The behavior of 3-ferrocenyl-1-methyl-1,2-pentamethyleneallyl and 1,5-diferrocenyl-3-methyl-2,4-tetramethylene-1,4-dienyl carbocations in the cationic dimerization of 1,3-dienes

Article abstract of DOI:10.1016/S0022-328X(00)00135-2

3-Ferrocenyl-1-methyl-1,2-pentamethyleneallyl carbocation 9 and 1,5-diferrocenyl-3-methyl-2,4-tetramethylene-1,4-dienyl carbocation 10 are transformed into linear 21 and cyclic 28 dimers, respectively, in low yields under conditions of the cationic dimerization (treatment with N,N-dimethylaniline). The former is preferentially deprotonated into 1-ferrocenylmethylidene-2-methylidenecycloheptane (19) and 3-ferrocenylmethylidene-2-methylcycloheptene (20), while the latter is reduced into 1,3-bisferrocenylmethylidene-2-methylcycloheptane (26). However, a linear dimer was obtained in the reaction of salt 9 with s-cis-diene 19, while the reaction of salt 10 with 1,3-bisferrocenylmethylidene-2-methylidenecycloheptane (27) results in a cyclodimer 28 together with a linear dimer 29. The results obtained corroborate the stepwise mechanism of cationic cycloaddition of 1,3-dienes and manifest the role of the electronic factor in the intramolecular cyclization of an intermediate linear dimeric allylic cation.

Full text of DOI:10.1016/S0022-328X(00)00135-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 602 (2000) 105–114
The behavior of 3-ferrocenyl-1-methyl-1,2-pentamethyleneallyl and
1,5-diferrocenyl-3-methyl-2,4-tetramethylene-1,4-dienyl carbocations
in the cationic dimerization of 1,3-dienes
Elena I. Klimova a,*, Marcos Mart´ınez Garc´ıa b, Tatiana Klimova a,
Jose´ Manuel Mendez Stivalet a
a Uni6ersidad Nacional Auto´noma de Me´xico, Facultad de Qu´ımica, Cd. Uni6ersitaria, Coyoaca´n, CP 04510, Mexico DF, Mexico
b Uni6ersidad Nacional Auto´noma de Me´xico, Instituto de Qu´ımica, Cd. Uni6ersitaria, Coyoaca´n, CP 04510, Mexico DF, Mexico
Received 21 December 1999; received in revised form 18 February 2000
Abstract
3-Ferrocenyl-1-methyl-1,2-pentamethyleneallyl carbocation 9 and 1,5-diferrocenyl-3-methyl-2,4-tetramethylene-1,4-dienyl carbo-
cation 10 are transformed into linear 21 and cyclic 28 dimers, respectively, in low yields under conditions of the cationic
dimerization (treatment with N,N-dimethylaniline). The former is preferentially deprotonated into 1-ferrocenylmethylidene-2-
methylidenecycloheptane (19) and 3-ferrocenylmethylidene-2-methylcycloheptene (20), while the latter is reduced into 1,3-bisferro-
cenylmethylidene-2-methylcycloheptane (26). However, a linear dimer was obtained in the reaction of salt 9 with s-cis-diene 19,
while the reaction of salt 10 with 1,3-bisferrocenylmethylidene-2-methylidenecycloheptane (27) results in a cyclodimer 28 together
with a linear dimer 29. The results obtained corroborate the stepwise mechanism of cationic cycloaddition of 1,3-dienes and
manifest the role of the electronic factor in the intramolecular cyclization of an intermediate linear dimeric allylic cation. © 2000
Elsevier Science S.A. All rights reserved.
Keywords: Carbocation; Cyclodimerization; Deprotonation; Reduction; Cycloaddition; Electronic factor; Ferrocene
were rationalized with account of a stepwise mechanism
of acid-catalyzed cyclodimerization of aliphatic conju-
gated dienes postulated by Hoffmann and Ernst [10,11].
According to this mechanism, cyclodimerization of fer-
rocenyl-1,3-dienes occurs by a scheme [9] involving a se-
ries of consecutive steps.
1. Introduction
It is known that ferrocenylmethylcarbocations [1–4]
and ferrocenylmethylallylic cations [5–9] undergo de-
protonation under the action of nucleophiles (N,N-
dimethylaniline, pyridine) leading to intermediate
a-ferrocenylethylenes and ferrocenyl-1,3-dienes, which
ultimately give the cationic dimerization and cyclodimer-
ization products, respectively. On the other hand, ferro-
cenylalkenes and ferrocenyl-1,3-dienes smoothly form
intermediate carbenium and allylic cations, respectively,
under the action of acids (HCl, AcOH) and then similar
linear and cyclic dimers. In addition to these two proce-
dures for performing cationic dimerization/cyclodimer-
ization of ferrocenyl-substituted alkenes or 1,3-dienes, a
third route is feasible, viz. the reactions of equimolar
amounts of the corresponding olefines/dienes with car-
bocationic/allyl-cationic components [5–9]. The regio-
and stereoselectivities of dimerization/cyclodimerization
* Corresponding author. Tel./fax: +52-5-6225366.
