Synthesis and some chemical properties of s-cis-diferrocenyltrienes. The role of stereoelectronic factors in cationic dimerization reactions

Article abstract of DOI:10.1016/S0022-328X(98)01204-2

Dehydration of 2,6-bis(ferrocenylmethylene)-1-methylcyclohexanol and 2,7-bis(ferrocenylmethylene)-1-methylcycloheptanol gave the corresponding diferrocenyltrienes with a fixed s-cissoidal conformation of the double bond system, viz. 1,3-bis(ferrocenylmethylene)-2-methylene-cyclohexane and -cycloheptane, respectively. These trienes easily afford the products of linear and cyclodimerization by a cationic cyclodimerization mechanism as well as [4 + 2]-cyclodimers. They also form Diels-Alder adducts with azodicarboxylic and maleic acid N-phenylimides. The latter products undergo stepwise oxidative dehydrogenation on SiO₂ up to the formation of phthalimide derivatives.

Full text of DOI:10.1016/S0022-328X(98)01204-2

Journal of Organometallic Chemistry 579 (1999) 30–37
Synthesis and some chemical properties of s-cis-diferrocenyltrienes.
The role of stereoelectronic factors in cationic dimerization reactions
Elena I. Klimova a,*, Tatiana Klimova Berestneva a, Marcos Mart´ınez Garc´ıa b,
Lena Ru´ız Ram´ırez a
a Uni6ersidad Nacional Auto´noma de Me´xico (UNAM), Facultad de Qu´ımica, Circuito Interior, Cuidad Uni6ersitaria, C.P.04510 Coyoaca´n,
Me´xico D.F., Mexico
b Uni6ersidad Nacional Auto´noma de Me´xico (UNAM), Instituto de Qu´ımica, Circuito Exterior, Cuidad Uni6ersitaria, C.P.04510 Coyoaca´n,
Me´xico D.F., Mexico
Received 22 September 1998
Abstract
Dehydration of 2,6-bis(ferrocenylmethylene)-1-methylcyclohexanol and 2,7-bis(ferrocenylmethylene)-1-methylcycloheptanol
gave the corresponding diferrocenyltrienes with a fixed s-cissoidal conformation of the double bond system, viz. 1,3-bis(ferrocenyl-
methylene)-2-methylene-cyclohexane and -cycloheptane, respectively. These trienes easily afford the products of linear and
cyclodimerization by a cationic cyclodimerization mechanism as well as [4+2]-cyclodimers. They also form Diels–Alder adducts
with azodicarboxylic and maleic acid N-phenylimides. The latter products undergo stepwise oxidative dehydrogenation on SiO2
up to the formation of phthalimide derivatives. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Alkylation; Cycloaddition; Cyclodimerization; Cycloheptane; Cyclohexane; Deprotonation; Ferrocene; Oxidative
dehydrogenation; Trienes
1. Introduction
Diene 1 could not be isolated in the individual state since
it easily underwent cyclodimerization irrespective of
conditions of dehydration of the starting alcohol. On the
contrary, dienes 2 and 3 proved to be stable and were
isolated in crystalline state. Dienes 2 and 3 afforded only
the products of linear dimerization under the conditions
of cationic cycloaddition, unlike other s-trans/s-cis-fer-
rocenylbuta-1,3-dienes examined by us so far [4–6],
which produced cyclodimers of a terpenoidal structure.
Obviously, the reason for the formation of the linear
dimers is strong steric hindrances in molecules of 2 and
3. It should be noted that this result has served as one
of the first proofs of the proposed stepwise mechanism
of cationic cyclo-dimerization.
In our previous work we discussed the role of
stereoelectronic factors in the chemical behavior of
ferrocenyl substituted 1,3-dienes with a fixed s-cissoidal
conformation of double bonds, viz. 2-ferrocenyl-
methylene-1-methylenetetraline
1
[1], 3-ferrocenyl-
methylene-2-methylenecamphane 2 [2], and 2-ferro-
cenylmethylene-3-methylenequinuclidine 3 [3], prepared
by dehydration of the corresponding alcohols.
2. Results and discussion
* Corresponding author. Fax: +52-5-6225366.
