From coordinated cyclooctatetraene to cis-5,7-disubstituted cycloocta-1,3-diene by iteratively applied nucleophilic and electrophilic addition

Article abstract of DOI:10.1021/om0300068

The addition of various carbanionic nucleophiles Nu¹ to the cationic complex [(η⁵-Cp)Fe-(η⁶-Cot)]⁺ (1) exclusively yields the neutral complex [(η⁵-Cp)Fe(1,2,3,4,5- η-C₈H₈Nu¹)] (2) with Nu¹ in exo position with respect to the metal center: Nu¹ = CH(CO₂Me)₂ (2a), CEt(CO₂Me)₂ (2b), CPh₂CN (2c), CH(CN)₂ (2d), C(CO₂Et)₂ (CH₂)₂CO₂Et (2e), C(CO₂ Et)₂(CH₂)₃CO₂Et (2f), C(CO₂Me)₂(CH₂)₂CN (2g), CH(COMe)CO₂Et (2h). Protonation of 2 by HBF₄ reveals the complexes [(η⁵-Cp)Fe(η⁶-C₈H₉ Nu¹)]BF₄ (3BF₄) with a 1,2,3,4,5,6-η coordination mode of the cyclo-C₈ ligand. The cationic complexes 3 are suitable for a second nucleophilic addition affording the exo-6,8-disubstituted cyclooctadienyl complex [(η⁵-Cp)Fe(1,2,3,4,5-η-C₈H₉-6- Nu¹-8-Nu²)] (4): Nu¹/Nu² = CH(CO₂Me)₂/CH(CO₂Me)₂ (4a), CEt(CO₂Me)₂/CH(CO₂Me)₂ (4b), CPh₂CN/CPh₂CN (4c). It can be shown that the nucleophilic addition occurs not only with the carbanionic nucleophiles, which must be prepared separately by deprotonation reactions with NaH, but also in-situ, when the cationic complex, the C,H acidic substrate, and the strong base tetramethyl guanidine (TMG) are present. The capability of facile deprotonation reaction by TMG enables a one-pot procedure of the synthesis of 4a without isolation of the intermediates 2 and 3. Attempts of intramolecular nucleophilic additions in 3dBF₄ (Nu¹ = C(CO₂Et)₂ (CH₂)₂CO₂Et) and 3eBF₄ (Nu¹ = C(CO₂Et)₂(CH₂)₃ CO₂Et) by application of TMG failed in the formation of cyclo-C₈-based bicycles but rather result in addition of TMG to the cyclo-C₈ ligand forming 4d and 4e with tetramethyl guanidinyl as Nu². The protonation of 4a-c in acetonitrile by addition of CF₃CO₂H splits off the cyclo-C₈ ligand as a cis-5,7-disubstituted cycloocta-1,3-diene (6): Nu¹/Nu² = CH(CO₂Me)₂/CH(CO₂Me)₂ (6a), CEt(CO₂Me)₂/CH(CO₂Me)₂ (6b), CPh₂CN/CPh₂CN (6c). The protonation of 4d and 4e cleaves the guanidinyl substituent and recovers the starting complexes 3d and 3e. When the steric demand of Nu¹ and Nu² is different, as in 4b, the isomer that bears the sterically most demanding nucleophile proximal to the endocyclic carbon - carbon double bond is preferentially formed.

Full text of DOI:10.1021/om0300068

Organometallics 2003, 22, 2097-2107
2097
F r om Coor d in a ted Cycloocta tetr a en e to
cis-5,7-Disu bstitu ted Cycloocta -1,3-d ien e by Iter a tively
Ap p lied Nu cleop h ilic a n d Electr op h ilic Ad d ition
Oliver Reimelt and J u¨rgen Heck*
Institut fu¨r Anorganische und Angewandte Chemie, Universita¨t Hamburg,
Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
Received J anuary 6, 2003
The addition of various carbanionic nucleophiles Nu1 to the cationic complex [(η5-Cp)Fe-
(η6-Cot)]+ (1) exclusively yields the neutral complex [(η5-Cp)Fe(1,2,3,4,5-η-C8H8Nu1)] (2) with
Nu1 in exo position with respect to the metal center: Nu1 ) CH(CO2Me)2 (2a ), CEt(CO2Me)2
(2b), CPh2CN (2c), CH(CN)2 (2d ), C(CO2Et)2(CH2)2CO2Et (2e), C(CO2Et)2(CH2)3CO2Et (2f),
C(CO2Me)2(CH2)2CN (2g), CH(COMe)CO2Et (2h ). Protonation of 2 by HBF4 reveals the
complexes [(η5-Cp)Fe(η6-C8H9Nu1)]BF4 (3BF4) with a 1,2,3,4,5,6-η coordination mode of the
cyclo-C8 ligand. The cationic complexes 3 are suitable for a second nucleophilic addition
affording the exo-6,8-disubstituted cyclooctadienyl complex [(η5-Cp)Fe(1,2,3,4,5-η-C8H9-6-
Nu1-8-Nu2)] (4): Nu1/Nu2 ) CH(CO2Me)2/CH(CO2Me)2 (4a ), CEt(CO2Me)2/CH(CO2Me)2 (4b),
CPh2CN/CPh2CN (4c). It can be shown that the nucleophilic addition occurs not only with
the carbanionic nucleophiles, which must be prepared separately by deprotonation reactions
with NaH, but also in-situ, when the cationic complex, the C,H acidic substrate, and the
strong base tetramethyl guanidine (TMG) are present. The capability of facile deprotonation
reaction by TMG enables a one-pot procedure of the synthesis of 4a without isolation of the
intermediates 2 and 3. Attempts of intramolecular nucleophilic additions in 3d BF4 (Nu1 )
C(CO2Et)2(CH2)2CO2Et) and 3eBF4 (Nu1 ) C(CO2Et)2(CH2)3CO2Et) by application of TMG
failed in the formation of cyclo-C8-based bicycles but rather result in addition of TMG to the
cyclo-C8 ligand forming 4d and 4e with tetramethyl guanidinyl as Nu2. The protonation of
4a -c in acetonitrile by addition of CF3CO2H splits off the cyclo-C8 ligand as a cis-5,7-di-
substituted cycloocta-1,3-diene (6): Nu1/Nu2 ) CH(CO2Me)2/CH(CO2Me)2 (6a ), CEt(CO2Me)2/
CH(CO2Me)2 (6b), CPh2CN/CPh2CN (6c). The protonation of 4d and 4e cleaves the guani-
dinyl substituent and recovers the starting complexes 3d and 3e. When the steric demand
of Nu1 and Nu2 is different, as in 4b, the isomer that bears the sterically most demanding
nucleophile proximal to the endocyclic carbon-carbon double bond is preferentially formed.
In tr od u ction
cleophilic and electrophilic additions on the correspond-
ing cationic Fe complex [(η5-Cp)Fe(η6-Cot)]+ which
enables a facile access to regio- and stereoselectively
modified cycloocta-1,3-dienes.
Nucleophilic addition to unsaturated organic ligands
is pertinent to synthetic organometallic chemistry.1
Since this type of reaction displays pronounced stereo-
and regioselectivity, it is used in the synthesis of natural
products.2 More recent investigations demonstrate that
this synthetic concept can be transferred to coordinated
carbocycles such as cyclooctatetraene (Cot),3,4 which
generates an access to multiple stereo- and regioselec-
tively functionalized cyclo-C8 compounds. They may be
of some importance in the synthesis of precursor com-
pounds for cyclo-C8 terpenoids,5 which illustrate inter-
esting biological activities.6 Recently, we published the
results of iterative nucleophilic and electrophilic addi-
tions to Ru-coordinated cyclooctatetraene resulting in
regio- and stereoselectively functionalized cyclo-C8
ligands, which demonstrate a remarkable coordination
chemistry.7 In this paper we present results obtained
from the iteratively applied reaction sequence of nu-
Resu lts a n d Discu ssion
The initial nucleophilic addition to [(η5-Cp)Fe(η6-
Cot)]+ (1+) occurs in good to excellent yields (63-96%)
with the exception of Nu1 ) HC(CN)2 (34%) and
exclusively at the “terminal” carbon atom of the coor-
dinated part of the Cot ligand as predicted from the
Davis-Green-Mingos (DGM) rules (Scheme 1).8 The
use of the bifunctionalized nucleophiles, which yields
the products 2e-h , was intended to perform a second,
but intramolecular nucleophilic addition gaining bicyclic
compounds (vide infra). In contrast to the corresponding
Ru complex7 the reaction product displays only a
1,2,3,4,5-η coordination mode of the cyclooctatrienyl
ligand in 2 (Scheme 1a), which has been shown for the
malonate derivative 2a (Nu ) CH(CO2Me)2) by means
of X-ray structure analysis9 and which can easily be
* Corresponding author. E-mail:
hamburg.de.
juergen.heck@chemie.uni-
10.1021/om0300068 CCC: $25.00 © 2003 American Chemical Society
Publication on Web 04/12/2003

2098 Organometallics, Vol. 22, No. 10, 2003
Reimelt and Heck
Sch em e 1. Rea ction Sequ en ce for th e F or m a tion
of 5,7-Disu bstitu ted Cycloocta -1,3-d ien es Sta r tin g
fr om Ir on -Coor d in a ted Cota
F igu r e 1. Nucleophilic attack on the two enantiotopic sites
generating two stereogenic centers.
ligands, the nucleophilic addition reveals chiral com-
plexes in a racemic mixture (Figure 1). As a result, the
two identical substituents on the Cot-linked carbon
atom in 2a -g (i.e., CO2Me, Ph) are diastereotopic and
thus display different NMR signals.
The addition of a second nucleophile requires a new
cationic complex, which is gained by the protonation of
2 with HBF4 in diethyl ether (Scheme 1b). The cationic
product 3 is obtained in good to excellent yields (68-
98%) and precipitates as a red crystalline material or
forms a red oil, which can easily be separated from the
reaction mixture. The product exclusively consists of
1,2,3,4,5,6-η haptomers, and no indication is found for
the formation of the 1,2-η:4,5,6,7-η haptomers as in the
case of the Ru congeners.7 Again the coordination mode
1
of the cyclo-C8 ligand is demonstrated by H-1H and
1H-13C correlation spectra. It is noteworthy that one
1H resonance signal of the endocyclic methylene group,
which shows the characteristic ddd pattern due to the
spin-spin coupling with three neighboring protons, is
shifted below -1.7 ppm. It is suggested that the ani-
sotropy cone of the diamagnetic sandwich complexes7,10
induces the upfield shift of 1H NMR signals for protons
in exo position with respect to the metal center.
a
(a) THF, NaNu1; (b) Et2O, HBF4, -78 °C; (c) THF, NaNu2,
The second nucleophilic addition can in principle
occur at two different terminal carbon atoms of the
coordinated cyclooctatriene ligand (Figure 2), if this
(d) MeCN, CF3CO2H.
proven by H-1H and H-13C correlation spectroscopy
1
1
for the other products of 2.7
(2) (a) Stephenson, G. R. In Organic Synthesis via Organometallics;
Do¨tz, K. H., Hoffmann, R. W., Eds.; Verlag Friedrich Vieweg and
Sohn: Braunschweig, Germany, 1991. (b) Rosenblum, M.; Watkins,
J . C. J . Am. Chem. Soc. 1990, 112, 6316-6322. (c) Kno¨lker, H.-J .;
Boese, R.; Hartmann, K. Angew. Chem. 1989, 101, 1745-1747; Angew.
Chem., Int. Ed. Engl. 1989, 28, 1678-1680. (d) Kno¨lker, H.-J .;
Bauermeister, M.; Bla¨ser, D.; Boese, R.; Pannek, J .-B. Angew. Chem.
1989, 101, 225-227; Angew. Chem., Int. Ed. Engl. 1989, 28, 223-225.
(e) Palotai, I. M.; Stephenson, G. R.; Kane-Maguire, L. A. P. J .
Organomet. Chem. 1987, 319, C5-C10. (f) Pearson, A. J . Pure Appl.
Chem. 1983, 55, 1767.
