WO2008102157A1

WO2008102157A1 - Catalytic method

Info

Publication number: WO2008102157A1
Application number: PCT/GB2008/000619
Authority: WO
Inventors: Michael Green; Duncan Frank Wass
Original assignee: The University Of Bristol
Priority date: 2007-02-23
Filing date: 2008-02-21
Publication date: 2008-08-28
Also published as: GB2447068A; GB0703509D0

Abstract

Methods for performing olefin metathesis or cross-coupling reaction are disclosed, the methods being performed in the presence of a catalyst system comprising a source of a d-block metal, a source of a 3-membered carbocyclic ligand and, optionally, a promoter, an activator and/or a base. Also disclosed are the catalyst systems, methods for producing the catalyst systems and uses of the catalyst systems to catalyse an olefin metathesis or a cross-coupling reaction.

Description

I

CATALYTIC METHOD

The present invention relates to methods for performing olefin metathesis or cross-coupling reactions in the presence of a catalyst system, catalyst systems for use in the methods, processes for preparation of the catalyst systems and uses of the catalyst systems in the methods.

Complexes of transition metals have found widespread use as homogeneous catalysts (Applied Homogeneous Catalysis with Organometallic Compounds, Cornils, B.; Herrmann, W.A. (Eds), VCH Weinheim, 1996, 258). They are particularly useful for catalytic reactions involving the formation of carbon-carbon or carbon-heteroatom (for example, H, N, O, P) bonds, two important classes of reaction being so-called 'cross- coupling' reactions (Metal Catalyzed Cross-Coupling Reactions, 2^nd ed, de Meijere and Diederich (eds), Wiley-VCH, 2004) and 'metathesis' reactions (also known as olefin metathesis reactions) (Handbook of Metathesis, Grubbs (ed) Wiley-VCH, 2003).

A crucial consideration in these applications is the supporting ligands around the transition metal centre, modification of which can lead to industrially useful benefits such as improved stability, selectivity and activity.

A number of such supporting ligands have been disclosed, often based on N- or P- donor sets. More recently, ligands based on cyclic heteroatom- stabilised C-donors have also been described, such ligands often being called N-heterocyclic carbenes (W.A. Herrmann, C. Kόcher, Angewandte Chemie International Edition, 1997, 36, 2162-2187) and, even more recently, carbocyclic (i.e. no heteroatom) carbene ligands based on 7-membered rings have been disclosed (W.A. Herrmann et al, Angewandte Chemie International Edition, 2006, 45, 3859-3862).

Metal complexes supported by 3-membered carbocyclic ring ligands are known. A particular palladium complex with a cyclopropene Iigand has been "shown to catalyse 'an isomerisation reaction as disclosed in EP-A- 0118801 and Yoshida et al Tetrahedron 44, (1988) p55. Other complexes based on cyclopropene have also been disclosed in Yoshida et al: Chemistry Letters, 1978, 241 and 1341 ; J. Phys. Org. Chem., 1988, 332; Ofele, Angewante Chemie, Int. Ed. 1968, 7, 950 (Cr); Schubert et al; J. Am. Chem. Soc, 1991 , 113, 2228 and Organometallics, 1988, 7, 784 (Mn).

However, use of these complexes as catalysts for reactions involving the formation of carbon-carbon or carbon-heteroatom bonds has not been disclosed.

We have found that, surprisingly, metal complexes with a 3-membered carbocyclic ring ligand are very efficient catalysts for such reactions and, moreover, show improved catalytic activity compared to other systems.

The present invention accordingly provides a method for performing an olefin metathesis or a cross-coupling reaction, characterised in that the method is performed in the presence of a catalyst system comprising, a) a source of a d-block metal, b) optionally a promoter, an activator and/or a base, and c) a 3-membered carbocyclic ligand or a source of a 3-membered carbocyclic ligand.

The d-block metal is preferably a Group VIII metal (referring to Chemical Abstracts Service group notation, 1986; Group VlII metals correspond to IUPAC recommended notation for Groups 8, 9 and 10 of the Periodic Table: the Fe, Co and Ni groups) or Cu, more preferably a Group VIII metal, and most preferably Ru, Rh, Ni, Pd or Pt. The most preferred d- block metals are Pd and Ru. Pd is particularly suitable for cross-coupling reactions and Ru for metathesis reactions.

Preferably, the 3-membered carbocyclic ligand comprises a group of formula

wherein

(i) R¹ and R² are independently selected from hydrocarbyl or heterohydrocarbyl groups, or (ii) R¹ and R², together with the carbons to which they are attached, form a five, six, seven or eight membered ring.