E-mail address: klimova@servidor.unam.mx (E.I. Klimova)
In continuation of our previous investigations in this
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01204-2

E.I. Klimo6a et al. / Journal of Organometallic Chemistry 579 (1999) 30–37
31
field, in the present work we examined the possibility of
synthesizing s-cis-diferrocenyltrienes starting from bis-
(ferrocenylmethylene)cyclohexanone 4 [7] and -cyclo-
heptanone 5:
It is quite obvious that compounds 10–12 originate
from an intermediate triene 8, which is formed upon
dehydration of alcohol 6. Thus 10 is the Diels–Alder
adduct, while dimers 11 and 12 are formed according to
the cationic linear and cyclodimerization schemes,
which imply the presence of both triene 8 and the
dienyl carbocation 13a:
Information on the synthesis and properties of
trienes of this type of structure is virtually lacking.
However, the chemical behavior of the exo-cyclic cross-
conjugated trienes under the conditions of both thermal
and cationic cycloaddition deserves, in our opinion,
special study. s-cis-Diferrocenyltrienes 8, 9 are of inter-
est, because at all stages of cationic cyclodimerization,
it should form the stable dimeric (linear and cyclic) allyl
carbocations [4–6]. One could expect then, that these
carbocations could be registered in the reaction mixture
by a reaction with N,N-dimethylaniline. The final prod-
ucts of this reaction could prove the simultaneous
existence of these cations and the stepped mechanism of
the cationic cyclodimerization.
The starting E,E-chalcones 4 and 5 [7–9] were ob-
tained by condensation of cyclohexanone and cyclohep-
tanone, respectively, with ferrocenecarbaldehyde in the
presence of t-BuOK. Alcohols 6 [10] and 7 (E,E-) were
prepared from 4 and 5 and MeLi [4,5].
We found that conventional dehydration of alcohols
6 with POCl3 in pyridine [4] did not afford the target
1,3-bis(ferrocenylmethylene)-2-methylenecyclohexane 8.
Instead, the following compounds were isolated from
the reaction mixture: spiro[2,6-bis(ferrocenylmethyl-
ene)cyclohexane-1,2%-(1-ferrocenyl-5-ferrocenylmethyl-
ene-1,2,3,4,5,6,7,8-octahydronaphthalene)] 10 (26%),
spiro[3-ferrocenylmethylene-2-methylenecyclohexane-1,
2%-(1,3-diferrocenyl-5-ferrocenylmethylene-1,2,3,4,5,6,7,
8-octahydronaphthalene)] 11 (41%), and 1,3-bis(ferro-
cenylmethylene)-2-[2-ferrocenyl-2-(3-ferrocenylmethyl-
ene-2-methylcyclohex-1-enyl)]ethylidenecyclohexane 12
(12%). Earlier, we reported the formation of traces of
compounds 10–12 from 1,5-diferrocenyl-3-methyl-2,4-
trimethylenepenta-1,4-dienylic carbocation tetrafluoro-
borate upon treatment with N,N-dimethylaniline
[10].
Cation 13a adds to the methylene group of triene 8 to
give a dimeric dienyl cation 14a, whose intramolecular
cyclization affords a cyclodimeric allylic cation 15a.
Deprotonation of cations 14a and 15a with a base
(pyridine) results in a linear dimer 12 and a cyclodimer
11, respectively.
In our opinion, this suggests, on the one hand, the
enhanced reactivity of triene 8 in cycloaddition and
dimerization reactions and, on the other hand, high
stability of the monomeric and dimeric carbocations
13a–15a.
Further, we found that, in contrast to compound 8,
1,3-bis(ferrocenylmethylene)-2-methylenecycloheptane 9
is a rather stable compound. It is formed in 30% yield
upon conventional dehydration of alcohol 7 (POCl3,
pyridine):

32
E.I. Klimo6a et al. / Journal of Organometallic Chemistry 579 (1999) 30–37
the individual state, we found that satisfactory results
were obtained with alumina (Brockmann activity II).
Using this reagent, we managed to isolate as much as
30% of triene 8 and 60% of triene 9.