Since the starting complex 1 contains a mirror plane,
which includes the Fe atom and bisects the Cp and Cot
(1) (a) Tsuji, J . Transition Metal Reagents and Catalysis; Wiley:
Chichester, England, 2000; Chapter 4. (b) McDaniel, K. F. In Com-
prehensive Organometallic Chemistry; Abel, E. W., Stone, F. G. A.,
Wilkinson, G., Hegedus, L. S., Eds.; Elsevier Science Ltd.: Oxford,
1995; Vol. 12, pp 601-622. Donaldson, W. A. In Comprehensive
Organometallic Chemistry; Abel, E. W., Stone, F. G. A., Wilkinson, G.,
Hegedus, L. S., Eds.; Elsevier Science Ltd.: Oxford, 1995; Vol. 12, pp
623-635. Pearson, A. J . In Comprehensive Organometallic Chemistry;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Hegedus, L. S., Eds.;
Elsevier Science Ltd.: Oxford, 1995; Vol. 12, pp 637-683. (c) Hegedus,
L. G. Transition Metal in the Synthesis of Complex Organic Molecules;
University Science Books: Mill Valley, CA, 1994; p 31 ff. (d) Elschen-
broich, Ch.; Salzer, A. Organometallics, A Concise Introduction, 2nd,
revised ed.; VCH: Weinheim, 1992; p 292 ff. (e) Casta˜no, A. M.;
Ba¨ckvall, J . F. J . Am. Chem. Soc. 1995, 117, 560-561. (f) Pearson, A.
J .; Balasubramanian, S.; Srinivasan, K. Tetrahedron 1993, 49, 5663-
5672. (g) Pearson, A. J .; Mallik, S.; Mortezali, R.; Perry, M. W. D.;
Shively, R. J ., J r.; Youngs, W. J . J . Am. Chem. Soc. 1990, 112, 8034-
8041. (h) Pearson, A. J .; Kole, S. K.; Yoon, J . Organometallics 1986, 5,
2075-2081. (i) Braterman, P. S. In Reactions of Coordinated Ligands;
Plenum: New York 1986. (j) Kane-Maguire, L. A. P.; Honig, E. D.;
Sweigart, D. A. Chem. Rev. 1984, 84, 525-543. (k) Faller, J . W.; Chao,
K.-H. Organometallics 1984, 3, 927-932. (l) Trost, B. M.; Verhoeven,
T. R. In Comprehensive Organometallic Chemistry; Wilkinson, G.,
Stone, F. G. A., Abel, E. W., Eds.; Pergamon: New York, 1982; Vol. 8,
pp 799-938. (m) Pearson, A. J . In Comprehensive Organometallic
Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Perga-
mon: New York, 1982; Vol. 8, pp 939-1011. (n) Birch, A. J .; Bandora,
B. M. R.; Chamberlain, K.; Chauncey, B.; Dahler, P.; Day, A. I.;
J enkins, I. D.; Kelley, L. F.; Knor, T. C.; Kretschmer, G.; Liepa, A. J .;
Narula, A. S.; Raverty, W. D.; Rizzardo, E.; Sell, C.; Stephenson, G.
R.; Thompson, D. J .; Williamson, D. H. Tetrahedron 1981, 37, Suppl.
1, 5289-5302. (o) Pearson, A. J . Acc. Chem. Res. 1980, 13, 463-469.
(3) Damen, M.; Haupt, E. T. K.; Heck, J .; Maters, M.; Voss, B.
Organometallics 1995, 14, 44-48.
(4) Heck, J .; Lange, G. A.; Reimelt, O. Angew. Chem. 1998, 110,
533-535; Angew. Chem., Int. Ed. 1998, 37, 520-522.
(5) Petasis, N. A.; Patane, M. A. Tetrahedron 1992, 48, 5757-5821.
(6) Ayanoglu, E.; Gebreyesus, T.; Beechan, C. M.; Djerassi, C.
Tetrahedron 1972, 35, 1035-1039. Wender, P. A.; Ihle, N. C.; Correia,
C. R. D. J . Am. Chem. Soc. 1988, 110, 5904-5906. Majetich, G.;
Lowery, D.; Khetani, V.; Song, J .-S.; Hull, K.; Ringold, C. J . Org. Chem.
1991, 56, 3988-4001. Majetich, G.; Lowery, D.; Khetani, V. Tetrahe-
dron Lett. 1990, 31, 55-58. Tringali, C.; Oriente, G.; Piatelli, M.;
Geraci, C.; Nicolosi, G.; Breitmeier, E. Can. J . Chem. 1988, 66, 2799-
2802. Schneider, B. Dtsch. Apoth. Ztg. 1994, 36, 3389-3400. Barrow,
K. D.; Barton, D. H. R. Chain, E.; Ohnsorge, U. F. W.; Sharma, R. P.
J . Chem. Soc., Perkin. Trans. 1 1973, 1590-1599. Wahlberg, I.; Eklund,
A. M.; Nishida, T.; Enzell, C. R.; Tetrahedron Lett. 1983, 24, 843-
846. Wender, P. A.; Badham, N. F.; Conway, S. P. J . Am. Chem. Soc.
1997, 119, 2755-2758.
(7) Lange, G.; Reimelt, O.; J essen, L.; Heck, J . Eur. J . Inorg. Chem.
2000, 1941-1952.
(8) Davies, S. G.; Green, M. L. H.; Mingos, D. M. P. Tetrahedron
1978, 34, 3047-3077.
(9) Beurskens, P. T.; Bosman, W. P.; Brussaard, H. C.; Heck, J .;
Klein Gebbink, R. J . M.; Maters, M.; Smits, J . M. M. J . Organomet.
Chem. 1994, 469, 197-203.
(10) Elschenbroich, Ch.; Koch, J .; Schneider, J .; Spangenberg, B.;
Schiess, P. J . Organomet. Chem. 1986, 317, 41-54.

From Cyclooctatetraene to Cycloocta-1,3-diene
Organometallics, Vol. 22, No. 10, 2003 2099
Sch em e 3. On e-P ot P r oced u r e to Syn th esize
Cycloocta d ien yl Der iva tives 4 w ith ou t Isola tion of
th e In ter m ed ia tes 2 a n d 3 (see Sch em e 1)
F igu r e 2. Possible target positions for the second nucleo-
philic addition.
Sch em e 2. Nu cleop h ilic Ad d ition Su p p or ted by
Tetr a m eth yl Gu a n id in e (TMG)
Sch em e 4. Attem p ts of a n In tr a m olecu la r
Nu cleop h ilic Ad d ition in th e P r esen ce of TMG
Resu ltin g in th e Ad d ition of TMG
addition obeys the DGM rules as well. However, prob-
ably for steric reasons the addition exclusively occurs
distal with respect to the first nucleophile Nu1, forming
the 6,8-disubstituted 1,2,3,4,5-η-cyclooctadienyl com-
plexes 4 in good yields (60-87%), and additionally both
nucleophiles are in exo position with respect to the metal
center (Scheme 1c). The structural characterization can
easily be carried out by taking into account the few
signals of 4a and 4c due to the local Cs symmetry of
the cyclo-C8 ligand and the results of 1H-1H and
1H-13C correlation spectra.
According to previous descriptions, the nucleophiles
used for the first and second nucleophilic addition have
been prepared separately by deprotonation reactions of
the C,H acidic precursor compounds with NaH; the
solutions of the obtained carbanions were added to the
cationic complexes 1 and 3, respectively. To simplify this
nucleophilic addition procedure, we attempted to gener-
ate the nucleophiles in-situ by adding the strong base
(but weak nucleophile) tetramethyl guanidine (TMG)
directly to a solution of the cationic starting complexes
and the C,H acidic precursor compounds in dichlo-
romethane. Due to its strong basicity, TMG11 is often
successfully used in Michael additions,12 in combina-
torial peptide synthesis,13 and in esterification reactions
of carboxylic acids with alkyl halides.14
The use of TMG as deprotonation reagent to form the
nucleophiles in-situ is successfully demonstrated for
dimethyl malonate and diphenyl acetonitrile (Scheme
2). The products 2a and 2c are obtained in very high
yields, 89 and 96%, respectively.
The successful application of TMG enables the nu-
cleophilic addition twice without isolation of the prod-
ucts 2 and 3 and without changing the solvent. The first
nucleophilic addition occurs when a 2-fold excess of
TMG is added to a CH2Cl2 solution of 1 and a 4-fold
excess of dimethyl malonate with respect to the amount
of 1. The reaction mixture is subsequently protonated
by addition of HBF4 at T ) -78 °C, until the solution
is slightly acidic. After warming to room temperature,
an excess of TMG is added again. After 18 h complex
4a is isolated in a yield of 64% (Scheme 3), while a
stepwise nucleophilic addition (Scheme 1) reveals a yield
of 66%.
Attempts to perform an intramolecular second nu-
cleophilic addition in 3d ,e fail although different non-
nucleophilic bases such as lithium diisopropylamide
(LDA), lithium tetramethyl piperidinide (LTMP), so-
dium bis(trimethylsilyl)amide (NaBTSA), and potas-
sium tert-butoxide (KtBuO) are used. Product mixtures
are formed, which are not yet analyzed. Only when the
strong base TMG is applied, one definite product is
isolated as a red oil, which is highly soluble in less polar
solvents as diethyl ether and toluene. However, by
means of FAB-MS, 1H NMR, and IR spectroscopy it
becomes evident that TMG is added to the cyclo-C8
ligand even in the case of the longer chain in 3e. The
formation of 4d and 4e is also associated with the
inclusion of varying amounts of [HTMG]BF4 salt and
TMG, which are very difficult to detach and thus make
a reliable elemental analysis impossible. Attempts to
separate the pure products by column chromatography
result in the decomposition of 4d and 4e (Scheme 4).
The stereo- and regioselectively substituted cyclo-C8
ligand is easily split off as a cycloocta-1,3-diene deriva-
tive 6 in the case of 4a -c by addition of CF3CO2H in
the presence of acetonitrile (Scheme 1d). For the guanid-
inyl derivatives 4d and 4e (Scheme 4) the guanidinyl
substituent is cleaved upon protonation and the starting
complexes 3d and 3e are recovered. The cleavage of a
N nucleophile upon protonation was already reported
from an amino-substituted cyclo-C8 ligand.7
(11) Kolthoff, I. M.; Chantooni, M. K., J r.; Bhowmik, S. J . Am. Chem.
Soc. 1968, 90, 23-28. Anderson, L. M.; Hammer, R. M. J . Chem. Eng.
J pn. 1967, 3, 442-447. Peter, K.; Vollhardt, K. P. C. Organische
Chemie, 1. Aufl.; Verlag Chemie: Weinheim, 1990.
(12) Pollini, G. P.; Barco, A.; De Giuli, G. Synthesis 1972, 44-46.
(13) Whitney, D. B.; Tam, J . P.; Merrifield, R. B. Tetrahedron 1984,
40, 4237-4244.
(14) Paquette, L. A. Encyclopedia of Reagents for Organic Synthesis;
Wiley-Interscience: 1995; Vol. 7, pp 4815-4818.
In the course of the protonation of 4b a Fe hydride
species 5 is formed (Scheme 5), which can be identified
1
by means of low-temperature H NMR spectroscopy at
T ) -30 °C. In Figure 3 the 1H NMR spectra of a

2100 Organometallics, Vol. 22, No. 10, 2003
Reimelt and Heck
with the two different sites of the cyclo-C8 ligand (C1,
C2, C8 vs C4, C5, C6) can also be identified by the shift
variation of the corresponding proton signals of positions
1, 2, 4, 5, 6, and 8 in 4b and 5: in the 1H NMR spectrum
of 4b the resonance signals are separated only about
0.22, 0.02, and 0.0 ppm for the protons in 1,5-, 2,4-, and
6,8-position, respectively; the difference increases dis-
tinctly upon protonation to 1.40, 0.43, and 0.08 ppm
in 5.
This site preference in the agostic interaction con-
secutively favors the formation of the regioisomer A of
the 5,7-disubstituted cycloocta-1,3-diene (Scheme 5).
The ratio of the two regioisomers A and B amounts to
1
12:1, which was calculated from the intensity of the H
NMR signals of the malonate proton H-10 in isomer A
and H-9 in isomer B, respectively. One rationale behind
this site preference of the agostic interaction may be
the reduced steric demand of Nu2 ) CH(CO2Me)2
compared to Nu1 ) CEt(CO2Me)2, both of which are in
exo position with respect to the metal center. The
smaller nucleophile Nu2 at carbon atom C6 allows
carbon atom C5 to deflect from the metal center upon
the agostic interaction rather than carbon atom C1,
which is next to carbon atom C8 bearing the sterically
more demanding nucleophile Nu1.
F igu r e 3. 1H NMR spectra of complex 4b (Nu1 ) CEtR2,
Nu2 ) CHR2, R ) CO2Et) (top) and the result of the
protonation of 4b with CF3CO2H after 5 min at T ) -30
°C (bottom) forming the hydride complex 5 (* ) CH2Cl2).