The broken line in the formula of the carbocyclic ligand indicates the bond to the d-block metal.

Suitable hydrocarbyl groups are alkyl, for example methyl, ethyl, n- propyl, isopropyl, t-butyl, adamantyl; aryl or substituted aryl, for example phenyl, ortho-to\y\, meta-tolyl, para-tolyl, ethylphenyl, isopropylphenyl, t- butylphenyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, 3,5-dimethylphenyl, 2,6- diisopropylphenyl, 2,4,6-trimethylphenyI, 2,4,6-triisopropylphenyl, naphthyl, benzyl, alkenyl or alkynl groups. Suitable heterohydrocarbyl groups may have one or more heteroatoms and this may be attached directly to the 3- membered ring or at any other substituent position on the group. Suitable examples where the heteroatom is attached directly to the 3-membered ring are: -Z(R³)_m where Z is Si and m is 3, Z is N and m is 2, Z is P and m is 2, Z is O and m is 1 , or Z is S and m is 1 ; the groups R³ are the same or different hydrocarbyl groups as defined above.

Suitable examples where the heteroatom(s) are in other positions are: CF₃, CF₂CF₃, CH₂OMe, CH₂NMe₂, CH₂CH₂NH₂, CHzCHzNCR¹^, CH₂CH₂P(R¹)₂, CH₂CH₂CH₂P(R¹)₂, fluorophenyl, perfluorophenyl, chlorophenyl, bromophenyl, C₆H₄(CF₃), C₆H₃(CF₃)₂, C₆H₄(OMe), C₆H₃(OMe)₂, C₆H₄(N(R¹)₂),-C₆H₄(P(R¹)₂), where -R¹ is as defined above.

For some values of R¹ and R², these groups may themselves act as supporting ligands to the metal, for example when R¹ is CH₂CH₂P(R¹)₂ the P- atom of this group may donate to the metal as a phosphine donor ligand. In this alternative, R¹ and/or R² are such that the 3-membered carbocyclic ligand is a multidentate ligand.

R¹ and R², together with the carbons of the 3-membered ring to which they are attached, may form a five, six, seven or eight membered ring so that the ligand has a bicyclic structure.

The catalyst system may be formed in situ during the reaction or the catalyst system may be pre-formed. Whether or not the catalyst system is pre-formed, the 3-membered carbocyclic ligand will be present.

If the catalyst system is pre-formed, the catalyst system may, preferably, comprise a compound of formula

wherein M is a d-block metal, n is 0 to 5 and the L groups, which may be the same or different, are ligands.

The L groups may be the same or different and are either additional ligands needed to stabilise the overall complex, for example, chloride, bromide, iodide, hydride, alkoxide, amide, acetate, acetylacetonate, amine, ether, water, phosphines such as triphenylphosphine or triphenoxyphosphine, pyridine, alkenes, alkynes, N-heterocyclic carbenes, etc; or reactive ligands that can be the active site of the catalysts, for example alkyl, aryl, carbene, alkylidene. Some of the L groups described as stabilising groups can also be reactive ligands in some circumstances, for example amide and hydride. L may also be a substrate molecule for the catalytic reaction being performed.

L may be a 3-membered carbocyclic ring ligand as defined above, giving an overall structure of:

in the case where one L group is an additional 3-membered carbocyclic ring. The catalyst system may comprise a compound of formula

wherein the X groups, which may be the same or different, are halide or pseudohalide and L² is PR3, wherein each R is independently selected from hydrocarbyl or H. Most preferred is when both X are chloride and L² is PPh₃ or PBu₃.

The catalyst system may comprise a compound of formula

wherein M is a d-block metal, the X groups, which may be the same or different, are halide or pseudohalide. The preferred d-block metal is Pd and the preferred X groups are Cl. The preferred R₁ and R₂ groups are all phenyl or all Pr₂N¹. Such a catalyst system is particularly suitable for cross-coupling reactions. The most preferred compounds according to this general formula are the palladium complexes 3

or 4

The catalyst system may, in the alternative, comprise a compound of one of the formulae:

wherein each R is a hydrocarbyl group or H or wherein two R groups, together with the carbon to which they are both attached, form a ring or multiple ring system, and the X¹ groups, which may be the same or different, are halide or pseudohalide. The preferred X¹ is a halide, most preferably choride. Such a catalyst system is particularly suitable for metathesis reactions. The most preferred ruthenium complex is 5 bis(triphenyl phosphine)-3-phenyl-1 H-inden- 1-ylidene ruthenium III dichloride

The olefin metathesis reaction may be selected from cross-metathesis, ring closing metathesis, enyne metathesis, ring opening metathesis, ring opening metathesis polymerisation, acyclic diene metathesis or alkyne metathesis.

