EP1311520A1

EP1311520A1 - Ruthenium complexes containing carboids

Info

Publication number: EP1311520A1
Application number: EP01967261A
Authority: EP
Inventors: Wolfram Stueer; Jörn KARL; Michael Röper; Stefan Jung; Justin Wolf; Helmut Werner
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-08-11
Filing date: 2001-08-10
Publication date: 2003-05-21
Also published as: KR20030022888A; WO2002014336A1; EA200300260A1; AU2001287677A1; DE10039389A1; CA2419368A1; MXPA03001161A; US20030195357A1; JP2004506644A; CN1447815A

Abstract

In ruthenium complexes of general formula A or B, X<1>, X<2> independently represent single or multidentate anionic ligands; R, R', R'' independently represent hydrogen or optionally substituted C1-20-alkyl, C6-20-aryl or C7-20-alkylaryl radicals; and L<1>, L<2> independently represent neutral electron donor ligands which are co-ordinated at the metallic centre as carboids, and which can be linked by a bridge W having 0 to 20 carbon atoms. Said bridge can be a constituent of a cyclic or aromatic group and can be split by heteroatoms, with the exception of C,N-heterocyclic five-membered ring systems.

Description

Ruthenium complexes containing carbenoids

The invention relates to ruthenium complexes containing carbenoids, which can be used, for example, as catalysts in metathesis reactions, and to processes for their preparation.

In its simplest form, olefin metathesis (disproportionation) describes the reversible, metal-catalyzed transalkylidation of olefins by breaking and reforming C = C double bonds. In the case of the metathesis of acyclic olefins, a distinction is made, for example, between self-metathesis, in which an olefin merges into a mixture of two olefins of different molar mass (example: propene → ethene + 2-butene), and cross- or co-metathesis, which is a reaction of two different ones Olefins describes (propene + 1-butene → ethene + 2-pentene). If one of the reactants is ethylene, this is generally referred to as ethenolysis. Further areas of application of olefin metathesis are syntheses of unsaturated polymers by ring-opening metathesis polymerization (ROMP) of cyclic olefins and acyclic diene metathesis polymerization (ADMET) of α, ω-dienes. More recent applications relate to the selective ring opening of cyclic olefins with acyclic olefins and ring closure reactions (RCM), with which - preferably from oc, ω-dienes - unsaturated rings of different ring sizes can be produced.

In principle, homogeneous and heterogeneous transition metal compounds are suitable as catalysts for metathesis reactions, in particular those of VI. - VIII.- Subgroup of the Periodic Table of the Elements as well as homogeneous and heterogeneous catalyst systems in which these compounds are contained.

In recent years, efforts have been made to produce homogeneous catalysts that are stable in protic medium and in atmospheric oxygen. DE-A-197 36 609 describes ruthenium alkylidene compounds of the general composition [RuX ₂ (= CHR) (PR ') ₂ ] (R = R' = alkyl, aryl) and synthesis methods for complexes of this type.

The catalysts of the general formula [RuCl ₂ (= CHR) L ₂ ] are very active for L = PCy ₃ in the metathesis of numerous olefins. In particular in the case of olefins with polar functional groups such as -OH, -CO ₂ R, -CN etc., however, these catalysts can in some cases be deactivated quickly. The activity of the catalysts and the rate of deactivation are very dependent on the olefin. The degree of substitution of the double bond as well as the position of functional groups for the double bond play a significant role.

More recently, heteroatom-substituted carbenes have been used as ligands instead of the phosphine ligands. In free form, these have an electron sextet on a carbon atom.

DE-A-198 15 275 describes N-heterocyclic carbenes as complex ligands whose ring is derived from imidazole or triazole. The complexes correspond to the general formula [RuX ¹ X ² L ¹ L ² (= CR "R ')] ₃ wherein at least one of the ligands L, L represents an N-heterocyclic carbene.

