2-arylimino(diferrocenyl)- and (di-p-anisyl)dihydropyrimidines: Novel synthesis, structures, and electrochemistry

Article abstract of DOI:10.1002/jhet.979

2,3-Differocenyl- and 2,3-dianisyl-1-methylsulfanylcyclopropenilium iodides react with 1,3-diphenyl- and 1,3-di-o-tolylguanidine to give 1-aryl-2-arylimino-5,6- (5a,5b) and -4,5-diferrocenyl-1,2-dihydropyrimidines (6a,6b) (～2:1) and, respectively, 5,6- and 4,5-dianisyl-3-phenyl-2- phenylimino-1,2-dihydropyrimidines (～2:1). Their structures were established based on the spectroscopic data and X-ray diffraction analysis of 5,6-diferrocenyl-1-(o-tolyl)-2-(o-tolyl)imino- and 4,5-diferrocenyl-1-phenyl-2- phenylimino-1,2-dihydropyrimidines (5b and 6a, respectively). Electrochemical behavior of compounds 5b, 6b, and 5a+6a were investigated using experiments of cyclic voltammetry and chronoamperometry. For all the compounds, two electrochemical processes (I, II), attributed to the oxidations of the ferrocenes moieties were observed. The values of ΔE^0' (II-I) and comproportionation constant K_com are also reported. Additionally, an electrochemical oxidation with a fast coupled chemical reaction related to the pyrimide ring was also detected.

Full text of DOI:10.1002/jhet.979

1156
2-Arylimino(diferrocenyl)- and (di-p-anisyl)dihydropyrimidines:
Vol 49
Novel Synthesis, Structures, and Electrochemistry
a
a
b
*
Elena I. Klimova, Eduardo A. Vázquez López, Marcos Flores Alamo,
Luis A. Ortiz-Frade,b Gerardo Hernández-Sánchez,b
Victor H. Sotelo Domínguez,a and Marcos Martínez Garcíac
aUniversidad Nacional Autónoma de México, Facultad de Química, Cd. Universitaria,
Coyoacán, C.P. 04510 México D.F., México
bCentro de Investigación y Desarrollo Tecnológico en Electroquímica S.C. Parque Tecnológico
Querétaro, Pedro de Escobedo, C.P. 76703 Querétaro, México
cUniversidad Nacional Autónoma de México, Instituto de Química, Cd. Universitaria,
Coyoacán, C.P. 04510 México D.F., México
*
E-mail: eiklimova@yahoo.com.mx
Received March 4, 2011
DOI 10.1002/jhet.979
Published online 26 October 2012 in Wiley Online Library (wileyonlinelibrary.com).
2,3-Differocenyl- and 2,3-dianisyl-1-methylsulfanylcyclopropenilium iodides react with 1,3-diphenyl- and
1,3-di-o-tolylguanidine to give 1-aryl-2-arylimino-5,6- (5a,5b) and -4,5-diferrocenyl-1,2-dihydropyrimidines
(6a,6b) (∼ 2:1) and, respectively, 5,6- and 4,5-dianisyl-3-phenyl-2-phenylimino-1,2-dihydropyrimidines
(∼ 2:1). Their structures were established based on the spectroscopic data and X-ray diffraction analy-
sis of 5,6-diferrocenyl-1-(o-tolyl)-2-(o-tolyl)imino- and 4,5-diferrocenyl-1-phenyl-2-phenylimino-1,2-
dihydropyrimidines (5b and 6a, respectively). Electrochemical behavior of compounds 5b, 6b, and
5a+6a were investigated using experiments of cyclic voltammetry and chronoamperometry. For all
the compounds, two electrochemical processes (I, II), attributed to the oxidations of the ferrocenes
0
moieties were observed. The values of ΔE0 (II-I) and comproportionation constant Kcom are also
reported. Additionally, an electrochemical oxidation with a fast coupled chemical reaction related to
the pyrimide ring was also detected.
J. Heterocyclic Chem., 49, 1156 (2012).
INTRODUCTION
multiple bonds, is known to confer them, in addition to
biological activity, certain useful properties. These com-
pounds are characterized by magnetic behavior, electrical con-
ductivity (even superconductivity), nonlinear optical effects,
and so on [11]. This fact increased interest in introduction of
ferrocene fragments in diverse organic compounds aimed at
preparing long-chained conjugated systems (linear, carbocy-
clic, and heterocyclic) as important category of materials.
The development of novel methods for an access to
ferrocenyl-substituted polynitrogen six-membered hetero-
cycles with a system of conjugated double bonds is of consid-
erable importance. The use of diferrocenylcyclopropenylium
salts for the synthesis of heterocycles allows introduction of
two ferrocenyl substituents at a time. This served as the
basis for the preparation of diferrocenyl-1,2,3-triazines [12],
-pyridazines [13], -1,2,4-triazines [14], and –oxazines [15].
So far, diferrocenylcyclopropenylium salts have not been
used for the synthesis of diferrocenylpyrimidines.
Pyrimidine and its derivatives pertain to important het-
erocyclic compounds, which is determined by the presence
of pyrimidines in nucleic acids vital for every organism as
their essential components (thymine, cytosine, and uracil)
[1,2], in many other compounds with practically valuable
properties, for example, barbituric and orotic acids [2–4].
