Synthesis and characterisation of extended π-bonding systems in cycloimmonium ylides derived from the 4,4′-bipyridine

Article abstract of DOI:10.3987/COM-02-9571

Disubstituted cycloimmonium ylides derived from the 4,4'-bipyridine with one, two or four ylidic systems in their molecular structure are described as stable compounds. Synthesis of some bridged 1,1'-disubstituted 4,4'-bipyridinium dimethylides in which 1,4- or 1,3-phenylene spacers may be used, provide some new macromolecular cycloimmonium ylides with spatially extended π-bonding system. These compounds were obtained by the chemical conversion of 4,4'-bipyridinium salts as viologens or bis-viologens, with acylating or carbamoylating agents, in basic media. The characterisation of all compounds has been mainly performed by ¹H and ¹³C NMR spectroscopy.

Full text of DOI:10.3987/COM-02-9571

HETEROCYCLES, Vol. 57, No. 12, 2002, pp. 2239 - 2254, Received, 16th July, 2002
SYNTHESIS AND CHARACTERISATION OF EXTENDED
π-BONDING SYSTEMS IN CYCLOIMMONIUM YLIDES
DERIVED FROM THE 4,4’-BIPYRIDINE
Ludovic Depature* and Gheorghe Surpateanu
Laboratoire de Synthèse Organique et Environnement, EA 2599, MREID, 145 rue
Maurice Schumann, 59140 Dunkerque, France
Email: (surpatea@univ-littoral.fr)
Abstract – Disubstituted cycloimmonium ylides derived from the 4,4’-bipyridine
with one, two or four ylidic systems in their molecular structure are described as
stable compounds. Synthesis of some bridged 1,1’-disubstituted 4,4’-bipyridinium
dimethylides in which 1,4- or 1,3-phenylene spacers may be used, provide some
new macromolecular cycloimmonium ylides with spatially extended π-bonding
system. These compounds were obtained by the chemical conversion of 4,4’-
bipyridinium salts as viologens or bis-viologens, with acylating or carbamoylating
agents, in basic media. The characterisation of all compounds has been mainly
performed by 1H and 13C NMR spectroscopy.
INTRODUCTION
Cycloimmonium ylide compounds are stables, enough to be isolated only when two electron withdrawing
groups are introduced on the carbanion. Disubstituted cycloimmonium ylide coumpounds have great
potentials, because they are particularly promising as conductive materials1-3 and are useful synthetic 1,3-
dipolar intermediates for the preparation of five-membered heterocyclic rings by various cycloaddition
reactions.4-7 As a part of our research program directed to better understanding their electrical behavior
and to the incorporation of the 4,4’-bipyridinium units in new macromolecular ylidic systems,8 we
synthesized some new disubstituted cycloimmonium ylides series with a progressive spatial extension of
the π-bonding system. To the best of our knowledge, there is no literature precedent for the synthesis of
conjugated homologues in the class of cycloimmonium ylides. We here report the synthesis of

the 1-disubstituted 4-(4’-pyridyl)pyridinium methylides (9,10) the 1,1’-disubstituted 4,4’-bipyridinium
dimethylides (13,14) and the bridged 1,1’-disubstituted 4,4’-bipyridinium dimethylide (18,19) with the
classical one, until two or four ylidic systems. The “salt method”9 has been applied and consist in the
chemical conversion of 4,4’-bipyridinium salts or viologen10,11 into disubstituted ylides. The general
procedure is schematically depicted in the Scheme 1. The non-isolable monosubstituted cycloimmonium
ylides (2) generated in basic media by the corresponding salts (1) react with acylating or carbamoylating
agents affording the disubstituted ylides (4) and (5) with two electron withdrawing carbanion groups.
Some new bridged viologens namely some new bis-viologens with phenylene spacers, were used as
starting materials to produce new bridged 4,4’-bipyridinium ylides with four ylidic systems. These
bridged 4,4’-bipyridinium compounds are also capable of behaving as molecular tweezers,11,12 a special
class of receptors that can hold planar π-electron guests through a π-π interaction resulting in sandwich-
type complexes, applied in host-guest chemistry.10-12 The NMR spectral assignments of the bridged 4,4’-
bipyridinium ylides have been performed with the easier NMR spectra of synthetic molecular models
(13,14b) and (25,26) based on pyridine, a useful source of NMR parameters to qualitatively estimate the
chemical conversion of bis-viologens.
_
X
Base
- HX
CONR'
_
+
+
R'NCO
+
N CH2R
N CHR
N CH
R
1
3
2
Base
R'COCl
- HCl
R = CN, COC6H5 ...
R' = C6H5 ...
CONHR'
R
COR'
R
_
+
_
N C
+
N C
5
4
Scheme 1
RESULTS AND DISCUSSION
In order to apply the salt method we have initially synthesized the 4,4’-bipyridinium salts. 1-
Ethoxycarbonylmethyl 4-(4’-pyridyl)pyridinium bromide (7) treated with bromide derivatives BrCH2R2
(R2=CO2C2H5, R2=COC6H5, R2=CN) provided, after recrystallisation, symmetrical or unsymmetrical 1-
ethoxycarbonylmethyl-1’-substitutent 4,4’-bipyridinium dibromides (11a-c) in good yields. The non-
isolable 4,4’-bipyridinium monosubstituted ylides (8) and (12) are readily generated “in-situ” from the
salts (7) and (11) respectively with a suspension of potassium carbonate in acetonitrile. These reactions
must be carried out without light in order to prevent the cleavage of C-—N+ bond. Then, intermediate

ylides (8) and (12) reacted with benzoyl chloride or phenyl isocyanate affording, after purification, the
stable 1-disubstituted 4-(4’-pyridyl)pyridinium methylides or 4,4’-bipyridinium monoylides (9) and (10)
and symmetrical or unsymmetrical 1,1’-disubstituted 4,4’-bipyridinium dimethylides or 4,4’-bipyridinium
bisylides (13a-c) and (14a-c) (Scheme 2) in good yields (Table 1). Two different ways are necessary to
isolate 4,4’-bipyridinium monoylides (9,10) and bisylides (13,14) from the solid inorganic layer
composed with an excess of K2CO3 and the formed KBr, KCl. Ylides (9,10) could be easily extracted
from the solid with solvent like chloroform, while this inorganic solid must be dissolved in water in order
to recuperate insoluble bisylides (13,14).
Scheme 2
-
-
-
+
BrCH2COC2H5
acetone
Br
Br
Br
BrCH2R2
+
+
R2H2C N
N CH2
CO2C2H5
N
N
N
N CH2
CO2C2H5
11a (R2 = CO2C2H5)
6
7
11b (R2 = COC6H5)
11c (R2 = CN)
K2CO3/CH3CN
K2CO3/CH3CN
_
+
_
_
+
+
N
N CHCO2C2H5
R2HC N
N CHCO2C2H5
8
12a-c
C6H5COCl or
C6H5NCO
2
C6H5COCl or
2
C6H5NCO
COR1
_
N C
R1OC
COR1
_
N C
_
C N
+
+
+
N
CO2C2H5
R2
CO2C2H5
9 (R1 = C6H5)
13a
(R = C H , R = CO C H )
1
6
5
2
2
2
5
10 (R1 = NHC6H5)
13b (R1 = C6H5, R2 = COC6H5)
13c (R1 = C6H5, R2 = CN)
14a (R1 = NHC6H5, R2 = CO2C2H5)
14b (R1 = NHC6H5, R2 = COC6H5)
14c (R1 = NHC6H5, R2 = CN)
Synthesis of defined molecular systems (18) and (19) containing four ylidic groups, required the
preparation of bridged 1’,1’’’-bis(ethoxycarbonylmethyl)-1,1’’-bis(carbonylmethyl) bis-4,4’-bipyridinium
tetrabromides (16a,b) also denominated by the bis-viologen name. Spacers between the free valences of
carbonyl groups connect the two viologens moieties. The electron withdrawing carbonyl groups are
essentials for the stabilization of the forthcoming disubstituted ylides. The bis-viologens (16a,b) with 1,4-
or 1,3-phenylene spacers respectively, are obtained by the treatment of the salt (7) with the synthetic
dibromide derivatives 2-bromo-1-[4 or 3-(2-bromoacetyl)phenyl]ethanone (15a,b) prepared by
procedures described in literature.13,14