These catalysts with N-heterocyclic carbenes as ligands are superior to the catalysts with phosphine ligands for some substrates, with a strong substrate dependence. However, the catalysts do not allow a wide variation in their structure. However, the task of synthesizing stable catalysts with a long service life for the metathesis of numerous different olefins cannot be achieved in this way. Because of the previous Experience shows that the catalyst must be adapted to the respective substrate. This "tuning" of the catalyst is usually carried out by varying the substituents within a class of ligands. The disadvantage of the N-heterocyclic carbenes is the definition of the organic backbone, which stands in the way of broad catalyst screening. By means of the C, N-5 Since the angle of the carbene carbon atom with its two neighboring atoms in the five-membered ring is specified within narrow limits, the space requirement of the ligand can be controlled almost exclusively via the substituents on the latter neighboring atoms.

The task was to develop basic ligand structures that allow a varied variation of the substituents and the framework to enable a variable catalyst design. It should be possible to vary the steric conditions and the electronic conditions in many ways. The aim was to find generally applicable syntheses that can be transferred to a variety of starting materials and thus allow the synthesis of a large number of ligands. Furthermore, the necessary starting materials should be as commercially available or easy to manufacture as possible. In order to achieve a high throughput, the synthesis should be transferable to an automatic machine in order to enable the automated construction of a ligand library and thus a catalyst library. This should make it possible to optimize ruthenium metathesis catalysts specifically for a substrate.

This object was achieved according to the invention by ruthemum complexes of the general formula A or B. '

A B

in which

x \ x ^2, independently of one another, mono- or multidentate anionic ligands,

R, R ', R "are independently hydrogen or, optionally substituted, Cι_ ₂ o-alkyl, C. ₆ ₂₀ aryl or C _7-20 -alkylaryl radicals, and

L \ L ^2, independently of one another, neutral electron donor ligands which are coordinated as carbenoids to the metal center and can be connected via a bridge W having 0 to 20 carbon atoms which can be part of a cyclic or aromatic group and can be interrupted by heteroatoms, with the exception of C, N-heterocyclic five-membered systems,

mean.

1 <y

Preferably, the neutral electron donor ligands L and L independently of one another have the general formula C, RR

in the

R ¹ to R ^4, independently of one another, denote electron pairs, hydrogen or, optionally substituted, C 1-20 alkyl, C _6-2 o aryl or C ₂₀ alkylaryl radicals, where (R ¹ and R ² ) and / or ( R ² and R ³ ) and / or (R ³ and R ⁴ ) can together form a cyclic radical, and

E ¹ and E ² independently of one another elements of the group B, CR ⁵ , SiR ⁵ with R ⁵ as defined for R ¹ to R ⁴ , represent N, P, As, Sb, O, S according to their valency.

The neutral electron donor ligands L ¹ and L ² are particularly preferably selected independently of one another from cyclic and non-cyclic diaminocarbenes (I, II with n ≥ 1, III), aminooxycarbenes (IV), bisoxycarbenes, aminothiocarbenes (V), ammophosphinocarbenes, phosphinooxycarbenes ( VII), PhospMnophosphinocarbenen (VIII), Phosphinosilylcarbenen (IX) and

1 diborylcarbenes (X), where the ligands L and L are also connected to one another by the bridge W and can therefore form a chelate ligand

II III

1 2 R R

R R ι T 1

0> -N - N 4

N 3

V 3 ^Λ •• RR

IV VI

VII VIII IX

R R

R • • •• R X

The anionic ligands are preferably weak or non-coordinating anions, for example ClO ^" , PF ₆ ^" , BF ₄ ^" , BAr ₄ ^" or sulfonate. The electronic properties of the carbene carbon atom can be determined by the

1 variable substitution with the same or different fragments ER R or E ² R ³ R ⁴ can be largely controlled. The electron deficiency in diamino carbenes is reduced by the π donor, σ acceptor character of the NR ₂ fragments. In diboryl carbenes, on the other hand, the electron deficiency of the carbon atom is exacerbated by the boron atoms acting as π acceptors and σ donors. In between, for example, the phosphoniosilyl carbenes are located (see Chem. Rev. 2000, 100, 39-91). The properties of the catalyst can thus be varied by coordinating with the transition metal ruthenium.