Con clu sion s
The reaction sequence “first nucleophilic addition f
protonation f second nucleophilic addition f second
protonation f ligand decomplexation” applied on coor-
dinated cyclooctatetraene in [(η5-Cp)Fe(η6-Cot)]+ enables
a facile access to cis-5,7-disubstituted cycloocta-1,3-
dienes. The two nucleophilic additions strongly obey the
DGM rules and are thus chemo-, regio-, and stereose-
lective. The nucleophilic addition can be conducted by
the addition of the carbanionic nucleophiles, which have
to be prepared separately, to the cationic sandwich
complexes 1 and 3, or in-situ by bringing together the
cationic complexes, the C,H acidic compound as the
nucleophile precursor, and tetramethyl guanidine (TMG)
simultaneously. The addition of TMG as a deprotonating
reagent allows a one-pot procedure for the synthesis of
exo-6,8-disubstituted cyclooctadienyl ligands with the
same nucleophiles. By adding different nucleophiles,
apparently that regioisomer is preferentially formed,
which bears one endocyclic double bond next to the
sterically most demanding nucleophile, as shown for 6b.
This method opens a facile access to a very rarely
investigated but remarkable class of compounds16 that
provides a great synthetic potential with regard to
terpenoid cyclo-C8 compounds.6 The synthesis of cis-5,7-
disubstituted cycloocta-1,3-dienes is a supplementation
of the synthesis of cis-5,8-disubstituted cycloocta-1,3-
dienes.1f Attempts of intramolecular nucleophilic addi-
tions in 3d and 3e, wherein the precursor function for
Nu2 is the end group of the bound nucleophile Nu1, are
unsuccessful in the presence of TMG, but instead result
in the addition of a guanidinyl unit to the cyclo-C8 ligand
Sch em e 5. P r oton a tion of Com p lex 4b F or m in g
th e Ir on -Hyd r id e Com p lex 5 a n d , Su bsequ en tly,
th e F r ee 1,3-Cycloocta d ien es (r .t. ) r oom
tem p er a tu r e)
solution of 4b in CD3CN without CF3CO2H (top) and
with an excess of CF3CO2H at -30 °C (bottom) mea-
sured 5 min after the sample preparation are shown.
Most indicative for the formation of the Fe hydride
complex 5 is the presence of the distinctly upfield shifted
signal of a single proton at δ ) -14.6 ppm. This shift
range is typically found for classical iron hydride
complexes.15 Another important indication for the for-
mation of a cationic species is the general low-field shift
of the corresponding signals of the protons attached to
the metal-bound carbon atoms on going from 4b to 5.
An exception is the high-field shift of the proton signal
5, which is superimposed by the doublet of proton 10,
but which can be assigned unequivocally by means of
1
1H-1H correlation spectra. In a H-1H COSY spectrum
the signal at -14.6 ppm demonstrates cross-peaks with
the proton signals at positions 5 and 4 of the cyclo-C8
ligand, indicating a preferential agostic interaction with
only one site of the eight-membered ring at T ) -30
°C. The different interactions of the Fe hydride function
(16) According to our literature research only three (!) representa-
tives of this type of compound have been reported (except ref 4), all of
which show a trans configuration in the 5,7 position: (a) Zhang, H.
Hebei Shifan Daxue Xuebao, Ziran Kexueban 1987, 1, 13-15. (b)
Kroener, M. Chem. Ber. 1967, 100, 3162-3171.
(15) J a¨nicke, M.; Hund, H.-U.; Berke, H. Chem. Ber. 1991, 124, 719-
724.

From Cyclooctatetraene to Cycloocta-1,3-diene
Organometallics, Vol. 22, No. 10, 2003 2101
Ta ble 1. P r ep a r a tive Deta ils for th e F ir st Nu cleop h ilic Ad d ition
HNu1
mg (mmol)
1PF6
mg (mmol)
reaction
time (h)
yield
mg (%)
HNu1
method
product
HCH(CO2Me)2
HCH(CO2Me)2
HCEt(CO2Me)2
HCPh2CN
289 (2.19)
40 (0.30)
115 (0.72)
92 (0.47)
41 (0.63)
244 (0.87)
327 (1.19)
188 (1.02)
47 (0.37)
809 (2.19)
74 (0.20)
A
B
A
B
A
A
A
A
A
4
4
12
18
3
18
3
3
2a
2a
2b
2c
2d
2e
2f
704 (91)
63 (89)
228 (83)
193 (96)
63 (34)
338 (62)
510 (86)
321 (77)
88 (65)
266 (0.72)
178 (0.48)
234 (0.63)
320 (0.87)
438 (1.19)
377 (1.02)
142 (0.38)
HCH(CN)2
HC(CO2Et)2(CH2)2CO2Et
HC(CO2Et)2(CH2)3CO2Et
HC(CO2Me)2(CH2)2CN
HCH(COMe)CO2Et
2g
2h
18
47.9 (C1), 44.5 (C5), 39.5 (C8) ppm. Anal. Calcd for C18H20O4-
Fe (356.20): C 60.70, H 5.66. Found: C 60.62, H 5.72.
(4d ,e). The protonation of the guanidinyl derivatives 4d
and 4e recovers the starting complexes 3d and 3c.
Exp er im en ta l Section
All reactions were carried out under a nitrogen atmosphere,
and all solvents were saturated with nitrogen. THF, Et2O,
hexane, and toluene were freshly distilled from the appropriate
alkali metal or metal alloy. Dichloromethane was dried over
CaH2 and distilled under N2. NMR: Bruker AM 360 and
Varian Gemini 200. IR: Nujol mull, KBr cells, FT-IR 1720X
(Perkin-Elmer). EI/FAB-MS: 70 eV, Finnigan MAT 311 A.
Elemental analysis: CHN-O-Rapid, Institut fu¨r Anorganische
und Angewandte Chemie, Universita¨t Hamburg (the elemental
analyses of the cationic products 3BF4 are often hampered by
the inclusion of varying amounts of CH2Cl2, as indicated by
1H NMR spectra). [(η5-Cp)Fe(η6-Cot)]PF6 (1PF6),17 CH(CO2Et)2-
(CH2)2CO2Et, CH(CO2Me)2(CH2)3CO2Et, CH(CO2Me)2(CH2)2-
CN,18 and the sodium salts of the malonester derivatives19
were synthesized as described. HBF4 was purchased as a 54%
solution in diethyl ether from Fluka.
Gen er a l P r oced u r e for th e F ir st Nu cleop h ilic Ad d i-
tion . Syn th esis of 2a -h : Meth od A. One equivalent of the
organic C,H acidic compound HNu1 was added to a suspension
of 1.3-1.5 equiv of NaH in THF at T ) -40 °C. The reaction
solution was allowed to warm to room temperature and was
stirred until gas evolution (H2) stopped. The THF solution was
separated from unreacted NaH and was transferred by a
cannula to a suspension of 1 equiv of 1PF6 in THF. The
reaction mixture was stirred at room temperature and evapo-
rated to dryness. The residue was extracted with toluene, and
the extract was filtered through Celite. After removal of the
solvent, the product was normally obtained as a red crystalline
powder or red oil. For more preparative details see Table 1.
(η5-Cyclop en ta d ien yl)[1,2,3,4,5-η-8-exo-1,1-d i(m eth oxy-
ca r bon yl)p r op -1-ylcycloocta tr ien -6-yl]ir on (II) (2b): red
crystalline powder, soluble in Et2O, more soluble in toluene.
Fp: 85 °C. IR (KBr): ν˜ 3115 (w), 3085 (w) ν(C-H, aromat.),
3019 (w), 2979 (m), 2951 (m) ν(C-H, aliph.), 1724 (s), 1739 (s)
ν(CdO), 1652 (w) ν(CdC), 1451 (m), 1432 (m) δ(CH2/CH3), 1332
(m), 1301 (m) δ(CH3), 1227 (s), 1202 (s) ν(C-O) cm-1. 1H NMR
3
3
(200 MHz, C6D6): δ 5.74 (ddd, J 5,6 ) 6.4 Hz, J 6,7 ) 10.8 Hz,
3
3
1 H, 6-H), 5.61 (dm, J 6,7 ) 10.8 Hz, 1 H, 7-H), 5.42 (t′, J 2,3
)
3J 3,4 ) 6.4 Hz, 1 H, 3-H), 4.30 (dd, J 3,4 ) 6.3 Hz, J 4,5 ) 8.8
Hz, 1 H, 4-H), 4.14 (dd, J 1,2 ) 8.8 Hz, J 2,3 ) 6.3 Hz, 1 H,
2-H), 3.93 (s, 5 H, Cp), 3.86 (dd, J 1,2 ) 8.8 Hz, J 1,8 ) 5.8 Hz,
1 H, 1-H), 3.76 (m, 1 H, 8-H), 3.50 (dd, J 4,5 ) 8.8 Hz, J 5,6
) 6.4 Hz, 1 H, 5-H), 3.36 (s, 3 H, CO2CH3), 3.28 (s, 3 H,
CO2CH3), 2.28 (m, 2 H, 10-H), 1.06 (t, J ) 7.5 Hz, 3 H, 11-H)
3
3
3
3
3
3
3
3
3
ppm. 13C{1H} NMR (50 MHz, C6D6): δ 172.0, 170.9 (CdO),
127.4 (C6), 127.0 (C7), 99.0 (C3), 77.8 (C4), 77.5 (C2), 77.2 (s,
Cp), 63.7 (C9), 51.6, 51.2 (CO2CH3), 44.6 (C8), 44.2 (C5), 43.1
(C1), 27.5 (C10), 10.3 (C11) ppm. EI-MS (70 eV): m/z (%) 384
(22) [M+], 355 (2) [M+ - C2H5], 325 (5) [M+ - COOCH3], 225
(41) [CpFeC8H8+], 186 (31) [CpFeC5H5+], 121 (35) [CpFe+], 104
(100) [C8H8+]. Anal. Calcd for C20H24O4Fe (384.26): C 62.41,
H 6.30. Found: C 62.41, H 6.44.
Meth od B. One equivalent of complex 1PF6, 1-1.5 equiv
of HNu1, and 1.5 equiv of TMG were dissolved in CH2Cl2 (20
mL) and stirred at room temperature. The workup procedure
occurred as described in method A. For more preparative
details see Table 1.
(η5-Cyclop en ta d ien yl)[1,2,3,4,5-η-8-exo-d i(m eth oxyca r -
bon yl)m eth ylcycloocta tr ien -6-yl]ir on (II) (2a ): red crys-
talline powder, soluble in Et2O, more soluble in toluene. Fp:
83 °C. IR (KBr): ν˜ 3092 (w) ν(C-H, aromat.), 2995 (m), 2951
(m) ν(C-H, aliph.), 1752 (s) ν(CdO), 1642 (w) ν(CdC), 1434
(m) d(CH2/CH3), 1290 (m), 1192 (s), 1156 (s) ν(C-O) cm-1. H
1
NMR (200 MHz, C6D6): δ 5.79 (m, 1 H, 6-H), 5.41 (m, 2 H,
(η5-Cyclopen tadien yl)[1,2,3,4,5-η-8-exo-(diph en ylcyan o)-
m eth ylcycloocta tr ien -6-yl]ir on (II) (2c): red crystalline
powder, sparingly soluble in Et2O, soluble in toluene. Fp: 163
°C. IR (KBr): ν˜ 3087 (w), 3057 (w), 3025 (w) ν(C-H, aromat.),
2973 (w), 2950 (m) ν(C-H, aliph.), 2237 (w) ν(CtN), 1677
(m), 1599 (m), 1493 (m), 1450 (m) ν(CdC, aromat.), 750 (s),
3
3
3-H, 7-H), 4.31 (dd, J 3,4 ) 6.2 Hz, J 4,5 ) 8.3 Hz, 1 H, 4-H),
4.07 (m, 2 H, 1-H, 2-H), 3.89 (s, 5 H, Cp), 3.82 (m, 1 H, 8-H),
3.51 (m, 1 H, 5-H), 3.42 (s, 3 H, Me), 3.25 (s, 3 H, Me), 3.10 (d,
3J 8,9 ) 8.8 Hz, 1 H, 9-H) ppm. 13C{1H} NMR (50 MHz, C6D6):
δ 169.2, 168.7 (CdO), 129.5 (C6), 125.6 (C7), 99.7 (C3), 78.4
(C4), 77.1 (s, Cp), 76.4 (C2), 60.4 (C9), 51.8, 51.6 (CO2CH3),
705 (s) δ(C-H, aromat.) cm-1
.
1H NMR (200 MHz, C6D6): δ
3
3
7.62 (d, J ortho,meta ) 7.7 Hz, 2 H, Hortho), 7.46 (d, J ortho,meta
7.7 Hz, 2 H, Hortho), 7.02 (m, 6 H, Hmeta,para), 5.67 (ddd, J 5,6
6.4 Hz, J 6,7 ) 10.7 Hz, 1 H, 6-H), 5.47 (t′, J 2,3
6.6 Hz, 1 H, 3-H), 5.18 (d, J 6,7 ) 10.7 Hz, 1 H, 7-H), 4.34 (dd,
)
)
)
3
(17) Heck, J .; Massa, W. J . Organomet. Chem. 1989, 376, C15-C19.
