Alkylidene complexes of ruthenium containing N-heterocyclic...

Details Alkylidene complexes of ruthenium containing N-heterocyclic... Alkylidene complexes of ruthenium containing N-heterocyclic...

2000-11-27

2003-10-21

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C556S021000, C556S136000, C585S527000

Reexamination Certificate

active

06635768

ABSTRACT:

The invention relates to alkylidene complexes of ruthenium containing N-heterocyclic carbene ligands and a process for preparing olefins by olefin metathesis from acyclic olefins having two or more carbon atoms or/and from cyclic olefins having four or more carbon atoms using at least one of these alkylidene complexes as catalyst.
C—C coupling reactions catalyzed by transition metals are among the most important reactions of organic synthetic chemistry. In this context, olefin metathesis makes a significant contribution, since this reaction enables by-product-free olefins to be synthesized. Olefin metathesis has not only a high potential in the area of preparative, organic synthesis (RCM, ethenolysis, metathesis of acyclic olefins) but also in polymer chemistry (ROMP, ADMET, alkyne polymerization). Since its discovery in the 1950s, a number of industrial processes have been able to be realized. Nevertheless, olefin metathesis has developed into a broadly applicable synthetic method only recently due to the discovery of new catalysts (J.C. Mol in: B. Cornils, W. A. Herrmann: Applied Homogeneous Catalysis with Organometallic Compounds, VCH, Weinheim, 1996, p. 318-332; M. Schuster, S. Blechert, Angew. Chem. 1997, 109, 2124-2144; Angew. Chem. Int. Ed. Engl. 1997, 36, 2036-2056).
Numerous, fundamental studies have made important contributions to the understanding of this transition metal-catalyzed reaction in which an exchange of alkylidene units between olefins occurs. The generally accepted mechanism involves metal-alkylidene complexes as active species. These react with olefins to form metallacyclobutane intermediates which undergo cycloreversion to once again form olefins and alkylidene complexes. The isolation of metathesis-active alkylidene and metallacyclobutane complexes supports these mechanistic hypotheses.
Numerous examples may be found, in particular, in the coordination chemistry of molybdenum and tungsten. Specifically the work of Schrock gave well-defined alkylidene complexes whose reactivity can be controlled (J. S. Murdzek, R. R. Schrock, Organometallics 1987, 6, 1373-1374). The introduction of a chiral ligand sphere in these complexes made possible the synthesis of polymers having a high tacticity (K. M. Totland, T. J. Boyd, G. C. Lavoie, W. M. Davis, R. R. Schrock, Macromolecules 1996, 29, 6114-6125). Chiral complexes of the same structural type have also been used successfully in ring-closing metathesis (O. Fujimura, F. J. d. L. Mata, R. H. Grubbs, Organometallics 1996, 15, 1865-1871). However, the high sensitivity toward functional groups, air and water is a drawback.
Recently, phosphine-containing complexes of ruthenium have become established (R. H. Grubbs, S. T. Nguyen, L. K. Johnson, M. A. Hillmyer, G. C. Fu, WO 96/04289, 1994; P. Schwab, M. B. France, J. W. Ziller, R. H. Grubbs, Angew. Chem., 1995, 107, 2179-2181; Angew. Chem. Int. Ed. Engl. 1995, 34, 2039-2041). Owing to the electron-rich, “soft” character of later transition metals, these complexes have a high tolerance toward hard, functional groups. This is demonstrated, for example, by their use in natural product chemistry (RCM of dienes) (Z. Yang, Y. He, D. Vourloumis, H. Vallberg, K. C. Nicolaou, Angew. Chem. 1997, 109, 170-172; Angew. Chem., Int. Ed. Engl. 1997, 36, 166-168; D. Meng, P. Bertinato, A. Balog, D. S. Su, T. Kamenecka, E. J. Sorensen, S. J. Danishefsky, J. Am. Chem. Soc. 1997, 119, 2733-2734; D. Schinzer, A. Limberg, A. Bauer, O. M. Böhm, M. Cordes, Angew. Chem. 1997, 109, 543-544; Angew. Chem., Int. Ed. Engl. 1997, 36, 523-524; A. Fürstner, K. Langemann, J. Am. Chem. Soc. 1997, 119, 9130-9136).
However, the range of variation of the phosphine ligands used is very restricted due to steric and electronic factors. Only strongly basic, bulky alkylphosphines such as tricyclohexylphosphine, triisopropylphosphine and tricyclopentylphosphine are suitable for the metathesis of acyclic olefins and relatively unstrained ring systems. Accordingly, the reactivity of these catalysts cannot be adjusted. Chiral complexes of this structural type have also not been able to be obtained.