Another object of the invention is the use of these catalyst systems in metathesis reactions of olefins. Compared to known ruthenium (II) alkylidene complexes of the type [RuCl ₂ (= CHR) L], which have a high application potential as homogeneous metathesis catalysts, the above-mentioned compounds are characterized by a significantly expanded variability of the structures and by a simple preparation of the property-determining ones Ligands L, L.

When used as metathesis catalysts, the complexes of type A or B can either react with the olefin without activation, or be activated in situ with acids HX or with light, where X is, for example, CF CO ₂ ^" or CF ₃ SO ₃ ^" .

In contrast to the known ruthenium-containing catalyst systems, the ligands used in the catalysts according to the invention can be produced on a large scale with different structures with the aid of automatic synthesizers. This makes it possible to automatically produce large ligand and catalyst libraries. The ligands and catalysts according to the invention allow extensive variation in steric and electronic terms. This makes it possible to manufacture a large number of catalysts with different properties, which are then suitable for one can be subjected to catalyst screening and "tuning" for a specific implementation. For example, an intended implementation can be carried out in parallel in a large number of reactors using different catalysts from the catalyst library, the catalyst or catalysts identified as being the most active or selective Corresponding combinatorial or automated production processes using automatic machines for this purpose are known, see for example AM La Pointe, J. Comb. Chem. 1999, 1, 101-104.

The ruthenium complexes according to the invention can be prepared by any suitable method, such as those listed in the documents cited above.

The invention thus relates to a process for the preparation of the ruthenium complexes according to the invention by reacting ruthenium complexes of the general formula [RuHX (H ₂ ) LL] with the free ligands L and L and acids HX ₂ or salts thereof, and alkynes or R "-C ₆ H ₅ , where L, L are neutral two-electron donors.

In addition, the invention relates to a process for the preparation of the ruthenium complexes by reaction of RuCl ₃ ^• xH ₂ O or [RuCl ₂ (olefin)] ₂ or [RuCl ₂ (COD)] _n with the free ligands L ¹ and L ^2, or with the salts [HL ^ X ¹ and [HL ² ] X ² in the presence of a base and hydrogen to form precursor compounds which in turn are reacted with alkynes and acids HX ¹ and HX ² .

The invention also relates to a process for the preparation of ruthenium complexes B by the reaction of [RuCl ₂ (arene)] ₂ or [(arene) RuCl ₂ (L ^* )] 2 with the free ligand L ¹ or the salt [HL ^ X ¹ in the presence of a base, where L is a neutral two-electron donor. To produce a plurality of different ruthenium complexes A and / or B, these processes can be carried out automatically in parallel in a plurality of reaction vessels.

The synthesis of the active components A and / or B can be carried out starting from numerous organometallic starting materials, for example

By reacting carbene complexes of the composition [RuX ¹ X ² (= CRR ') L ^* L ^** ] with the free carbenes of type C.

A possible starting compound for the production of the active component A is, for example, the compound [RuCl ₂ ( ^: = CHCH ₃ ) (PCy ₃ ) ₂ ]. According to the literature, it can be obtained by reacting the non-isolated intermediate [RuHCl (H ₂ ) (PCy ₃ ) ₂ ] with 1-alkynes in the presence of HCl sources (DE-A-197 36 609). [RuHCl (H ₂ ) (PCy ₃ ) ₂ ] in turn is accessible, for example, from the polymeric ruthenium precursor [RuCl ₂ (COD)] _x (COD = cyclooctadiene) in i-propanol in the presence of PCy ₃ under a hydrogen atmosphere (Werner et al ., Organometallics 1996, 15, 1960-1962) or starting from the same starting material in sec-butanol in the presence of PCy ₃ and tert. Amines (NEt ₃ ) under a hydrogen atmosphere (Grubbs et al., Organometallics 1997, 16, 3867-3869). [RuHCl (H ₂ ) (PCy ₃ ) ₂ ] is also accessible starting from RuCl _{3 *} H ₂ O in THF by reaction with PCy in the presence of activated magnesium under a hydrogen atmosphere and is preferably converted in situ with 1-alkynes to the corresponding hydrido ( chloro) vinylidene