Vitamin B1 is a pyrimidine derivative, it is a constituent
of carboxylase, the enzyme which catalyses carbohydrate
metabolism. Several antibiotics, antitumor, antiepileptic,
and other therapeutics, photographical materials, and so
on, comprise pyrimidine structural elements.
The most general approach to the synthesis of pyrimidine
derivatives is coupling of 1,3-dicarbonyl compounds with
gem-diamino (or gem-amino-imino) compounds such as urea,
guanidines or amidines [5–8]. First monoferrocenyl-substituted
pyrimidines have been prepared by coupling of ferrocenyl-a,
b-enones with urea [9,10]. However, ferrocenylpyrimidines
still pertain to little-studied compounds.
In this work, we studied reactions of 2,3-differocenyl- and
2,3-dianisyl-1-methylsulfanylcyclopropenylium iodides (1a
and 1b) with 1,3-diphenyl- and 1,3-di-o-tolylguanidine.
The presence of one or several ferrocenyl substituents
in heterocycles, especially in those containing conjugated
© 2012 HeteroCorporation

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2-Arylimino(diferrocenyl)- and (di-p-anisyl)dihydropyrimidines: Novel
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Synthesis, Structures, and Electrochemistry
RESULTS AND DISCUSSION
of the molecules 5b and 6a are given in Figure 1(a,b)
and their principal geometric parameters are listed in
Table 1.
The starting cyclopropenylium salts 1a and 1b were prepared
according to a well-proven procedure developed earlier [16,17]:
2,3-diferrocenyl- and 2,3-di(p-anisyl)-cyclopropenones were
converted into morpholino derivatives 2a,b (Scheme 1), which
were elaborated to 2,3-differocenyl- and 2,3-di(p-anisyl)-1-
methylsulfanylcyclopropenylium iodides (1a and 1b) via
thiones 3a,b.
We found that diferrocenyl(morpholino)cyclopropeny-
lium tetrafluoroborate 1a reacts with 1,3-diphenyl- and
1,3-di-o-tolylguanidine (4a and 4b) in the presence of
triethylamine in boiling benzene to afford regioselectively
two reaction products, viz., 5a,b and 6a,b, in the ratio
∼ 2:1 separated by column chromatography on alumina
(Scheme 2).
The data from X-ray diffraction showed that com-
pound 5b is 5,6-diferrocenyl-1-(o-tolyl)-2-(o-tolyl)imino-1,
2-dihydropyrimidine and compound 6a is 4,5-diferrocenyl-
1-phenyl-2-phenylimino-1,2-dihydropyrimidine.
We found further that 2,3-di(p-anisyl)-1-methylsulfa-
nylcyclopropenylium iodide (1b) reacted analogously
with 1,3-diphenylguanidine (4a) to afford a mixture
of two heterocycles 7 and 8 (ca. 1:1, 1H NMR data)
(Scheme 3):
The structures of compounds 7 and 8 were established
1
based on the data from H and 13C NMR spectroscopy,
mass spectrometry, and elemental analysis. The olefinic
1
signal in the H NMR spectrum of compound 7 resonated
The structures of compounds obtained were established
in a lower field (d 7.78) as compared with the position of
1
based on the data from H and 13C NMR spectroscopies,
1
the corresponding resonance in the H NMR spectrum of
mass spectrometry, and elemental analysis. 1,2-Dihydro-
pyrimidines 5a and 5b were isolated as dark red crystalline
substances stable on storage. 1,2-Dihydropyrimidines 6a
and 6b represented dark violet crystalline substances. The
1H NMR spectra of the former pair contain each one sin-
glet for the olefinic proton (d 8.76 and 8.78, respectively)
and the appropriate amount of signals for the protons of
two ferrocenyl and two aryl substituents. The olefinic
compound 8 (d 7.42), therefore, by analogy with diferroce-
nyl-1,2-dihydropyrimidines 5a,5b and 6a,6b the structure
of 5,6-di(p-anisyl)-1-phenyl-2-phenylimino-1,2-dihydropyr-
imidine was ascribed to the former and 4,5-di(p-anisyl)-1-
phenyl-2-phenylimino-1,2-dihydropyrimidine was ascribed
to the latter.
Putative mechanisms of formation of 1,2-dihydropyri-
midines 5a, 5b, 7 and 6a, 6b, 8 are depicted in Schemes
4–6. The two nucleophilic sites of 1,3-diarylguanidines
attack sequentially (Schemes 4 and 5) or simultaneously
(Scheme 6) the carbon atoms in positions 1 and 2 of the
starting compounds 1a,1b to afford bicyclic intermediates
9 and 10. Their intramolecular transformations via divinyl-
carbenes 11 and 12 result ultimately in 1,2-dihydropyrimi-
dines 5 - 8.
1
protons in the H NMR spectra of pyrimidines 6a and 6b
resonate at higher field (d 8.07 and 7.85, respectively).
The 13C NMR spectra of compounds 5a,5b and 6a,6b
corroborate completely their pyrimidine structures.
X-Ray diffraction analysis of single crystals of com-
pounds 5b and 6a obtained by crystallization from
dichloromethane was undertaken to determine the spatial
structures of the compounds obtained. The general views
The following features of the reactions studied are
noteworthy: (1) in all cases, mixtures of structurally
similar diferrocenyl- or di(p-anisyl)-1,2-dihydropyrimi-
dines formed; (2) the ratios of the isomeric 5,6- and
4,5-disubstituted 1,2-dihydropyrimidines was always about
2:1; (3) the presence of ferrocenyl or p-anisyl (aryl) substitu-
ents in the starting cyclopropenylium salts exerted no
effect on the ratios of the final products; (4) unambiguous
identification of each compound is possible based on the
position of the characteristic signal for the olefinic proton
in its 1H NMR spectrum.