E-mail address: klimova@servidor.unam.mx (E.I. Klimova)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 0 ) 0 0 1 3 5 - 2

106
E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
Rigorous proof of this mechanism requires that
2.1. Supposed results
dimeric linear 3a–c or cyclic 4a–c cations or the prod-
ucts of p-alkylation of N,N-dimethylaniline with the
corresponding cations were isolated.
In our opinion, the cation 9 presents interest since
this should generate linear dimeric allylic cation 11
more stable than the cyclodimeric cation of the type 12
in the intermediate steps of the cationic cyclodi-
merization.
However, all attempts at isolating N,N-dimethylani-
line alkylation products 6a–c, 7a–c, and 8a–c to exper-
imentally prove the mechanism suggested have failed,
which made us to consider this mechanism as
hypothetical.
Unlike 9, the dienyl cation 10 should generate
dimeric linear 13a,b and cyclic 14a,b allylic cations of
nearly the same stabilities [12,13].
One of probable reasons for these results seems to be
associated with the effect of electronic factors, viz. with
lesser stability and higher proneness to deprotonation
of the cations 4a–c compared to the allylic cations
3a–c [12,13], which shifts the reaction equilibrium.
The formation of linear dimeric cations has previ-
ously been observed in the study of cationic cy-
clodimerization of bulky s-cis-ferrocenyl-1,3-dienes
such as 3-ferrocenylmethylidene-2-methylidenecam-
phane and 2-ferrocenylmethylidene-3-methylidenequin-
uclidine [14–16]. Both the alkylation products of
N,N-dimethylaniline with linear, dimeric allylic cations
and linear dimers were isolated in these cases. The
absence of cyclic dimers seems to be associated with a
combination of unfavorable steric and electronic factors
in the intermediates that formed. These data has been
used only to support the idea on the formation of linear
dimeric intermediates 3a–c rather than to prove the
entire scheme.
Thus, linear dimers should most probably be formed
in the former case, while in the latter case there are
good premises for simultaneous detection of linear and
cyclic dimers in the reaction mixture. This would be
direct proof of an asynchronic mechanism of cationic
cyclodimerization.
2. Results and discussion
In search for the facts confirming the stepwise char-
acter of cationic cyclodimerization of ferrocenyl-1,3-di-
enes, we have synthesized 1-ferrocenylmethylidene-2-
methylcycloheptan-2-yl and 1,3-bis(ferrocenylmethyli-
dene)-2-methylcycloheptan-2-yl tetrafluoroborates (9
and 10) and studied their properties.
2.2. Synthesis of starting compounds
The starting E-2-ferrocenylmethylidene- and E-,E-
2,7-bis(ferrocenylmethylidene)cycloheptanone (15 and
16) prepared by condensation of ferrocenecarbaldehyde

E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
107
with cycloheptanone in the presence of ButOK [16–19]
served as precursors for tetrafluoroborates 9 and 10,
respectively.
The reaction with methyllithium alllowed conversion
of the chalcones 15 and 16 into the alcohols E-17 and
E-,E-18 [17–19]. Treatment of these alcohols with
HBF4 etherate resulted in the target tetrafluoroborates
E-9 and E-,E-10 [7,9].
1
The H-NMR spectrum of the dimer 21a,b contains
the following characteristic signals which confirm its
linear, dimeric structure: two singlets for protons of the
methyl groups; two pairs of singlets for the protons of
the C5H5 groups of the ferrocenyl substituents; two
doublets for the protons of the Fc–CH groups, and
two doublets for the olefinic protons of the ꢀCHꢁ
groups. The integral intensity ratios for all the groups
of signals were equal to ca. 2:1.
Compound 19 represents a ferrocenyl-1,3-diene with
a fixed s-cis-configuration of the double bonds. It
reacts readily with N-phenylmaleimide to give a mix-
ture of endo- and exo-adducts (22a and 22b, respec-
1
tively) in a ca. 1:1 ratio (according to H-NMR spectral
data, Table 1).
The salts 9 and 10 are solid, virtually black powders
sufficiently stable if stored in a dry inert atmosphere.
The 1H-NMR spectral data of these salts (Table 1)
corroborate completely their structures.
2.3. Chemical transformations of tetrafluoroborate 9
We found that the treatment of tetrafluoroborate 9
with N,N-dimethylaniline resulted in deprotonation
products of (ferrocenyl)methylallyl cation, viz. com-
pounds 19 and 20, together with a linear dimer 21.
The structures of these compounds separated by
chromatography on alumina (Brockmann activity III)
were established based on 1H-NMR spectral data
(Table 1). The spectra of compounds 19 and 20 are
sufficiently simple and prove their structures unambigu-
ously. According to the NMR spectral data, the dimer
21 represents a ca. 2:1 mixture of isomers 21a and 21b.
These isomers could not be separated, and their
configurations (Z- or E-) were not determined.
The Diels–Alder adducts 22a and 22b were separated
by chromatography. The endo- and exo-structures were
ascribed to these products based on the previously
elaborated H-NMR criteria for the assignment of the
ferrocenyl substituted Diels–Alder adducts to either
1
endo- or exo-isomers [6,20].