-
+
-
Br
Br
+
BrH2C
O
O
(C2H5O2C)H2C N
N CH2
O
O
C
C
K2CO3/CH3CN
R3
C
7
+
R3
C
-
Br
+
-
Br
+
BrH2C
(C2H5O2C)H2C N
N CH2
15a (R3 = p-C6H4)
15b (R3 = m-C6H4)
16a (R3 = p-C6H4)
16b (R3 = m-C6H4)
R1OC
COR1
_
+
_
_
+
_
N C
+
+
(C2H5O2C)HC N
N CH
C N
O
O
O
C
C H O C
C
4 C6H5COCl or
4 C6H5NCO
2
5
2
R3
C
R3
C
O
R1OC
_
+
_
+
_
+
_
+
(C2H5O2C)HC N
N CH
C N
N C
C2H5O2C
COR1
17a,b
18a (R1 = C6H5, R3 = p-C6H4)
18b (R1 = C6H5, R3 = m-C6H4)
19a (R1 = NHC6H5, R3 = p-C6H4)
19b (R1 = NHC6H5, R3 = m-C6H4)
Scheme 3
Table 1. 4,4’-bipyridinium monoylides (9,10), bisylides (13,14) and tetraylides (18,19) prepared.
R3
(spacers)
Number of
ylidic system
Compounds
R1
R2
Yielda (%)
COC6H5
CONHC6H5
COC6H5
COC6H5
COC6H5
CONHC6H5
CONHC6H5
CONHC6H5
COC6H5
COC6H5
CONHC6H5
CONHC6H5
66
64
55
52
60
54
52
52
5
1
1
2
2
2
2
2
2
4
4
4
4
9
10
−
−
−
−
−
−
−
−
−
−
CO2C2H5
COC6H5
CN
CO2C2H5
13a
13b
13c
14a
14b
14c
18a
18b
19a
19b
COC6H5
CN
−
−
−
−
p-C6H4
m-C6H4
p-C6H4
m-C6H4
11
4
5
a Yields are given for purified products.
Next, according to the procedure described previously, monosubstituted ylides (17a,b) reacted with
benzoyl chloride or phenyl isocyanate affording, bridged 1’,1’’’-bis(ethoxycarbonyl substituent)-1,1’’-
bis(carbonyl substituent) bis-4,4’-bipyridinium tetramethylides or 4,4’-bipyridinium tetraylides (18-
19a,b) with 1,4- or 1,3-phenylene spacers (Scheme 3), in lower yields (Table 1). Tetraylides (18) and (19)
could be isolated from the solid inorganic layer by the two different ways exposed previously, but
extraction with chloroform provide crude products easier to purify.

1H and 13C NMR signals of disubstituted tetraylides (18) and (19) were elucidated using some synthesized
ylidic models. These models intend to reproduce the chemical environment around the 4,4’-bipyridinium
head moieties in bisylides (13b, 14b) and around the phenylene spacers (R3) in 1,4- or 1,3-(1,1’-
bis(carbonyl substituent) bis-pyridinium dimethylide)phenylene (25-26a,b) (Scheme 4). In a first
approach, the 1-phenacylpyridinium methylide (23), generated from the pyridinium salt (21) in the
presence of triethylamine in chloroform, reacted with 1,4- or 1,3-phenylenedicarbonyl chloride affording,
bisylides (25a,b) in good yields (75-80%). In a second approach, and in the same way as 4,4’-
bipyridinium ylide synthesis, the chemical conversion of the 1,1’-1,4- or 1,3-phenylenedicarbonylmethyl
bis-pyridinium dibromides (22a,b) provided bisylides (26a,b) in moderate yields (54-56%). In this case,
the best conditions for converting 22 into 26 among several examinations were TEA/CHCl3.
-
2 BrCH2COC6H5
Br
_
4TEA/CHCl3
-2 HBr
+
+
acetone
N CH2
N CHCOC6H5
2
2
2
N
COC6H5
23
20
21
ClCOR3COCl
-2 HCl
O
_
N C
O
_
C N
25a (R1 = C6H5, R3 = p-C6H4)
C
C
R3
+
+
25b (R1 = C6H5, R3 = m-C6H4)
26a (R1 = NHC6H5, R2 = p-C6H4)
26b (R1 = NHC6H5, R2 = m-C6H4)
TEA = TriEthylAmine
15a,b
R1OC
COR1
2 C6H5NCO
O
O
O
_
N CH
O
_
HC N
-
-
+
C
C
C
C
R3
R3
Br
N CH2
Br
H2C N
2TEA/CHCl3
-2 HBr
+
+
+
22a (R3 = p-C6H4)
22b (R3 = m-C6H4)
24a,b
Scheme 4
The structures of all new compounds were supported by elemental analysis and spectroscopic data (IR,
1
MS, H and 13C-NMR spectrometries). IR spectra of all ylidic compounds show a strong C=O stretching
band at 1650-1600 cm-1. The 4,4’-bipyridinium salts and ylides were characterized by ESMS spectra in
acetonitrile-water (1:1) as mobile phase for ylides and with an addition of formic acid (0.1%) for salts.
ESMS spectra revealed in all instances, some peaks at m/z values corresponding to the molecular peak
[M+ + H] for ylides and to the loss of bromine counterions [M - 2Br]+ for viologens and [M - 4Br]+ for
bis-viologens. A complete spectral assignment of 13C NMR signals was obtained with 2D (1H-13C)
HMQC and long range (1H-13C) HMBC heteronuclear correlation experiments. It is significant to mention
1
that the H-chemical shifts were assigned only on the basis of (1H-1H) COSY experiments. HMQC
13
experiment is used to determine C-chemical shifts of protonated carbons and HMBC experiment to