The freshly prepared triene 8 is formed as orange
needles, which undergo rapid decomposition even when
stored at low temperature (−5 to 0°C) to give cy-
clodimer 10. In solution (hexane, benzene), the forma-
tion of cyclodimer 10 occurs much faster, and it
precipitates as an orange powder.
In addition, dimeric products 16–18 similar to those
formed upon dehydration of alcohol 6 were isolated
from the reaction mixture:
Thermal cyclodimerization of triene 9 occurs much
more slowly. The best results were obtained when it
was refluxed in benzene for 1–2 h, the yield of cy-
clodimer 16 being ca 70%.
With azodicarboxylic acid N-phenylimide, com-
pounds 8 and 9 form the Diels–Alder adducts 19 and
20, respectively, in virtually quantitative yield at 0°C:
Compound 16 is a Diels–Alder adduct, and com-
pounds 17 and 18 are the products of cationic dimeriza-
tion that obviously occurs by an analogous scheme:
With the same ease, compounds 8 and 9 react with
N-phenylmaleimide to give adducts 21 and 22,
respectively:
Py
Py
14b “ 18 15b “ 17
+
+
−H
−H
Dimerization and cyclodimerization reactions pro-
ceed diastereoselectivelly. Compounds 10–12 and 16–
18 were isolated as one diastereomeric form. However,
the objective spatial structure of these compounds have
not been established yet.
1
The parameters of the H-NMR spectra (number of
proton signals, values of chemical shifts and of spin–
spin interaction constants) of the aliphatic and olefinic
protons in compounds 10–12 [10], 16–18 confirm the
suggested chemical structure of these compounds. Ad-
ditional information on the structure of compounds
10–12, 16–18 is obtained by the 13C-NMR spectra. The
presence of four signals from quaternary carbon atoms
in the ferrocenyl fragments of compounds 10–12, 16–
18, together with the signals from four C5H5 groups
unambiguously prove the formation of dimers. The
presence of Cspiro signals confirms the suggested cyclic
structure of compounds 10, 11, 16 and 17. The number
of 13C-NMR signals from the C, CH, CH2 and CH3
groups in compounds 10–12, 16–18 correspond to
their chemical structure.
The condensations occur stereospecifically, and com-
pounds 21 and 22 were formed as the single isomers,
presumably, with endo-structures. The endo-structures
were ascribed to these products based on the previously
1
elaborated H-NMR criteria for the assignment of ei-
ther endo- or exo-structures to the ferrocenyl substi-
tuted Diels–Alder adducts [9,11]. The fact that one of
the protons of the C5H4 groups and two protons of the
phenyl groups in these compounds resonate at higher
fields than the protons of nonsubstituted cyclopentadi-
enyl rings and three other protons of the phenyl rings
are evidence of their endo-structures.
We found that compounds 21 and 22 undergo
smooth auto-oxidation when subjected to thin-layer
