Welcome to LookChem.com Sign In|Join Free

Article Doi

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

DOI: 10.1021/om0300068

Source and publish data:

Organometallics p. 2097 - 2107 (2003)

Update date:2022-07-29

Topics:

Authors:

Reimelt, OliverReimelt, Oliver

Heck, JuergenHeck, Juergen

Read Full Text PDF DownLoad Join now for total 90,000,000 free articles

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.

View More

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  

Products guided by the article

Product name:(η5-cyclopentadienyl)[1,2,3,4,5-η-6,8-exo,exo-bis((diphenylcyano)methyl)cyclooctadienyl]iron(II)

Cas No:537704-59-9

537704-59-9

R&D Labs maybe for 537704-59-9

Relevant to this article

Hot Product