Fig. SI‐38 and SI‐ immediately after the mixing of the reagents at 70 °C showed
42). Chemico‐physical data of compounds 7a were according presence of compound 5a in a relative molar ratio 57/43 with
to those reported in the literature18 but since they were WMa
partial, below we report complete NMR and mass data. In case of reaction of
1,1',1''‐(2‐Nitrosobenzene‐1,3,5‐triyl)tripiperidine (7a) 18
red recorded at 70 °C immediately after the mixing of the
solid, 12.5 mg (70%). 1H NMR (400 MHz, CDCl3, 25 °C):
= 5.50 reagents showed presence of other signals, some of them
(s, 2 H, arom), 3.48 3.42 (m, 4 H, NCH2), 3.36 3.24 (m, 8 H, ascribed to compound 5c and 6c. These latter fall in the same
NCH2), 1.81 1.61 ppm (m, 18 H, NCH2CH2 and NCH2CH2CH2). region of WMc but were distinguishable because the signals of
13C NMR (100.56 MHz, CDCl3, 25 °C):
= 158.0 (C), 147.7 (C), WMc broadened and disappeared on raising the temperature
8. The system was monitored after various times and at different
6
a
7
8


2



c
.
2
with 3c, the 1H NMR spectrum
:






103.0 (C), 88.6 (CH), 52.5 (NCH2), 48.5 (NCH2), 25.8 (NCH2CH2),
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Journal Name
10 J. Miller, Aromatic Nucleophilic Substitution in Reaction
while those of 6c increased on raising the temperature probe
and remained stable.
mechanisms in organic chemistry, Monograph V8i.ewEAarbticolernO,nlCin.e,
DOI: 10.1039/C6OB00243A
Chapman, N. B. (Eds) Elsevier: Amsterdam, 1968.
11 (a) C. D. Hurd and K. L. Kreuz, J. Am. Chem. Soc., 1952, 74
3,4,5‐Trinitro‐2‐(2,4,6‐tri(piperidin‐1‐yl)cyclohexa‐2,4‐dien‐1‐
,
1
ylium‐1‐yl)‐2,3‐dihydrothiophen‐3‐ide
MHz, CD2Cl2,
(br.s, 1 H), 4.95 (br.s, 1 H), 4.05
(
WMa): H NMR: (400
2965; (b) A. H. Blatt, N. Gross and E. W. Tristram, J. Org.
Chem., 1957, 22, 1588; (c) R. Motoyama, S. Nishimura, E.
Imoto and L. Murakani, Nippon Kagaku Zasshi, 1957, 78, 954
(Chem. Abstr., 1960, 54, 14224c); (d) D. Spinelli, C. Dell'Erba
and A. Salvemini, Ann. Chim. (Rome, Italy), 1962, 52, 1156.
12 C.W. Bird, Tetrahedron, 1992, 48, 335.

70 °C): d = 5.48 (br.s, 1 H), 5.36 (br.s, 1 H), 4.98
3.51 (m, 4 H), 3.5 3.23 (m, 8
0.90 ppm (m, 18 H, overl. with those of 5a). g‐HSQC


H), 1.85
(CD2Cl2,
1

70 °C): H‐13C correlations (solvent signal set at
 =
54.47 ppm): 5.48‐91.8, 5.36‐87.4, 4.95‐55.3, 4.98‐39.3.
3,4,5‐Trinitro‐2‐(2,4,6‐tri(pyrrolidin‐1‐yl)cyclohexa‐2,4‐dien‐1‐
13 (a) D. Spinelli, V. Armanino and A. Corrao, J. Heterocycl.
Chem., 1970, 7, 1441; (b) C. Dell’Erba, F. Sancassan, M. Novi,
1
D. Spinelli and G. Consiglio, J. Chem. Soc., Perkin Trans. 2,
1991, 1631; (c) G. Consiglio, C. Dell’Erba, V. Frenna, M. Novi,
G. Petrillo, F. Sancassan and D. Spinelli, Gazz. Chim. It., 1996,
126, 165.
ylium‐1‐yl)‐2,3‐dihydrothiophen‐3‐ide
MHz, CD2Cl2, 70 °C): = 5.03 (d, J = 2.36, 1 H), 4.87 (br.s, 1 H),
4.78 (br.s, 1 H), 4.73 (br.s, 1 H), 3.82 3.40 and 2.20 1.50 ppm
(signals overl. with those of other compounds); g‐COSY
(CD2Cl2, 4.73; g‐HSQC (CD2Cl2,
70 °C): 1H‐1H correlation: 5.03
70 °C): H‐13C correlations: 5.03‐54.9, 4.87‐89.4, 4.78‐85.8,
(WMc): H NMR: (400




14 (a) D. Spinelli and C. Dell'Erba, Ann. Chim. (Rome, Italy),
1964, 54, 281; (b) G. G. Chirakadze, E. E. Geliashvili and M.


