New method for the synthesis of substituted ruthenocenes

Full text of DOI:10.1007/s11172-008-0275-5

2032
Russian Chemical Bulletin, International Edition, Vol. 57, No. 9, pp. 2032—2033, September, 2008
New method for the synthesis of substituted ruthenocenes
E. E. Karslyan, A. I. Konovalov, D. S. Perekalin, P. V. Petrovskii, and A. R. Kudinov
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
2
8 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Eꢀmail: arkudinov@ineos.ac.ru
Ruthenocene derivatives are widely used as catalysts,
carbonate was added to quench the acid that can catalyze
the polymerization of cyclopentadiene.
polymer materials, receptors, and biologically active subꢀ
strates.1 Unsubstituted ruthenocene and its symmetriꢀ
cal derivatives can easily be prepared by the reaction
of ruthenium chloride with cyclopentadienes.7—9 Howevꢀ
er, the known methods for the synthesis of unsymmetriꢀ
cally substituted compounds have limitations. In particuꢀ
lar, the electrophilic substitution in ruthenocene and its
—6
Unfortunately, the reaction of compound 1 with
methylcyclopentadiene does not afford the target
CpRu(C H Me) complex apparently due to rapid dimerꢀ
5
4
1
4
ization of C H Me. However, the reaction of compound
5
5
1 with C Me H gives pentamethylruthenocene 2b in 82%
5
5
yield. These facts indicate that the steric effects have no
influence on the reaction pathway.
1
metallation proceed with low selectivity. The direct methꢀ
ods are most promising. For example, the reactions of
Since free formylꢀ and acetylꢀsubstituted cyclopentaꢀ
dienes are unstable, we studied the reactions of comꢀ
8
15
[
Cp*RuCl ] with cyclopentadiene and cyclopentadienꢀ
2
2
1
0
ide anions afford ruthenocenes containing one pentameꢀ
thylated ring. It was suggested11 to use the CpRu(η ,η ꢀ
pound 1 with the corresponding anions. These reactions
produced ruthenocenes 2c,d in ∼ 90% yield. The structures
2
2
1
1
,5ꢀC H )Cl complex for the synthesis of compounds
of compounds 2a—d were confirmed by H NMR specꢀ
8
12
containing the unsubstituted ring; however, the preparaꢀ
tion of this complex is rather difficult. In the present study,
we developed a new procedure for the synthesis of unsymꢀ
metrical ruthenocene derivatives based on the photochemꢀ
ical reaction of the readily available naphthalene complex
troscopy.
To summairze, the presented method allows the synꢀ
thesis of unsymmetrical ruthenocenes, including those
containing functional groups, in high yields.
of ruthenium12 [CpRu(η ꢀC H )] (1) with cyclopentaꢀ
6
+
All reactions were carried out under argon; the operations
associated with the isolation of compounds were performed in
air. Tetrahydrofuran and CH Cl were purified according to stanꢀ
dard procedures and distilled under argon. The starting comꢀ
pounds [CpRu(η ꢀC H )]BF (1—BF ), Na[C H CHO], and
1
0
8
dienes and cyclopentadienide anions.
Earlier,13 we have shown that the visible light irradiaꢀ
2
2
tion of cation 1 with benzene derivatives leads to the reꢀ
6
12
10
8
4
4
5
4
placement of the naphthalene ligand by arene to form the
15
Na[C H COMe] were synthesized according to procedures
5
4
6
+
[
CpRu(η ꢀC R )] complexes. It appeared that the analoꢀ
described earlier. The irradiation was carried out in a Schlenk
tube with a diameter of 15 mm using a mercury luminescent lamp
with a power of 400 W (DRL 400). The Schlenk tube and the lamp
were placed in a vessel of the appropriate size covered inside with
aluminum foil; the cooling was accomplished with running waꢀ
6
6
gous reaction of compound 1 with excess cyclopentadiene
is also accompanied by the displacement of naphthalene
giving ruthenocene Cp Ru (2a) in 73% yield (Scheme 1).
2
Apparently, this reaction proceeds through the intermediꢀ
1
ter. The H NMR spectra were recorded on a Bruker Avanceꢀ
4
+
ate formation of the diene complex [CpRu(η ꢀC H )]
5
6
4
00 instrument in CDCl . The chemical shifts are given in ppm
3
followed by the proton abstraction to form 2a. Potassium
with respect to the signals of the residual protons of the solvent as
the internal standard.
Scheme 1
Ruthenocene (2a) and pentamethylruthenocene (2b). The
complex 1—BF4 (20 mg, 0.05 mmol) was dissolved in a 1 : 1
CH Cl —THF mixture (4 mL). Then C H or C Me H (0.1 mL)
2
2
5
6
5
5
and K CO3 (5 mg, 0.036 mmol) were added to the solution,
2
the reaction mixture was irradiated with visible light for 12 h,
H O (2 mL) was added to the solution, and the reaction mixture
2
was carefully concentrated in vacuo at 50 °C (to remove naphthaꢀ
lene together with the vapor). The residue was dissolved in petroꢀ
leum ether (2 mL) and eluted through a 3ꢀcm alumina column.
The eluted fraction was concentrated, the solid residue was dried
in vacuo, and colorless crystalline compounds 2a,b were obtained.
1
R = H (a), Me5 (b), CHO (c), COMe (d)
Compound 2a; the yield was 9 mg (73%). H NMR, δ: 4.55
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1997—1998, September, 2008.
066ꢀ5285/08/5709ꢀ2032 © 2008 Springer Science+Business Media, Inc.
1