1
3
determine the multiple bond H-13C correlations involving the J coupling constant between the ylidic
carbon and the alpha protons of the heterocycle. Some typical 1H and 13C NMR signals were extracted to
support firmly the ylidic structures. As we expected, some characteristic features in the 1H NMR spectra
of ylidic models are the chemical shifts of 4,4’-bipyridinium and spacer moieties which resonate as
indicate in Table 2. Total conversion of bis-viologens (16a,b) into tetraylides (18) and (19) may be
1
conveniently monitored by H NMR spectral analysis on the basis of simultaneous presences of similar
4,4’-bipyridinium and spacer signals in tetraylide spectrum.
Table 2. 1H and 13C NMR spectral characterisation of tetraylides (18) and (19).
δ1H-bipyridinium
(head)
δ1H-C6H4
(spacers)
δN1H
δ13CO
δ13Cyl
Compounds
9.13(dd, J=6.3, 6.4
Hz ), 8.67(m)
182.8, 180.3
163.4
–
–
–
–
–
–
124.9, 110.7
124.7
13b
25a
25b
18a
18b
–
6.90(s)
182.3, 181.7
182.3, 181.9
–
7.22(d), 6.96(t)
6.56(t, J=7.6 Hz)
–
124.9
9.09(m), 8.65(m)
9.09(m), 8.66(m)
6.96(s)
–
7.28(m), 7.02(m)
6.65(t, J=7.7 Hz)
182.5, 182.1
180.4, 163.5
177.5, 163.3
163.0, 162.8
124.9, 110.7
9.03(m), 8.48(d,
–
12.62, 10.74
114.8, 97.9
14b
J=6.5 Hz)
–
–
6.89(s)
12.48
12.48
176.6, 163.1
176.7, 163.1
114.8
114.8
26a
26b
7.09(s), 6.80(s)
9.03, 8.97(dd, J=6.8,
6.8 Hz), 8.47(m)
9.02, 8.95 (dd, J=6.9,
6.9 Hz), 8.48(m)
6.90(s)
6.97(s)
12.49, 10.76
12.49, 10.76
–
–
19a
19b
176.8, 163.2
163.0, 162.8
114.8, 97.9
Although, the presence of large phenyl NMR signals complicated, especially the assignments of 1,3-
1
phenylene spacer, the 1,3-phenylene identification is unequivocally performed with the H-signals
observed at 6.65 and 6.97 ppm for tetraylides (18b) and (19b) respectively (Table 2). The ylidic carbon
chemical shifts are exactly determined for all studied ylides and are presents in the range 124.9-79.5 ppm.
They are greatly affected by the magnetic anisotropy effect of the carbonyl (deshielding) and cyano
(shielding) substituents. Two distinct signals are observed for unsymmetrical bisylides and tetraylides
(Table 2). The delocalization phenomena of the ylidic carbon charge tends to increase the electron density
on the carbonyl groups consequently, the carbonyl 13C-chemical shifts are displaced to the stronger
magnetic field in comparison with the corresponding salts (δCO(salt 11b)=190.4,166.2, δCO(ylide
13b)=182.8,180.3,163.4). The N1H chemical shifts, particularly affected by the formation of the NH---O=C
intramolecular hydrogen bond (δ(ylide 14b)=12.62,10.74), may also be considered as characteristic signals

for supporting ylidic structures stemming from the carbamoylation (Table 2). In conclusion, a simple and
useful preparation of new disubstituted cycloimmonium ylides derived from the 4,4’-bipyridine have been
achieved. Synthesis of spatially extended π-bonding system with four ylidic groups by spacing bisylides
provides new macromolecular ylidic systems involving the 4,4’-bipyridinium units. Total conversion of
1
bis-viologens may be monitored by H NMR spectral analysis with the useful NMR parameters of
synthesized head and spacer ylidic models.
EXPERIMENTAL
13
(1H-1H) COSY, C, (1H-13C) HMQC and HMBC NMR spectra were recorded in dimethyl sulfoxide
(DMSO-d6) at 298°K with tetramethysilane (TMS) as internal reference standard using a Bruker AM 250
spectrometer. MS spectra were recorded on a Platform II Micromass apparatus equipped with an
electrospray ionization source. IR spectra were recorded on a Perkin Elmer 2000 FT-IR using KBr pellets.
Melting points were determined in open capillary tubes with a Buchi Tottoli apparatus and are
uncorrected. TLC was performed on plates of silica-gel 60 F254 (SDS). Column chromatography SDS
silica gel 60 (70-200 µm) and neutral alumina gel (50-200 µm) were used. Chloroform and acetonitrile
were freshly distilled over CaH2. Potassium carbonate (K2CO3) was left for 12 h in an oven at 150°C, the
solid was triturated and then stored in a moisture-free atmosphere. Triethylamine, benzoyl chloride and
phenyl isocyanate were freshly distilled and stored in an inert atmosphere obtained by a stream of Argon
in a glassware equipped with rubber septa. All other compounds and solvents were used as received from
commercial sources.
General procedure for the synthesis of 1-disubstituted 4-(4’-pyridyl)pyridinium methylides (9,10):
To a solution of 7.00 g (44.8 mmol) of 4,4’-bipyridine in acetone (70 mL), 4.97 mL (44.8 mmol) of ethyl
bromoacetate dissolved in acetone (50 mL) is added. The reaction mixture is stirred at rt for 24 h. The salt
(7) is collected by filtration and recrystallised from acetone-ethanol (mp 182°C) to yield 13.90 g (96%).
To a stirred suspension of an excess of anhydrous K2CO3 (2.76 g, 20 mmol) in dry acetonitrile (100 mL)
is added 1.29 g (4 mmol) of the salt (7). The characteristic red-orange color of monosubstituted ylide (8)
is observed. Next, to this mixture, 0.49 mL (4.2 mmol) of benzoyl chloride or 0.46 mL (4.2 mmol) of
phenyl isocyanate dissolved in dry acetonitrile (5 mL) is added drop-wise. The reaction mixture is stirred
for 12 h at rt, under nitrogen atmosphere, in absence of light. The suspension is filtered and thoroughly
washed with chloroform (50 mL). The solvent is evaporated. The residue is dissolved in water (100 mL)
and then extracted twice with chloroform (2×100 mL) in order to eliminate the residual K2CO3, KBr and
KCl. The organic layer is dried on anhydrous MgSO4, filtered and concentrated to dryness. The crude

products (9) and (10) are purified by silica gel column chromatography with acetone-ethanol (3:1) and
acetone-hexane (3:1) respectively as eluents.
1-(1-Benzoyl-1-ethoxycarbonyl) 4-(4’-pyridyl)pyridinium methylide (9): Yield 0.91 g (66%), mp
171°C Anal. Calcd for C21H18N2O3: C, 72.80; H, 5.24; N, 8.09. Found: C, 72.91; H, 5.25; N, 8.12 − 1H
NMR (DMSO-d6/TMS): 8.96 (d, 2H, J = 7.0 Hz, CH ortho/N+), 8.84 (d, 2H, J = 6.1 Hz, CH ortho/N),
8.44 (d, 2H, J = 7.0 Hz, CH meta/N+), 8.04 (d, 2H, J = 6.1 Hz, CH meta/N), 7.40, 7.30 (m, 5H, phenyl),
3.78 (q, 2H, J = 7.1 Hz, CH2), 0.81 (t, 3H, J = 7.1 Hz, CH3) − 13C NMR (DMSO-d6): 180.3, 163.5 (CO),
150.9 (CH ortho/N), 150.3 (Cq pyridinium), 150.0 (CH ortho/N+), 141.4 (Cq pyridyl), 143.8, 127.6, 127.3,
126.8 (phenyl), 123.9 (CH meta/N+), 121.8 (CH meta/N), 110.5 (Cyl), 57.6 (CH2), 14.0 (CH3) − IR (KBr):
3105 cm-1, 3039, 2981, 2895, 1643, 1503, 1373, 1315, 1162, 1064, 1047 − MS (ES+, cone 39), m/z (%):
[M++Na+] = 369.3 (100), [M++H] = 347.3 (20).
1-(1-Ethoxycarbonyl-1-N-phenylcarbamoyl) 4-(4’-pyridyl)pyridinium methylide (10): Yield 0.92 g
(64%), mp 174°C. Anal. Calcd for C21H19N3O3: C, 69.78; H, 5.30; N, 11.63. Found: C, 69.59; H, 5.26; N,
11.51 − 1H NMR (DMSO-d6/TMS): 10.76 (s, 1H, NH), 8.94 (d, 2H, J = 6.9 Hz, CH ortho/N+), 8.84 (d,
2H, J = 6.1 Hz, CH ortho/N), 8.40 (d, 2H, J = 6.9 Hz, CH meta/N+), 8.04 (d, 2H, J = 6.1 Hz, CH meta/N),
7.54 (d, 2H, J = 7.8 Hz, CH ortho/phenyl), 7.22 (t, 2H, J = 7.8 Hz, CH meta/phenyl), 6.89 (t, 1H, J = 7.3
Hz, CH para/phenyl), 4.03 (q, 2H, J = 7.0 Hz, CH2), 1.11 (t, 3H, J = 7.0 Hz, CH3) − 13C NMR (DMSO-
d6): 163.5, 163.2 (CO), 150.9 (CH ortho/N), 150.3 (CH ortho/N+), 149.6 (Cq pyridinium), 141.3 (Cq
pyridyl), 140.8, 128.7, 121.0, 118.1 (phenyl), 123.6 (CH meta/N+), 121.8 (CH meta/N), 97.3 (Cyl), 57.7
(CH2), 14.8 (CH3) − IR (KBr): 3268 cm-1, 3184, 3112, 3039, 2969, 2921, 1632, 1580, 1524, 1446, 1373,
1091, 1076 − MS (ES+, cone 39), m/z (%): [M++Na+] = 384.3 (90), [M++H] = 362.3 (100).
General procedure for the synthesis of 1,1’-disubstituted 4,4’-bipyridinium dimethylides (13,14): To
a solution of the salt 7 (6.19 mmol, 2.00 g) in anhydrous ethanol (20 mL) is added dropwise ethyl
bromoacetate (6.19 mmol, 0.68 mL) dissolved in anhydrous ethanol (10 mL) or phenacyl bromide (6.19
mmol, 1.23 g) dissolved in dimethylformamide (10 mL) or 2-bromoacetonitrile (6.19 mmol, 0.44 mL)
dissolved in acetone (20 mL). The reaction mixture is stirred and refluxed for 24 h. The yellow powders
are collected by vacuum filtration and washed with acetone (50 mL). The salts (11a-c) were recrystallised
from anhydrous ethanol, ethanol-water and acetone-ethanol respectively. To a stirred suspension of an
excess of anhydrous K2CO3 (20 mmol, 2.76 g) in dry acetonitrile (100 mL) is added 0.98 g (2 mmol) of
the salt (11a) or 1.04 g (2 mmol) of the salt (11b) or 0.88 g (2 mmol) of the salt (11c). The characteristic
red-purple colors of monosubstituted ylides (12a-c) are observed. Next, to this mixture, 0.51 mL (4.4
mmol) of benzoyl chloride or 0.48 mL (4.4 mmol) of phenyl isocyanate dissolved in dry acetonitrile (5