[RuClH (= C = CHR) (PCy ₃ ) ₂ ] implemented. The latter can be isolated or react in situ with HCl sources to [RuCl ₂ (= CHCH ₃ ) (PCy ₃ ) ₂ ]. The last-mentioned compound is reacted with the free carbene ligands type C to give the active component A according to the invention, one equivalent of PCy _{3 being} split off. The presentation of the free ligands of type C is in the review by Bourissou et al. (Chem. Rev. 2000, 100, 39-91) and the literature cited therein. Type C carbenes can be prepared, for example, by the following reaction sequence. Type I and III diaminocarbenes can be synthesized as follows. Such sequences can be carried out by automatic synthesizers. Due to the large number of commercially available starting materials, the synthesis of diverse type C carbene ligands is possible.

egg

The following sequence can also be used for symmetrical diamino carbenes:

BF,

The implementation of the free carbenes with carbene complexes of the type [RuX ¹ X ² (= CRR ') LL] is described for N-heterocyclic carbenes: Hermann et al. in Angew. Che. 1998, 110, 2631-2633, Angew. Chem. 1999, 111, 2573-2576, DE-A-198 15 275, Grubbs et al. Tetrahedron Lett. 1999, 40, 2247-2250, Organic Lett. 1999, 1, 953-956; Nolan et al. J. Am. Chem. Soc. 1999, 121, 2674-2678 and can be carried out in a similar manner for the type C carbenes. The reactions are advantageously carried out in an automatic synthesizer.

1 1

• by implementing arene complexes of the type [ArenRuX XL] with free carbenes of type C. Arenameric complexes such as [(p-cymene) RuCl ₂ (PPh ₃ )] are obtained by stirring the dimeric starting materials with PPh ₃ . Thus [(p-cymene) RuCl ₂ ] reacts with PPh ₃ in organic solvents to [(p-cymene) RuCl ₂ (PPh ₃ )]. The latter compound or a dimer such as [(p-cymene) RuCl ₂ ] ₂ is reacted with the free carbene ligands of type C to give the active components B according to the invention, with one equivalent of PPh _{3 being} split off.

• by reacting compounds of the type [RuX ¹ X ² (= CRR ') L ¹ L ² ] or [ArenRuX ^ L ¹ ] with the in situ generated carbenes of type C.

The carbenes of type C can be produced in the presence of the organometallic starting material by reacting the carbene precursors [L ^ JY or P ^ H ^ Y ^" with strong bases, such as, for example, KOtBu, LDA (lithium diisopropylamide) and react directly to the active components A and / or B without being isolated beforehand.

Reactions to the active components A and / or B are carried out in organic solvents under an inert gas atmosphere. The reaction is preferably carried out in THF or toluene or mixtures of the two at temperatures from -100 to + 100 ° C., preferably 0 to 100 ° C. and pressures from 1 mbar to 100 bar, preferably at 0.5 to 5 bar.

The reaction can be carried out using one or more molar equivalents of C or precursors of C. The compositions obtained in this way and containing the active components A and / or B can be used in situ as a highly active metathesis catalyst system or isolated and stored under an inert gas atmosphere. If necessary, the active components A or B are used in isolated form. As a rule, the reaction of substances of general structure C or their precursors with suitable ruthenium complexes to form A or B is complete after 1 s to 10 h, preferably after 3 s to 1 h. Suitable reaction vessels are generally glass or steel containers, which may be lined with ceramic.

Another object of the invention is the use of these catalyst systems in metathesis reactions of olefins. Compared to ruthenium (II) alkylidene complexes of the type [RuCl ₂ (= CHR) L ₂ ] known from the literature, which have a high application potential as homogeneous metathesis catalysts, the abovementioned compounds are distinguished by a significantly expanded variability of the structures and by a simple preparation of the property-determining ligands L, L. In contrast to the systems described above, the catalysts can therefore be easily optimized for a specific substrate.