Gill, T. P.; Mann, K. R. J . Organomet. Chem. 1981, 216, 65-71.
(18) Ho¨rnfeld, K.; Antoni, G.; Långstro¨m, B. Chem. Scand. 1992,
46, 87-91.
3
3
)
3J 3,4
3
3
(19) Pearson, A. J .; J . Chem. Soc., Perkin Trans. 1 1977, 2069-2077.
3J 3,4 ) 6.6 Hz, J 4,5 ) 9.0 Hz, 1 H, 4-H), 4.08 (m, 1 H, 1-H),

2102 Organometallics, Vol. 22, No. 10, 2003
Reimelt and Heck
3
3
3.97 (dd, J 1,2 ) 9.0 Hz, J 2,3 ) 6.6 Hz, 1 H, 2-H), 3.83 (s,
Anal. Calcd for C25H32O6Fe (484.37): C 61.96, H 6.66. Found:
C 60.71, H 7.03.
3
3
5 H, Cp), 3.82 (m, 1 H, 8-H), 3.37 (dd, J 4,5 ) 9.0 Hz, J 5,6
)
δ
6.4 Hz, 1 H, H-5) ppm. 13C{1H} NMR (50 MHz, C6D6):
141.5, 139.9 (s, C-phenyl), 131.8 (C6), 129.0, 128.9, 127.6 (s,
C-phenyl), 123.5 (C7), 121.9 (s, CN), 99.9 (C3), 78.1 (C4),
77.7 (C2), 77.0 (s, Cp), 59.9 (C9), 47.8 (C1), 45.3 (C8), 43.5 (C5)
ppm. FAB-MS (70 eV): m/z (%) 417 (9) [M+], 391 (3) [M+
-
CN], 225 (100) [CpFeC8H8+]. Anal. Calcd for C27H23NFe
(417.33): C 77.71, H 5.55, N 3.36. Found: C 77.31, H 5.71,
N 3.18.
(η5-Cyclop en ta d ien yl)[1,2,3,4,5-η-8-exo-(1,1,4-tr ieth oxy-
ca r bon yl)bu t-1-ylcycloocta tr ien -6-yl]ir on (II) (2f): red oil,
highly soluble in Et2O, toluene. IR (KBr): ν˜ 3106 (w) ν(C-H,
aromat.), 2980 (s) ν(C-H, aliph.), 1732 (s) ν(CdO), 1630 (w)
ν(CdC), 1446 (m), 1422 (m) δ(CH3/CH2), 1367 (m) δ(CH3),
1238-1158 (s) ν(C-O) cm-1. 1H NMR (360 MHz, C6D6): δ 5.70
3
3
3
(ddd, J 5,6 ) 6.4 Hz, J 6,7 ) 10.8 Hz, 1 H, 6-H), 5.64 (dm, J 6,7
) 10.8 Hz, 1 H, 7-H), 5.49 (t′, J 2,3 ) 3J 3,4 ) 6.4 Hz, 1 H, 3-H),
3
(η5-Cyclop en ta d ien yl)[1,2,3,4,5-η-8-exo-(d icya n o)m eth -
ylcycloocta tr ien -6-yl]ir on (II) (2d ): red crystalline powder,
sparingly soluble in Et2O, soluble in toluene. Decomp: 118 °C.
IR (KBr): ν˜ 3085 (w) ν(C-H, aromat.), 2994 (s), 2947 (s), 2892
(s) ν(C-H, aliph.), 2248 (w) ν(CtN), 1678 (m) ν(CdC), 1420
3
3
4.35 (dd, J 3,4 ) 6.4 Hz, J 4,5 ) 9.0 Hz, 1 H, 4-H), 4.19 (dd,
3J 2,3 ) 6.4 Hz, 1 H, 2-H), 4.00 (m, 1 H, 1-H), 3.99 (s, 5 H, Cp),
3.86-4.10 (m, 6 H, CO2CH2CH3), 3.83 (m, 1 H, 8-H), 3.51 (dd,
3J 4,5 ) 9.0 Hz, J 5,6 ) 6.4 Hz, 1 H, 5-H), 2.36 (m, 2 H, 12-H),
3
2.21 (t, 3J ) 7.4 Hz, 2 H, 10-H), 1.87 (m, 2 H, 11-H), 0.99,
0.95, 0.91 (t, 3J ) 7.4 Hz, 9 H, CO2CH2CH3) ppm. 13C{1H}
NMR (50 MHz, C6D6): δ 172.6, 171.4, 170.4 (CdO), 127.3 (C6),
127.1 (C7), 99.2 (C3), 77.6 (C2), 77.5 (C4), 77.2 (Cp), 62.8 (C9),
60.8, 60.5, 60.0 (CO2CH2CH3), 44.5 (C1), 44.0 (s, C8), 43.3 (s,
C5), 34.7 (s, C10), 33.5 (s, C12), 21.2 (s, C11), 14.3, 14.2, 14.0
(s, CO2CH2CH3) ppm. EI-MS (70 eV): m/z (%) 498 (74) [M+],
453 (15) [M+ - C2H5O], 225 (100) [CpFeC8H8+], 186 (45)
[CpFeC5H5+], 121 (81) [CpFe+]. Anal. Calcd for C26H34O6Fe
(498.40): C 62.66, H 6.88. Found: C 62.76, H 6.88.
1
(m) δ(CH3/CH2) cm-1. H NMR (200 MHz, C6D6): δ 5.66 (ddd,
3
3
3
3J 5,6 ) 6.8 Hz, J 6,7 ) 10.5 Hz, 1 H, 6-H), 5.40 (t′, J 2,3 ) J 3,4
3
) 6.8 Hz, 1 H, 3-H), 4.79 (dm, J 6,7 ) 10.5 Hz, 1 H, 7-H), 4.25
(dd, J 3,4 ) 6.8 Hz, J 4,5 ) 9.0 Hz, 1 H, 4-H), 3.99 (dd, J 1,2
3
3
3
)
3
9.0 Hz, J 2,3 ) 6.8 Hz, 1 H, 2-H), 3.78 (s, 5 H, Cp), 3.60 (m, 1
H, 1-H), 3.31 (dd, 3J 4,5 ) 9.0 Hz, 3J 5,6 ) 6.8 Hz, 1 H, 5-H), 2.68
(m, 1 H, 8-H), 2.28 (d, J 8,9 ) 6.4 Hz, 1 H, 9-H) ppm. 13C{1H}
3
NMR (50 MHz, C6D6): δ 133.3 (C6), 121.4 (C7), 113.3, 113.0
(s, CN), 100.7 (C3), 78.8 (C4), 77.3 (s, Cp), 75.8 (C2), 44.7 (C1),
44.2 (C5), 41.4 (C8), 30.4 (C9) ppm. EI-MS (70 eV): m/z (%)
290 (25) [M+], 225 (64) [CpFeC8H8+], 199 (23) [CpFeC6H6+],
186 (38) [CpFeC5H5+], 121 (100) [CpFe+]. Anal. Calcd for
C
16H14N2Fe (290.15): C 66.23, H 4.86, N 9.65. Found: C 65.49,
H 5.29, N 8.24.
(η5-Cyclop en t a d ien yl)[1,2,3,4,5-η-8-exo-(3-cya n o-1,1-
d im et h oxyca r b on yl)p r op -1-ylcyclooct a t r ien -6-yl]ir on -
(II) (2g): orange red crystalline powder. Decomp: > 95 °C.
IR (KBr): ν˜ 3083 (w), 3015 (m) ν(C-H, aromat.), 2953 (m)
ν(C-H, aliph.), 2247 (w) ν(CtN), 1732 (s) ν(CdO), 1438 (m)
δ(CH3/CH2), 1296 (s) δ(CH3), 1246 (m), 1226 (m), 1195 (m)
(η5-Cyclop en ta d ien yl)[1,2,3,4,5-η-8-exo-(1,1,3-tr ieth oxy-
ca r bon yl)p r op -1-ylcycloocta tr ien -6-yl]ir on (II) (2e): red
oil, highly soluble in Et2O, toluene. IR (KBr): ν˜ 3084 (w)
ν(C-H, aromat.), 2981 (m), 2952 (m), 2904 (m) ν(C-H, aliph.),
1732 (s) ν(CdO), 1631 (w) ν(CdC), 1445 (m) δ(CH3/CH2), 1368
1
3
ν(C-O) cm-1. H NMR (360 MHz, C6D6): δ 5.68 (ddd, J 6,7
)
3
3
3
10.8 Hz, J 5,6 ) 6.8 Hz, 1 H, 6-H), 5.35 (t′, J 2,3 ) J 3,4 ) 6.4
3
Hz, 1 H, 3-H), 5.28 (dm, J 6,7 ) 10.8 Hz, 1 H, 7-H), 4.24 (dd,
(m), 1300 (m) δ(CH3), 1243-1181 (s) ν(C-O) cm-1
.
1H NMR
3J 3,4 ) 6.4 Hz, J 4,5 ) 9.0 Hz, 1 H, 4-H), 3.99 (dd, J 2,3 ) 6.4
3
3
3
3
3
(200 MHz, C6D6): δ 5.71 (ddd, J 5,6 ) 6.5 Hz, J 6,7 ) 10.8 Hz,
Hz, J 1,2 ) 9.2 Hz, 1 H, 2-H), 3.89 (s, 5 H, Cp), 3.78 (m, 1 H,
3
3
3
3
1 H, 6-H), 5.55 (dm, J 6,7 ) 10.8 Hz, 1 H, 7-H), 5.44 (t′, J 2,3
)
8-H), 3.58 (ddd, J 1,2 ) 9.2 Hz, J 1,8 ) 5.8 Hz, 1 H, 1-H), 3.43
(dd, 3J 4,5 ) 9.0 Hz, 3J 5,6 ) 6.8 Hz, 1 H, 5-H), 3.34 (s, 3 H, CH3),
3.23 (s, 3 H, CH3), 2.11 (m, 4 H, 10-H, 11-H) ppm. 13C{1H}
NMR (50 MHz, C6D6): δ 170.9, 170.1 (CdO), 129.0 (C6), 125.4
(C7), 119.6 (CN), 99.3 (C3), 78.1 (C4), 77.3 (Cp), 77.2 (C2), 61.4
(C9), 52.1, 51.7 (CH3), 45.2 (C8), 44.0 (C5), 42.5 (C1), 28.8, 13.7
(C10, C11) ppm. EI-MS (70 eV): m/z (%) 409 (18) [M+], 343
(36), 225 (44) [CpFeC8H8+], 199 (28) [CpFeC6H6+], 186 (42)
[CpFeC5H5+], 121 (79) [CpFe+], 104 (85) [C8H8+]. Anal. Calcd
for C21H23N1O4Fe (409.26): C 61.63, H 5.66, N 3.42. Found:
C 60.80, H 5.75, N 3.46.
3
3
3J 3,4 ) 6.5 Hz, 1 H, 3-H), 4.30 (dd, J 3,4 ) 6.5 Hz, J 4,5 ) 9.0
3
3
Hz, 1 H, 4-H), 4.15 (dd, J 1,2 ) 8.3 Hz, J 2,3 ) 6.5 Hz, 1 H,
2-H), 4.08-3.80 (m, 8 H, CO2CH2CH3, 8-H, 1-H), 3.90 (s, 5 H,
Cp), 3.47 (dd, 3J 4,5 ) 9.0 Hz, 3J 5,6 ) 6.5 Hz, 1 H, 5-H), 2.69 (m,
4 H, 10-H, 11-H), 0.92 (m, 9 H, CO2CH2CH3) ppm. 13C{1H}
NMR (50 MHz, C6D6): δ 173.0, 171.4, 170.3 (CdO), 128.0 (C6),
126.6 (C7), 99.3 (C3), 77.7 (C4), 77.6 (C2), 77.2 (Cp), 62.1 (C9),
61.0, 60.7, 60.2 (CO2CH2CH3) 45.2 (C1), 44.0 (C8), 43.1 (C5),
30.8 (C10), 28.6 (C11), 14.2, 14.1, 13.9 (CO2CH2CH3) ppm. EI-
MS (70 eV): m/z (%) 484 (29) [M+], 439 (7) [M+ - C2H5O], 315
(24) [M+ - {(C2H5O)2 (COOC2H5)}], 225 (67) [CpFeC8H8+], 199
(36) [CpFeC6H6+], 186 (68) [CpFeC5H5+], 121 (100) [CpFe+].