chromatography on alumina or silica to form phthal-
imide derivatives as the end products:
In the search for other methods of dehydration of
alcohols 6 and 7 aimed at isolating trienes 8 and 9 in

Table 1
1H-NMR spectral data of compounds 5, 7–9 and 16–26 (l, J/Hz)
Compound
C5H5
C5H4
CH2
CH
CH3, OH, Ph
5
7
4.16 s (10H)
4.12 s (10H)
4.38 m (4H), 4.53 m (4H)
4.24 m (4H), 4.38 m (2H), 4.40 m (2H)
1.94 m (4H), 2.60 m (4H)
1.86 bs (4H), 2.25 m (2H), J=4.5, 2.42 m
(2H), J=4.5
7.14 s (2H)
6.43 s (2H)
–
1.59 d (3H), J=
4.5, 1.63 s (1H)
–
8
4.10 s, 4.16 s
4.05 m (1H), 4.06 m (1H), 4.07 m (1H),
4.09 m (1H), 4.13 m (2H), 4.21 m (2H)
4.25 m (4H), 4.42 m (4H)
4.06 m (2H), 4.11 m (2H), 4.14 m (2H),
4.22 m (4H), 4.24 m (2H), 4.27 m (2H),
4.52 m (2H)
2.01 m (2H), 2.77 m (4H), 5.32 s (2H)
6.20 s (2H)
9
16
4.14 s (10H)
4.12 s, 4.16 s
(10H), 4.17 s
1.87 m (4H), 2.42 m (4H), 4.98 s (2H)
1.24–1.30 m (2H), 1.81–1.87 m (4H),
1.89–2.05 m (4H), 2.17–2.42 m (6H),
2.60–2.82 m (4H)
6.42 s (2H)
4.20 s (1H), 6.04 s (1H), 6.25 s (1H),
6.57 s (1H)
–
–
/
17
18
4.05 s, 4.08 s,
4.16 s, 4.17 s
3.95–4.07 m (8H), 4.22 m (2H), 4.30 m
(2H), 4.33 m (2H), 4.48 m (2H)
1.52–1.65 m (2H), 1.78–1.95 m (4H),
2.00–2.10 m (4H), 2.20–2.30 m (4H),
2.41–2.46 m (2H), 2.78 m (2H), 4.21 d (1H),
J=1.2, 5.98 d (1H), J=1.2
4.09 m (1H), J=5.8, 4.22 s (1H) 6.27 s
(1H), 6.41 s (1H)
–
4.15 s (10H),
4.17 s, 4.20 s
4.06–4.52 m (16H)
1.23–2.81 m (16H)
4.75 d (1H), J=10.2, 6.05 d (1H),
J=10.2, 5.94 s (1H), 6.36 s (1H), 6.57 s
(1H)
1.89 s (1H)
19
20
21
4.16 s, 4.22 s
4.14 s, 4.20 s
4.11 s, 4.14 s
4.14 m (2H), 4.18 m (2H), 4.26 m (2H),
4.47 m (2H)
4.05 m (2H), 4.25 m (2H), 4.28 m (2H),
4.39 m (2H)
3.93 m (1H), 4.10 m (2H), 4.26 m (2H),
4.28 m (1H), 4.37 m (1H), 4.39 m (1H)
1.75–2.82 m (6H), 4.39 bs (1H), 5.12 d
(1H), J=1.0
1.30–2.85 m (8H), 4.44 bs (1H), 5.24 d
(1H), J=1.2
1.87 m (2H), 2.21 m (2H), 2.58–2.65 m
(2H), 2.77 m (1H), 2.98 m (1H)
5.68 s (1H), 6.51 s (1H)
7.28–7.60 m (5H)
7.32–7.61 m (5H)
5.69 s (1H), 6.48 s (1H)
3.25 m (1H), J=12.1, 3.31 dd (1H),
J=12.1, 5.4, 3.88 d (1H), J=5.4,
6.27 s (1H)
7.05 d (2H), J=
6.9, 7.38 m (3H)
579
22
4.12 s, 4.125 s
3.98 m (1H), 4.10 m (1H), 4.14 m (1H),
4.18 m (1H), 4.27 m (2H), 4.38 m (1H),
4.42 m (1H)
1.86 m (4H), 2.35–2.65 m (4H), 2.73 m
(1H), 2.81 m (1H)
3.25 m (1H), J=12.1, 3.34 dd (1H),
J=12.1; 5.8, 3.89 d (1H), J=5.8
7.09 d (2H), J=
(
6.9, 7.43 m (3H)
3
23
24
25
26
4.16 s, 4.19 s
4.14 s, 4.19 s
4.15 s, 4.185 s
4.094 s, 4.16 s
4.38 m (2H), 4.47 m (2H), 4.55 m (2H),
4.69 m (2H)
4.34 m (2H), 4.46 m (2H), 4.52 m (2H),
4.65 m (2H)
1.90 m (2H), 2.79 m (2H), 3.40 m (2H)
6.94 s (1H), 8.13 s (1H)
7.35–7.71 m (5H)
7.36–7.58 m (5H)
7.11–7.50 m (5H)
7.25–7.48m (5H)
1.31 m (2H), 1.43–1.56 m (2H), 1.80–1.86 m
(2H), 2.60–3.10 m (2H)
1.25–2.00 m (6H), 2.81 td (1H), J=11.8,
6.2, 4.9, 3.48 dd (1H), J=11.8, 6.2
1.27–2.05 m (8H), 3.01 m (1H), 3.65 m (1H)