The cross-coupling reaction may be selected from:

1 ) Cross-coupling reactions with organoboron compounds, for example Suzuki coupling,

2) Cross-coupling reactions with organotin compounds for example Stille coupling,

3) Cross-coupling reactions with organozinc compounds,

4) Cross-coupling reactions with organomagnesium compounds,

5) Cross-coupling reactions with other organometallic compounds, for example Negishi coupling,

6) Cross-coupling reactions with allylic compounds,

7) Cross-coupling reactions with conjugated diene compounds,

8) Carbometallation reactions,

9) Cross-coupling reactions with alkyne compounds, for example Sonogashira reaction,

10) Cross-coupling reactions with olefinic compounds, for example Heck ' reaction,

11) Cross-coupling reactions involving a cyclometallation step,

12) Cross-coupling reactions for the formation of carbon-heteroatom bonds (e.g. C-N, C-O), for example Buchwald-Hartwig reactions The details of such reactions are well-known to the skilled person as described in, for example, "Metal Catalysed Cross-coupling Reactions" 2^nd edition, edited by de Meijere and Diederich, Wiley-VCH 2004.

Catalytic reactions may be carried out on a wide variety of substrates including those that have been previously disclosed for cross coupling or metathesis catalysis and at temperatures between -100⁰C and 25O⁰C, preferably between O⁰C and 200⁰C. Reactions are typically carried out in a solvent diluent, although the substrates or reaction products themselves may also be used as solvents. The solvent diluent of choice will depend on the solubility characteristics of the specific catalysts and substrates used and a wide variety of suitable solvents are suitable, including hydrocarbons (e.g. alkanes, benzene, toluene, xylene) and polar solvents (e.g. ethers, halocarbons, acetone, DMA, DMF, DMSO, MeCN etc.). Alternatively, the catalyst may be in the solid phase by heterogenisation on a suitable carrier such as a polymer, silica, carbon, alumina, etc.

For cross coupling catalysis, it is usually required to add a catalyst promoter, in excess, stoichiometric or sub-stoichiometric amounts to the substrates used. This promoter is usually a suitable base, such as an amine, amide, alkoxides, hydroxide, carbonate, phosphate or similar. Other possible promoters include halide ions. For metathesis catalysis, a promoter is usually not required, although in some specific cases one may be required to generate an active system.

In a second aspect, the present invention provides a catalyst system for catalysing olefin metathesis or cross-coupling reactions, the catalyst system comprising, a) a source of a d-block metal, b) optionally a promoter, an activator and/or a base, and c) a 3-membered carbocyclic ligand or a source of a 3-membered carbocyclic ligand.

Optional and/or preferred features of the catalyst system are generally as described above in relation to the first aspect of the invention. Catalyst systems may be either pre-formed or formed in situ by mixing the component parts of the catalyst. Even in cases where a pre-formed catalyst system in the form of a discrete metal-ligand complex is used, this will often undergo further reaction during a catalytic run, resulting in a new complex in which the groups L have been removed, replaced or transformed into new L groups. Pre-formed catalyst systems may be made by those skilled in the art by reaction of a transition metal source, a source of a 3- membered carbocyclic ligand and, optionally, a further reagent such as a base (for example: amines, amides, alkoxides, hydroxides, carbonates, BuLi or similar reagents), an acid, a reducing agent, an oxidising agent, or further group as defined as L above (or a source of a further group as defined as L).

Thus, in a third aspect, the present invention provides a method for producing a catalyst system for catalysing olefin metathesis or cross-coupling reactions, the method comprising combining a) a source of a d-block metal, b) optionally, a further reagent, c) a 3-membered carbocyclic ligand or a source of a 3-membered carbocyclic ligand.

Suitable sources of a transition metal are the metal itself, the metal dispersed on a suitable carrier material (for example silica or carbon) or a metal complex of formula ML_m, where M and L are as defined above, and the value of m will vary depending on the nature of L and the required valency of M but will generally be between 1 and 6.