(η5-Cyclop e n t a d ie n yl)[1,2,3,4,5-η-8-exo-(1,3-d ioxo-1-
eth oxy)bu t-2-ylcycloocta tr ien -6-yl]ir on (II) (2h ): red oil,

From Cyclooctatetraene to Cycloocta-1,3-diene
Organometallics, Vol. 22, No. 10, 2003 2103
Ta ble 2. P r ep a r a tive Deta ils of th e F ir st
P r oton a tion
starting
complex
mg
(mmol)
yield
product mg (%)
Nu1
2a
2b
2c
2e
2f
CH(CO2Me)2
CEt(CO2Me)2
CPh2CN
211 (0.59) 3a BF4 176 (67)
274 (0.71) 3bBF4 333 (98)
128 (0.31) 3cBF4 107 (68)
C(CO2Et)2(CH2)2CO2Et 238 (0.49) 3d BF4 230 (83)
C(CO2Et)2(CH2)3CO2Et 337 (0.68) 3eBF4 272 (68)
2g
2h
C(CO2Me)2(CH2)2CN
CH(COMe)CO2Et
300 (0.73) 3fBF4 357 (98)
122 (0.34) 3gBF4 121 (80)
very soluble in Et2O, toluene. IR (KBr): ν˜ 3092 (w) ν(C-H,
aromat.), 2983 (m), 2952 (m) ν(C-H, aliph.), 1739 (s), 1712
(s) ν(CdO), 1638 (w) ν(CdC), 1421 (m) δ(CH3/CH2), 1356 (m)
BF4FeO4‚1/5(CH2Cl2) (461.0): C 47.42, H 4.68. Found: C 47.63,
H 4.58.
δ(CH3), 1243(m), 1155(m) ν(C-O) cm-1
.
1H NMR (360 MHz,
3
3
C6D6): δ 5.81, 5.76 (ddd, J 5,6 ) 7.3 Hz, J 6,7 ) 10.6 Hz, 1 H,
6-H), 5.42, 5.39 (t′, J 2,3 ) 3J 3,4 ) 6.2 Hz, 1 H, 3-H), 5.35, 5.25
3
3
3
(dm, J 6,7 ) 10.6 Hz, 1 H, 7-H), 4.31, 4.29 (dd, J 3,4 ) 6.2 Hz,
3J 4,5 ) 8.9 Hz, 1 H, 4-H), 4.08-3.90 (m, 6 H, CH2, 2-H), 3.89,
3
3.88 (s, 5 H, Cp), 3.85 (dd, J 1,2 ) 7.3 Hz, 1 H, 1-H), 3.79 (m,
3
3
3 H, 1-H, 8-H), 3.54, 3.49 (dd, J 4,5 ) 8.9 Hz, J 5,6 ) 7.3 Hz, 1
3
H, 5-H), 3.10, 2.95 (d, J 8,9 ) 8.9 Hz, 1 H, 9-H), 2.07, 1.84 (s,
3
3 H, CH3), 0.95, 0.84 (t, J ) 7.1 Hz, 3 H, CO2CH2CH3) ppm.
13C{1H} NMR (50 MHz, C6D6): δ 169.4, 168.9 (CdO), 129.7,
129.6 (C6), 126.2, 125.5 (C7), 99.8, 99.7 (C3), 78.4, 78.2 (C4),
77.1 (Cp), 76.3, 76.1 (C2), 68.5 (C9), 60.9, 60.8 (C8), 48.6, 48.0
(CO2CH2CH3), 44.7, 44.3 (C5), 39.4, 39.1 (C1), 29.8, 29.4 (CH3),
14.2, 14.0 (CO2CH2CH3) ppm. EI-MS (70 eV): m/z (%) 354 (22)
[M+], 311 (12) [M+ - CH3CO], 225 (40) [CpFeC8H8+], 186 (77)
[CpFeC5H5+], 121 (96) [CpFe+], 104 (89) [C8H8+]. Anal. Calcd
for C19H22O3Fe (354.23): C 64.42, H 6.26. Found: C 64.16, H
6.66.
[(η5-Cyclop en ta d ien yl){1,2,3,4,5,6-η-8-exo-d i(m eth oxy-
ca r b on yl)p r op -1-ylcyclooct a -1,3,5-t r ien e}ir on (II)] Tet -
r a flu or obor a te (3bBF 4): red crystalline powder, soluble in
acetone and dichloromethane. Fp: 48 °C. IR (KBr): ν˜ 3116
(w) ν(C-H, aromat.), 2953 (w), 2884 (w) ν(C-H, aliph.), 1725
(s) ν(CdO), 1457 (m), 1433 (m) δ(CH3/CH2), 1241 (s) ν(C-O),
1154-1058 (s) ν(BF4-) cm-1 1H NMR (200 MHz, CD3C(O)-
.
CD3): δ 7.14 (dd, 3J 3,4 ) 8.7 Hz, 3J 4,5 ) 7.0 Hz, 1 H, 4-H), 6.98
3
3
3
(dm, J 1,2 ) 10.4 Hz, 1 H, 1-H), 6.92 (t′, J 2,3 ) J 3,4 ) 8.9 Hz,
3
3
1 H, 3-H), 6.70 (dd, J 4,5 ) 7.0 Hz, J 5,6 ) 7.3 Hz, 1 H, 5-H),
5.73 (m, 2 H, 6-H, 2-H), 5.32 (s, 5 H, Cp), 4.25 (ddd, 3J 1,8 ) 5.5
3
3
Hz, J 7exo,8 ) 13.7 Hz, J 7endo,8 ) 8.8 Hz, 1 H, 8-H), 3.69 (s, 3
H, CO2CH3), 3.67 (s, 3 H, CO2CH3), 1.81 (m, 2 H, 10-H), 1.42
3
(m, 1 H, 7endo-H), 0.92 (t, J ) 7.6 Hz, 3 H, 11-H), -1.84 (ddd,
3J 6,7exo ) 10.5 Hz, J 7exo,7endo ) 12.2 Hz, J 7exo,8 ) 13.7 Hz, 1 H,
3
3
7
exo-H) ppm. 13C{1H} NMR (50 MHz, CD3C(O)CD3): δ 170.1
(CdO), 104.1 (C3), 97.0 (C4), 94.3 (C5), 92.4 (C1), 89.4 (C2),
85.5 (C6), 82.4 (Cp), 63.7 (C9), 52.8 (C8), 51.8 (CO2CH3), 26.9
(C10), 25.2 (C7), 8.4 (C11) ppm. FAB-MS: m/z (%) 385 (100)
[M+ - BF4]. Anal. Calcd for C20H25 BF4FeO4 (472.07): C 50.89,
H 5.34. Found: C 49.42, H 5.45.
Gen er a l P r oced u r e for th e F ir st P r oton a tion (Syn -
th esis of 3a BF 4-3gBF 4). Compound 2 was dissolved in Et2O
(50 mL). If a derivative of 2 was only sparingly soluble in Et2O,
a minimum amount of CH2Cl2 was added until a clear solution
was obtained. At T ) -78 °C an equimolar amount of HBF4
dissolved in Et2O was added. After 30 min stirring the reaction
mixture was allowed to warm to room temperature. The
product was obtained as a light red crystalline material or red
oil. The upper layer was decanted, and the remaining oily or
solid product was washed several times with Et2O and dried
under high vacuum. For more details see Table 2.
[(η5-Cyclop en ta d ien yl){(1,2,3,4,5,6-η-8-exo-d i(m eth oxy-
ca r bon yl)m eth ylcycloocta -1,3,5-tr ien e}ir on (II)] Tetr a flu -
or obor a t e (3a BF 4): red oil, highly soluble in acetone and
dichloromethane. IR (KBr): ν˜ 3099 (w) ν(C-H, aromat.), 2953
[(η5-Cyclop en t a d ien yl){1,2,3,4,5,6-η-8-exo-{(d ip h en yl-
cya n o)m eth ylcycloocta -1,3,5-tr ien e}ir on (II)] Tetr a flu o-
r obor a te (3cBF 4): light red crystalline powder, soluble in
acetone and dichloromethane. Decomp. > 115 °C. IR (KBr):
ν˜ 3109 (w), 3059 (w) ν(C-H, aromat.), 2946 (w) ν(C-H,
aliph.), 2239 (w) ν(CtN), 1696 (w), 1600 (w), 1492 (m), 1449
ν(CdC, aromat.), 1084-1001 (s) ν(BF4-), 750 (m), 701 (m)
(w) ν(C-H, aliph.), 1732 (s) ν(CdO), 1436 (m) (m) δ(CH3/CH2),
-
1260 (m), 1198 (m), 1155 (s) ν(C-O), 1084-1056 (s) ν(BF4
)
3
cm-1
.
1H NMR (200 MHz, CD3C(O)CD3): δ 7.20 (dd, J 3,4
)
9.0 Hz, J 4,5 ) 6.8 Hz, 1 H, 4-H), 6.98 (dd,3J 2,3 ) 9.8 Hz, J 3,4
3
3
3
) 9.0 Hz, 1 H, 3-H), 6.90 (m, 1 H, 1-H), 6.71 (dd, J 4,5 ) 6.8
3
3
3
1
Hz, J 5,6 ) 7.3 Hz, 1 H, 5-H), 5.85 (dd, J 5,6 ) 7.3 Hz, J 6,7
)
δ(C-H, aromat.) cm-1. H NMR (360 MHz, CD3C(O)CD3): δ
3
3
3
10.5 Hz, 1 H, 6-H), 5.73 (t′, J 1,2 ) J 2,3 ) 9.8 Hz, 1 H, 2-H),
5.32 (s, 5 H, Cp), 4.21 (m, 1 H, 8-H), 3.74 (s, 3 H, CH3), 3.62
(s, 3 H, CH3), 3.33 (d,3J 8,9 ) 7.1 Hz, 1 H, 9-H), 1.33 (m, 1 H,
7.93 (d, J ortho,meta ) 7.9 Hz, 2 H, phenylortho), 7.54 (m, 4 H,
3
phenylortho,meta), 7.44 (t, J meta,para ) 7.2 Hz, 1 H, phenylpara),
3
3
7.34 (dd, J ortho,
) 7.9 Hz, J meta,para ) 7.2 Hz, 2 H,
meta
3
7
endo-H), -1.75 (m, 1 H, 7exo-H) ppm.- 13C{1H}NMR (50
phenylmeta), 7.25 (t, J meta,para ) 7.2 Hz, 1 H, phenylpara), 7.20
3
3
3
MHz, C6D6): δ ) 168.9 (CdO), 105.4 (C3), 97.6 (C4), 95.1
(C5), 93.9 (C1), 89.5 (C2), 88.0 (C6), 82.9 (Cp), 58.2 (C9), 52.7,
(dd, J 3,4 ) 8.9 Hz, J 4,5 ) 7.6 Hz, 1 H, 4-H), 7.02 (dd, J 2,3 )
3 3 3
9.2 Hz, J 3,4 ) 8.9 Hz, 1 H, 3-H), 6.70 (dd, J 4,5 ) 7.6 Hz, J 5,6
3 3
52.6 (CH3), 51.2 (C8), 27.6 (C7) ppm. Anal. Calcd for C18H21
-
) 7.2 Hz, 1 H, 5-H), 6.56 (ddd, J 1,2 ) 10.2 Hz, J 1,8 ) 6.9 Hz,

2104 Organometallics, Vol. 22, No. 10, 2003
Reimelt and Heck
1 H, 1-H), 5.84 (m, 2 H, 2-H, 6-H), 5.31 (s, 5 H, Cp), 5.27 (m,
90.3 (C2), 86.5 (C6), 83.1 (Cp), 63.5 (C9), 62.0, 61.9, 60.7
(CO2CH2CH3), 53.5 (C8), 34.2 (C12), 33.7 (C11), 25.9 (C7), 20.2
(C10), 14.6, 14.3, 14.2 (CO2CH2CH3) ppm. FAB-MS: m/z, (%)
499 (100) [M+ - BF4], 385 (2) [M+ - BF4 - CH2CH2CH2-
CO2C2H5], 274 (3) [HC(CO2Et)2(CH2)3CO2Et+]. Anal. Calcd
for C26H35BF4FeO6‚1/3(CH2Cl2) (614.52): C 51.47, H 5.85.
Found: C 51.64, H 5.87.
1 H, 8-H), 1.12 (m, 1 H, 7endo-H), -1.60 (m, 1 H, 7exo-H) ppm.
13C{1H} NMR (50 MHz, CD3C(O)CD3):
δ 141.8, 139.6
(Cq-phenyl), 131.1, 130.6 (Cmeta-phenyl), 129.8, 129.6 (Cpara
-
phenyl), 128.5, 127.2 (Cortho-phenyl), 122.1 (CN), 105.8 (C3),
98.5 (C4), 95.9 (C5), 91.3 (C2), 90.9 (C1), 86.2 (C6), 83.8 (Cp),
61.5 (C9), 56.8 (C8), 27.4 (C7) ppm. FAB-MS: m/z (%) 418 (100)
[M+ - BF4], 313 (32) [M+ - BF4 - C8H9], 226 (57) [CpFeC8H8+].