Scheme 1
ELECTROCHEMISTRY
Scheme 2
Figure 2 shows a typical voltammetric response of
compound 6b in acetonitrile solution containing 0.1M
tetra-N-butylammonium tetrafluoroborate (TBABF4).
When the potential scan was initiated in positive direction,
three oxidation signals (Ia and IIa IIIa) were detected. It
can be noticed a slightly overlap between signals Ia and
IIa. Then when the cycle was completed two reduction
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E. I. Klimova, E. A. Vázquez López, M. F. Alamo, L. A. Ortiz-Frade, G. Hernández-Sánchez,
Victor H. Sotelo Domínguez, and M. M. García
Vol 49
Figure 1. (a) Crystal structure of 5b; (b) crystal structure of 6a.
0
signals (Ic and IIc) were observed. In this case, there is also
an overlap between the reduction signals Ic and IIc.
ΔE0 (II-I) = 0.140 V with a comproportionation constant
Kcom of 236 [18,19].
The estimated anodic peak potentials values Epa(IIa) and
Epa(IIIa) are 0.174 and 0.654 V/Fc-Fc+, respectively. On
the other hand, the cathodic peak potential value for signals
Ic was –0.0150 V/Fc-Fc+. This electrochemical behavior is
typical for a two consecutive electron transfer mechanism
(EE), with slightly electronic communication between
redox moieties. Therefore, for compound 6b, the processes
I and II correspond to the consecutive oxidations of
ferrocene moieties. According to literature, for the obtained
value of ΔEp (IIa-Ic) of 0.189, it was calculated a value of
To obtain the number of exchanged electrons in process
IIIa, one-step chronoamperometry experiments were per-
formed at two potential step conditions; first at E2 = 0.3 V
V/Fc-Fc+, related to processes Ia and IIa and then at
E2 = 0.8 V V/Fc-Fc+, where all the oxidation processes are
presented (Fig. 3).
For two consecutive electron transfer reactions
controlled by diffusion, the currents are established by
the Cottrell eqs. (1) and (2) [18]. These relationships indi-
cate that when a potential is held at the electrode surface
with a constant value that promotes either the first (eq. 1)
or the second electrochemical reaction [eq. 2], the current
depends on the diffusion of the electroactive species from
a solution to the electrode surface and the number of
exchanged electrons. Under these conditions, the current I(t)
is a function of tꢀ1/2, due to the growth of a diffusion layer
caused by the electrolysis near the electrode.
Table 1
Selected bond lengths and angles for compounds 5b and 6a.
Bond lengths [Å]
Bond angles [ꢂ]
5b
N(1)–C(35)
N(1)–C(36)
N(2)–C(36)
N(3)–C(36)
N(3)–C(33)
C(33)–C(34)
C(34)–C(35)
N(2)–C(27)
N(3)–C(21)
6a
1.294(4)
1.366(4)
1.281(4)
1.418(4)
1.384(4)
1.375(4)
1.420(4)
1.403(4)
1.448(4)
C(34)–C(33)–N(3)
118.2(3)
115.8 (3)
126.8(3)
118.5(3)
117.9(3)
122.6(2)
120.6(3)
116.8(3)
125.4(3)
C(33)–C(34)–C(35)
N(1)–C(35)–C(34)
C(35)–N(1)–C(36)
N(1)–C(36)–N(3)
C(36)–N(3)–C(33)
C(36)–N(2)–C(27)
N(2)–C(36)–N(3)
N(2)–C(36)–N(1)
IðtÞ ¼ n1FAD1=2
p
ꢀ1=2Co ꢁ tꢀ1=2
(1)
(2)
0
IðtÞ ¼ ðn1 þ n2ÞFAD1=2
p
ꢀ1=2Co ꢁ tꢀ1=2
0
For the first condition, where the oxidation on both
ferrocene moieties is presented, a linear relationships of
N(1)–C(23)
N(2)–C(25)
N(2)–C(24)
C(23)–C(22)
C(22)–C(24)
N(1)–C(25)
N(3)–C(25)
N(3)–C(26)
C(23)–N(1)
N(2)–C(32)
1.319(3)
1.412(3)
1.362(3)
1.450(3)
1.356(3)
1.363(3)
1.291(3)
1.409(3)
1.319(3)
1.434(3)
N(3)–C(25)–N(2)
C(25)–N(2)–C(24)
N(2)–C(24)–C(22)
C(24)–C(22)–C(23)
C(22)–C(23)–N(1)
C(23)–N(1)–C(25)
N(1)–C(25)–N(3)
C(25)–N(2)–C(32)
N(1)–C(25)–N(2)
C(11)–C(22)–C(23)
117.0(2)
119.2 (2)
124.1(2)
114.7(2)
121.5(2)
122.7(2)
125.4(2)
121.2(2)
117.5(2)
126.2(2)
Scheme 3
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Synthesis, Structures, and Electrochemistry
Scheme 4
Scheme 6
The processes I and II correspond to the reversible
oxidation of ferrocene moieties. The formal electrode
potential for processes I and II was calculated as
0
0
E0 = (Epa + Epc). The calculated values were E0 (I) = 0.018 V/
0
Fc-Fc+ and E0 (II) = 0.165 V/Fc-Fc+. The value of
current I(t) and tꢀ1/2 was obtained, with the equation
I(t)= 9.77 tꢀ1/2 + 0.28 (r = 0.998). For the second condition
a similar relationship was estimated I(t) = 14 tꢀ1/2 + 0.8
(r = 0.999). Considering the same values of diffusion
coefficient, and that for the first relationship two electrons
are exchanged (n1 = 2), the ratio of the slopes from the
obtained relationships allows us to estimate that one electron
is exchanged in the oxidation process IIIa (n2 = 1). Despite
the different pulse time width in chronoamperometric experi-
ments and that a scan rate of 2 V sꢀ1 was used in cyclic
voltammetry, the product of the oxidation in the process IIIa
was not detected. An inspection of molecular structure
suggests that this signal is related to the pyrimide ring oxida-
tion with an electrochemical reaction (EC) mechanism.