mL) is added drop-wise. The reaction mixture is stirred for 48 h at rt, under nitrogen atmosphere, in
absence of light. The suspension is filtered and thoroughly washed with acetonitrile (50 mL). The solid is
triturated in water (100 mL) with ultrasound stirring in order to dissolve the excess of K2CO3 and the
formed KBr, KCl. The crude products are filtered and successively washed with water (10 mL),
acetonitrile (10 mL) and ether (50 mL). Bisylides (13a-c) are recrystallized from acetonitrile-
dimethylformamide. Bisylides (14a-c) are washed in boiling chloroform and finally isolated by filtration.
1,1’-Bis(ethoxycarbonylmethyl) 4,4’-bipyridinium dibromide (11a): Yield 2.15 g (71%), mp 185°C.
Anal. Calcd for C18H22N2O4Br2: C, 44.26; H, 4.54; N, 7.74. Found: C, 44.41; H, 5.60; N, 7.82 – 1H NMR
(DMSO-d6/TMS): 9.45 (d, 4H, J = 5.8 Hz, CH ortho/N+), 8.98 (d, 4H, J = 5.8 Hz, CH meta/N+), 5.87 (s,
4H, CH2N+), 4.28 (q, 4H, J = 7.1 Hz, CH2), 1.29 (t, 6H, J = 7.1 Hz, CH3) – 13C NMR (DMSO-d6): 166.1
(CO), 149.6 (Cq bipyridinium), 147.2 (CH ortho/N+), 126.6 (CH meta/N+), 62.5 (CH2), 60.3 (CH2N+),
14.0 (CH3) – IR (KBr): 3040 cm-1, 3006, 2934, 2857, 1754, 1643, 1458, 1381, 1351, 1231, 1201, 1026 –
MS (ES+, cone 70), m/z (%): [M-2Br]+ = 329.3 (90), 243.1 (42), 214.8 (100).
1-Ethoxycarbonylmethyl-1’-phenacyl 4,4’-bipyridinium dibromide (11b): Yield 2.41 g (75%), mp
221°C. Anal. Calcd for C22H22N2O3Br2: C, 50.77; H, 4.26; N, 5.38. Found: C, 50.69; H, 4.38; N, 5.24 –
1H NMR (DMSO-d6/TMS): 9.43, 9.37 (dd, 4H, J = 6.6, 6.6 Hz, CH ortho/N+), 8.97 (m, 4H, CH meta/N+),
8.12 (d, 2H, J = 7.3 Hz, CH ortho/phenyl), 7.83 (t, 1H, J = 7.7 Hz, CH para/phenyl), 7.70 (t, 2H, J = 7.7
Hz, CH meta/phenyl), 6.68 (s, 2H, CH2N+), 5.85 (s, 2H, CH2N+), 4.29 (q, 2H, J = 7.1 Hz, CH2), 1.30 (t,
13
3H, J = 7.1 Hz, CH3) – C NMR (DMSO-d6): 190.4, 166.2 (CO), 149.8, 149.3 (Cq bipyridinium), 147.2
(CH ortho/N+), 134.8, 133.5, 129.2, 128.3 (phenyl), 126.6 (CH meta/N+), 66.3 (CH2N+), 62.4 (CH2), 60.4
(CH2N+), 14.0 (CH3) – IR (KBr): 3032 cm-1, 2944, 1756, 1686, 1637, 1595, 1577, 1555, 1506, 1453,
1338, 1214, 1021 – MS (ES+, cone 70), m/z (%): [M-2Br]+ = 361.3 (100), 274.5 (20), 169.3 (90).
1-Ethoxycarbonylmethyl-1’-cyanomethyl 4,4’-bipyridinium dibromide (11c): Yield 2.05 g (75%),
mp 191°C. Anal. Calcd for C16H17N3O2Br2: C, 43.54; H, 3.88; N, 9.53. Found: C, 43.66; H, 3.91; N, 9.62
1
– H NMR (DMSO-d6/TMS): 9.57, 9.42 (dd, 4H, J = 6.6, 6.6 Hz, CH ortho/N+), 8.94 (m, 4H, CH
meta/N+), 6.18 (s, 2H, CH2N+), 5.84 (s, 2H, CH2N+), 4.28 (q, 2H, J = 7.1 Hz, CH2), 1.29 (t, 3H, J = 7.1
Hz, CH3) – 13C NMR (DMSO-d6): 166.2 (CO), 150.3, 149.3 (Cq bipyridinium), 147.3, 146.5 (CH
ortho/N+), 127.2, 126.6 (CH meta/N+), 114.1 (CN), 62.5 (CH2), 60.4, 47.7 (CH2N+), 14.0 (CH3) – IR
(KBr): 3045 cm-1, 2915, 2989, 2861, 2818, 1742, 1641, 1560, 1511, 1458, 1372, 1348, 1225 – MS (ES+,
cone 70), m/z (%): [M-2Br]+ = 282.2 (53), 242.9 (20), 169.7 (100).
1,1’-(1,1’-Ethoxycarbonyl-1,1’-benzoyl) 4,4’-bipyridinium dimethylide (13a): Yield 0.59 g (55%), mp
1
237°C. Anal. Calcd for C32H28N2O6: C, 71.61; H, 5.26; N, 5.22. Found: C, 71.72; H, 5.20; N, 5.28 – H