Table 1
1H-NMR spectral data of compounds 9, 10, 15, 17, 19–24, 26, 30–33 (300 MHz, CDCl3, TMS); l (ppm), J (Hz)
Compound C5H5
C5H4
CH2
CH
CH3, Ar, OH
2.09 s (3H)
9
4.58 s (5H)
5.18 m (2H), 5.63 m (2H)
1.44 m (2H), 1.75–1.90 m (4H),
2.20–2.80 m (4H)
8.14 s (1H)
10
15
17
4.65 s (10H)
4.14 s (5H)
4.08 s (5H)
5.26 m (4H), 5.72 m (4H)
4.38 m (2H), 4.48 m (2H)
4.19 m (1H), 4.21 m (1H),
4.31 m (1H), 4.35 m (1H)
1.93 m (4H), 2.89 m (4H)
1.78 m (6H), 2.67 m (4H)
1.38 m (2H), 1.56 m (1H), 1.88
m (3H), 1.93 m (3H), 2.75 m
(1H)
8.25 s (2H)
7.30 s (1H)
6.39 s (1H)
2.18 s (3H)
–
1.33 s (3H), 1.61 s (1H)
19
4.11 s (5H)
4.25 m (1H), 4.48 m (1H),
4.69 m (2H)
1.68 m (2H), 1.83 m (4H), 2.43
m (2H), 2.66 m (2H), 5.03 d
(2H), J=2.4
6.29 s (1H)
–
E-20
Z-20
21a
4.10 s (5H)
4.22 m (2H), 4.37 m (2H)
4.14 m (2H), 4.30 m (2H)
1.73 m (4H), 2.17 m (2H), 2.47
m (2H)
1.83 m (4H), 2.21 m (2H), 2.39
m (2H)
1.66 m (8H), 1.79 m (8H), 2.40
m (2H), 2.65 m (2H)
1.84 m (6H), 2.17 m (4H), 2.47
m (6H), 2.77 m (4H)
5.63 m (1H), J=5.4, 6.12 s
(1H)
5.39 m (1H), J=6.4, 5.89 s
(1H)
4.21 d (1H), J=10.8; 5.54 d
(1H), J=10.8; 7.27 s (1H)
4.26 d (1H), J=9.6; 6.30 d
(1H), J=9.6; 7.40 s (1H)
3.14 m (1H), 3.22 dd (1H),
J=5.7, 9.6; 3.80 d (1H), J=
5.7
1.93 s (3H)
1.88 s (3H)
1.84 s (3H)
1.92 s (3H)
4.12 s (5H)
/
4.12 s (5H), 4.14 s (5H)
4.13 s (5H), 4.16 s (5H)
4.11 s (5H)
4.24 m (2H), 4.26 m (2H),
4.45 m (2H), 4.47 m (2H)
4.22 m (4H), 4.37 m (4H)
21b
22a
3.89 m (1H), 4.07 m (1H),
4.09 m (1H), 4.11 m (1H)
1.67–1.88 m (4H), 2.25 m (2H),
2.44 m (4H), 2.67 m (2H)
7.00–7.03 m (2H), 7.35–7.40 m
(3H)
22b
4.10 s (5H)
4.06 m (1H), 4.12 m (2H),
4.14 m (1H)
1.53 m (3H), 1.82 m (3H), 2.05
m (1H), 2.24 m (1H), 2.41 m
(2H), 2.70 m (2H)
3.11 m (1H), 3.20 dd (1H),
J=6.3, 9.6; 3.78 d (1H), J=
6.3
6.95–6.98 m (2H), 7.27–7.37 m
(3H)
23
24
4.16 s (5H)
4.45 m (2H), 4.56 m (2H)
1.75 m (4H), 1.94 m (2H), 3.05
m (2H), 3.83 m (2H)
1.28–1.50 m (4H), 1.61–1.82 m
(4H), 2.08–2.34 m (4H), 2.51–
2.83 m (8H), 3.12 d (2H), J=8.4
1.40–1.60 m (2H), 1.80–2.06 m
7.65 s (1H)
7.32–7.48 m (5H)
4.12 s (5H), 4.19 s (5H)
4.00 m (2H), 4.09 m (2H),
4.15 m (2H), 4.28 m (2H)
3.64 m (1H), J=8.4; 4.42 s
(1H)
1.94 s (3H), 2.98 s (6H), 6.54 d
(2H), 6.69 d (2H), J=8.1
602
)
26
30
4.10 s (5H), 4.12 s (5H)
4.18 m ((2H), 4.20 m (2H),
4.31 m (1H), 4.33 m (1H),
4.35 m (1H), 4.38 m (1H)
3.61 kd (1H), J=6.9, 1.5; 5.95
1.31 d (3H), J=6.9
(4H), 2.20 m (1H), 2.78 m (1H) d (1H), J=1.5; 6.01 s (1H)
105
4.08 s (5H), 4.10 s (5H), 4.13 s 4.03–4.35 m (16H)
(5H), 4.16 s (5H)
1.30–1.50 m (4H), 1.72–1.88 m
(4H), 2.24–2.43 m (4H), 2.52–
2.68 m (4H), 3.06 d (2H),
J=9.06
3.71 t (1H), J=9.06, 4.70 s
(1H), 6.18 s (1H), 6.29 s (1H)
2.01 s (3H), 3.02 s (6H), 6.49 d
(2H), 6.74 d (2H), J=8.2
1
31
32
33
4.07 s (5H), 4.10 s (5H), 4.12 s 3.98 m (2H), 4.02 m (2H),
1.35–1.60 m (4H), 2.16–2.60 m
(4H), 2.81–3.10 m (4H), 3.14–
3.22 m (4H), 3.68 d (2H), J=6.8
3.79 m (1H), J=6.8; 4.57 s
(1H), 4.63 s (1H), 6.25 s (1H)
1.97 s (3H), 3.01 s (6H), 6.40 d
(2H), 6.61 d (2H), J=8.5
(5H), 4.14 s (5H)
4.06 m (2H), 4.11 m (2H),
4.18 m (2H), 4.21 m (2H),
4.24 m (2H), 4.32 m (2H)