1
Sh. Gagolishvili, Izv. Akad. Nauk Gruzii, Ser. Khim., 1999, 25
203.
,

4.73‐44.6.
15 (a) D. Spinelli and C. Dell’Erba, Ann. Chim. (Rome, Italy),
1961, 51, 1306; (b) C. Boga, M. Calvaresi, P. Franchi, M.
Lucarini, S. Fazzini, D. Spinelli and D. Tonelli, Org. Biomol.
Chem., 2012, 10, 7896.
16 (a) T. C. Parker and S. R. Marder, Synthetic methods in
organic electronic and photonic materials: a practical guide,
Royal Society of Chemistry Cambridge 2015; (b) Handbook of
Thiophene‐Based Materials: Applications in Organic
Electronics and Photonics, I. F. Perepichka and D. F.
Perepichka, (Eds) John Wiley & Sons, Ltd, Chichester, 2009.
17 L. Forlani, A. Ferrara, A. Lugli and P. E. Todesco, J. Chem. Soc.,
Perkin Trans. 2, 1994, 1703.
Acknowledgements
Work supported by Alma Mater Studiorum – Università di
Bologna (RFO funds). Authors thank Mr. L. Zuppiroli for mass
spectra.
Notes and references
18 (a) F. Effenberger, W. Kurtz and P. Fischer, Chem. Ber., 1974,
107, 1285; (b) P. Fischer, W. Kurtz and F. Effenberger, Chem.
Ber., 1974, 107, 1305.
1
2
3
A. Hagfeldt, G. Boschloo, L. Sun, L. Kloo and H. Pettersson,
Chem. Rev., 2010, 110, 6595.
G. S. He, L.‐S. Tan, Q. Zheng, P. N. Prasad, Chem. Rev., 2008,
108, 1245.
(a) F. Terrier Modern Nucleophilic Aromatic Substitution,
Wiley‐VCH, Weinheim, 2013; (b) F. Terrier, Nucleophilic
Aromatic Displacement, VCH, New York, 1991.
(a) L. Forlani and C. Boga, Targets Heterocycl. Systems:
Chem. Prop., 2011, 15, 372 and ref. therein; (b) D. Spinelli, G.
Consiglio, C. Dell’Erba and M. Novi, Nucleophilic Substitution
of Thiophene Derivatives in The Chemistry of Heterocyclic
Compounds, Vol. 44: Thiophene and Its Derivatives, Part IV,
Gronowitz, S. Ed., J. Wiley & Sons: New York, 1991, pp. 295;
(c) L. Bianchi, C. Dell'Erba, M. Maccagno, S. Morganti, G.
Petrillo, E. Rizzato, F. Sancassan, E. Severi, D. Spinelli and C.
Tavani, Arkivoc, 2006, 169‐185; (d) G. Consiglio, D. Spinelli, C.
19 C. Boga, L. Forlani, S. Tozzi, E. Del Vecchio, A. Mazzanti, M.
Monari and N. Zanna, Curr. Org. Chem., 2014, 18, 512 and
ref. therein.
20 W. Runge and J. Z. Firl, Naturforsch., 1976, 31b, 1515.
4
Dell’Erba, M. Novi and G. Petrillo, Gazz. Chim. It., 1997, 127
,
753.
5
6
C. Boga, E. Del Vecchio, L. Forlani, A. Mazzanti and P. E.
Todesco, Angew. Chem. Int. Ed., 2005, 44, 3285.
C. Boga, E. Del Vecchio, L. Forlani, A. Mazzanti, C. Menchen
Lario, P. E. Todesco and S. Tozzi, J. Org. Chem., 2009, 74
,
5568.
7
8
G. Micheletti, C. Boga, M. Pafundi, S. Pollicino and N. Zanna,
Org. Biomol. Chem., 2016, 14, 768.
(a) F. Terrier, S. Lakhdar, T. Boubaker and R. Goumont, J.
Org. Chem., 2005, 70, 6242; (b) S. Lakhdar, R. Goumont, F.
Terrier, T. Boubaker, J. M. Dust and E. Buncel, Org. Biomol.
Chem., 2007, 5, 1744.
(a) C. Boga, E. Del Vecchio, L. Forlani, R. Goumont, F. Terrier
and S. Tozzi, Chem Eur. J., 2007, 13, 9600; (b) L. Forlani, C.
Boga, A. Mazzanti and N. Zanna, Eur. J. Org. Chem., 2012,
1123.
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