6.38 s (1H), 7.75 s (1H)
4.16–4.20 m (8H)
4.22 dd (1H), J=6.2, 4.9, 6.69 s (1H)
4.19 dd (1H), J=6.3, 4.8, 6.33 s (1H)
4.06–4.20 m (8H)

Table 2
13C-NMR spectral data of compounds 7–9, 16–18, 21 and 22 (l)
Compound C5H5
C5H4
CipsoFc
CH=, CH2=
124.36
C
CH, CH3
CH2
CHFc
7
68.99, 69.08
68.58, 68.64, 68.75, 68.76,
69.12, 69.19, 69.95, 69.97
66.45, 66.95, 67.14, 67.30,
69.39, 69.56, 69.65, 70.30
67.16, 67.51, 68.24, 68.75,
69.35, 69.53, 70.12, 70.35
66.88, 67.01, 67.38, 67.40,
67.58, 68.16, 68.21, 68.51,
68.78, 68.96, 69.11, 69.19,
69.25, 69.30, 69.34, 69.64
66.80, 67.38, 67.70, 68.15,
68.22, 68.71, 68.93, 69.05,
69.27, 69.35, 69.39, 69.50,
69.52, 69.61, 70.23, 70.37
65.98, 66.81, 67.04, 67.63,
67.85, 68.26, 68.33, 68.56,
68.64, 68.75, 68.78, 68.94,
69.43, 69.52, 69.76, 69.95
67.22, 68.14, 68.55, 68.58,
68.73, 68.85, 69.27, 69.78
81.96, 82.14
83.58, 90.05
78.87, 81.80
40.55, 140.44, 158.27
135.29, 136.84, 137.22
140.45, 144.48, 144.49
19.97
30.22, 31.24
–
–
–
8
68.80, 69.00
69.03, 69.06
120.48, 129.21
121.20, 124.38
–
–
–
24.23, 28.23, 31.92
29.33, 29.84, 30.20, 31.22
/
9
16
68.66, 68.85,
68.95, 69.12
82.30, 82.86,
83.65, 89.15
122.78, 123.43,
124.98
51.23, 132.21, 135.60,
137.15, 142.25, 150.58
20.04, 25.93, 26.81, 28.94, 62.45
29.74, 30.56, 31.03, 32.22,
41.63
17
18
69.12, 69.14,
69.21, 69.27
81.10, 81.58,
81.99, 82.76
107.76, 124.98,
130.08
50.36, 133.48, 139.03,
141.96, 142.16, 148.78
–
25.98, 26.80, 29.81, 29.83, 63.02, 64.21
30.22, 31.03, 31.49, 47.69,
47.86
68.52, 68.88,
69.05, 69.07
81.95, 82.54,
83.23, 92.63
121.14, 126.78,
132.51, 137.74
122.77, 138.29, 142.09,
142.16, 144.23, 148.17
17.95
22.63, 26.40, 29.59, 31.20, 55.37
32.43, 34.31, 36.86, 40.47
579
21
22
68.83, 69.10
68.76, 69.04
82.96, 84.54
82.75, 84.60
119.99
118.73
128.32, 130.17, 131.72,
134.28, 136.91, 177.53,
179.14
127.73, 129.95, 131.64,
134.18, 137.03, 177.41,
179.20
39.39, 42.75
39.34, 43.06
21.80, 23.21, 27.78, 31.33
46.62
(
3
67.15, 67.96, 68.40, 68.51,
68.70, 68.76, 69.21, 69.80
20.96, 21.99, 22.74, 23.86, 46.58
30.87

E.I. Klimo6a et al. / Journal of Organometallic Chemistry 579 (1999) 30–37
35
hindrances in cycloalkane moieties (the steric effect),
which distinguishes these compounds from camphane-
[2] and quinuclidine-based [3] s-cis-dienes studied by us
previously.
The combination of these factors has permitted the
isolation of both the cyclic (11 and 17) and linear (12
and 18) dimers. Thus, we have fixed the principal stages
of the asynchronic, stepwise cyclodimerization, viz. the
intermediate formation of the linear dienyl carbocations
(14a and b) and cyclic allylic carbocations (15a and b)
resulting from the addition of methyl bisferrocenyldi-
enyl cations 13a and b to the methylene groups of
trienes 8 and 9. The scheme of asynchronic cationic
cyclodimerization discussed previously [1–6,12–17] is
thereby strongly substantiated.