4.01 s (5H), 4.04 s (5H), 4.08 s 3.93 m (2H), 3.95 m (2H),
1.26–1.53 m (4H), 1.68–1.80 m
(4H), 2.43–2.65 m (4H), 2.81–
3.05 m (4H), 3.44 d (2H), J=6.3
3.60 t (1H), J=6.3; 4.75 s
(1H), 6.18 s (1H), 6.40 s (1H)
1.94 s (3H), 3.05 s (6H), 6.58 d
(2H), 6.74 d (2H), J=9.1
(5H), 4.11 s (5H)
4.03 m (2H), 4.07 m (2H),
4.13 m (2H), 4.16 m(2H),
4.19 m (2H), 4.22 m (2H)
4.05 s (5H), 4.09 s (5H), 4.16 s 4.01 m (2H), 4.07 m (2H),
1.42–1.61 m (4H), 1.74–1.93 m
(4H), 2.14–2.40 m (4H), 2.61–
2.73 m (4H), 3.18 m (2H)
3.67 td (1H), J=6.2, 1.2; 3.86 t
(1H), J=6.8; 6.24 d (1H), J=1.2;
6.29 s (1H), 6.52 s (1H)
1.94 s (3H)
(5H), 4.20 s (5H)
4.14 m (4H), 4.19 m (4H),
4.24 m (2H), 4.32 m (2H)

E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
109
1
of the electronic factors on the cyclization of intermedi-
ate, linear dimeric cations (see above).
Complete analysis of the H-NMR spectra of com-
pounds 22a and 22b was complicated due to a number
of circumstances (i.e. partial overlapping of the signals
related to ꢀCH2ꢀ groups and masking of the multiplets
related to H1, H2 and H3 with that related to the C5H4
fragment). As was shown earlier for compounds of the
type under consideration, at least one of the protons of
2.4. Chemical transformations of tetrafluoroborate 10
In our opinion, the chemical behavior of tetrafluorob-
orate 10 should resemble that of (3-ferrocenylmethyli-
dene - 2 - methylcyclohex - 1 - enyl)ferrocenylmethylium
tetrafluoroborate (25). The reaction of the latter with
N,N-dimethylaniline results mainly in all possible alky-
lation products by monomeric and dimeric linear and
cyclic cations [21].
However, unlike 25, the cation 10 is preferentially re-
duced to 1,3-bis(ferrocenylmethylidene)-2-methylcyclo-
heptane (26, ca. 65%) when treated with N,N-
dimethylaniline. Simultaneously, deprotonation and cy-
clodimerization occur leading to bisferrocenyltriene (27,
ca. 7%) and a spiro compound (28 [17], ca. 8%). No
products of N,N-dimethylaniline alkylation were
detected.
1
the C5H4 ring always exhibits in the H-NMR spectrum
a signal at higher field than the singlet related to the
C5H5 group in endo-isomers and never in exo-isomers
[6,20]. Thus, the endo-structure should be preferably as-
signed to 22a, in which the signals for all the protons of
the C5H4 fragment are located in higher field than the
singlet for the protons of unsubstituted cyclopentadienyl
ring in ferrocene, and not to 22b.
We also found that compounds 22a and 22b undergo
smooth oxidative dehydrogenation by atmospheric oxy-
gen when subjected to TLC on SiO2 to form phthal-
imide derivative 23 as the end product.
Similar oxidative dehydrogenation of the N-phenyl-
maleimide Diels–Alder adducts has been described by
us previously [17]. Compound 20 represents a ferro-
cenyl-1,3-diene with a fixed s-trans-configuration of the
double bonds. It does not give Diels–Alder adducts
with N-phenylmaleimide. The treatment of the diene 20
with HBF4 results in the original tetrafluoroborate 9 in
quantitative yield.
Further we have found that the linear dimer 21a,b (ca.