Synthesis of ruthenocenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
2033
1
2
(
(
(
s, 10 H, Cp) (cf. lit. data ). Compound 2b; the yield was 12 mg
6. S. A. Kuklin, A. M. Sheloumov, F. M. Dolgushin, M. G.
Ezernitskaya, A. S. Peregudov, P. V. Petrovskii, A. A. Koꢀ
ridze, Organometallics, 2006, 25, 5466.
1
82%). H NMR, δ: 1.95 (s, 15 H, Cp*); 4.16 (s, 5 H, Cp)
8
cf. lit. data ).
Formylruthenocene (2c) and acetylruthenocene (2d). The
7. P. Pertici, G. Vitulli, M. Paci, L. Porri, J. Chem. Soc., Dalton
Trans., 1980, 1961.
complex 1—BF (20 mg, 0.05 mmol) and Na[C H CHO]•THF
4
5
4
or Na[C H COMe]•THF (12 mg, 0.06 mmol) were dissolved in
8. A. R. Kudinov, M. I. Rybinskaya, Yu. T. Struchkov, A. I.
Yanovskii, P. V. Petrovskii, J. Organomet. Chem., 1987,
336, 187.
9. A. Bauer, U. Englert, S. Geyser, F. Podewils, A. Salzer,
Organometallics, 2000, 19, 5471.
10. P. G. Gassman, C. H. Winter, J. Am. Chem. Soc., 1988,
110, 6130.
11. M. O. Albers, D. C. Liles, D. J. Robinson, A. Shaver,
E. Singleton, M. B. Wiege, J. C. A. Boeyens, D. C. Levendis,
Organometallics, 1986, 5, 2321.
5
4
a 1 : 1 CH Cl —THF mixture (4 mL). The reaction mixture was
2
2
irradiated with visible light for 12 h, the solvent was removed
in vacuo, and the residue was eluted with petroleum ether through
a 10ꢀcm alumina column. The yellow fraction was concentrated,
the solid residue was dried in vacuo, and paleꢀyellow crystalline
compounds were obtained. Compound 2c; the yield was 11 mg
1
(
2
87%). H NMR, δ: 4.64 (s, 5 H, Cp); 4.85 and 5.07 (both m,
1
6
H each); 9.72 (s, 1 H, CHO) (cf. lit. data ). Compound 2d;
the yield was 12 mg (89%). H NMR, δ: 2.28 (s, 3 H, COMe); 4.58
s, 5 H, Cp); 4.76 and 5.07 (both m, 2 H each) (cf. lit. data ).
1
1
7
(
12. E. P. Kündig, F. R. Monnier, Adv. Synth. Catal., 2004,
3
46, 901.
1
3. E. E. Karslyan, D. S. Perekalin, P. V. Petrovskii, A. O. Borisꢀ
ova, A. R. Kudinov, Izv. Akad. Nauk, Ser. Khim., 2009, 572
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Received May 29, 2008