The oxidative dehydrogenation occurs in a stepwise
manner via intermediate cyclohexadienes 25 and 26,
which were isolated by chromatography and character-
ized. These compounds are stable in the crystalline
state, while in solutions or being absorbed on Al2O3 or
SiO2 they undergo smooth oxidation to 23 and 24.
4. Experimental
1
All H- and 13C-NMR spectra were recorded on a
Unity Inova Varian spectrometer (at 300 and 75 MHz)
in CDCl3 solutions with Me4Si as an internal standard
(Tables 1 and 2). The elemental analyses data are listed
in Table 3.
3. Conclusions
Thus, for the first time we have isolated spiro-cy-
clodimers 11 and 17 with a methylene fragment, which
originate from the diferrocenyltriene systems, together
with the linear dimers 12 and 18. The observed pecu-
liarities of the behavior of trienes 8 and 9 under the
conditions of mild acid catalysis seem to be related to
the enhanced stability of the intermediate ferrocenyl
allylic and dienyl carbocations of the type 13–15 (the
electronic effect) and to the absence of substantial steric
4.1. 2,6-Bis( ferrocenylmethylene)cyclohexanone 4 and
2,7-bis( ferrocenylmethylene)cycloheptanone 5
These were obtained from ferrocenecarbaldehyde and
the corresponding ketone in t-butyl alcohol in the
presence of t-BuOK. The yield of chalcone 4 was 72%
[7] and of chalcone 5, 38%; orange crystals, m.p. 173–
174°C.
Table 3
Elemental analyses data
Compound
Molecular formula
Found (Calculated) (%)
C
H
Fe
N
5
7
8
9
C
29H28Fe2O
68.93 (69.08)
69.37 (69.25)
71.51 (71.34)
71.63 (71.74)
71.87 (71.74)
71.58 (71.74)
71.61 (71.74
67.27 (67.00)
67.51 (67.38)
70.71 (70.82)
70.89 (71.13)
71.42 (71.25)
71.30 (71.56)
70.86 (71.04)
71.43 (71.34)
5.77 (5.60)
6.03 (6.20)
5.98 (5.78)
5.91 (6.02)
6.19 (6.02)
5.87 (6.02)
5.83 (6.02)
4.83 (5.01)
5.06 (5.21)
5.44 (5.33)
5.37 (5.52)
4.54 (4.75)
4.83 (4.95)
4.91 (5.04)
5.11 (5.24)
22.41 (22.15)
21.56 (21.47)
22.55 (22.88)
22.37 (22.24)
22.11 (22.24)
22.38 (22.24)
22.43 (22.24)
16.73 (16.84)
16.63 (16.48)
17.04 (16.89)
16.73 (16.54)
16.91 (17.00)
16.87 (16.63)
17.08 (16.94)
16.73 (16.59)
–
–
–
–
–
–
–
C30H32Fe2O
C29H28Fe2
C30H30Fe2
C60H60Fe4
C60H60Fe4
16
17
18
19
20
21
22
23
24
25
26
C60H60Fe4
C37H33Fe2N3O2
C38H35Fe2N3O2
C39H35Fe2NO2
C40H37Fe2NO2
C39H31Fe2NO2
C40H33Fe2NO2
C39H33Fe2NO2
C40H35Fe2NO2
6.47 (6.33)
6.34 (6.20)
2.26 (2.12)
1.95 (2.07)
2.21 (2.13)
1.91 (2.08)
2.21 (2.12)
1.98 (2.08)

36
E.I. Klimo6a et al. / Journal of Organometallic Chemistry 579 (1999) 30–37
4.2. Alcohols 6 and 7
with hexane, and dried. Cyclodimer 10 was obtained in
a yield of 0.38 g (77%), m.p. 258–259°C.
These were synthesized from chalcones 4 and 5,
respectively, and methyllithium [4,5]. The yield of cyclo-
hexanol 6 was 73%, yellow crystals, m.p. 156–157°C
[10]; the yield of cycloheptanol 7 was 74%, orange
crystals, m.p. 167–168°C.