2.1:1) is formed in good yield upon mixing equimolar
amounts of diene 19 and salt 9 with N,N-dimethylani-
line as a nucleophile in the final reaction step. In addi-
tion, a product of N,N-dimethylaniline p-alkylation
with an intermediate dimeric allylic cation (compound
24) was isolated.
The reduction of ferrocenylallylic cations has been
also observed earlier (e.g. for 3-ferrocenylmethylidene-
1,2,7,7-tetramethylbicyclo[2.2.1]hept-2-yl cation [16], 1-
ferrocenyl-1-phenyl- [22] and 1-(1-naphthyl)allylic
cations [23]), which seems to be associated with the par-
ticipation of the iron atoms. However, the yields of the
reduction products did not exceed ca. 10%.
The 1H-NMR spectrum of compound 26 contains
two different signals for the olefinic protons of the
Fc1CHꢁ and Fc2CHꢁ groups (l1=5.95, d, J=1.5 Hz;
l2=6.01, s), which suggests their nonequivalence. Tak-
ing into account the equivalence of the analogous pro-
tons in the original chalcone 16 and alcohol 18 (see
Table 1) and (E,E)-configuration of the double bonds in
these compounds [24], one may suggest that the reduc-
tion of the cation 10 is accompanied by Z-/E-isomeriza-
tion of one of the ferrocenylmethylidene fragments [19].
Thus, the structure (Z,E)-1,3-bis(ferrocenylmethyli-
dene)-2-methylcycloheptane should be ascribed to com-
pound 26.
No cyclodimeric products were detected in this reac-
tion, which is in full accord with suggestions on the role

110
E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
form. However, their spatial structures are not estab-
To avoid formation of considerable amount of
lished yet.
the reduction product 26, we have performed the
reaction of salt 10 with pure triene 27 under conditions
identical with those described above for the rreaction
of tetrafluoroborate 9 with diene 19. As expected, the
following compounds were isolated following treatment
of the reaction mixture with N,N-dimethylaniline:
cyclodimer 28 [17], linear dimer 29 [17], three pro-
ducts of p-alkylation of N,N-dimethylaniline
(30–32), and a reduction product of dimeric linear
cation 33.
1
The H-NMR spectral data for compounds 30–32,
viz. the number of proton signals, their chemical shift
values, and spin–spin coupling constants for aliphatic
and olefinic protons, corroborate the assigned struc-
tures. Additional information is gained from the 13C-
NMR spectra of these compounds. The presence of
four Cipso atoms of the ferrocene fragments together
with the presence of signals for four nonsubstituted
ferrocene cyclopentadienyl rings unambiguously prove
their dimeric character. The presence of signals for
Cspiro atoms proves the structure of compounds 31 and
32. The number of signals for C, CH, CH2, and CH3
groups in compounds 30–32 fully corresponds to their
structures.
Obviously, p-alkylation of N,N-dimethylaniline with
intermediate dimeric cations 13, 14a, and 14b, deproto-
nation of these cations, and reduction of the linear
dimeric cation 13 are competitive reactions, which re-
sults in virtually all theoretically possible reaction
products.
3. Conclusions
Thus, we managed to isolate the alkylation products
of N,N-dimethylaniline with mesomeric cyclic dimeric
allylic cations 14a and 14b together with the alkylation
product of N,N-dimethylaniline with the linear dimeric
cation 13. These results may be regarded as direct
evidence for the existence of all consecutive steps in a
stepwise mechanism of cationic cyclodimerization of
1,3-dienes, viz. 1) the addition of a carbocation to the
methylene group of 1,3-diene through its secondary
carbocationic center, which results in a linear dimeric
allylic cation of the type 3; 2) the possibility for in-
tramolecular cyclization of the cation 3 into a cyclic
carbocation 4; 3) base-induced deprotonation of (ferro-
cenyl)methylcarbocation 4 leading to cyclodimers con-
taining a CH2ꢁ fragment in the molecules of the type 5.
4. Experimental
1
All H- and 13C-NMR spectra were recorded on a
All of the reaction products were isolated by column
chromatography on alumina (activity III) and by TLC
Unity Inova Varian spectrometer (300 and 75 MHz) in
CDCl3 solutions (except for 1H-NMR spectra of te-
trafluoroborates 9 and 10 recorded in CH2Cl2) with
TMS as internal standard (Tables 1 and 2). The elemen-
tal analysis data are listed in Table 3.
1
(silica gel). The H- and 13C-NMR spectral data of the
obtained compounds 30–33 are listed in Tables 1 and
2. The structures of dimers 28 and 29 were discussed
earlier [17].
Column chromatography was carried out on Al2O3
(Brockmann activity III), TLC was performed on plates
with a fixed SiO2 layer.