Suitable sources of a 3-membered carbocyclic ligand include the free carbene ligand:

Such ligands are often unstable in their free form, and another suitable 3-membered carbocyclic ligand source is where the ligand has been stabilized by co-ordination to a Lewis acid fragment, as illustrated:

where Z is a suitable Lewis acid, for example a main group Lewis acid such as a borane (e.g. BH₃, BCI₃, BL₃ and the like), appropriate group 13 compounds (e.g. AICI₃), appropriate group 14 compounds, (e.g. stannanes, SnCI₂, SnCI₄ and the like), appropriate group 15 compounds (e.g. SbFs); or a further transition metal compound ML_m, as defined above.

Other suitable sources of a 3-membered carbocyclic ligand are substituted 3,3'-cyclopropene compounds as illustrated:

where the X groups may be the same or different and may be a halide (F, Cl, Br, I, etc), pseudo-halide (e.g. N₃ ^', CN^", NCO^', OCN^", etc.) or weakly- coordinating anion (e.g. BF₄, PF₆, CIO₄, AsF₆, AICI₄, B(C₆F₅)₄, etc), H, a main group metal or main group metal fragment (e.g. Li, Na, K, MgCI) or transition metal fragment ML_m as defined above.

The reagents may be combined in order to synthesise a pre-formed catalyst in a number of ways; for example: oxidative addition reaction of a low oxidation state metal source (e.g. Pd metal, [Pd(PPh₃)J, [RhCI(PPh₃)₃], [Ni(CO)₄],- etc) with a 3,3'-dihalocyclopropene compound or analogous pseudo-halide or weakly-coordinating anion compound; reaction of a metal source with the free carbene; reaction of a metal source with 3,3'- dihalocyclopropene compound or analogous pseudo-halide or weakly- coordinating anion compound in the presence of a suitable reducing agent; reaction of a metal source with the free carbene; reaction of a metal source with the Lewis acid-protected carbene; reaction of a metal source with 3- halocyclopropene compound or analogous pseudo-halide or weakly- coordinating anion compound in the presence of a suitable base.

Subsequent modification of the complex to make other preformed catalysts with different L groups can be achieved by standard methods of ligand substitution, addition and/or removal.

Catalysts may also be formed in situ during a catalytic reaction, by addition of the various components as described above either in the presence or absence of the substrates to be converted during catalysis without isolating a discrete metal-ligand complex, although it is likely that similar complexes to those made using a the pre-formed method with be generated.

In this specification, for clarity, the bonding between the 3-membered carbocyclic ligand and the d block metal has been illustrated as

This is only one of a number of resonance forms for this fragment having the same overall formula that could reasonably be drawn by those skilled in the art, and the description is not limited to this specific representation. The resonance form giving most accurate representation of this fragment is likely to vary between specific compounds and will depend on the other groups bonding to the 3-membered carbocycle.

In this specification, unless otherwise specified, "hydrocarbyl" refers to an optionally substituted hydrocarbon group and includes alkyl, alkenyl, alkynyl, 5- or 6- membered rings (that may be alicyclic or aryl and includes monocyclic, bicyclic or polycyclic fused ring- systems), preferably Ci to C₃₂, more preferably C₁ to C₂₄, most preferably Ci to C₁₈. "Heterohydrocarbyl" refers to a group as defined above for hydrocarbyl but containing one or more heteroatoms preferably selected from Si, P, N, O, S and F.

"Alkyl" is preferably Ci to CQ, more preferably straight chain Ci to C₆ in particular methyl, ethyl, n-propyl or n-butyl.

"Halide" is fluoride, chloride, bromide or iodide.

"Pseudohalides" are groups which resemble halides in their chemistry and include N₃ ^", CN^", NCO^", OCN^", and SCN^".

The invention is illustrated by the Figure which is a single crystal X-ray diffraction structure of the compound described in Example 2.

The invention is further illustrated by the following Examples in which all procedures were carried out under an inert (N₂) atmosphere using standard Schlenk line techniques or in an inert atmosphere (Ar) glovebox. Chemicals were obtained from Sigma Aldrich and used without further purification unless otherwise stated.

Example 1. Synthesis of i ^-diphenyl-S^-dichlorocyclopropene 1

Diphenylcyclopropenone (1.00 g, 4.85 mmol) was heated at 40 ⁰C for 2 h in 2 ml of thionyl chloride. The volatiles were removed in vacuo to give a beige powder. The solid was dissolved in 6 ml of cyclohexane with heating and placed in a freezer overnight to give i ^-diphenyl-S.S-dichlorocyclopropene as pale yellow crystals in 59 % yield (0.75 g, 2.88 mmol).