Figure 4 shows the voltammetry of compounds 5a+6a,
which allows to observe the presence of three oxidation
signals (Ia, IIa, and IIIa) and two reduction signals (Ic
and IIc). The obtained values of anodic and cathodic peak
potentials Epa(I) and Epc(I) for signal Ia and Ic were 0.056
V/Fc-Fc+ and ꢀ0.020 V/Fc-Fc+, respectively. For signals
IIa and IIc, the peak potential values Epa(II) and Epc(II)
are 0.240 and 0.089 V/Fc-Fc+.
0
ΔE0 (II-I) for processes I and II was 0.147 V with its
corresponding value of comproportionation constant Kcom
of 310. The anodic peak potential for signal IIIa Epa (IIIa)
was 0.680 V/Fc-Fc+, which is also related to pyrimide ring
as it was observed in compound 6b.
The electrochemical response of compounds 5b is very
similar than that presented in compound 6b. A summary
of the electrochemical responses for all the compounds
studied is presented in Table 2.
The calculated values of Kcom for all compounds
suggests that the electronic charge is slightly delocalized
in the mixed valence state generated electrochemically,
according to the Robin-Day classification (class II)
[19,20]. The similar value of Kcom for all compounds sug-
gests no effect of the substituent in the mixed valence state.
EXPERIMENTAL
All the solvents were dried according to the standard procedures
and were freshly distilled before use [20]. Column chromatography
1
was carried out on alumina (Brockmann activity III). The H and
13C NMR spectra were recorded on a Unity Inova Varian spectrom-
eter (300 and 75 MHz) for solutions in CDCl3 and CD2Cl2, with
Me4Si as the internal standard. The IR spectra were measured with
an FTIR spectrophotometer (Spectrum RXI PerkinElmer instru-
ments) using KBr pellets. The mass spectra were obtained on a
Varian MAT CH-6 instrument (electron impact mass spectrometry
(EI MS), 70 eV). Elementar Analysensysteme LECO CHNS-900
was used for elemental analyses. The following reagents were pur-
chased from Aldrich: tetrachlorocycloropropene, 98%; ferrocene,
98%; anisole anhydrous, 99.7%; aluminum chloride, 99.99%;
triethyloxonium tetrafluoroborate, 1.0M solution in dichloro-
methane; morpholine, 99+%; sodium hydrosulfide hydrate
NaHSꢃxH2O; iodomethane, 99.5%; 1,3-di-o-tolylguanidine, 99%;
1,3-diphenylguanidine, 97%.
Scheme 5
All electrochemical measurements were performed in acetoni-
trile solution containing 0.1M TBABF4. A potentiostat/galvanostat
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E. I. Klimova, E. A. Vázquez López, M. F. Alamo, L. A. Ortiz-Frade, G. Hernández-Sánchez,
Victor H. Sotelo Domínguez, and M. M. García
Vol 49
Figure 2. Cyclic voltammograms for a solution 1.0 ꢄ 10ꢀ3 mol dmꢀ3 of
compound 6b in the presence of 0.1M TBABF4 in acetonitrile. Working
Figure 4. Cyclic voltammograms for a solution 1.0 ꢄ 10ꢀ3 mol dmꢀ3 of
compound 5a+6a in the presence of 0.1 M TBABF4 in acetonitrile. Work-
electrode platinum, scan rate 0.1 V sꢀ1
.
ing electrode platinum, scan rate 0.10 V sꢀ1
.
EG&G PAR model 263A was used. A typical three-electrode array
was used for all electrochemical measurements: platinum disk as
working electrode, platinum wire as counter-electrode, and a silver
wire as pseudo reference electrode. The silver electrode was
immersed in a acetonitrile (MeCN) solution with 0.1M tetra-N-buty-
lammonium chloride in a separate compartment that was connected
to the working cell through a bioanalytical system (BAS) vycor™
tip. All potentials were reported versus the couple Fc/Fc+ according
to International Union of Pure and Applied Chemistry (IUPAC)
[21]. Cyclic voltammetry were initiated from open circuit potential
(Eocp). One-step chronoamperometry experiments were performed,
initiating at E1 = Eocp to different potential values, E2, using a pulse
width of 1 s.
with triethyloxonium tetrafluoroborate (1.0M solution in
dichloromethane) [17]. Their reactions with morpholine in
dichloromethane [17,22] afforded morpholino(differocenyl)-
and -di(p-anisyl)cyclopropenylium tetrafluoroborates (2a and
2b). The latter gave 2,3-diferrocenyl- and 2,3-di(p-anisyl)
cyclopropenethiones (3a and 3b) when treated with an
aqueous solution of NaSH [22].