According to the NMR data the dimerization and
cyclodimerization occur diastereoselectively. Com-
pounds 28–32 were isolated in just one diastereomeric

Table 2
13C-NMR spectroscopy data for compounds 17, 22, 24, 26, 30–32 (75 MHz, CDCl3, TMS); l (ppm)
Assignment
C5H5
17
22a
22b
24
26
30
31
32
69.05
68.72
68.67
68.59, 68.91
68.93, 68.96
68.35, 68.53, 68.74, 68.53, 68.72, 69.03, 68.50, 68.72. 68.91,
69.04 69.36 69.11
C5H4
68.33, 68.45,
68.51, 69.72
67.16, 67.93, 68.87, 67.40, 68.20, 68.45, 66.72, 66.84, 67.11,
68.12, 68.15, 68.23, 65.76, 65.98, 66.07, 66.72, 66.79, 66.96, 66.41, 66.62, 66.81,
68.25, 68.37, 68.40, 66.44, 66.61, 66.83, 67.19, 68.05, 68.34, 66.90, 67.82, 68.21,
/
69.06
68.80
67.35, 67.59, 68.14,
68.73, 70.15
69.26, 69.54
82.86, 82.90
67.18, 67.65, 68.14, 68.48, 68.61, 68.90, 68.43, 68.56, 68.83,
68.28, 68.56, 68.79, 69.12, 69.50, 69.56, 69.04, 69.46, 69.84,
68.98, 69.32, 69.51, 69.83, 70.05, 70.13, 70.12, 70.21, 70.84,
69.85
78.84, 82.09, 82.87, 79.24, 82.81, 92.05, 79.15, 81.97, 92.10,
83.70 94.13 93.30
28.75, 31.57, 32.61, 20.05, 20.28, 21.10, 26.11, 26.28, 27.36, 24.83, 26.15, 26.31,
71.12
71.55
CipsoFc
82.23
84.62
84.70
79.98, 82.17
CH2
23.66, 28.19,
29.58, 30.29,
42.88
22.24, 27.25, 29.36, 26.69, 26.85, 28.39, 20.12, 20.31, 21.17,
31.83, 35.86, 36.25 29.11, 31.58, 32.15
21.28, 22.18, 22.32,
24.85, 25.01, 28.63,
29.17, 31.01
34.80
22.14, 24.81, 26.19, 27.40, 29.70, 29.84, 28.27, 29.91, 30.16,
28.32, 30.43, 30.89
30.33, 30.58, 40.79
30.73, 33.50, 33.62
CH3
C
19.89
33.50, 137.26
–
–
18.25, 40.06
18.21
143.40, 145.00
18.56, 41.12
129.92, 130.40,
131.18, 131.24,
134.86, 135.22,
147.72
20.02, 47.44
47.80, 133.60,
133.66, 134.21,
137.06, 138.39,
148.52
17.88, 39.98
135.34, 137.36
131.73, 132.32
127.83, 129.45,
131.41, 134.17,
145.18
47.63, 53.06, 129.82,
132.12, 134.81,
137.26, 145.60
602
(
CHꢁ
120.53
126.61, 128.76,
128.95
126.64, 128.25,
128.71
127.86, 128.53,
129.41, 130.72
119.31, 122.98
112.19, 113.91,
128.08, 129.81,
130.40, 134.15
47.26, 48.30
–
112.27, 122.99,
129.03, 129.30
131.42
41.02, 47.20, 57.61
–
116.04, 118.20,
127.82, 129.80,
136.11 136.32
47.62, 56.80
–
105
1
CH
CꢁO
Cipso
–
–
–
39.12, 44.06, 48.12 39.49, 41.23, 48.39
177.68, 178.99
148.97
44.13, 45.05
–
137.30
42.61
–
–
177.64, 178.90
149.25
139.74
143.86
142.10

112
E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
4.1. 2-Ferrocenylmethylidenecycloheptanone (15) and
2,7-bis( ferrocenylmethylidene)cycloheptanone (16)
HCl, and again with water. The organic layer was dried
with Na2SO4 and the solvent was evaporated in vacuo.
Chromatography of the residue on alumina in hexane
afforded 3-ferrocenylmethylidene-2-methylcycloheptene
(20) (0.43 g, 28%), orange crystals, m.p. 101–102°C;
1 - ferrocenylmethylidene - 2 - methylidenecycloheptane
(19) (0.40 g, 26%), orange crystals, m.p. 77–78°C; and
1-ferrocenylmethylidene-2-[2-ferrocenyl-2-(2-methyl-
cyclohept-1-enyl)]ethylidenecycloheptane (21a,b) (ca.
2:1, 0.30 g, 19%), yellow powder, m.p. 175–177°C.
Obtained from ferrocenecarbaldehyde and cyclo-
heptanone in tert-butyl alcohol in the presence of
ButOK. The yield of chalcone 15 was 43%, orange
crystals, m.p. 78–79°C and the yield of chalcone 16 was
38%, m.p. 173–174°C (lit. [17], m.p. 173–174°C).
4.2. Alcohols 17 and 18
Synthesized from chalcones 15 and 16, respectively,
and methyllithium [6,9]. The yield of alcohol 17 was
71.5%, yellow crystals, m.p. 122–123°C; the yield of
alcohol 18 was 74%, orange crystals, m.p. 166–168°C
(lit. [17], m.p. 167–168°C).