Anal. Calcd for C27H24BF4FeN‚1/5(CH2Cl2) (522.13): C 62.57,
H 4.71, N 2.68 for C27H24BF4FeN. Found: C 62.63, H 4.87, N
2.69.
[(η5-Cyclop en ta d ien yl){1,2,3,4,5,6-η-8-exo-(3-cya n o-1,1-
dim eth oxycar bon yl)-pr op-1-ylcycloocta-1,3,5-tr ien e}ir on -
(II)] Tetr a flu or obor a te (3fBF 4): orange powder, sparingly
soluble in acetone, very soluble in acetonitrile. Fp: 85 °C. IR
(KBr): ν˜ 3107 (w) ν(C-H, aromat.), 2954 (w) ν(C-H, aliphat.),
2248 (m) ν(CtN), 1726 (s) ν(CdO), 1432 (m) δ(CH3/CH2), 1240
[(η5-Cyclop en t a d ien yl){1,2,3,4,5,6-η-8-exo-{(1,1,3-t r i-
e t h oxyca r b on yl)p r op -1-ylcyclooct a -1,3,5-t r ie n e }ir on -
(II)] Tetr a flu or obor a te (3d BF 4): red oil, very soluble in
acetone and dichloromethane. IR (KBr): ν˜ 3107 (w) ν(C-H,
aromat.), 2985 (w) ν(C-H, aliph.), 1726 (s) ν(CdO), 1635 (w)
ν(CdC), 1447 (m), 1419 (m) δ(CH3/CH2), 1370 (m) δ(CH3), 1227
(s), 1163 (s) ν(C-O), 1083-1030 (s) ν(BF4-) cm-1. 1H NMR (200
1
(s) ν(C-O), 1084-1037 (s) ν(BF4-) cm-1. H NMR (360 MHz,
3
3
CD3C(O)CD3): δ 7.17 (dd, J 3,4 ) 8.8 Hz, J 4,5 ) 7.0 Hz, 1 H,
3
3
4-H), 6.99 (ddd, J 1,2 ) 10.3 Hz, J 1,8 ) 5.9 Hz, 1 H, 1-H), 6.95
3
3
3
(dd, J 2,3 ) 9.2 Hz, J 3,4 ) 8.8 Hz, 1 H, 3-H), 6.73 (t′, J 4,5
)
3
3
MHz, CD3C(O)CD3): δ 7.15 (dd, J 3,4 ) 8.9 Hz, J 4,5 ) 6.8 Hz,
3J 5,6 ) 7.0 Hz, 1 H, 5-H), 5.79 (m, 1 H, 2-H) 5.76 (m, 1 H, 6-H),
3
3
1 H, 4-H), 6.98 (dm, J 1,2 ) 10.6 Hz, 1 H, 1-H), 6.92 (t′, J 2,3
)
3
3
5.31 (s, 5 H, Cp), 4.29 (ddd, J 1,8 ) 5.9 Hz, J 7exo,8 ) 10.5 Hz,
1 H, 8-H), 3.73 (s, 3 H, Me), 3.70 (s, 3 H, Me), 2.65 (t′, 3J ) 7.4
3J 3,4 ) 8.9 Hz, 1 H, 3-H), 6.69 (dd, J 4,5 ) 6.8 Hz, J 5,6 ) 7.6
Hz, 1 H, 5-H), 5.75 (m, 2 H, 2-H, 6-H), 5.32 (s, 5 H, Cp), 4.26
(m, 1 H, 8-H), 4.17 (t, 3J ) 7.3 Hz, 4 H, 2 × CO2CH2CH3), 4.09
3
3
3
Hz, 2 H, 11-H), 2.43 (ddd, J ) 7.4 Hz, 1 H, 10-H), 2.23 (ddd,
3J ) 7.4 Hz, 1 H, 10-H), 1.45 (m, 1 H, 7endo-H), -1.78 (ddd,
3
(t, J ) 7.3 Hz, 2 H, CO2CH2CH3), 2.29 (m, 4 H, 10-H, 11-H),
3
3
2J 7exo,7endo ) 12.5 Hz, J 7exo,8 ) J 6,7exo ) 10.5 Hz, 1 H, 7exo-H)
ppm. 13C{1H} NMR (50 MHz, CD3C(O)CD3): δ 169.9, 169.8
(CdO), 133.1 (CN), 105.2 (C3), 97.9 (C4), 95.2 (C5), 91.6 (C1),
90.3 (C2), 86.2 (C6), 83.3 (Cp), 62.6 (C9), 54.2 (C8), 53.1, 53.0
(CH3), 39.9 (C11, C12), 26.0 (C7) ppm. FAB-MS: m/z (%) 410
(100) [M+ - BF4]. Anal. Calcd for C21H24BF4FeNO4 (497.08):
C 50.74, H 4.87, N 2.82. Found: C 50.03, H 5.07, N 2.47.
1.43 (m, 1 H, 7endo-H), 1.22 (m, 9 H, CO2CH2CH3), -1.77 (m, 1
H, 7exo-H) ppm. 13C{1H} NMR (50 MHz, CD3C(O)CD3): δ 173.1,
170.0, 169.9 (CdO), 104.9 (C3), 97.8 (C4), 95.1 (C5), 92.7 (C1),
90.4 (C2), 86.4 (C6), 83.2 (Cp), 62.6 (C9), 62.1, 62.0, 60.9
(CO2CH2CH3), 54.2 (s, C8), 30.5, 29.0 (s, C10, C11), 26.0 (s,
C7), 14.5, 14.3, 14.2 (s, CO2CH2CH3) ppm. FAB-MS: m/z (%)
485 (100) [M+ - BF4]. Anal. Calcd for C25H33BF4FeO6‚
(CH2Cl2) (657.12): C 47.52, H 5.37. Found: C 47.76, H 5.99.
[(η5-Cyclop en ta d ien yl){1,2,3,4,5,6-η-8-exo-(1,3-d ioxo-1-
eth oxy)bu t-2-ylcycloocta -1,3,5-tr ien e}ir on (II)] Tetr a flu o-
r obor a te (3gBF 4): orange oil, very soluble in acetone and
dichloromethane. IR (KBr): ν˜ 3109 (w) ν(C-H, aromat.), 2986
(w), 2939 (w) ν(C-H, aliph.), 1731 (s), 1710 (s) ν(CdO), 1454
(w), 1419 (w) δ(CH3/CH2), 1367 (w) δ(CH3), 1248 (m) ν(C-O),
[(η5-Cyclop e n t a d ie n yl){1,2,3,4,5,6-η-8-exo-(1,1,4-t r i-
et h oxyca r b on yl)b u t -1-ylcyclooct a -1,3,5-t r ien e)ir on (II)]
Tetr a flu or obor a te (3eBF 4): red oil, only sparingly soluble
in Et2O, but very soluble in dichloromethane and acetone. IR
(KBr): ν˜ 3115 (w) ν(C-H, aromat.), 2983 (w), 2939 (w)
ν(C-H, aliphat.), 1723 (s) ν(CdO), 1431 (m) u, 1420 (m)
δ(CH3/CH2), 1370 (m) δ(CH3), 1212 (s) u, 1177 (s) ν(C-O), 1083
1118-1051 (s) ν (BF4-) cm-1 1H NMR (360 MHz, CD3C(O)-
.
3
3
CD3): δ 7.20 (m, 2 H, 4-H), 6.97, 6.95 (dd, J 2,3 ) 9.2 Hz, J 3,4
3
3
) 8.9 Hz, 1 H, 3-H), 6.85, 6.84 (dd, J 1,2 ) 10.2 Hz, J 1,8
)
(s) u, 1053 (s) ν(BF4-) cm-1
CD3): δ 7.13 (dd, 3J 3,4 ) 9.0 Hz, 3J 4,5 ) 7.0 Hz, 1 H, 4-H), 7.03
.
1H NMR (200 MHz, CD3C(O)-
4.3 Hz, 1 H, 1-H), 6.68 (t′, J 4,5 )
3J 5,6 ) 7.2 Hz, 1 H, 5-H),
3
3
3
5.83 (m, 2 H, 6-H), 5.71 (dd, J 1,2 ) 10.2 Hz, J 2,3 ) 9.2 Hz, 1
H, 2-H), 5.30 (s, 10 H, Cp), 4.25, 4.06 (q, 3J ) 7.2 Hz, 2 H,
3
3
3
(dm, J 1,2 ) 10.3 Hz, 1 H, 1-H), 6.90 (t′, J 2,3 ) J 3,4 ) 9.0 Hz,
3
3
3
1 H, 3-H), 6.69 (dd, J 4,5 ) 7.0 Hz, J 5,6 ) 7.6 Hz, 1 H, 5-H),
5.75 (m, 2 H, 2-H, 6-H), 5.30 (s, 5 H, Cp), 4.28 (m, 1 H, 8-H),
CO2CH2CH3), 4.20 (m, 2 H, 8-H), 3.49, 3.34 (d, J 8,9 ) 7.9 Hz,
3
1 H, 9-H), 2.25, 2.11 (s, 3 H, CH3), 1.29, 1.17 (t, J ) 7.2 Hz,
3
4.13 (m, 6 H, 3 × CO2CH2CH3), 2.36 (t′, J ) 6.7 Hz, 2 H, 12-
3 H, CO2CH2CH3), 1.27 (m, 2 H, 7endo-H), -1.82 (m, 2 H,
H), 1.72 (m, 4 H, 10-H, 11-H), 1.49 (m, 1 H, 7endo-H), 1.23 (dt,
3J ) 7.1 Hz, 3 H, CO2CH2CH3), 1.21 (t,3J ) 7.1 Hz, 3 H,
CO2CH2CH3), 1.12 (t, 3J ) 7.1 Hz, 3 H, CO2CH2CH3), -1.80
7
exo-H) ppm. 13C{1H} NMR (50 MHz, CD3C(O)CD3): δ 167.2
(s, CdO), 104.9, 104.6 (C3), 96.9 (C4), 94.4 (C5), 94.2 (C1), 88.8,
88.7 (C2), 88.1, 88.0 (C6), 82.3, 82.2 (Cp), 66.0 (C9), 61.5, 61.2
(CO2CH2CH3), 50.3 (s, C-8), 27.5, 26.6 (s, C-7), 29.0 (s, CH3),
27.5, 26.6 (s, C-7), 13.6, 13.5 (s, CO2CH2CH3) ppm. FAB-MS:
m/z (%) 356 (100) [M+ - BF4], 225 (25) [CpFeC8H8+]. Anal.
2
3
(ddd, J 7exo,7endo ) 12.5 Hz, J 6,7exo
exo-H) ppm. 13C{1H} NMR (50 MHz, CD3C(O)CD3): δ 173.3,
170.2, 170.1 (CdO), 104.9 (C3), 97.7 (C4), 95.0 (C5), 93.6 (C1),
)
3J 7exo,8 ) 10.5 Hz, 1 H,
7

From Cyclooctatetraene to Cycloocta-1,3-diene
Organometallics, Vol. 22, No. 10, 2003 2105
Ta ble 3. P r ep a r a tive Deta ils of th e Secon d Nu cleop h ilic Ad d ition
starting
complex
reaction
time (h)
yield
mg (%)
Nu1
mg (mmol)
HNu2
mg (mmol)
base
product
3a BF4
3a BF4
3bBF4
3cBF4
3d BF4
CH(CO2Me)2
CH(CO2Me)2
CEt(CO2Me)2
CPh2CN
C(CO2Et)2-
(CH2)2CO2Et
C(CO2Et)2-
(CH2)3CO2Et
1831 (4.52)
52 (0.13)
201 (0.43)
274 (0.54)
200 (0.35)
HCH(CO2Me)2
HCH(CO2Me)2
HCH(CO2Me)2
CPh2CN
704 (4.57)
26 (0.20)
54 (0.41)
100 (0.52)
NaH
TMG
NaH
NaH
TMGa
2
23
18
24
3
4a
4a
4b
4c
4d
1943 (87)
56 (86)
174 (79)
261 (79)
n.d.b
3eBF4
260 (0.52)
TMGa
3
4e
n.d.b
a
b
Attempts of an intramolecular nucleophilic addition. n.d. ) not determined since varying amounts of [HTMG]BF4 and TMG were
present in the product.
Calcd for C19H23BF4FeO3‚1/6(CH2Cl2) (456.10): C 50.47, H
ethyl ether, very soluble in toluene. IR (KBr): ν˜ 3090 (w)
ν(C-H, aromat.), 2952 (m) ν(C-H, aliph.), 1732 (s) ν(CdO),
5.52. Found: C 50.68, H 5.42.
1436 (m) δ(CH2/CH3), 1238 (s), 1156 (s), 1132 (s) ν(C-O) cm-1
.