NMR (DMSO-d6/TMS): 9.09 (d, 4H, J = 6.3 Hz, CH ortho/N+), 8.63 (d, 4H, J = 6.3 Hz, CH meta/N+),
13
7.41, 7.32 (m, 10H, phenyl), 3.80 (q, 4H, J = 7.0 Hz, CH2), 0.82 (t, 6H, J = 7.0 Hz, CH3) – C NMR
(DMSO-d6): 180.3, 163.4 (CO), 150.0 (CH ortho/N+), 146.5 (Cq bipyridinium), 143.7, 127.6, 127.2,
126.8 (phenyl), 124.8 (CH meta/N+), 110.7 (Cyl), 57.7 (CH2), 14.0 (CH3) – IR (KBr): 3121 cm-1, 3028,
2976, 2923, 1653, 1623, 1525-1511, 1360, 1299 – MS (ES+, cone 39), m/z (%): [M++Na+] = 559.2 (100),
[M++H] = 537.2 (28).
1,1’-(1-Ethoxycarbonyl-1’-benzoyl-1,1’-benzoyl) 4,4’-bipyridinium dimethylide (13b): Yield 0.59 g
(52%), mp 250°C. Anal. Calcd for C36H28N2O5: C, 76.03; H, 4.96; N, 4.93. Found: C, 76.22; H, 5.04; N,
1
4.98 – H NMR (DMSO-d6/TMS): 9.13 (dd, 4H, J = 6.3, 6.4 Hz, CH ortho/N+), 8.67 (m, 4H, CH
meta/N+), 7.42, 7.32, 7.24, 7.00 (m, 15H, phenyl), 3.80 (q, 2H, J = 7.0 Hz, CH2), 0.83 (t, 3H, J = 7.0 Hz,
CH3) – 13C NMR (DMSO-d6): 182.8, 180.3, 163.4 (CO), 150.0 (CH ortho/N+), 146.9, 146.5 (Cq
bipyridinium), 143.7, 142.0, 128.4, 127.2, 126.8 (phenyl), 124.9, 124.8 (CH meta/N+), 124.9, 110.7 (Cyl),
57.6 (CH2), 14.0 (CH3) – IR (KBr): 3117 cm-1, 3033, 2973, 1645, 1630, 1530, 1499, 1382, 1360, 1307,
1290 – MS (ES+, cone 39), m/z (%): [M++Na+] = 591.3 (35), [M++H] = 569.3 (100).
1,1’-(1-Ethoxycarbonyl-1’-cyano-1,1’-benzoyl) 4,4’-bipyridinium dimethylide (13c): Yield 0.58 g
(60%), mp 234°. Anal. Calcd for C30H23N3O4: C, 73.59; H, 4.74; N, 8.59. Found: C, 73.42; H, 4.59; N,
1
8.68 – H NMR (DMSO-d6/TMS): 9.49 (d, 4H, J = 6.3 Hz, CH ortho/N+), 9.06 (d, 4H, J = 6.0 Hz, CH
ortho/N+), 8.63 (d, 4H, J = 6.5 Hz, CH meta/N+), 8.56 (d, 4H, J = 6.4 Hz, CH meta/N+), 7.71, 7.47, 7.42,
7.32 (m, 10H, phenyl), 3.80 (q, 2H, J = 7.0 Hz, CH2), 0.83 (t, 3H, J = 7.0 Hz, CH3) – 13C NMR (DMSO-
d6): 180.4, 178.5, 163.5 (CO), 150.0, 140.6 (CH ortho/N+), 146.2, 140.1 (Cq bipyridinium), 143.7, 142.4,
130.0, 128.0, 127.7, 127.5, 127.3, 126.8 (phenyl), 125.2, 124.1 (CH meta/N+), 121.7 (CN), 110.7, 89.4
(Cyl), 57.7 (CH2), 14.1 (CH3) – IR (KBr): 3105 cm-1, 3050, 2979, 2175, 1641, 1622, 1544, 1516, 1480,
1369, 1341, 1312, 1260, 1208 – MS (ES+, cone 39), m/z (%): [M++Na+] = 512.3 (100), [M++H] = 490.4
(59).
1,1’-(1,1’-Ethoxycarbonyl-1,1’-N-phenylcarbamoyl) 4,4’-bipyridinium dimethylide (14a): Yield 0.61
g (54%), mp 158°C. Anal. Calcd for C32H30N4O6: C, 67.81; H, 5.34; N, 9.89. Found: C, 67.92; H, 5.23;
N, 9.98 – 1H NMR (DMSO-d6/TMS): 10.76 (s, 2H, NH), 9.04 (d, 4H, J = 6.5 Hz, CH ortho/N+), 8.55 (d,
4H, J = 6.5 Hz, CH meta/N+), 7.54 (d, 4H, J = 7.9 Hz, CH ortho/phenyl), 7.23 (t, 4H, J = 7.7 Hz, CH
meta/phenyl), 6.90 (t, 2H, J = 7.1 Hz, CH para/phenyl), 4.06 (q, 4H, J = 6.8 Hz, CH2), 1.13 (t, 6H, J = 6.8
13
Hz, CH3) – C NMR (DMSO-d6): 163.4, 162.9 (CO), 150.1 (CH ortho/N+), 145.8 (Cq bipyridinium),
140.7, 128.7, 121.1, 118.2 (phenyl), 124.3 (CH meta/N+), 97.8 (Cyl), 57.9 (CH2), 14.8 (CH3) – IR (KBr):