2,3-Diferrocenyl- and 2,3-di(p-anisyl)(methylthio)cycloprope-
nylium iodides (1a and 1b) were obtained from the cycloprope-
nethiones 3a,b and iodomethane [22].
Freshly prepared and thoroughly dried iodides 1a and 1b were
used in the reactions with 1,3-diarylguanidines (4a and 4b).
The physical and 1H-NMR spectroscopic characteristics of
compounds 1a, 2a, and 3a were in accord with the literature data
[16,17,22].
2,3-Diferrocenyl- and 2,3-di(p-anisyl)cyclopropenones were
obtained from ferrocene and anisole and tetrachlorocyclopro-
pene in the presence of AlCl3 according to a standard
procedure [16] and converted to ethoxy(diferrocenyl)- and -
di(p-anisyl)cyclopropenylium tetrafluoroborates by treatment
2,3-Di(p-anisyl)cyclopropenone. Yield 78%, white power,
m.p. 142–143ꢂC; IR: 1455, 1512, 1551, 1599 (C¼C, C6H4),
1832 (C¼O), 1070, 1175, 1255, 2844 (OCH3), 3101 (C—H)
cmꢀ1 1H-NMR (CDCl3): d 3.79 (s, 6H, 2CH3), 7.11 (d, 4H,
;
J = 8.7 Hz, C6H4), 7.99 (d, 4H, J = 8.7 Hz, C6H4) ppm; ms: m/z
266 (M)+. Anal. Calcd. for C17H14O3: C, 76.67; H, 5.30.
Found: C, 76.49; H, 5.45.
1-Mopholino-2,3-di(p-anisyl)cyclopropenilium tetrafluoro-
borate (2b). Yield 72%, white crystals, m.p. 167–169ꢂC;
1H-NMR (CD2Cl2): d 3.96 (s, 6H, 2CH3), 4.02 (m, 4H, 2CH2),
4.10 (m, 4H, 2CH2), 7.19 (d, 4H, J = 9.0 Hz, C6H4), 8.03
(d, 4H, J = 9.0 Hz, C6H4) ppm; ms: m/z 423 (M)+. Anal. Calcd.
for C21H22 BF4NO3: C, 59.58; H, 5.24; N, 3.31. Found: C,
59.63; H, 5.18; N, 3.39.
2,3-Di(p-anisyl)cyclopropenethione (3b). Yield 81%, yellow
powder, m.p. 155–156ꢂC; IR: 1461, 1503, 1598 (C6H4), 1653 (C
¼S), 1789 (C¼C), 1173, 1248, 2835 (OCH3), 2993, 3199 (C—H)
cmꢀ1; 1H-NMR (CDCl3): d 3.90 (s, 6H, 2CH3), 7.04 (d, 4H, J =
8.7 Hz, C6H4), 7.91 (d, 4H, J = 8.7 Hz, C6H4) ppm; ms: m/z 282
(M)+. Anal. Calcd. for C17H14SO2: C, 72.33; H, 5.00; S, 11.33.
Found: C, 72.21; H, 4.87; S, 11.42.
2,3-Di(p-anisyl)-1-methylsulfanylcyclopropenilium iodide
(1b). Yield 66%, yellow powder, m.p. 177–178ꢂC; 1H-NMR
(CD2Cl2): d 3.52 (s, 3H, CH3), 5.97 (s, 6H, 2CH3), 9.25 (d, 4H,
Figure 3. One-step potential chronoamperometric experiments for 6b
in the presence 0.1M TBABF4 in CH3CN. The initial potential was the
open potential circuit value Eocp. The potential step values (E1) were
(a) 0.3 V/Fc-Fc+ and (b) 0.8 V/Fc-Fc+.
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Synthesis, Structures, and Electrochemistry
Table 2
Electrochemical behavior, Epa(IIa), Epc(Ic), Epa(IIIa), ΔE0 (II-I), and constant Kcom for compounds 6b, 5b, and 5a+6a.
Epa(IIa)a
Epa(Ic)a
Epa(IIIa)b
ΔEp(IIa-Ic)a
ΔEꢂ(IIꢀI)a
Kcom
a
Compounds
6b
5b
5a+6a
0.174
0.250
0.240
ꢀ0.015
0.116
ꢀ0.02
0.654
0.653
0.680
0.189
0.134
0.260
0.140
0.095
0.147£
236
40.75
310
Reported potentials versus ferrocene in 0.1 M TBABF4-acetonitrile.
aScan rate 0.10 V sꢀ1 related to ferrocene.
bScan rate 0.10 V sꢀ1 related to Pyrimidine moieties.cCalculated directly from two waves.