4.5. Reaction of tetrafluoroborate 10 with
N,N-dimethylaniline
This reaction was conducted as for the salt 9. Start-
ing from tetrafluoroborate 10 (2.95 g, 5 mmol) and
N,N-dimethylaniline (1.2 g, 10 mmol) in 100 ml of
CH2Cl2 the following products were obtained: diene 26
(1.5 g, 60%), orange needles, m.p. 136–137°C; triene 27
(0.25 g, 10%), orange plates, m.p. 147–148°C (lit. [17],
m.p. 148°C); and spiro-cyclodimer 28, orange powder,
m.p. 255–256°C (lit. [17], m.p. 254–256°C).
4.3. Tetrafluoroborates 9 and 10
Synthesized by addition of HBF4 etherate to an
ethereal solution of the corresponding alcohols 17 and
18. The precipitated salts 9 and 10 were separated by
filtration, washed with dry ether and dry hexane on the
filter, and dried in vacuo. The yield of salt 9 was 78%,
black powder, m.p. 236–237°C; the yield of salt 10 was
84%, black crystals, m.p. ꢀ320°C (dec.).
4.6. Reaction of s-cis-ferrocenyldiene 19 with
N-phenylmaleimide
A mixture of dienes 19 (0.3 g, 1 mmol) and 0.3 g of
N-phenylmaleimide in 50 ml of dry benzene was boiled
under reflux for 1 h. The solvent was removed in vacuo,
and the residue was chromatographed on alumina (hex-
ane) to give N-phenyl-1-ferrocenylbicyclo[5.4.0]undec-
10(11)ene-2,3-dicarboximide (22) (0.35 g, 72%) as a
mixture of endo- and exo-isomers (22a and 22b, ca.
1:1), yellow crystals, m.p. 161–163°C. The isomers were
separated by TLC on silica gel (hexane–benzene, 3:1),
4.4. Reaction of tetrafluoroborate 9 with
N,N-dimethylaniline
N,N-Dimethylaniline (1.2 g, 10 mmol) was added to
a solution of salt 9 (1.47 g, 5 mmol) in dry CH2Cl2 (50
ml) in a dry inert atmosphere. The mixture was stirred
for 1 h at 20°C, then the excess of N,N-dimethylaniline
was removed by washing the solution with water, 1%
Table 3
Elemental analysis data for the obtained compounds
Compound
Anal. Found (%)
Formula
Calc. (%)
C
C
H
Fe
N, F
H
Fe
N, F
9
10
15
17
19
20
21a,b
22a,b
23
24
26
28
30
31
32
33
58.03
61.19
70.29
70.53
74.70
74.36
74.73
72.63
73.36
75.41
71.66
71.99
72.30
72.32
72.41
71.78
5.71
5.52
6.31
7.65
7.41
7.17
7.09
6.03
5.11
7.54
6.18
5.84
6.48
6.51
6.21
6.38
14.37
18.71
18.25
17.01
18.03
18.38
18.31
11.84
11.99
15.36
22.41
22.47
19.73
20.03
19.69
22.01
19.42
13.04
–
–
–
–
–
2.74
2.73
2.04
–
C
19H23BF4Fe
57.91
61.06
70.14
70.38
74.52
74.52
74.52
72.81
73.27
75.20
71.45
71.74
72.55
72.55
72.55
71.60
5.88
5.30
6.54
7.46
7.24
7.24
7.24
5.90
5.30
7.70
6.40
6.02
6.36
6.36
6.36
6.20
14.18
18.93
18.12
17.22
18.24
18.24
18.24
11.68
11.75
15.20
22.15
22.24
19.85
19.85
19.85
22.20
19.29
12.88
–
–
–
–
–
2.93
2.95
1.90
–
C30H31BF4Fe2
C18H20FeO
C19H24FeO
C19H22Fe
C19H22Fe
C38H44Fe2
C29H28FeNO2
C29H25FeNO2
C46H56Fe2N
C30H32Fe2
–
C60H60Fe4
–
1.40
1.35
1.12
–
C68H71Fe4N
C68H71Fe4N
C68H71Fe4N
C60H62Fe4
1.24
1.24
1.24
–

E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
113
the yield of compound 22b was 0.14 g, Rf 0.54, m.p.
172–173°C; the yield of the endo-adduct 22a was 0.13
g, Rf 0.47, m.p. 191–192°C.
aminophenyl)-3-ferrocenylmethylidene-2-methylidene-
cycloheptane-1,7%-(6,8-diferrocenyl-1-ferrocenylmethyli-
dene-2,3,4,5,6,7,8,9-octahydro-1H-benzocycloheptene)]
(32) (0.25 g, 11%) (Rf=0.38), yellow powder, m.p.
216–217°C, and spiro{3-[(4-dimethylaminophenyl)-
ferrocenyl]methyl-2-methylcyclohept-2-ene-1,7%-(6,8-
diferrocenyl - 1 - ferrocenylmethylidene - 2,3,4,5,6,7,8,9-
octahydro-1H-benzocycloheptene)} (31) (0.29 g, 13%)
(Rf=0.30), yellow powder, m.p. 237–238°C.
4.7. Oxidati6e dehydrogenation of N-phenylimides 22a,b
Oxidative dehydrogenation of N-phenylimides 22a,b
was carried out analogously to the previously published
procedure [18]. The yield of N-phenyl-1-ferrocenyl-
6,7,8,9-tetrahydro-5H-benzocycloheptene-2,3-dicarbox-
imide (23) was 58%, Rf=0.68 (hexane–benzene, 2:1),
red crystals, m.p. 214–215°C.
Acknowledgements
4.8. Reaction of tetrafluoroborate 9 with diene 19
Financial support from DGAPA-UNAM (grant no.
IN203599) is gratefully acknowledged.
A solution of diene 19 (0.61 g, 2 mmol) in 50 ml of
dry CH2Cl2 was added to a solution of salt 9 (0.86 g,
2.2 mmol) in 50 ml of the same solvent. The mixture
was stirred for 30 min at 20°C and then N,N-dimethyl-
aniline (0.5 ml) was added. Stirring was continued for
an additional 30 min, then the reaction mixture was
washed with water, 1% HCl, and again with water. The
organic layer was dried with Na2SO4 and the solvent
was evaporated in vacuo. Chromatography of the
residue on alumina (4:1 hexane–chloroform) afforded
compound 21a,b (ca. 2.1:1), m.p. 174–176°C, and 1-[(4-
dimethylaminophenyl)ferrocenyl]methyl-2-[2-ferrocenyl-
2-(2-methylcyclohept-1-enyl)]ethylcyclohept-1-ene (24)
(0.14 g, 11%), yellow powder, m.p. 218–219°C.
References
[1] W.M. Horspool, R.G. Sutherland, B.J. Thomson, J. Chem. Soc.
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[2] A.N. Nesmeyanov, V.A. Sazonova, B.A. Surkov, V.M. Kra-
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4.9. Reaction of tetrafluoroborate 10 with triene 27
[8] E.G. Perevalova, A.N. Pushin, E.I. Klimova, Yu.L. Slovokho-
tov, Yu.T. Struchkov, Metalloorg. Khim. 2 (1989) 1405.
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(1993) 1273.
Analogously, the reaction of salt 10 (1.25 g, 2.1
mmol) with triene 27 (1.0 g, 2 mmol) followed by the
work-up and chromatography on Al2O3 resulted in two
fractions (1) yield 1.12 g, eluted with hexane and (2)
yield 0.83 g, eluted with a 2:1 hexane–benzene mixture.
Each fraction was rechromatographed on SiO2 in a
2:1 hexane–benzene mixture to yield (from fraction 1):
1,3-bis(ferrocenylmethylidene)-2-[2-ferrocenyl-2-(3-ferro-
cenylmethylidene-2-methylcyclohept-1-enyl)]ethylcyclo-
heptane (33) (0.16 g, 8%), (Rf=0.70), yellow powder,
m.p. 198–199°C; 1,3-bis(ferrocenylmethylidene)-2-[2-
ferrocenyl-2-(3-ferrocenylmethylidene-2-methylcyclo-
hept-1-enyl)]ethylidenecycloheptane (29) (0.18 g, 9%)
(Rf=0.66), orange powder, m.p. 183–185°C (lit. [17],
m.p. 183–184°C); and spiro[3-ferrocenylmethylidene-2-
methylidenecycloheptane-1,7%-(6,8-diferrocenyl-1-ferro-
cenylmethylidene-2,3,4,5,6,7,8,9-octahydro-1H-benzocyc
loheptene)] (28) (0.62 g, 31%) (Rf=0.54), yellow pow-
der, m.p. 254–255°C (lit. [17], m.p. 254–256°C).
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kova, J.M. Me´ndez, E.I. Klimova, Russ. Chem. Bull. 47 (1998)
1193.
From fraction
2 were obtained: 1-[(4-dimethyl-
aminophenyl)ferrocenyl]methyl - 2 - [2 - ferrocenyl - 2 - (3-
ferrocenylmethylidene-2-methylcyclohept-1-enyl)]ethyl-
3-ferrocenylmethylidenecyclohept-1-ene (30) (0.16 g,
7%), (Rf=0.48), orange oil; spiro[2-(4-dimethyl-
[21] E.I. Klimova, T. Klimova Berestneva, M. Mart´ınez Garc´ıa, L.
Ru´ız Ram´ırez, Mendeleev Commun. (1998) 233.

114
E.I. Klimo6a et al. / Journal of Organometallic Chemistry 602 (2000) 105–114
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Mart´ınez Garc´ıa, T.C. Alvarez, P.G. Espinosa, R.A. Toscano, J.
Organomet. Chem. 545–546 (1997) 191.
R.A. Toscano, R. Moreno Esparza, L. Ru´ız Ram´ırez, J.
Organomet. Chem. 566 (1998) 175.
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R.A. Toscano, L. Ru´ız Ram´ırez, J. Organomet. Chem. 585
(1999) 106.
[23] E.I. Klimova, M. Mart´ınez Garc´ıa, T. Klimova, C. Alvarez,
.