3205 cm-1, 3115, 2980, 1637, 1605, 1579, 1529, 1439, 1343, 1305, 1086 – MS (ES+, cone 39), m/z (%):
[M+ + Na+] = 589.5 (25), [M+ + H] = 567.5 (100).
1,1’-(1-Ethoxycarbonyl-1’-benzoyl-1,1’-N-phenylcarbamoyl) 4,4’-bipyridinium dimethylide (14b):
Yield 0.62 g (52%), mp 156°C. Anal. Calcd for C36H30N4O5: C, 72.21; H, 5.05; N, 9.36. Found: C, 72.34;
1
H, 5.13; N, 9.48 – H NMR (DMSO-d6/TMS): 12.62 (s, 1H, NH), 10.74 (s, 1H, NH), 9.03 (m, 4H, CH
ortho/N+), 8.48 (d, 4H, J = 6.5 Hz, CH meta/N+), 7.61, 7.53 (dd, 4H, J = 7.8, 7.8 Hz, CH ortho/phenyl),
7.28, 7.22, 7.20 (mms, 9H, CH meta/phenyl, CH phenyl), 6.96, 6.89 (tt, 2H, J = 7.3, 7.3 Hz, CH
para/phenyl), 4.04 (q, 2H, J = 7.0 Hz, CH2), 1.12 (t, 3H, J = 7.0 Hz, CH3) – 13C NMR (DMSO-d6): 177.5,
163.3, 163.0, 162.8 (CO), 150.2, 150.1 (CH ortho/N+), 146.6, 145.1 (Cq bipyridinium), 140.8, 140.7,
140.4, 128.8, 128.7, 128.4, 128.0, 127.0, 121.7, 121.1, 118.8, 118.2 (phenyl), 124.4, 124.3 (CH meta/N+),
114.8, 97.9 (Cyl), 58.0 (CH2), 14.8 (CH3) – IR (KBr): 3273 cm-1, 3056, 2929, 1632, 1604, 1581, 1534,
1478, 1237, 1091, 1073 – MS (ES+, cone 39), m/z (%): [M++Na+] = 621.1 (46), [M++H] = 599.1 (100).
1,1’-(1-Ethoxycarbonyl-1’-cyano-1,1’-N-phenylcarbamoyl) 4,4’-bipyridinium dimethylide (14c):
Yield 0.54 g (52%), mp 166°C. Anal. Calcd for C30H25N5O4: C, 69.34; H, 4.85; N, 13.48. Found: C,
1
69.12; H, 4.73; N, 13.28 – H NMR (DMSO-d6/TMS): 10.75 (s, 1H, NH), 9.25 (d, 2H, J = 7.0 Hz, CH
ortho/N+), 8.93 (d, 2H, J = 7.1 Hz, CH ortho/N+), 8.92 (s, 1H, NH), 8.42 (m, 4H, CH meta/N+), 7.57, 7.53
(dd, 4H, J = 7.8, 7.8 Hz, CH ortho/phenyl), 7.25, 7.22 (tt, 4H, J = 8.0, 7.8 Hz, CH meta/phenyl), 6.97,
6.89 (tt, 2H, J = 7.3, 7.3 Hz, CH para/phenyl), 4.04 (q, 2H, J = 7.0 Hz, CH2), 1.12 (t, 3H, J = 7.0 Hz,
13
CH3) – C NMR (DMSO-d6): 163.4, 163.0, 162.1 (CO), 150.0, 136.4 (CH ortho/N+), 145.9, 136.4 (Cq
bipyridinium), 140.7, 140.0, 128.7, 128.3, 122.1, 121.0, 120.0, 118.1 (phenyl), 124.6, 122.8 (CH
meta/N+), 120.6 (CN), 97.4, 79.5 (Cyl), 57.8 (CH2), 14.8 (CH3) – IR (KBr): 3122 cm-1, 3103, 3035, 2171,
1582, 1531, 1366, 1336, 1264, 1217, 1186 – MS (ES+, cone 39), m/z (%): [M++Na+] = 542.0 (11), [M++
H] = 520.1 (100).
General procedure for the synthesis of 1,4- or 1,3-(1’,1’’’-bis(ethoxycarbonylsubstituent)-1,1’’-
bis(carbonylsubstituent) bis-4,4’-bipyridinium tetramethylide)phenylene (18,19): To a solution of
2.00 g (6.20 mmol) of the salt (7) in dimethylformamide (80 mL) or in anhydrous ethanol (80 mL), is
added 1.00 g (3.10 mmol) of (15a) dissolved in dimethylformamide (80 mL) or 1.00 g (3.10 mmol) of
15b dissolved in acetone (80 mL) respectively. The reaction mixture is stirred and heated to 60°C for 72
h. The green powders are collected by vacuum filtration and washed with dichloromethane. Crude
products are purified by silica gel column chromatography (Methanol-NH4Claq 2M, 3:2) to afford
products (Rf = 0.38) which were dissolved in water. After the addition of saturated NH4PF6aq, (16a.4PF6)
or (16b.4PF6) precipitated out as red-purple solid, filtered and washed in water (10 mL), methanol (20

mL), ether (20 mL) sucessively. These products are dissolved in nitromethane. After the addition of a
saturated solution of (C2H5)4N+Br- in nitromethane, (16a) or (16b) precipitated out as yellow solid,
filtered and washed in nitromethane (10 mL), ether (20 mL). To a stirred suspension of an excess of
anhydrous K2CO3 (20 mmol, 2.76 g) in dry acetonitrile (100 mL) is added 0.96 g (1 mmol) of the salt
(16a) or (16b). The characteristic purple color of monosubstituted ylides (17) is observed. Next, to this
mixture, 0.56 mL (4.8 mmol) of benzoyl chloride or 0.52 mL (4.8 mmol) of phenyl isocyanate dissolved
in dry acetonitrile (5 mL) is added drop-wise. The reaction mixture is stirred for 72 h at rt, under nitrogen
atmosphere, in absence of light. The suspension is filtered and thoroughly washed with acetonitrile. Tetra-
ylides (18) and (19) are extracted from the solid with chloroform. The solvent is removed. Crude products
(18-19a) and (18-19b) are washed in acetonitrile with ultrasound stirring and chromatographed on neutral
alumina gel with 20% or 10 % methanol in dichloromethane respectively as eluents.
1’,1’’’-Bis(ethoxycarbonylmethyl)-1,1’’-1,4-phenylenedicarbonylmethyl bis-4,4’-bipyridinium
tetrabromide (16a): Yield 1.08 g (36%), mp 190°C (decomp). Anal. Calcd for C38H38N4O6Br4: C,
47.40; H, 5.82; N, 9.97. Found: C, 47.62; H, 5.93; N, 9.78 – 1H NMR (DMSO-d6/TMS): 9.45 (m, 8H, CH
ortho/N+), 9.02 (m, 8H, CH meta/N+), 8.38 (s, 4H, CH phenylene), 6.83 (s, 4H, CH2N+), 5.88 (s, 4H,
13
CH2N+), 4.29 (q, 4H, J = 7.1 Hz, CH2), 1.30 (t, 6H, J = 7.1 Hz, CH3) – C NMR (DMSO-d6): 190.3,
166.2 (CO), 149.7, 149.4 (Cq bipyridinium), 147.2 (CH ortho/N+), 137.7, 128.9 (phenylene), 126.6, 126.5
(CH meta/N+), 66.6, 60.3 (CH2N+), 62.5 (CH2), 14.0 (CH3) – IR (KBr): 3039 cm-1, 2942, 2858, 1746,
1702, 1641, 1562, 1504, 1454, 1375, 1342, 1222 – MS (ES+, cone 78), m/z (%): [M-4Br]+ = 643.8 (10),
557.9 (11), 471.9 (6), 242.9 (39), 214.9 (51), 169.7 (100).
1’,1’’’-Bis(ethoxycarbonylmethyl)-1,1’’-1,3-phenylenedicarbonylmethyl bis-4,4’-bipyridinium
tetrabromide (16b): Yield 1.12 g (37%), mp 190°C (decomp). Anal. Calcd for C38H38N4O6Br4: C, 47.40;
H, 5.82; N, 9.97. Found: C, 47.56; H, 5.95; N, 9.81 – 1H NMR (DMSO-d6/TMS): 9.42 (d, 8H, J = 5.6 Hz,
CH ortho/N+), 8.97 (m, 8H, CH meta/N+), 8.67 (s, 1H, CH phenylene), 8.53 (d, 2H, J = 7.8 Hz, CH
phenylene), 8.04 (t, 1H, J = 7.8 Hz, CH phenylene), 6.81 (s, 4H, CH2N+), 5.83 (s, 4H, CH2N+), 4.29 (q,
13
4H, J = 7.0 Hz, CH2), 1.30 (t, 6H, J = 7.0 Hz, CH3) – C NMR (DMSO-d6): 190.1, 166.2 (CO), 149.7,
149.4 (Cq bipyridinium), 147.2 (CH ortho/N+), 134.3, 134.0, 130.3, 127.3 (phenylene), 126.6 (CH
meta/N+), 66.4, 60.4 (CH2N+), 62.5 (CH2), 14.0 (CH3) – IR (KBr): 3041 cm-1, 3039, 2984, 2928, 2859,
1730, 1696, 1337, 1224, 1179, 1021, 824 – MS (ES+, cone 78), m/z (%), [M-4Br]+ = 643.7 (28), 557.8
(12), 471.8 (17), 242.8 (47), 215.1 (84), 169.7 (100).
1,4-(1’,1’’’-(1’,1’’’-Ethoxycarbonyl-1’,1’’’-benzoyl)-1,1’’-(1,1’’-carbonyl-1,1’’-benzoyl) bis-4,4’-
bipyridinium tetramethylide)phenylene (18a): red solid. Yield 0.046 g (5%). Anal. Calcd for