Example 2. Synthesis of palladium complex 2

i ^-diphenyl-S.S-dichlorocyclopropene (47 mg, 0.18 mmol) and tetrakis(triphenylphosphine)palladium(0) (208 mg, 0.18 mmol) were weighed into a Schlenk flask. 10 ml of toluene was added to give a yellow solution and a colourless precipitate immediately. The mixture was stirred overnight. The precipitate was collected by filtration and dried in vacuo to give the illustrated compound 2 as a white solid in 50% yield. The product 2 can be recrystallised from CHCI₃.

Characteristic data: ³¹P{¹H} NMR (121 MHz, CDCI₃): δ = 27.6, ¹H NMR (400 MHz, CDCI₃): δ = 8.03 (m, 4H), 7.64 (m, 8H), 7.53 (m, 4H), 7.25 (m, 3H), 7.15 (m, 6H).

A single crystal X-ray diffraction structure of this compound was obtained and is shown in the Figure with significant bond lengths and angles in Table 1. In the Figure, hydrogen atoms are omitted for clarity.

Table 1. Bond lengths (A) and angles (°)

Catalytic Experiments (see Table 2):

Examples 3-10

The same basic method was adopted for all of these examples for the illustrated reaction.

A Schlenk flask was charged with base as indicated in Table 2 (3.0 mmol), the aryl halide as indicated in Table 2 (2.0 mmol) and the internal standard diethylene glycol di-n-butyl ether (100mg). Then n-butyl acrylate (3 mmol) and degassed N,N-dimethylacetamide (DMA) (2 ml) were added and the reaction heated to 145 ⁰C. When the reaction had reached temperature, the required amount of catalyst 2 was added and the reaction stirred for the required run time. At the end of the reaction, the reaction mixture was allowed to cool, washed with dilute HCI (aq), extracted with dichloromethane and the organic phase dried over MgSO₄. Conversion and yield was determined by GC relative to the internal standard.

Examples 11 -16

Essentially the same method was used as described above, only n-butyl acrylate was replaced with phenylboronic acid, DMA was replaced with xylene and the reaction temperature was 130 ⁰C. Table 2:

Example 17. Synthesis of palladium complex 3

i .i-dichloro^.S-diphenylcyclopropene (210 mg, 0.805 mmol) and [Pd(dba)₂] (dba = dibenzylideneacetone) (440 mg, 0.765 mmol) were suspended in benzene (20 ml) and stirred at 65 ⁰C overnight. The fine brownish solid deposited was filtered through a glass filter, washed with benzene and ether, and dried in air to give the illustrated compound 3 in 68%. Characteristic data: ¹H NMR (CD₃CN, 399.8 MHz): 8.57 (m, 8H o-arom.), 7.88 (m, 4H p-arom.), 7.77 (m, 8H m-arom.). MS-ESI: 1065.8 (15%) [Pd₃(Cyc)₃Cl₅]⁺, correct isotopic pattern.

Example 18. Synthesis of palladium complex 4

2,3-Di(diisopropylamino)cyclopropenium tetrafluoroborate was prepared following the procedure of Bertrand and co-workers (Science, 2006, 312, 722). A Schlenk flask was charged with 2,3- di(diisopropyiamino)cyclopropenium tetrafluoroborate (0.34 g, 1.05 mmol), PdCI₂(COD) (COD = cycloocta-1 ,5-diene) (0.2 g, 0.7 mmol) and potassium bis(trimethylsilyl)amide (2.1 ml_, 1.05 mmol) and cooled to -78 ⁰C. Dichloromethane (15 ml_) was added slowly and the reaction mixture stirred for 30 minutes. After this time, the reaction was left to warm to room temperature and stirred overnight. The solvent was evaporated under reduced pressure to yield the illustrated compound 4 as a brown solid in 60 % yield.

Characteristic data: ¹H-NMR (CDCI₃): δ 1.29 (d, 12H), 1.31 (d, 12H)₁ 3.79 (sept, 2H), 4.06 (sept, 2H). ¹³C-NMR (CDCI₃): δ 20.74 (CHCH₃), 22.50 (CHCH₃), 48.39 (C-ring), 58.02 (C-ring), 94.00 (CH-ring), 132.50 (C-ring).

Examples 19 -26

The reaction

was conducted in the presence of a catalyst system.