Triene 9 (0.52 g, 1 mmol) was dissolved in 50 ml of
dry benzene, and the solution was refluxed for 2 h. The
solvent was removed in vacuo, and the residue was
purified by crystallization from acetonitrile to give 0.36
g (70%) of cyclodimer 16, m.p. 237–239°C.
4.3. Dehydration of alcohols 6 and 7 in pyridine in the
presence of POCl3
4.6. Reaction of trienes 8 and 9 with azodicarboxylic
acid N-phenylimide
A total of 1 ml of POCl3 was added drop-wise to a
solution of alcohol 6 (3.0 mmol) in 100 ml of dry
pyridine at 5–10°C, the reaction mixture was stirred for
3 h at 10°C, and diluted with water. The reaction
products were extracted with benzene. The solvent was
removed in vacuo, and the residue was subjected to
TLC on SiO2 (hexane–benzene, 2:1) to give 0.17 g
(12%) of the linear dimer 12 (Rf=0.67), orange crys-
tals, m.p. 226–227°C [8]; 0.38 g (26%) of adduct 10,
(Rf=0.52), orange crystals, m.p. 259–260°C [8], and
0.60 g (41%) of cyclodimer 11, orange crystals, m.p.
262–263°C [8].
To a stirred solution of triene 8 (or 9) (1 mmol) in 20
ml of dry benzene, was added azodicarboxylic acid
N-phenylimide (0.18 g) portion-wise as the mixture
discolored, in the temperature range 0–5°C. The mix-
ture was stirred for an additional 30 min. The crystals
that precipitated were filtered off and purified by crys-
tallization from benzene to give 0.47 g (71%) of 1-ferro-
cenyl-5-ferrocenylmethylene-2,3-diazabicyclo[4.4.0]dec-
9(10)ene-2,3-dicarboxylic acid N-phenylimide 19, yel-
low crystals, m.p. 293–294°C, and, respectively, 0.46 g
(67%) of 1-ferrocenyl-5-ferrocenylmethylene-2,3-diaz-
abicyclo[5.4.0]undec-10(11)-ene-2,3-dicarboxylic
acid
Under analogous conditions, alcohol 7 (1.56 g, 3.0
mmol) afforded the following products: triene 9 (0.45 g,
30%), (Rf=0.85), orange needles, m.p. 147–148°C; 1,3-
bis(ferrocenylmethylene)-2-[2-ferrocenyl-2-(3-ferrocen-
ylmethylene-2-methylenecyclohept-1-enyl)ethylidenecy-
cloheptane 18, (0,14 g, 9%) (Rf=0.68), orange powder,
N-phenylimide 20, m.p. 301–303°C.
4.7. Reaction of trienes 8 and 9 with
N-phenylmaleimide
m.p.
183–184°C;
spiro[2,7-bis(ferrocenylmethyl-
A mixture of trienes 8 or 9 (1 mmol) and 0.3 g of
N-phenylmaleimide in 20 ml of dry benzene was stirred
for 5 h at 20°C. The solvent was removed in vacuo, and
the residue was chromatographed on alumina (Brock-
mann activity III, hexane–benzene as the eluent) to
give 0.43 g (65%) of endo-1-ferrocenyl-5-ferrocenyl-
methylene-1,2,3,4,5,6,7,8-octahydronaphthalene-2,3-di-
carboxylic acid N-phenylimide 21, yellow crystals, m.p.
251–252°C, or 0.49 g (72%) of endo-1-ferrocenyl-5-fer-
rocenylmethylenebicyclo[5.4.0]undec-10(11)-ene-2,3-
dicarboxylic acid N-phenylimide 22, yellow crystals,
m.p. 264–265°C.
ene)cycloheptane-1,7%-(6-ferrocenyl-1-ferrocenylmethyl-
ene-2,3,4,5,6,7,8,9-octahydro-1H-benzocycloheptene)]
16, (0.24 g, 16%) (Rf=0.61), yellow crystals, m.p.