C66H50N4O10: C, 47.40; H, 5.82; N, 9.97. Found: C, 47.56; H, 5.75; N, 9.81 – 1H NMR (DMSO-d6/TMS):
9.09 (m, 8H, CH ortho/N+), 8.65 (m, 8H, CH meta/N+), 7.41, 7.32, 7.23, 7.00, 6.96 (m, 24H, CH phenyl,
phenylene), 3.79 (q, 4H, J = 7.0 Hz, CH2), 0.83 (t, 6H, J = 7.0 Hz, CH3) – Partial 13C NMR (DMSO-d6):
150.0 (CH ortho/N+), 128.5, 124.5 (CH phenyl, phenylene) – IR (KBr): 3114 cm-1, 3035, 2964, 1629,
1490, 1370, 1260, 1094, 1044, 815 – MS (ES+, cone 81), m/z (%): [M++Na+] = 1082.5 (37), [M++H] =
1059.3 (3), 892.1 (100), 701.7 (17), 369.2 (25).
1,3-(1’,1’’’-(1’,1’’’-Ethoxycarbonyl-1’,1’’’-benzoyl)-1,1’’-(1,1’’-carbonyl-1,1’’-benzoyl) bis-4,4’-
bipyridinium tetramethylide)phenylene (18b): red solid. Yield 0.116 g (11%). Anal. Calcd for
C66H50N4O10: C, 47.40; H, 5.82; N, 9.97. Found: C, 47.66; H, 5.95; N, 9.91 – 1H NMR (DMSO-d6/TMS):
9.09 (m, 8H, CH ortho/N+), 8.66 (m, 8H, CH meta/N+), 7.42, 7.32, 7.28, 7.02 (m, 23H, CH phenyl,
phenylene), 6.65 (t, 1H, J = 7.7 Hz, CH phenylene), 3.81 (q, 4H, J = 7.0 Hz, CH2), 0.83 (t, 6H, J = 7.0
Hz, CH3) – 13C NMR (DMSO-d6): 182.5, 182.1, 180.4, 163.5 (CO), 150.0, 149.8 (CH ortho/N+), 146.8,
146.5 (Cq bipyridinium), 143.7, 141.9, 140.3, 128.5, 128.3, 127.7, 127.3, 126.9, 124.5 (phenyl,
phenylene), 125.0, 124.8 (CH meta/N+), 124.9, 110.7 (Cyl), 57.7 (CH2), 14.0 (CH3) – IR (KBr): 3116
cm-1, 3070, 3034, 2968, 1625, 1490, 1365, 816, 700 – MS (ES+, cone 81), m/z (%): [M++Na+] = 1082.4
(48), [M++H] = 1059.4 (15), 893.0 (100), 702.1 (42), 369.2 (58).
1,4-(1’,1’’’-(1’,1’’’-Ethoxycarbonyl-1’,1’’’-N-phenylcarbamoyl)-1,1’’-(1,1’’-carbonyl-1,1’’-N-
phenylcarbamoyl) bis-4,4’-bipyridinium tetramethylide)phenylene (19a): Purple solid. Yield 0.045 g
(4%). Anal. Calcd for C66H54N8O10: C, 70.81; H, 4.86; N, 10.01. Found: C, 70.68; H, 4.75; N, 9.92 – 1H
NMR (DMSO-d6/TMS): 12.49 (s, 2H, NH), 10.76 (s, 2H, NH), 9.03, 8.97 (dd, 8H, J = 6.8, 6.8 Hz, CH
ortho/N+), 8.47 (m, 8H, CH meta/N+), 7.52 (m, 8H, CH ortho/phenyl), 7.22 (m, 8H, CH meta/phenyl),
6.95, 6.90 (ms, 8H, CH para/phenyl, CH phenylene), 4.01 (q, 4H, J = 7.0 Hz, CH2), 1.07 (t, 6H, J = 7.0
Hz, CH3) – Partial 13C NMR (DMSO-d6): 150.3, 150.1 (CH ortho/N+), 128.9, 118.0 (CH phenyl,
phenylene) – IR (KBr): 3116 cm-1, 3051, 2978, 1632, 1584, 1520, 1440, 1234, 1090, 1072 – MS (ES+,
cone 39), m/z (%): [M++H] = 1119.5 (82), 915.1 (100), 709.3 (21).
1,3-(1’,1’’’-(1’,1’’’-Ethoxycarbonyl-1’,1’’’-N-phenylcarbamoyl)-1,1’’-(1,1’’-carbonyl-1,1’’-N-
phenylcarbamoyl) bis-4,4’-bipyridinium tetramethylide)phenylene (19b): Purple solid. Yield 0.056 g
(5%). Anal. Calcd for C66H54N8O10: C, 70.81; H, 4.86; N, 10.01. Found: C, 70.68; H, 4.75; N, 9.92 – 1H
NMR (DMSO-d6/TMS): 12.49 (s, 2H, NH), 10.76 (s, 2H, NH), 9.02, 8.95 (dd, 8H, J = 6.9, 6.9 Hz, CH
ortho/N+), 8.48 (m, 8H, CH meta/N+), 7.54 (m, 8H, CH ortho/phenyl), 7.23 (m, 9H, CH meta/phenyl, CH
phenylene), 6.97, 6.90 (sm, 7H, CH phenylene, CH para/phenyl), 4.00 (q, 4H, J = 7.0 Hz, CH2), 1.07 (t,
6H, J = 7.0 Hz, CH3) – 13C NMR (DMSO-d6): 176.8, 163.2, 163.0, 162.8 (CO), 150.1, 150.0 (CH