3
3
1H NMR (360 MHz, C6D6): δ 5.59 (t′, J 2,3 ) J 3,4 ) 6.5 Hz, 1
3
H, 3-H), 3.94 (s, 5 H, Cp), 3.92 (m, 1 H, 1-H), 3.83 (dd, J 3,4
)
3
3
3
6.5 Hz, J 4,5 ) 8.4 Hz, 1 H, 4-H), 3.82 (dd, J 1,2 ) 8.4 Hz, J 2,3
3
) 6.5 Hz, 1 H, 2-H), 3.66 (dm, J 4,5 ) 8.4 Hz, 1 H, 5-H), 3.45,
3
3.43, 3.41, 3.33 (s, 3 H, CO2CH3), 3.34 (d, J 6,12 ) 9.2 Hz, 1 H,
3
10-H), 2.83 (m, 1 H, 6-H), 2.72 (dm, J 7,8 ) 12.2 Hz, 1 H,
8-H), 2.34 (m, 1 H, 11-H), 2.12 (m, 1 H, 11-H), 1.08 (m, 1 H,
7
7
endo-H), 1.05 (t, 3J ) 7.5 Hz, 3 H, 12-H), -0.76 (m, 1 H,
exo-H) ppm. 1H NMR (360 MHz, CD3CN): δ 5.94 (t′, J 2,3
)
3
3J 3,4 ) 6.6 Hz, 1 H, 3-H), 4.28 (s, 5 H, Cp), 3.99 (dd, 3J 3,4 ) 6.6
3
3
3
Hz, J 4,5 ) 8.4 Hz, 1 H, 4-H), 3.97 (dd, J 1,2 ) 8.4 Hz, J 2,3
)
3
Secon d Nu cleop h ilic Ad d ition (Syn th esis of 4a -d ).
The second nucleophilic addition was performed in close
analogy with the first one (vide supra). For more preparative
details see Table 3. Attempts of the intramolecular second
nucleophilic addition: 1 equiv of 3d BF4 (200 mg, 0.35 mmol)
and 3eBF4 (260 mg, 0.52 mmol), respectively, were dissolved
in CH2Cl2 (20 and 30 mL, respectively), and 8 equiv of TMG
was added slowly. After stirring for 3 h the solvent was
removed in vacuo. The residue was too soluble in Et2O and
hydrocarbon solvents, and attempts of chromatography led to
decomposition of the product. Hence, the products were
characterized by means of 1H, 13C NMR, and IR spectroscopy
and FAB-MS.
6.6 Hz, 1 H, 2-H), 3.75 (dm, J 1,2 ) 8.4 Hz, 1 H, 1-H), 3.68 (s,
3 H, CO2CH3), 3.59 (s, 6 H, CO2CH3), 3.58 (s, 3 H, CO2CH3),
3
3
3.53 (dm, J 4,5 ) 8.4 Hz, 1 H, 5-H), 3.07 (d, J 6,12 ) 7.6 Hz, 1
H, 10-H), 2.30 (m, 2 H, 6-H, 8-H), 2.08 (m, 1 H, 11-H), 1.90
3
(m, 1 H, 11-H), 0.83 (t, J ) 7.5 Hz, 3 H, 12-H), 0.52 (m, 1 H,
7
endo-H), -1.11 (m, 1 H, 7exo-H) ppm. 13C{1H} NMR (50 MHz,
C6D6): δ 171.5, 171.4, 169.1, 168.6 (CdO), 103.2 (C3), 77.5
(Cp), 74.6 (C4), 72.8 (C2), 65.0 (C9), 61.8 (C10), 51.7, 51.6,
51.4 (CO2CH3), 48.2 (C5), 46.9 (C6), 46.8 (C1), 43.6 (C8),
27.5 (C11), 24.4 (C7), 9.8 (C12) ppm. FAB-MS: m/z, (%)
516 (62) [M+], 484 (18) [M+ - CH4O], 450 (68) 385 (56) [M+
-
(CH(COOCH3)2)], 357 (92) [M+ - C(COOCH3)2Et]. Anal. Calcd
for C25H32O8Fe‚1/3(C7H8) (547.09): C 59.98, H 6.39. Found: C
59.88, H 6.65.
[(η5-Cyclop en t a d ien yl)(1,2,3,4,5-η-6,8-exo,exo-b is{d i-
(m e t h o x y c a r b o n y l)m e t h y l}c y c lo o c t a d ie n y l]ir o n (I I )
(4a ): orange powder, soluble in diethyl ether, very soluble in
toluene. Fp: 142 °C. IR (KBr): ν˜ 3002 (w) ν(C-H, aromat.),
2980 (w), 2950 (m) ν(C-H, aliph.), 1729 (s) ν(CdO), 1631 (w)
ν(CdC), 1439 (m), 1423 (m) δ(CH2/CH3), 1343 (m) δ(CH3), 1256
1
(m), 1229 (m), 1191 (m), 1163 (m), 1154 (m) ν(C-O) cm-1. H
3
3
NMR (200 MHz, C6D6): δ 5.55 (t′, J 2,3 ) J 3,4 ) 5.3 Hz, 1 H,
3-H), 3.89 (s, 5 H, Cp), 3.78 (m, 4 H, 1-H, 2-H, 4-H, 5-H), 3.39
(s, 3 H, CH3), 3.34 (s, 9 H, CH3), 3.32 (m, 2 H, 9-H, 10-H), 2.83
2
(m, 2 H, 6-H, 8-H), 1.03 (d, J 7exo,7endo ) 12.8 Hz, 1H, 7endo-H),
-0.63 (m, 1 H, 7exo-H). 13C{1H} NMR (50 MHz, C6D6): δ 169.1,
168.7 (CdO), 103.6 (C3), 77.5 (Cp), 73.0 (C2, C4), 61.3 (C9,
C10), 51.7, 51.6 (CH3), 48.8 (C1, C5), 42.4 (C6, C8), 26.3 (C7)
ppm. Anal. Calcd for C23H28FeO8 (488.32): C 56.57, H 5.78.
Found: C 56.61, H 5.68.
(η5 -C y c lo p e n t a d ie n y l)[1,2,3,4,5-η-6,8-exo,exo-b is -
{(d ip h en ylcya n o)m eth yl}cycloocta d ien yl]ir on (II) (4c):
orange-red powder, sparingly soluble in diethyl ether, very
soluble in dichloromethane and toluene. IR (KBr): ν˜ 3086 (w),
3058 (w), 3022 (w) ν(C-H, aromat.), 2961 (w), 2930 (w) ν(C-
H, aliph.), 2237 (w) ν(CtN), 1657 (w), 1599 (m), 1493 (s), 1450
(s) ν(CdC, aromat.), 746 (s), 703 (s) δ(C-H, aromat.) cm-1. 1H
3
NMR (360 MHz, C6D6): δ 7.66 (d, J ortho,meta ) 7.6 Hz, 4 H,
phenylortho), 7.15-6.92 (m, 10 H, phenyl), 6.75 (m, 6 H,
phenylmeta,para), 5.70 (t′, 3J 2,3 ) 3J 3,4 ) 6.8 Hz, 1 H, 3-H), 4.05
(dd, 3J 1,2 ) 3J 4,5 ) 8.6 Hz, 3J 2,3 ) 3J 3,4 ) 6.8 Hz, 2 H, 2-H, 4-H),
3
3
3.73 (s, 5 H, Cp), 3.69 (dm, J 1,2 ) J 4,5 ) 8.6 Hz, 2 H, 1-H,
3
5-H), 2.89 (dm, J 6,7exo
)
3J 7exo,8 ) 11.9 Hz, 2 H, 6-H, 8-H),
2
0.77 (dm, J ) 12.8 Hz, 7endo-H), -0.42 (m, 1 H, 7exo-H) ppm.
13C{1H} NMR (50 MHz, C6D6): δ 141.3, 139.8 (Cq-phenyl),
129.1, 128.9 (Cmeta-phenyl), 127.6 (Cortho-phenyl), 127.1, 126.7
(Cpara-phenyl), 121.3 (CN), 103.1 (C3), 77.1 (Cp), 75.9 (C2, C4),
61.1 (C9, C10), 50.5 (C6, C8), 45.7 (C1, C5), 42.5 (C7) ppm.
(η5-Cyclop en ta d ien yl)[1,2,3,4,5-η-6-exo-d i(m eth oxyca r -
b on yl)m et h yl-8-exo-d i(m et h oxyca r b on yl)p r op -1-yl-cy-
cloocta d ien yl]ir on (II) (4b): orange powder, soluble in di-

2106 Organometallics, Vol. 22, No. 10, 2003
Reimelt and Heck
FAB-MS: m/z (%) 532 (7) [M+ - C6H6], 418 (92) [M+-
CPh2CN], 313 (62) [M+ - {(CPh2CN)(C8H9)}], 226 (100)
[CpFeC8H8+]. Anal. Calcd for C41H34FeN2 (610.58): C 80.65,
H 5.61, N 4.59. Found: C 79.24, H 5.64, N 4.68.
of 1 equiv of 4a -c in MeCN. The reaction mixture changed
from red to violet and finally became colorless after 30 min.
After 2 h stirring at room temperature, the reaction mixture
was evaporated to dryness. The residual brownish oil was
chromatographed on silica gel 60, with hexane-ethyl acetate,
2:7, as eluent. The fractions of the column chromatography
were monitored by TLC. For more details see Table 4.
cis-5,7-Bis[(d im eth oxyca r bon yl)m eth yl]cycloocta -1,3-
(η5-Cyclop e n t a d ie n yl)[1,2,3,4,5-η-6-exo-t e t r a m e t h -
ylgu a n id in yl-8-exo-[1,1,3-tr ieth oxyca r bon yl)p r op -1-ylcy-
cloocta d ien yl]ir on (II) (4d ): red oil, light and moisture
sensitive, highly soluble in diethyl ether and toluene. IR
(KBr): ν˜ 3083 (w) ν(C-H, aromat.), 2981 (w), 2938 (m)
ν(C-H, aliph.), 1732 (s) ν(CdO), 1608 (s) ν(CdN), 1449 (w),
1
d ien e (6a ): colorless oil. H NMR (200 MHz, CDCl3): δ 6.01
3
3
(dd, J 1,2 ) 10.5 Hz, J 2,3 ) 3.4 Hz, 1 H, 2-H), 5.91 (m, 1 H,
3-H), 5.80 (dd, 3J 1,2 ) 10.5 Hz, 3J 1,8cis ) 8.1 Hz, 1 H, 1-H), 5.58
1367 (m) δ(CH3/CH2), 1240 (s), 1181 (s), 1036 (s) ν(C-O)
3
3
3
cm-1
.
1H NMR (500 MHz, C6D6): δ 5.70 (t′, J 2,3
)
3J 3,4
)
(dd, J 3,4 ) 10.8 Hz, J 4,5 ) 7.8 Hz, 1 H, 4-H), 3.75, 3.74, 3.73,
3
3.72 (s, 3 H, CH3), 3.46 (d, J 5,10 ) 8.3 Hz, 1 H, 10-H), 3.31 (d,
6.2 Hz, 1 H, 3-H), 4.15-3.83 (m, 10 H, 4-H, 2-H, 6-H, 1-H,
3J 7,9 ) 7.6 Hz, 1 H, 9-H), 2.86 (m, 1 H, 5-H), 2.26 (dd, J 1,8
)
3
3
CO2CH2CH3), 3.97 (s, 5 H, Cp), 3.65 (dm, J 4,5 ) 6.3 Hz, 1 H,
2
3
8.1 Hz, J 8,8 ) 12.7 Hz, 1 H, 8cis-H), 2.11 (m, 1 H, 7-H), 1.86
5-H), 3.00 (dm, J 7exo,8 ) 12.4 Hz, 1 H, 8-H), 2.88-2.65 (m, 4
3
2
(ddd, J 7,8 ) 8.6 Hz, J 8,8 ) 12.7 Hz, 1 H, 8trans-H), 1.46
H, 10-H, 11-H), 2.66 (m, 12 H, NCH3), 1.15 (m, 1 H, 7endo-H),
2
3
3
(dd, J 6,6 ) 13.2 Hz, J 6,7 ) 3.7 Hz, 1 H, 6cis-H), 1.25 (m, 1 H,
0.95, 0.92, 0.91 (t, J ) 7.0 Hz, 3 H, CO2CH2CH3), -0.23 (m,
trans-H) ppm. 13C{1H} NMR (50 MHz CDCl3): δ 169.0, 168.2
1 H, 7exo-H) ppm. 13C{1H} NMR (125 MHz, C6D6): δ 172.9,
171.2, 170.8 (s, CdO), 103.0 (s, C-3), 77.1 (s, Cp), 74.8 (s,
C-2), 74.4 (s, C-4), 63.5 (s, C-9), 62.0 (C-6), 60.7, 60.2 (s,
CO2CH2CH3), 55.0 (C5), 47.7 (C8), 45.8 (C1), 40.3 (NCH3), 31.0
(C10), 28.9 (C11), 29.6 (C7), 14.3, 14.2, 14.1 (CO2CH2CH3)
6
(CdO), 132.0, 130.6, 127.8. 126.8 (C1-C4), 57.9, 57.2, (C9,
C10), 52.4 (CH3), 38.2, 35.5, 31.7, 31.4, (C5-C8). MS (70 eV):
m/z (%) 368 (4) [M+], 336 (5), 305 (8), 276 (13), 236 (17), 189
(20), 176 (49), 133 (21), 117 (89), 105 (100). Anal. Calcd for
ppm. FAB-MS: m/z, (%) 599 (3) [M+], 485 (100) [M+
-
C
18H24O8 (368.38): C 58.69, H 6.57. Found: C 58.87, H 6.91.