An analogous procedure was followed in each case and is illustrated here for example 19. Compound 2 (0.01 mmol) and NaO^fBu (1.4 mmol) were suspended in toluene (8 ml) followed by addition of P-CF₃C₆H₄Br (1 mmol), morpholine (1 mmol) and hexadecane as a standard. The reaction mixture was heated at 100 ⁰C and stirred for 18 hours. After this time, the solution was allowed to cool to room temperature and water (2 ml) added. The organic phase was separated and dried over Na₂SO₄. 0.5 ml of this solution was diluted with toluene (0.5 ml) and analyzed by GC to determine yield. The results are shown in Table 3.

Example 27

An analogous procedure to example 19 was followed only compound 3 (0.01 mmol) was used instead of compound 2. The result is shown in Table 3.

Examples 28-30

An analogous procedure to example 27 was followed only tri-tert- butylphosphine (0.02 mmol) was added at the start of the experiment. The results are shown in Table 3.

Table 3

a: Example performed at 25 ⁰C rather than 100 ⁰C.

Examples 31-34

The reaction

was conducted in the presence of a catalyst.

Essentially the same method as example 3 was used, only compound 2 was replaced with compound 3, n-butyl acrylate was replaced with tributylstannylbenzene, DMA was replaced with xylene and 0.01 mmol tri-tert- butylphosphine was added. 0.01 mmol of compound 3 was used in each case. The results are shown in Table 4.

Table 4

Example 35. Synthesis of ruthenium complex 5

Bis(triphenylphosphine)-3-phenyl-1 H-inden-1-ylideneruthenium (II) dichloride was prepared as reported by Mynott and co-workers (Chemistry - A European Journal, 2001 , 7, 4811). Bis(dipropylamino)cyclopropenium tetraphenyl borate (0.122g, 0.219 mmol) and potassium bis(trimethylsilyl)amide (0.44 mL, 0.219 mmol) were placed in a Schlenk flask and cooled to -78 ⁰C. THF (5 mL) was added slowly and the mixture stirred at that temperature for 10 min. After this time, a solution of Bis(triphenylphosphine)-3-phenyl-1 H-inden-1- ylideneruthenium (II) dichloride (0.15 g, 0.169 mmol) in THF (5ml_) was added at -78 ⁰C and stirred for 30 min and then the reaction mixture was allowed to warm to room temperature. The mixture was then heated under reflux for 2 hours. Solvents were evaporated under vacuum and the residue was redissolved in dichloromethane (5 mL) and filtered through celite, The solvent was evaporated under vacuum and the solid residue was washed with hexane (3 x 10 mL) and dried under vacuum to yield the illustrated compound 5 in 30% yield.

Characteristic data: ³¹P NMR (CD₂CI₂, 121.0 MHz): δ = 29.9.

Example 36: Ring Opening Metathesis Polymerisation of Norbornene

CβDβ (1 ml) was added to compound 5 (0.01 mmol) in an NMR tube. Norbornene (10 mmol) was added and the tube heated to 70 °C. After 1 hour, ¹H NMR signals consistent with the formation of the ring opened metathesis polymer were observed. After 12 hours the contents of the NMR tube had solidified, indicating high conversion to polymer. Example 37: Ring Opening Metathesis Polymerisation of Cycloocta-1 ,5-diene

C₆D₆ (1 ml) was added to compound 5 (0.05 mmol) in an NMR tube. Cycloocta-1 ,5-diene (5 mmol) was added and the tube heated to 70 °C. After 3 hour, ¹H NMR signals consistent with the formation of the ring opened metathesis polymer were observed. After 48 hours, the conversion to polymer was 50%.

Claims

1. A method for performing an olefin metathesis or a cross-coupling reaction, characterised in that the method is performed in the presence of a catalyst system comprising, a) a source of a d-block metal, b) optionally a promoter, an activator and/or a base, and c) a source of a 3-membered carbocyclic ligand.

2. A method as claimed in claim 1 , wherein the d-block metal is a Group VIII metal or Cu.

3. A method as claimed in claim 2, wherein the d-block metal is selected from Ru, Rh, Ni, Pd or Pt.

4. A method as claimed in any one of the preceding claims, wherein the 3-membered carbocyclic ligand comprises a group of formula

wherein

5. A method as claimed in claim 4, wherein the hydrocarbyl groups are selected from alkyl, aryl, alkenyl or alkynyl groups.

6. A method as claimed in claim 5, wherein the alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, t-butyl and adamantyl.

7. A method as claimed in claim 5, wherein the aryl group is selected from phenyl, ortho-to\y\, mefa-tolyl, para-tolyl, ethylphenyl, isopropylphenyl, t-butyl phenyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, 3,5- dimethylphenyl, 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, 2,4,6- triisopropylphenyl, naphthyl and benzyl.