ortho/N+), 146.6, 145.2 (Cq bipyridinium), 140.9, 140.8, 140.4, 128.8, 128.6, 127.1, 126.7, 125.5, 121.7,
121.1, 118.8, 118.2 (phenyl, phenylene), 124.4, 124.3 (CH meta/N+), 114.8, 97.9 (Cyl), 58.1 (CH2), 14.7
(CH3) – IR (KBr): 3116 cm-1, 3054, 2977, 1632, 1584, 1522, 1441, 1234, 1092, 1073 – MS (ES+, cone
39), m/z (%): [M++H] = 1119.6 (78), 915.1 (100), 709.6 (25), 400.7 (42).
General procedure for the synthesis of 1,4- or 1,3-(1,1’-bis(carbonyl substituent) bis-pyridinium
dimethylide)phenylene (25,26): To a stirred suspension of 0.55 g (2 mmol) of 1-phenacylpyridinium
bromide in dry chloroform (20 mL) is added an excess of TEA (5 mmol, 0.69 mL). A clear yellow
solution of monosubstituted ylide (23) is observed. Next, to this solution, 0.20 g (1 mmol) of 1,4- or 1,3-
phenylenedicarbonyl chloride dissolved in dry chloroform (20 mL) is added drop-wise. The reaction
mixture is stirred for 24 h at rt, under nitrogen atmosphere, in absence of light. The product (25a) is
filtered, washed in chloroform. The crude product, dissolved in water (20 mL) with small addition of 1M
HCl, is washed twice with chloroform (2×50 mL). The aqueous layer is neutralised with small addition of
20% Na2CO3 until no further precipitation is observed. The precipitate is collected and washed with
acetone. For 25b, the solvent is evaporated, the residue is triturated with ultrasound stirring in 10%
Na2CO3 (100 mL) and then extracted twice with dichloromethane (2×100 mL). The organic layer is dried
on anhydrous MgSO4, filtered and concentrated to dryness. The crude product (25b) crystallised from
acetone with diethyl ether.
1,4-(1,1’-(1,1’-Carbonyl-1,1’-benzoyl) bis-pyridinium dimethylide)phenylene (25a): Yield 0.42 g
(80%), mp 273°C. Anal. Calcd for C34H26N4O4: C, 77.83; H, 4.61; N, 5.34. Found: C, 77.61; H, 4.68; N,
1
5.23 – H NMR (DMSO-d6/TMS): 8.79 (d, 4H, J = 5.7 Hz, CH ortho/N+), 8.45 (t, 2H, J = 7.7 Hz, CH
para/N+), 7.99 (t, 4H, J = 7.0 Hz, CH meta/N+), 7.19 (d, 4H, J = 6.8 Hz, CH ortho/phenyl), 7.07 (t, 2H,
13
CH para/ phenyl), 6.99 (t, 4H, CH meta/phenyl), 6.90 (s, 4H, CH phenylene) – C NMR (DMSO-d6):
182.3, 181.7 (CO), 149.5 (CH ortho/N+), 143.4 (CH para/N+), 142.1, 128.4, 128.0, 126.9 (phenyl), 126.9
(CH meta/N+), 141.8, 126.7 (phenylene), 124.7 (Cyl) – IR (KBr): 3110 cm-1, 3089, 1627, 1566, 1547,
1484, 1464, 1390, 1338, 1209, 897, 734 – MS (ES+, cone 39), m/z (%): [M++Na+] = 547.3 (100), [M++
H] = 525.3 (27).
1,3-(1,1’-(1,1’-Carbonyl-1,1’-benzoyl) bis-pyridinium dimethylide)phenylene (25b): Yield 0.39 g
(75%), mp 172°C. Anal. Calcd for C34H26N4O4: C, 77.83; H, 4.61; N, 5.34. Found: C, 77.91; H, 4.57; N,
1
5.32 – H NMR (DMSO-d6/TMS): 8.79 (d, 4H, J = 5.4 Hz, CH ortho/N+), 8.47 (t, 2H, J = 7.7 Hz, CH
para/N+), 8.04 (t, 4H, J = 7.1 Hz, CH meta/N+), 7.22 (s, 1H, CH phenylene), 7.20 (d, 4H, J = 6.8 Hz, CH
ortho/phenyl), 6.96 (m, 8H, CH para and meta/phenyl, CH phenylene), 6.56 (t, 1H, J = 7.6 Hz, CH
phenylene) – 13C NMR (DMSO-d6): 182.3, 181.9 (CO), 149.5 (CH ortho/N+), 143.5 (CH para/N+),

142.1, 129.2, 126.8, 125.4 (phenylene), 140.4, 128.4, 128.3, 128.1 (phenyl), 126.8 (CH meta/N+), 124.9
(Cyl) – IR (KBr): 3119 cm-1, 3072, 1623, 1481, 1465, 1389, 1336, 1200, 936, 730 – MS (ES+, cone 39),
m/z (%): [M++Na+] = 547.3 (100), [M++H] = 525.3 (10).
To a solution of 0.50 mL (6.20 mmol) of pyridine in anhydrous ethanol (20 mL) is added 1 g (3.10 mmol)
of 15a or 15b dissolved in dimethylformamide (20 mL) or acetone (20 mL) respectively. The reaction
mixture is refluxed for 24 h. The crude products are collected by vacuum filtration and washed with
dichloromethane. The salts (22a,b) are finally recrystallised from ethanol-water (mp 266°C) and
dimethylformamide (mp 262°C) to yield 0.49 g (33%) and 1.05 g (71%) respectively. To a stirred
suspension of 0.48 g (1 mmol) of the salt (22a) or (22b) in dry chloroform (20 mL) is added an excess of
TEA (2.5 mmol, 0.35 mL). The characteristic yellow color of monosubstituted ylides (24) is observed.
Next, to this solution, 0.24 mL (2.2 mmol) of phenyl isocyanate dissolved in dry chloroform (5 mL) is
added drop-wise. The reaction mixture is stirred for 24 h at rt, under nitrogen atmosphere, in absence of
light. The product (26a) is filtered, washed in chloroform. The crude product, dissolved in water (20 mL)
with small addition of 1M HCl, is washed twice with chloroform (2×50 mL). The aqueous layer is
neutralised with small addition of 20% Na2CO3 until no further precipitation is observed. The precipitate
is collected and washed with acetone. For 26b, the solvent is evaporated, the residue is triturated with
ultrasound stirring in 10% Na2CO3 (100 mL) and then extracted twice with dichloromethane (2×100 mL).
The organic layer is dried on anhydrous MgSO4, filtered and concentrated to dryness. The crude product
(26b) crystallised from acetone with diethyl ether.
1,4-(1,1’-(1,1’-Carbonyl-1,1’-N-phenylcarbamoyl) bis-pyridinium dimethylide)phenylene (26a):
Yield 0.30 g (54%), mp 200°C. Anal. Calcd for C34H26N4O4: C, 73.62; H, 4.73; N, 10.10. Found: C,
1
73.41; H, 4.64; N, 10.22 – H NMR (DMSO-d6/TMS): 12.48 (s, 2H, NH), 8.69 (d, 4H, J = 5.5 Hz, CH
ortho/N+), 8.40 (t, 2H, J = 7.8 Hz, CH para/N+), 7.81 (t, 4H, J = 7.0 Hz, CH meta/N+), 7.54 (d, 4H, J =
7.9 Hz, CH ortho/phenyl), 7.24 (t, 4H, CH meta/phenyl), 6.93 (t, 2H, CH para/phenyl), 6.89 (s, 4H, CH
phenylene) – 13C NMR (DMSO-d6): 176.6, 163.1 (CO), 149.9 (CH ortho/N+), 144.0 (CH para/N+),
140.4, 128.8, 121.5, 118.6 (CH phenyl), 126.5 (CH meta/N+), 140.7, 126.1 (phenylene), 114.8 (Cyl) – IR
(KBr): 3116 cm-1, 3062, 3034, 1619, 1592, 1541, 1509, 1405, 1232, 1155, 754 – MS (ES+, cone 39), m/z
(%): [M+Na+] = 577.2 (12), [M++H ] = 555.3 (100).
1,3-(1,1’-(1,1’-Carbonyl-1,1’-N-phenylcarbamoyl) bis-pyridinium dimethylide)phenylene (26b):
Yield 0.31 g (56%), mp 180°C. Anal. Calcd for C34H26N4O4: C, 73.62; H, 4.73; N, 10.10. Found: C,
1
73.53; H, 4.61; N, 10.02 – H NMR (DMSO-d6/TMS): 12.48 (s, 2H, NH), 8.71 (d, 4H, J = 5.7 Hz, CH
ortho/N+), 8.40 (t, 2H, J = 7.7 Hz, CH para/N+), 7.88 (t, 4H, J = 7.5 Hz, CH meta/N+), 7.57 (d, 4H, J =

7.6 Hz, CH ortho/phenyl), 7.26 (t, 4H, CH meta/phenyl), 7.09 (s, 1H, CH phenylene), 6.94 (t, 2H, CH
para/phenyl), 6.80 (s, 3H, CH phenylene) – 13C NMR (DMSO-d6): 176.7, 163.1 (CO), 149.9 (CH
ortho/N+), 144.0 (CH para/N+), 140.4, 128.8, 121.5, 118.6 (CH phenyl), 126.6 (CH meta/N+), 140.9,
127.1, 126.6, 125.7 (phenylene), 114.8 (Cyl) – IR (KBr): 3116 cm-1, 3067, 3035, 1619, 1589, 1544, 1509,
1401, 1232, 1173, 761 – MS (ES+, cone 39), m/z (%): [M++H] = 555.3 (100).
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