NC(N(CH3)2)2], 315 (22) [M+ - {(C2H5O)2(COOC2H5)}]. C30H45
-
c i s -5-[1′,1′,-D i (m e t h o x y c a r b o n y l)p r o p -1-y l]-7-d i -
(m eth oxyca r bon yl)m eth ylcycloocta -1,3-d ien e (6b): color-
less oil. IR (KBr): ν˜ 2953 (m) ν(C-H, aliph.), 1735 (s) ν(CdO),
1627 (w) ν(CdC), 1436 (m) δ(CH3/CH2), 1295-1156 (s)
ν(C-O) cm-1. 1H NMR (400 MHz, CDCl3): δ 5.98 (m, 2 H, 2-H,
3-H), 5.86 (ddd, 3J 1,2 ) 10.2 Hz, 3J 1,8cis ) 7.9 Hz, 3J 1,8trans ) 7.9
FeN3O6 (599.55).
3
3
Hz, 1 H, 1-H), 5.59 (dd, J 3,4 ) 10.2 Hz, J 4,5 ) 9.2 Hz, 1 H,
3
4-H), 3.73 (s, 6 H, CH3), 3.72, 3.71 (s, 3 H, CH3), 3.31 (d, J 7,9
3
) 7.6 Hz, 1 H, 9-H), 2.76 (t′, J 4,5
)
3J 5,6trans ) 9.2 Hz, 1 H,
5-H), 2.20 (dd, 3J 1,8 ) 7.9 Hz, 2J 8,8 ) 12.7 Hz, 1 H, 8cis-H), 2.10
(m, 1 H, 7-H), 1.95-1.78 (m, 3 H, 11-H, 8trans-H), 1.71 (dd, 2J 6,6
3
3
) 13.2 Hz, J 6,7 ) 3.6 Hz, 1 H, 6cis-H), 0.98 (ddd, J 5,6 ) 9.2
Hz, 2J 6,6 ) 13.2 Hz, 3J 6,7 ) 12.2 Hz, 1 H, 6trans-H), 0.71 (t, 3J )
7.6 Hz, 3 H, 12-H) ppm. 13C{1H} NMR (500 MHz, CDCl3): δ
171.9, 171.8, 169.5, 169.4 (CdO), 132.0 (C2), 131.7 (C3), 127.8
(C4), 127.2 (C1), 62.9 (C10), 57.8 (C9), 52.8, 52.7, 52.5, 52.4
(CO2CH3), 41.1 (C5), 35.9 (C7), 32.5 (C6), 32.1 (C8), 27.6
(C11), 9.1 (C12) ppm. EI-MS (70 eV): m/z (%) 396 (6) [M+],
365 (6) [M+ - CH3O], 304 (10) [M+ - {(CO2CH3)(CH4O)}],
337 (24) [M+ - CO2CH3], 276 (8) [M+ - {(CO2CH3)(CH3O)2}],
237 (12) [M+ - (C(CO2CH3)2Et)], 205 (29) [M+ - {(CO2CH3)2-
(η5-Cyclop e n t a d ie n yl)[1,2,3,4,5-η-6-exo-t e t r a m e t h -
ylgu an idin yl-8-exo-{1,1,4-tr ieth oxycar bon yl)bu tylcyclooc-
t a d ien yl]ir on (II) (4e): red oil, light and moisture sensi-
tive, highly soluble in diethyl ether and toluene. IR (KBr): ν˜
3109 (w) ν(C-H, aromat.), 2981 (w) ν(C-H, aliph.), 1728 (s)
ν(CdO), 1456 (m), 1413 (m) δ(CH3/CH2), 1649 (m), 1611 (s),
1567 (m) ν(CdN), 1234 (s), 1160 (s) ν(C-O) cm-1 1H NMR
.
3
3
(500 MHz, C6D6): δ 5.94 (t′, J 2,3 ) J 3,4 ) 6.3 Hz, 1 H, 3-H),
4.46 (dd, 3J 3,4 ) 6.3 Hz, 1 H, 4-H), 4.21 (s, 5 H, Cp), 4.16-3.99
(m, 6 H, 2-H, 1-H, 2 × CO2CH2CH3), 3.95 (q, 3J ) 7.3 Hz, 2 H,
(CH2COOCH3)}], 160 (85) [M+ - (CO2CH3)4], 145 (59) [M+
-
{(CO2CH3)4(CH3)}], 105 (100) [C8H9+]. Anal. Calcd for C20H28O8
(396.44): C 60.59, H 7.12. Found: C 60.76, H 6.98.
3
CO2CH2CH3), 3.78 (m, 1 H, 5-H), 3.66 (dm, J 6,7 ) 12.0 Hz, 1
cis-5,7-Bis[(d ip h en ylcya n o)m et h yl]cyclooct a -1,3-d i-
en e (6c): light yellow powder. IR (KBr): ν˜ 3062 (w), 3011 (w)
ν(C-H, aromat.), 2928 (m), 2853 (w) ν(C-H, aliph.), 2237 (w)
ν(CtN), 1599 (w), 1494 (m), 1451 (s) ν(CdC, aromat.), 745 (s),
H, 6-H), 2.83 (m, 1 H, 8-H), 2.60 (m, 12 H, N-CH3), 2.42 (m, 1
H, 10-H), 2.22 (m, 3 H, 10-H,12-H), 1.93 (m, 1 H, 11-H), 1.75
(m, 1 H, 11-H), 1.16 (m, 1 H, 7endo-H), 1.12, 1.05, 0.98 (t,
3J ) 7.3 Hz, 3 H, CO2CH2CH3), -0.52 (m, 1 H, 7exo-H) ppm.
13C{1H} NMR (50 MHz, C6D6): δ 172.7, 171.2, 170.5 (CdO),
160.0 (TMG), 104.4 (C3), 77.8 (Cp), 75.4 (C2), 73.4 (C4), 63.7
(C9), 61.3 (C6), 61.0, 60.2 (CO2CH2CH3), 48.3 (C5), 46.6 (C1),
45.9 (C8), 39.3 (NCH3), 34.3 (C10), 33.3 (C12), 27.6 (C7), 20.6
(C11), 14.3, 14.2 (CO2CH2CH3) ppm. FAB-MS: m/z (%) 614
(3) [M+], 499 (100) [M+ - NC(N(CH3)2)2], 225 (9) [CpFeC8H8+].
1
700 (s) δ(C-H, aromat.) cm-1. H NMR (400 MHz, CDCl3): δ
7.45 (d, 3J ortho,meta ) 7.6 Hz, 2 H, phenylortho), 7.33 (t, 3J ortho,meta
) 7.6 Hz, 2 H, phenylmeta), 7.25 (m, 7 H, phenyl), 7.19 (m, 4 H,
3
3
phenyl), 7.00 (m, 5 H, phenyl), 6.17 (dd, J 1,2 ) 10.2 Hz, J 2,3
) 10.7 Hz, 1 H, 2-H), 5.99 (dd, 3J 2,3 ) 10.7 Hz, 3J 3,4 ) 11.2 Hz,
1 H, 3-H), 5.92 (ddd, J 1,2 ) 10.2 Hz, J 1,8trans ) 8.1 Hz, 1 H,
1-H), 5.77 (dd, J 3,4 ) 11.2 Hz, J 4,5 ) 8.7 Hz, 1 H, 4-H), 3.37
3
3
3
3
3
3
3
C
26H34FeO6 (613.58).
(t′, J 4,5 ) J 5,6trans ) 8.7 Hz, 1 H, 5-H), 2.36 (dd, J 7,8cis ) 8.1
2 3
Gen er a l P r oced u r e to Clea ve th e Cycloocta d ien e
Liga n d . Ten equivalents of CF3COOH was added to a solution
Hz, J 8,8 ) 12.7 Hz, 1 H, 8cis-H), 2.26 (ddd, J 6trans,7 ) 11.7 Hz,
3J 6cis,7 ) 3.1 Hz, 3J 7,8trans ) 9.2 Hz, 1 H, 7-H), 2.13 (dd, 3J 7,8trans

From Cyclooctatetraene to Cycloocta-1,3-diene
Organometallics, Vol. 22, No. 10, 2003 2107
3
3
3
Ta ble 4. P r ep a r a tive Deta ils Con cer n in g th e
Clea va ge of th e Cycloocta d ien e Liga n d s in 4a -c
(dd, J 2,3 ) 7.6 Hz, J 3,4 ) 6.9 Hz, 1 H, 3-H), 5.98 (dd, J 1,2
)
6.9 Hz, 3J 2,3 ) 7.6 Hz, 1 H, 4-H), 5.55 (t′, 3J 3,4 ) 3J 4,5 ) 6.9 Hz,
1 H, 2-H), 5.12 (s, 5 H, Cp), 4.61 (brs, 1 H, 1-H), 3.75, 3.74,
starting
complex
mg
(mmol)
MeCN
(mL)
yield
mg (%)
3
product
Rfa
3.68, 3.65 (s, 3 H, CO2CH3), 3.22 (d, J 6,12 ) 8.4 Hz, 1 H,
3
10-H), 3.21 (m, 1 H, 1-H), 2.46 (d, J 7,8 ) 11.4 Hz, 1 H, 8-H),
4a
4b
4c
300 (0.35)
200 (0.39)
261 (0.43)
80
25
30
6a
6b
6c
0.24
0.22
0.39
129 (57)
95 (62)
125 (60)
2.38 (m, 1 H, 6-H), 2.00 (m, 1 H, 11-H), 0.85 (m, 1 H, 7endo-H),
0.84 (t, 3J ) 7.6 Hz, 3 H, 12-H), -0.75 (m, 1 H, 7exo-H), -14.64
3
(brd, J ) 3.1 Hz, 1 H, Fe-H) ppm.
a
Rf from TLC.
2
2
) 9.2 Hz, J 8,8 ) 12.7 Hz, 1 H, 8trans-H), 1.57 (dd, J 6,6 ) 13.7
3
Hz, J 6cis,7 ) 3.1 Hz, 1 H, 6cis-H), 1.46 (m, 1 H, 6trans-H) ppm.
13C{1H} NMR (500 MHz, CDCl3): δ 139.6, 139.2, 139.0,
138.9 (Cq-phenyl), 125.4, 126.2, 126.6, 127.1, 127.3, 127.5,
127.6, 128.7, 129.0, 129.1 (C-phenyl), 133.3 (C4), 131.4 (C1),
127.8 (C2), 128.4 (C3), 120.8, 120.3 (CN), 58.3, 58.0 (C9, C10),
44.6 (C5), 41.7 (C7), 31.4 (C8), 28.9 (C6) ppm. EI-MS (70
eV): m/z (%) 490 (2) [M+], 298 (100) [M+ - CPh2CN], 192 (90)
[CPh2CN+], 165 (99) [CPh2H], 105 (45) [C8H9+]. Anal. Calcd
for C36H30N2(CH2Cl2) (575.58): C 77.21, H 5.60, N 4.87.
Found: C 77.73, H 5.99, N 4.50.
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft (HE 1309/2-1) and
the Fonds der Chemischen Industrie. We thank BASF
for the donation of cyclooctatetraene.
[(η5-Cyclop en t a d ien yl){1,2,3,4,5-η-6-exo-d i(m et h oxy-
c a r b o n y l)m e t h y l-8-exo-d i (m e t h o x y c a r b o n y l)p r o p -
1-ylcyclooct a d ien yl}h yd r id oir on (II)] Tr iflu or oa cet a t e
1
(5CF 3CO2). H NMR (360 MHz, CD3CN, T ) -30 °C): δ 7.21
OM0300068