For these reasons, it is an object of the invention to develop tailored metathesis catalysts which have a high tolerance toward functional groups as a result of a variable ligand sphere and which allow fine adjustment of the catalyst for specific properties of different olefins.
This object is achieved according to the invention by a complex of ruthenium of the structural formula I,
where X
1
and X
2
are identical or different and are each an anionic ligand,
R
1
and R
2
are identical or different and can also contain a ring, and R
1
and R
2
are each hydrogen or/and a hydrocarbon group, where the hydrocarbon groups are identical or different and are selected independently from among straight-chain, branched, cyclic or/and noncyclic radicals from the group consisting of alkyl radicals having from 1 to 50 carbon atoms, alkenyl radicals having from 1 to 50 carbon atoms, alkynyl radicals having from 1 to 50 carbon atoms, aryl radicals having from 1 to 30 carbon atoms and silyl radicals,
where one or more of the hydrogen atoms in the hydrocarbon or/and silyl groups can be replaced independently by identical or different alkyl, aryl, alkenyl, alkynyl, metallocenyl, halogen, nitro, nitroso, hydroxy, alkoxy, aryloxy, amino, amido, carboxyl, carbonyl, thio or/and sulfonyl groups,
the ligand L
1
is an N-heterocyclic carbene of the formulae II-V and the ligand L
2
is an uncharged electron donor, in particular an N-heterocyclic carbene of the formulae II-V or an amine, imine, phosphine, phosphite, stibine, arsine, carbonyl compound, carboxyl compound, nitrile, alcohol, ether, thiol or thioether,
where R
1
, R
2
, R
3
and R
4
in the formulae II, III, IV and V are identical or different and are each hydrogen or/and a hydrocarbon group,
where the hydrocarbon groups comprise identical or different, cyclic, noncyclic, straight-chain or/and branched radicals selected from the group consisting of alkyl radicals having from 1 to 50 carbon atoms, alkenyl radicals having from 1 to 50 carbon atoms, alkynyl radicals having from 1 to 50 carbon atoms and aryl radicals having from 1 to 30 carbon atoms, in which at least one hydrogen may be replaced by functional groups, and where one or both of R
3
and R
4
may be identical or different halogen, nitro, nitroso, alkoxy, aryloxy, amido, carboxyl, carbonyl, thio or/and sulfonyl groups.
The alkyl radicals, alkenyl radicals or alkynyl radicals in the formulae I to V preferably have from 1 to 20 carbon atoms, particularly preferably from 1 to 12 carbon atoms.
The complexes of the invention are highly active catalysts for olefin metathesis. They are particularly inexpensive. In olefin metathesis, the catalysts of the invention display not only a high tolerance toward a variety of functional groups but also a wide range of possible variations in the ligand sphere. Variation of the preparatively readily obtainable N-heterocyclic carbene ligands enables activity and selectivity to be controlled in a targeted manner and, in addition, chirality can be introduced in a simple way.
The anionic ligands X
1
and X
2
of the complex of the invention, which are identical or different, are preferably each halide, pseudohalide, tetraphenylborate, perhalogenated tetraphenylborate, tetrahaloborate, hexahalophosphate, hexahaloantimonate, trihalomethanesulfonate, alkoxide, carboxylate, tetrahaloaluminate, tetracarbonylcobaltate, hexahaloferrate(III), tetrahaloferrate(III) or/and tetrahalopalladate(II), with preference being given to halide, pseudohalide, tetraphenylborate, perfluorinated tetraphenylborate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, trifluoromethanesulfonate, alkoxide, carboxylate, tetrachloroaluminate, tetracarbonylcobaltate, hexafluoroferrate(III), tetrachloroferrate(III) or/and tetrachloropalladate(II) and preferred pseudohalides being cyanide, thiocyanate, cyanate, isocyanate and isothiocyanate.
In the formulae II, III, IV and V, some or all of the hydrogen in the hydroc

Affiliated with

Also associated with

Rating

Alkylidene complexes of ruthenium containing N-heterocyclic... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Alkylidene complexes of ruthenium containing N-heterocyclic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Alkylidene complexes of ruthenium containing N-heterocyclic... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3118180