J = 8.7 Hz, C6H4), 10.15 (d, 4H, J = 8.7 Hz, C6H4) ppm; ms: m/z
424 (M)+. Anal. Calcd. for C18H17IO2S: C, 50.95; H, 4.04; S,
7.54. Found: C, 50.83; H, 4.11; S, 7.62.
142.21, 149.71, 149.90, 166.50, 170.63 (5C) ppm; ms: m/z 615
(M)+. Anal. Calcd. for C36H29Fe2N3: C, 70.27; H, 4.75; Fe,
18.16; N, 6.82. Found: C, 70.49; H, 4.64; Fe, 18.17; N, 6.76.
5,6-Diferrocenyl-1-(o-tolyl)-2-(o-tolyl)imino-1,2-dihydro-
pyrimidine 5b. Yield 1.81 g (56%), red crystals, m.p. 223–
224ꢂC; IR: 815, 825, 1002, 1036, 1106, 1382, 1434, 1468,
1592, 1615, 1677 (C ¼ C, C ¼ N, Fc, C6H4), 1172, 1290
2-Arylimino-1,2-dihydropyrimidines 5a,b; 6a,b; 7 and 8.
A mixture of the 1-methylsulfanylcyclopropenilium iodides
(1a or 1b, 5.0 mmol), 1,3-diarylguanidines (4a or 4b, 7.0
mmol), and 1.0 mL triethylamine in bezene (60 mL) was
stirred in a dry inert atmosphere under reflux (4 h). The
solvents were removed in vacuo, the residues were dissolved
in dichloromethane (50 mL). The solution was mixed with
Al2O3 (activity III) (20 g), and the solvent was evaporated in
air. This sorbent was applied onto a column with Al2O3 (the
height of alumina is ca. 30 cm) and the reaction products
were eluted from the column first with petroleum ether and
then with a 1:2 dichloromethane–petroleum ether solvent
system. The elution order is as follows: (i) 2,3-diferrocenyl-
or 2,3-di(p-anisyl)cyclopropenethione (3a or 3b; ∼ 5–8%);
(ii) 5,6-diferrocenyl-2-phenylimino-, 5,6-diferrocenyl-2-(o-tolyl)
imino- or 5,6-di(p-anisyl)-2-phenylimino-1,2-dihydropyrimidines
5a, 5b, or 7; (iii) compouds 6a, 6b, or 8.
(C—N), 2921, 3014, 3076, 3177 (C—H) cmꢀ1 1H-NMR
;
(CDCl3): d 2.01 (s, 3H, CH3), 2.31 (s, 3H, CH3), 3.92
(s, 5H, C5H5), 4.17 (s, 5H, C5H5), 3.39 (m, 1H, C5H4), 3.90
(m, 1H, C5H4), 4.04 (m, 1H, C5H4), 4.07 (m, 1H, C5H4), 4.13
(m, 1H, C5H4), 4.25 (m, 1H, C5H4), 4.36 (m, 1H, C5H4), 4.42
(m, 1H, C5H4), 6.81–6.88 (m, 2H, C6H4), 7.10 (m, 2H,
C6H4), 7.31 (m, 4H, C6H4), 8.78 (s, 1H, CH ¼ ) ppm;
13C-NMR (CDCl3): d 18.18, 18.42 (2CH3), 69.57, 70.26
(2C5H5), 67.94, 68.23, 68.58, 69.92, 70.04,71.06, 7.13, 73.09
(2C5H4), 86.63, 111.88 (2CipsoFc), 147.12 (CH¼), 122.08,
126.12, 126.45, 128.64, 130.04 (2C), 130.89, 131.14
(2C6H4), 140.89, 141.50, 148.70, 150.64, 154.57, 162.89,
165.67 (7C) ppm; ms: m/z 643 (M)+. Anal. Calcd. for
C38H33Fe2N3: C, 70.94; H, 5.17; Fe, 17.36; N, 6.53. Found:
C, 70.79; H, 5.23; Fe, 17.42; N, 6.35.
5,6-Diferrocenyl-1-phenyl-2-phenylimino-1,2-dihydropyri-
midine 5a. Yield 1.66 g (54%), red powder, m.p. 206–207ꢂC;
IR: 809, 820, 1003, 1027, 1104, 1381, 1442, 1471, 1594, 1613,
1675 (C¼C, C¼N, Fc, C6H4), 1176, 1298 (C—N), 2929, 3012,
4,5-Diferrocenyl-1-(o-tolyl)-2-(o-tolyl)imino-1,2-dihydro-
pyrimidine 6b. Yield 0.9
g (27%), red crystals, m.p.
241–243ꢂC; IR: 816, 823, 1005, 1037, 1104, 1385, 1439, 1472,
1590, 1615, 1686 (C¼C, C¼N, Fc, C6H4), 1181, 1289 (C—N),
2932, 3028, 3079, 3163 (C—H) cmꢀ1; 1H-NMR (CDCl3): d 2.13
(s, 3H, CH3), 2.48 (s, 3H, CH3), 3.98 (s, 5H, C5H5), 4.14 (s, 5H,
C5H5), 4.20 (m, 2H, C5H4), 4.22 (m, 2H, C5H4), 4.28 (m, 2H,
C5H4), 4.31 (m, 2H, C5H4), 7.11–7.14 (m, 4H, C6H4), 7.39–7.45
(m, 4H, C6H4), 7.85 (s, 1H, CH¼) ppm; 13C-NMR (CDCl3): d
18.24, 18.57 (2CH3), 69.43, 70.32 (2C5H5), 69.35, 69.78, 70.41,
71.08 (2C5H4), 81.21, 84.46 (2CipsoFc), 149.41 (CH¼), 126.24,
126.45, 126.64, 127.13, 128.72, 130.37, 130.89, 131.14 (2C6H4),
139.20, 143.11, 150.44, 151.19, 154.38, 163.22, 166.18 (7C)
ppm; ms: m/z 643 (M)+. Anal. Calcd. for C38H33Fe2N3: C, 70.94;
H, 5.17; Fe, 17.36; N, 6.53. Found: C, 70.81; H, 5.05; Fe, 17.39;
N, 6.68.