8. A method as claimed in claim 4, wherein at least one heterohydrocarbyl group is attached directly to the 3-membered ring.

9. A method as claimed in claim 8, wherein the heterohydrocarbyl group is of formula -Z(R³)_m wherein Z is selected from Si, N, P, O or S, m is 1 to 4, and wherein the groups R³ may be the same or different and each is a hydrocarbyl group.

10. A method as claimed in claim 4, wherein at least one heterohydrocarbyl group is not attached directly to the 3-membered ring.

11. A method as claimed in claim 10, wherein at least one heterohydrocarbyl group is selected from CF₃, CF₂CF₃, CH₂OMe, CH₂NMe₂, CH₂CH₂NH₂, CH₂CH₂N(R¹)₂, CH₂CH₂P(R¹ )₂, CH₂CH₂CH₂P(R¹ )₂, fluorophenyl, perfluorophenyl, chlorophenyl, bromophenyl, C₆H₄(CF₃), C₆H₃(CFs)₂, C₆H₄(OMe), C₆H₃(OMe)₂, C₆H₄(N(R¹)₂), C₆H₄(P(R¹ )₂), where R¹ is as defined in claim 4.

12. A method as claimed in claim 4, wherein R¹ and/or R² are such that the 3-membered carbocyclic ligand is a multidentate ligand.

13. A method as claimed in claim 12, wherein R¹ and/or R² are of formula CH₂CH₂P(R)L wherein R is a hydrocarbyl group.

14. A method as claimed in any one of the preceding claims, wherein the catalyst system is formed in situ during the reaction.

15. A method as claimed in any one of claims 1 to 13, wherein the catalyst system is pre-formed.

16. A method as claimed in claim 15, wherein the catalyst system comprises a compound of formula

17. A method as claimed in claim 16, wherein the L groups are stabilising ligands selected from chloride, bromide, iodide, hydride, alkoxide, amide, acetate, acetylacetonate, amine, ether, water, phosphines, pyridine, alkene, alkyne and N-heterocyclic carbenes.

18. A method as claimed in claim 16, wherein the L groups are reactive ligands selected from alkyl, aryl, carbene, alkylidene.

19. A method as claimed in claim 16, wherein at least one L is a substrate molecule for the reaction.

20. A method as claimed in claim 16, wherein at least one L is a 3- membered carbocyclic ligand, giving a compound of formula

wherein the L¹ groups which may be the same or different, are ligands, p is 0 to 5, and R⁴ and R⁵ are as defined for R¹ and R² in claim 4.

21. A method as claimed in claim 16, wherein the catalyst system comprises a compound of formula

wherein the X groups, which may be the same or different, are halide or pseudohalide and L² is PR₃, wherein each R is independently selected from hydrocarbyl or H.

22. A method as claimed in claim 15, wherein the catalyst system comprises a compound of formula

wherein M is a d-block metal, the X groups, which may be the same or different, are halide or pseudohalide.

23. A method as claimed in claim 15, wherein the catalyst system comprises a compound of formula

wherein each R is a hydrocarbyl group or H or wherein two R groups together with the carbon to which they are both attached form a ring or multiple ring system, and the X¹ groups, which maybe the same or different, are halide or pseudohalide.

24. A method as claimed in any one of the preceding claims, wherein the olefin metathesis reaction is selected from cross-metathesis, ring closing metathesis, enzyme metathesis, ring opening metathesis, ring opening metathesis polymerisation, acyclic diene metathesis or alkyne metathesis.

25. A method as claimed in any one of claims 1 to 23, wherein the cross- coupling reaction is selected from reactions with organoboron compounds, reactions with organotin compounds, reactions with organozinc compounds, reactions with organomagnesium compounds, reactions with other organometallic compounds, reactions with allylic compounds, reactions with conjugated diene compounds, carbometallation reactions, reactions with alkyne compounds, reactions with olefinic compounds, reactions involving a cyclometallation step and reactions for the formation of carbon-heteroatom bonds.

26. A catalyst system for catalysing olefin metathesis or cross-coupling reactions, the catalyst system comprising, a) a source of a d-block metal, b) optionally a promoter, an activator and/or a base, and c) a source of a 3-membered carbocyclic ligand.

27. A catalyst system as claimed in claim 26, wherein the d-block metal is a Group VIII metal or Cu.

28. A catalyst system as claimed in claim 27, wherein the d-block metal is selected from Ru, Rh, Ni, Pd or Pt.

29. A catalyst system as claimed in any one of claims 26 to 28, wherein the 3-membered carbocyclic ligand comprises a group of formula

wherein

30. A catalyst system as claimed in claim 29, wherein the hydrocarbyl groups are selected from alkyl, aryl, alkenyl or alkynyl groups.