The catalyst complexes A and B thus obtained can be used, inter alia, for

• Self-metathesis of one olefin or cross-metathesis of two or more

Olefins ring opening metathesis polymerization (ROMP) of cyclic olefins selective ring opening of cyclic olefins with acyclic olefins

Acyclic diene metathesis polymerization (ADMET) • Ring closure metathesis (RCM) and other novel metathesis variants.

Claims

claims

1. Ruthenium complexes of the general formula A or B

B

in which

X ^X , X ² independently of one another are monodentate or multidentate anionic ligands,

R, R ', R "are independently hydrogen or optionally substituted C ^ o-alkyl, C _{_6-20} aryl or C _-20 alkylaryl radicals and

L ¹ , L ² independently of one another are neutral electron donor ligands which are coordinated as carbenoids to the metal center and via a bridge W with 0 to 20 carbon atoms, which can be part of a cyclic or aromatic group and through

Heteroatoms may be interrupted, may be connected, with the exception of C, N-heterocyclic five-membered systems,

mean.

2. ruthenium complexes according to claim 1, characterized in that the

1 ^ neutral electron donor ligands L and L independently of one another have the general formula C,

R R

R « _m R

in the

R ¹ to R ⁴ independently of one another electron pairs, hydrogen or, optionally substituted, C _1-20 -alkyl-, C ₆ . ₂ o-aryl or C. ₂₀ - Alkylaryl radicals, where (R ¹ and R ² ) and / or (R ² and R ³ ) and / or (R ³ and R) together can form a cyclic radical, and

3. ruthenium complexes according to claim 2, characterized in that the neutral electron donor ligands L ¹ and L ^{2 are} independently selected from cyclic and non-cyclic diaminocarbenes (I, II with n ≥ 1, III), aminooxycarbenes (IV), bisoxycarbenes, Aminothiocarbenes (V), aminophosphinocarbenesή, phosphinooxycarbenes (VII), phosphinophosphinocarbenes (VIII), phosphinosilylcarbenes (IX) and diborylcarbenes

1 1

(X), the ligands L and L also being connected to one another by the bridge W and thus being able to form a chelate ligand

II III

IV V VI

VII VIII IX

R R

X

4. ruthenium complexes according to any one of claims 1 to 3, characterized in that the anionic ligands are weak or non-coordinating anions.

5. Process for the preparation of ruthenium complexes according to one of claims 1 to 4 by reacting ru emum complexes of the general formula [RuHX (H ₂ ) LL] with the free ligands L and L and acids HX or salts thereof, and alkynes or R "- C ₆ H ₅ , where L, L are neutral two-electron donors.

6. A process for the preparation of ruthenium complexes A according to one of claims 1 to 4 by reaction of RuCl ₃ ^• xH ₂ O or [RuCl ₂ (olefin)] ₂

1 9 or [RuCl ₂ (COD)] _n with the free ligands L and L or with the salts [HL ^ X ¹ and [HL ² ] X ² in the presence of a base and hydrogen

Precursor compounds, which in turn are reacted with alkynes and acids HX ¹ and HX ² .

7. A process for the preparation of ruthenium complexes B according to any one of claims 1 to 4 by reaction of [RuCl ₂ (arene)] ₂ or

[(Arene) RuCl ₂ (L ^* )] ₂ with the free ligand L ¹ or the salt [HL ^ X ¹ in the presence of a base, where L is a neutral two-electron donor.

8. The method according to any one of claims 5 to 7, characterized in that it is carried out automatically in parallel in a plurality of reaction vessels for the production of a plurality of different ruthenium complexes A and / or.

9. Use of complexes of type A or B according to one of claims 1 to 4 as catalysts for metathesis reactions of olefins.

10. Use according to claim 9, characterized in that the complexes of type A or B either react with the olefin without activation, or in situ with acids HX in which X is CF ₃ CO or CF ₃ SO ₃ , or with

Light can be activated.