3069, 3179 (C—H) cmꢀ1 1H-NMR (CDCl3): d 3.84 (s, 5H,
;
C5H5), 4.18 (s, 5H, C5H5), 3.69 (m, 2H, C5H4), 4.02 (m, 2H,
C5H4), 4.24 (m, 2H, C5H4), 4.30 (m, 2H, C5H4), 6.91 (m, 3H,
C6H5), 7.23 (m, 3H, C6H5), 7.34–7.45 (m, 4H, C6H5), 8.76
(s, 1H, CH¼) ppm; 13C-NMR (CDCl3): d 69.47, 70.07 (2C5H5),
67.98, 68.86, 70.51, 72.97 (2C5H4), 86.16, 99.84 (2 CipsoFc),
148.94 (CH¼), 122.58, 127.95 (2C), 128.62 (2C), 128.66 (3C),
130.27 (2C) (2C6H5), 138.87, 149.93, 152.18, 161.20, 165.60
(5C) ppm; ms: m/z 615 (M)+. Anal. Calcd. for C36H29Fe2N3: C,
70.27; H, 4.75; Fe, 18.16; N, 6.82. Found: C, 70.15; H, 4.83;
Fe, 18.21; N, 7.01.
4,5-Diferrocenyl-1-phenyl-2-phenylimino-1,2-dihydropyri-
midine 6a. Yield 0.83 g (27%), violet crystals, m.p. 214–
216ꢂC; IR: 811, 820, 1000, 1033, 1106, 1384, 1440, 1469,
1601, 1617, 1681 (C¼C, C¼N, Fc, C6H4), 1178, 1293 (C—N),
5,6-Di(p-anisyl)-1-phenyl-2-phenylimino-1,2-dihydropyri-
midine 7. Yield 1.2 g (52%), red powder, m.p. 138–139ꢂC; IR:
1467, 1492, 1513, 1572, 1590, 1602, 1627, 1643 (C¼C, C¼N,
C6H5, C6H4), 1072, 1245, 2835 (OCH3), 1180,1350 (C—N),
2929, 3017, 3068, 3193 (C—H) cmꢀ1 1H-NMR (CDCl3): d
;
4.04 (s, 5H, C5H5), 4.19 (s, 5H, C5H5), 4.23 (m, 2H, C5H4),
4.27 (m, 2H, C5H4), 4.29 (m, 2H, C5H4), 4.34 (m, 2H, C5H4),
7.17 - 7.30 (m, 2H, C6H5), 7.42 (m, 3H, C6H5), 7.55 (m, 3H,
C6H5), 7.66 (m, 2H, C6H5), 8.07 (s, 1H, CH¼) ppm; 13C-NMR
(CDCl3): d 68.87, 69.98 (2C5H5), 67.96, 70.88, 71.45, 72.08
(2C5H4), 80.17, 85.12 (2CipsoFc), 148.11 (CH ¼ ), 121.28,
123.72 (2C), 126.26 (2C), 127.93 (3C), 129.5 (2C) (2C6H5),
2932, 2956, 3006 (C—H) cmꢀ1 1H-NMR (CDCl3): d 3.77
;
(s, 3H, CH3), 3.81 (s, 3H, CH3), 6.80 (d, 2H, J = 8.7 Hz,
C6H4), 7.12 (d, 2H, J = 8.7 Hz, C6H4), 7.45 (d, 2H, J = 9.0
Hz, C6H4), 7.57 (d, 2H, J = 9.0 Hz, C6H4), 6.99 (m, 3H,
C6H5), 7.22 (m, 2H, C6H5), 7.33 (m, 3H, C6H5), 7.70 (m, 2H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

1162
E. I. Klimova, E. A. Vázquez López, M. F. Alamo, L. A. Ortiz-Frade, G. Hernández-Sánchez,
Victor H. Sotelo Domínguez, and M. M. García
Vol 49
C6H5), 7.78 (s, 1H, CH¼) ppm; 13C-NMR (CDCl3): d 54,87,
55.34 (2CH3), 147.23 (CH¼), 113.25, 114.15, 123.68, 123.74,
126.77, 128.23, 128.32, 129.91, 130.08, 131.87 (2C6H5,
2C6H4), 142.11, 146.70, 146.76, 147.06, 149.28, 149.61,
158.91, 161.29, 167.49 (9C) ppm; ms: m/z 459 (M)+. Anal.
Calcd. for C30H25N3O2: C, 78.41; H, 5.49; N, 9.14. Found: C,
78.57; H, 5.38; N, 9.22.
const/retrieving.html [or from the Cambridge Crystallographic
Data Centre, 12, Union Road,Cambridge DB2 1EZ, UK;
Fax: (internat.) +44-1223/336-033; E-mail: deposit@ccdc.
cam.ac.uk].