31. A catalyst system as claimed in claim 30, wherein the alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, t-butyl and adamantyl.

32. A catalyst system as claimed in claim 30, wherein the aryl group is selected from phenyl, ortho-to\y\, mefø-tolyl, para-tolyl, ethylphenyl, isopropylphenyl, t-butylphenyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, 3,5-dimethylphenyl, 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, 2,4,6- triisopropylphenyl, naphthyl and benzyl.

33. A catalyst system as claimed in claim 29, wherein at least one heterohydrocarbyl group is attached directly to the 3-membered ring.

34. A catalyst system as claimed in claim 33, wherein the heterohydrocarbyl group is of formula -Z(R³)_m wherein Z is selected from Si, N, P, O or S and M is 1 to 4, and wherein the groups R³ may be the same or different and each is a hydrocarbyl group.

35. A catalyst system as claimed in claim 29, wherein at least one heterohydrocarbyl group is not attached directly to the 3-membered ring.

36. A catalyst system as claimed in claim 35, wherein at least one heterohydrocarbyl group is selected from CF₃, CF₂CF₃, CH₂OMe, CH₂NMe₂, CH₂CH₂NH₂, CH₂CH₂N(R¹)₂, CH₂CH₂P(R¹ )₂, CH₂CH₂CH₂P(R¹)₂, fluorophenyl, perfluorophenyl, chlorophenyl, bromophenyl, C₆H₄(CF₃), C₆H₃(CFs)₂, C₆H₄(OMe), C₆H₃(OMe)₂, C₆H₄(N(R¹J₂), C₆H₄(P(R¹)₂), where R¹ is as defined in claim 4.

37. A catalyst system as claimed in claim 29, wherein R¹ and/or R² are such that the 3-membered carbocyclic ligand is a multidentate ligand.

38. A catalyst system as claimed in claim 37, wherein R¹ and/or R² are of ' formula CH₂CH₂P(R)₂ wherein R is a hydrocarbyl group.

39. A catalyst system as claimed in any one of claims 26 to 38, wherein the catalyst system comprises a compound of formula

40. A catalyst system as claimed in claim 39, wherein the L groups are stabilising ligands selected from chloride, bromide, iodide, hydride, alkoxide, amide, acetate, acetylacetonate, amine, ether, water, phosphine, pyridine, alkene, alkyne and N-heterocyclic carbenes.

41. A catalyst system as claimed in claim 39, wherein the L groups are reactive ligands selected from akyl, aryl, carbene and alkylidene.

42. A catalyst system as claimed in claim 39, wherein at least one L is a substrate molecule for the reaction.

43. A catalyst system as claimed in claim 39, wherein at least one L is a 3- membered carbocyclic ligand, giving a compound of formula

wherein the L¹ groups which may be the same or different, are ligands, p is 0 to 5, and R⁴ and R⁵ are as defined for R¹ and R^2- in claim 4.

44. A method for producing a catalyst system for catalysing olefin metathesis or cross-coupling reactions, the method comprising combining a) a source of a d-block metal, b) optionally, a further reagent, c) a source of a 3-membered carbocyclic ligand.

45. A method as claimed in claim 44, wherein the further reagent is selected from one or more of a base, an acid, a reducing agent, an oxidising agent or a ligand.

46. A method as claimed in claim 45, wherein the base is selected from one or more amines, amides, alkoxides, hydroxides, carbonates and BuLi.

47. A method as claimed in any one of claims 44 to 46, wherein the source of a d-block metal is selected from the appropriate elemental metal, the elemental metal dispersed on a suitable carrier material or a metal complex of formula ML_q where M and L are as defined in claim 16 and q is an integer of 1 to 6.

48. A method as claimed in any one of claims 44 to 47, wherein the source of a 3-membered carbocyclic ligand is selected from the free carbene ligand of formula

a carbene ligand stabilised by coordination to a Lewis acid fragment of formula

wherein Z is a Lewis acid fragment; or a substituted 3,3 cyclopropene compound of formula

wherein the X groups may be the same or different and are selected from halide, pseudohalide, weakly coordinating anion, H, a main group metal, a main group metal fragment or a d-block metal fragment ML_q as defined in claim 44.

49. Use of a catalyst system as claimed in any one of claims 26 to 43 to catalyse an olefin metathesis or a cross-coupling reaction.