237–238°C; and spiro[3-ferrocenylmethylene-2-methyl-
enecycloheptane-1,7%-(6,8-diferrocenyl-1-ferrocenylmet-
hylene-2,3,4,5,6,7,8,9-octahydro-1H-benzocyclohept-
ene)] 17, (0.32 g, 21%) (Rf=0.52), yellow powder, m.p.
254–256°C.
4.4. Dehydration of alcohols 6 and 7 on Al2O3
A solution of alcohols 6 or 7 (2 mmol) in 30 ml of
chloroform was applied onto 20 g of alumina (Brock-
mann activity II) and left for 2 h at 20°C. Then it was
transferred into a column with alumina of the same
activity (layer height, 30 cm) and eluted with hexane.
The yield of triene 8 was 0.31 g (30%), orange needles,
m.p. 126–127°C, the yield of triene 9 was 0.63 g (61%),
orange needles, m.p. 148°C.
4.8. Oxidati6e dehydrogenation of N-phenylimides 21
and 22
A solution of compound 21 (0.22 g) in 10 ml of
benzene was applied on thin layer silica gel and left
overnight in air. Subsequent chromatography in hex-
ane–benzene (1:1) yielded 0.07 g (30%) of 1-ferrocenyl-
5-ferrocenylmethylene-5,6,7,8-tetrahydronaphthalene-2,
3-dicarboxylic acid N-phenylimide 23, Rf=0.72, red
crystals, m.p. 236–237°C, and 0.08 g (35%) of 1-ferro-
cenyl-5-ferrocenylmethylene-3,4,5,6,7,8-hexahydrona-
phthalene-2,3-dicarboxylic acid N-phenylimide 25,
Rf=0.63, violet crystals, m.p. 258–259°C.
4.5. Thermal cyclodimerization of trienes 8 and 9
Compound 8 (0.5 g, 1.0 mmol) was dissolved in 50
ml of hexane. The solution was kept at 20°C for 12 h.
The precipitate that formed was filtered off, washed

E.I. Klimo6a et al. / Journal of Organometallic Chemistry 579 (1999) 30–37
37
Meleshonkova, A. Mar´ın Becerra, Dokl. Akad. Nauk 351 (1996)
776.
[4] E.G. Perevalova, E.I. Klimova, V.V. Kryuchkova, A.N. Pushin,
Zh. Obshch. Khim. 59 (1989) 873.
[5] E.I. Klimova, A.N. Pushin, V.A. Sazonova, J. Organomet.
Chem. 270 (1984) 319.
[6] V.N. Postnov, E.I. Klimova, A.N. Pushin, N.N. Meleshonkova,
Metalloorg. Khim. 4 (1991) 116.
Analogously, 0.22 g of compound 22 yielded 0.08 g
(36%) of 1-ferrocenyl-5-ferrocenylmethylene-6,7,8,9-te-
trahydro-5H-benzocycloheptene-2,3-dicarboxylic acid
N-phenylimide 24, Rf=0.72, red powder, m.p. 269–
270°C, and 0.05 g (23%) of 1-ferrocenyl-5-ferrocenyl-
methylene-3,4,6,7,8,9-hexahydro-3H,4H,5H-benzocyclo-
heptene-2,3-dicarboxylic acid N-phenylimide 26, Rf=
0.64, red powder, m.p. 241–242°C.
[7] M. Salisova, M. Pusiova, V.N. Postnov, S. Toma, Chem. Papers
Chem. Zvesti 44 (1990) 201.
[8] E.I. Klimova, T. Klimova, B.M. Mart´ınez Garc´ıa, N.N.
Meleshonkova, L. Ru´ız Ram´ırez, Mendeleev Commun. (1997)
233.
Acknowledgements
[9] M. Mart´ınez Garc´ıa, T. Klimova Berestneva, N.N. Meleshon-
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[10] E.I. Klimova, M. Mart´ınez, G.T. Klimova, B.L. Ru´ız Ram´ırez,
Mendeleev Commun. (1998) 233.
Financial support from CONACYT (Mexico) is
gratefully acknowledged. We would like to thank Oscar
Salvador Yan˜ez Mun˜oz for the 1H- and 13C-NMR
spectra.
[11] A.N. Pushin, E.I. Klimova, V.A. Sazonova, Zh. Obshch. Khim.
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