Acknowledgments. This work was supported by the CONACyT
(Mexico, grant 100970).
4,5-Di(p-anisyl)-1-phenyl-2-phenylimino-1,2-dihydropyr-
imidine 8. Yield 0.6 g (26%), red powder, m.p. 151–152ꢂC;
IR: 1468, 1510, 1574, 1590, 1600, 1627, 1648 (C¼C, C¼N,
C6H5, C6H4), 1100, 1245, 2835 (OCH3), 1174,1351 (C—N),
REFERENCES AND NOTES
1
2931, 2956, 3001 (C¼H) cmꢀ1; H-NMR (CDCl3): d 3.75 (s,
3H, CH3), 3.84 (s, 3H, CH3), 6.68 (d, 2H, J = 8.7 Hz, C6H4),
6.82 (d, 2H, J = 8.7 Hz, C6H4), 7.03 (d, 2H, J = 8.4 Hz,
C6H4), 7.24 (d, 2H, J = 8.4 Hz, C6H4), 6.93 (m, 2H, C6H5),
7.18 (m, 3H, C6H5), 7.35 (m, 3H, C6H5), 7.47 (m, 2H, C6H5),
7.42 (s, 1H, CH–) ppm; 13C-NMR (CDCl3): d 55,36, 55.41
(2CH3), 147.03 (CH–), 118.52, 117.13, 123.65, 123.98,
125.42, 127.39, 128.51, 129.07, 130.43, 131.95 (2C6H5,
2C6H4), 138.23, 140.79, 145.34, 147.77, 148.53, 149.79,
157.84, 161.63, 168.04 (9C) ppm; ms: m/z 459 (M)+. Anal.
Calcd. for C30H25N3O2: C, 78.41; H, 5.49; N, 9.14. Found: C,
78.36; H, 5.53; N, 9.07.
Determining the crystal structures. The unit cell parameters
and the X-ray diffraction intensities were recorded on a Siemens
P4 diffractometer. The structures of compounds 5b and 6a
were solved by the direct method (SHELXS -97 [23]) and
refined using full-matrix least-squares on F2.
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Crystal data for C38H33Fe2N3 ꢃCH2Cl2 (5b). M = 728.30
gmolꢀ1, monoclinic Cc, a = 21.9397(5), b = 19.8766(4),
c = 7.5004(2) Å, a = 90, b = 98.509(2), g = 90ꢂ, V = 3234.82
(13) Å3, T = 103(2) K, Z = 4, r = 1.495 Mg/m3, l (Mo – Ka)
= 0.71073 Å, F(000) = 1504, absorption coefficient 1.096
mmꢀ1, index ranges ꢀ2 ≤ h ≤ 27, ꢀ24 ≤ k ≤ 24, ꢀ9 ≤ l ≤ 8,
scan range 3.43 ≤ θ ≤ 26.05ꢂ, 5376 independent reflections,
Rint = 0.0280, 11664 total reflections, 417 refinable parameters,
final R indices [I > 2s(I)] R1 = 0.0311, wR2 = 0.0689,
R indices (all data) R1 = 0.0376, wR2= 0.0705, goodness-of-fit
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Corsini, M. Zanello, P. Hernandez Ortega, S.; Martinez Garcia, M. Eur J
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on F2 0.986, largest difference peak and hole 0.710/ꢀ0.303 eÅꢀ3
.
Crystal data for C36H29 Fe2N3 CH2Cl2 (6a). M = 700.25
gmolꢀ1, monoclinic P-1, a = 10.5679(5), b = 12.0009(8),
c = 12.1763(8) Å, a = 76.602(5), b = 84.849(4), g = 84.793
(5)ꢂ, V = 1492.25(16) Å3, T = 424(2) K, Z = 2, r = 1.558 Mg/m3,
l (Mo ꢀ Ka) = 0.71073 Å, F(000) = 720, absorption coefficient
9.696 mmꢀ1, index ranges ꢀ12 ≤ h ≤ 8, ꢀ14 ≤ k ≤ 13, ꢀ14
≤ l ≤ 14, scan range 3.74 ≤ θ ≤ 68.20ꢂ, 5428 independent
reflections, Rint = 0.0280, 10388 total reflections, 397 refinable
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[19] Zanello, P. Inorganic Electrochemistry, Theory, Practice
and Application; The Royal Society of Chemistry: Cambridge, UK,
2003.
parameters, final R indices [I > 2s(I)] R1 = 0.0344, wR2
=
[20] Robin, M. B. Day, P. Adv Inorg Chem Radiochem 1967,
10, 247.
[21] Gritzner, G. Küta, J. Pure Appl Chem 1984, 4, 461.
[22] Klimova Berestneva, T.; Klimova, E. I. Méndez Stivalet,
J. M.; Hernández-Ortega, S.; Martínez García, M. Eur J Org Chem
2005,4406.
0.0829, R indices (all data) R1 = 0.0477, wR2= 0.0868,
goodness-of-fit on F2 1.011, largest difference peak and hole
0.737/ꢀ0.710 eÅꢀ3
.
CCDC-813003 (for 5b) and CCDC-813004 (for 6a) contain
the supplementary crystallographic data for this article. These
data can be obtained free of charge at www.ccdc.cam.ac.uk/
[23] Sheldrick, G. M. SHELXS-97, Program for the Refinement of
Crystal Structures; University of Göttingen: Germany, 1994.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet