MXPA00001400A - Method for producing ruthenium complexes - Google Patents

Abstract

The invention relates to ruthenium complexes of the general formulas (I) RuX2(=CH-CH2R)L1L2 or (IV) RuXY(=CH-CH2R)L1L2, where X, Y are anionic ligands, R is hydrogen or a possibly substituted C1-C20 alkyl rest or C6-C20 aryl rest, and L1 and L2 independently of each other are neutral electron donor ligands. Said ruthenium complexes are produced by (a) reacting RuX3 with L1 and L2 in an inert solvent in the presence of a reducing agent and hydrogen, and (b) by reacting the resulting product with compounds of the general formula (II) R-C=CH, where R has the meaning given above, possibly in the presence of water and possibly after isolation of the intermediate stage with HY, (HL1)Y or (HL2)Y.

Description

PREPARATION OF RUTHENIUM The present invention relates to processes for the preparation of ruthenium complexes that can be used, for example, as catalysts in metathesis reactions. In its simplest form, the olefins metathesis (disproponation) is a reversible catalyzed metal transalkylidenation of olefins by breaking and reforming carbon-carbon double bonds. In the metathesis of acyclic olefins a distinction is made, for example, between auto-metathesis, in which an olefin is converted into a mixture of two olefins of different molar masses (for example, the conversion of propene into ethene and 2-butene) , and cross-metathesis or co-metathesis, which describes the reaction of two different olefins (for example, propene with 1-butene to obtain ethene and 2-pentene). Other areas of application of olefin metathesis are the synthesis of unsaturated polymers by ring-opening metathesis polymerization (ROMP) of cyclic olefins and polymerization by acyclic dienes (ADMET) of α, β-dienes. The most recent applications are the selective ring opening of the cyclic olefins using acyclic olefins, and also the ring closure reactions (RCM) by means of which the unsaturated rings of different ring sizes can be produced preferably from a,? - diens. Suitable catalysts for metathesis reactions are, in principle, homogeneous and heterogeneous transition metal compounds, in particular ruthenium compounds. Heterogeneous catalysts, for example molybdenum oxide, tungsten oxide or rhenium oxide on inorganic oxidic supp, have a high activity and regeneration capacity in non-functionalized olefin reactions but usually have to be pretreated with an alkylating agent to increase the activity when functionalized olefins are used as methyl oleate. Olefins having protic functional groups (such as hydroxyl, carboxyl or amino groups) give rise to spontaneous deactivation of the heterogeneous catalyst. In recent years, increasing eff have been made to prepare homogeneous catalysts that are stable in a protic medium and in the presence of atmospheric oxygen. Catalysts that have been found of particular interest are specific ruthene-alkylidene compounds. These complexes and preparation process thereof are known. WO 93/20111 discloses ruthenone- and osmium-carbene complexes for polymerization by olefin metathesis. The complexes have the structure R11X2 (= CH-CH = CR2) 2. The ligands L used are triphenylphosphine and substituted triphenylphosphine. The preparation is carried out, for example, by the reaction of RuCl2 (PPh.3) 3 with disubstituted cyclopropene suitable as carbene precursors. However, the synthesis of cyclopropene derivatives consists of a number of stages and is of little interest from an economic point of view. Similar reactions are described in WO 96/04289. In addition, the processes for polymerization by olefin metathesis are indicated. The use of these catalysts by cross-linking with ROMP polymer peroxide is described in WO 97/03096. WO 97/06185 in the same manner describes catalysts for metathesis based on ruthenium-carbene complexes. In addition, the process described above, these can also be prepared by the reaction of RuCl2 (PPh3) 3 with diazoalkanes. However, the handling of diazoalkanes presents a safety risk, particularly when the process is carried out on an industrial scale. In addition, the initial organometallic materials of the form RuCl2 (PPh3) 3 have to be prepared from RUCI3.3H2O using a large excess of triphenyl phosphine. Subsequently, the PPh.3 ligands are lost again by exchange of ligands in the catalyst synthesis itself. The carbene precursors used require synthesis in multiple stages and do not have an unlimited storage life. In Organometallics 1996, 1960-1962 describes a process for the preparation of ruthenium complexes in which the [RuCl2 (cyclooctadiene)] x polymeric in i-propanol is reacted with nitrogen in the presence of phosphine. This eliminates the need for phosphine exchange. An undefined mixture of products is obtained. In addition, prolonged reaction times are required when starting from a polymeric starting material. The cyclooctadiene present in the initial organometallic material does not contribute to the reaction and is lost. In J. Chem. Soc. Commun. 1997, 1733-1734 describes the synthesis of a methylene complex RuCl2 (= CH2) (PCy3) 2 starting from dichloromethane and the ruthenium polyhydride RuH2 (H2) (PCY3) 2 however, it is difficult to obtain the complex ruthenium-polyhydride. In addition, long reaction times are required. The synthetic routes known for the preparation of catalysts for metathesis of the type RUX2 (= CH-CH2R) (PR'3) 2 are inexpensive for the reasons mentioned. An object of the present invention is to provide the processes for the preparation of ruthenium alkylidene complexes of the type RuX2 (= CH-CH2R) LXL2 or RuXY (= CH-CH2R) L 1L2, whose process gives rise, in a fast and economical reaction in atoms starting from the initial available materials, to the desired products without exchange of ligands. The processes must also be non-expensive and give high yields under moderate reaction conditions. We have found that this goal is achieved by a process to prepare ruthenium complexes of formula I: RuXY (= CH-CH2R) LXL2 (I) where X is an anionic ligand, R is hydrogen or a substituted or unsubstituted C1-C20 alkyl radical or C6-C20 aryl radical and L1 and L2 are, independent of each other, electron donating ligands without charge, by (a ) the RUX3 reaction with L 1 and L 2 in an inert solvent in the presence of a reducing agent and hydrogen and, without isolation of the intermediates, (b) the subsequent reaction with the compounds of the formula II R-C = CH (II) where R is as defined above, in the presence or absence of water This objective is also achieved by a process for the preparation of ruthenium complexes of formula IV RuXY (= CH-CH2R) L1L2 (IV) where X, Y are identical or different anionic ligands, R is hydrogen or a substituted or unsubstituted C1-C20 alkyl radical or C2-C2o aryl radical, and L \ Lz are, independently of one another, electron donating globules, without charge by 1 2 (a) the reaction RUX3 with L and L in an inert solvent in the presence of a reducing agent and hydrogen with compounds of the formula II R-C = CH (II) where R is as already defined, in the presence or absence of water, to form a compound of the formula V.

RuXH (= C-CHR) L1L2 (V) where X, R, L1, L2 are as defined above, (b) the separation of the compound of formula V from the reaction mixture and the subsequent reaction with HY, (HL 1) Y or (HL 2) Y in an inert solvent with compounds of the formula II.

R-C = CH d i: where R is as defined, in the presence or absence of water, and (c) the subsequent reaction with HY, [HL] Y or [HL] Y. It has been found that the aforementioned ruthenium complexes can be obtained in very good yields directly from RUX3, preferably RuCl3 '3 (H2O), by simple reaction with ligands L1 and L2, hydrogen and terminal alkynes of the formula II in presence of reducing agents without isolation of the intermediaries. The ruthenium complexes do not have vinyl substituents on the carbene carbon atom. The initial materials can be prepared in a non-expensive and readily available form. To prepare the mixed anion compounds of formula IV, the intermediate of formula 5 is isolated and subsequently subjected to another reaction. This allows different X and Y ligands to be introduced. I Firstly, the reaction of RUX3 with ligands L 2 and L is carried out in an inert solvent in the presence of a reducing agent and hydrogen. The solvents that can be used are aromatic ethers, cyclic or acyclic heteroaromatics. Preferred solvents are toluene, NMP, tetrahydrofuran, dialkyl ethers, glycol ethers and dioxane. Particular preference is given to tetrahydrofuran. The reducing agent used can be any reducing agent that reduces Ru (III) or Ru (II) under the reaction conditions. Preferably, the reduction is carried out using hydrogen in the presence of a metallic or non-metallic reducing agent, preferably in the presence of an alkali metal, alkaline earth metal or transition metal, for example palladium or zinc, which is present in metallic form and / or can be applied to a support. The ferrous alkali metals, preferably magnesium, are preferably used in an activated form. This activation can be carried out, for example, by having it in contact with an organic solvent containing chlorine. For example, in a single vessel reaction under an atmosphere of an inert gas, the magnesium can be placed in an organic solvent containing diluted chlorine, for example, dichloroethane and, after an introduction period from one second to 10 hours , preferably from one minute to one hour, is reacted with the solvent, RUX3 and the ligands L 1 and L 2 under an atmosphere of hydrogen. The temperature in this reaction step (a) is preferably from 0 to 100 ° C, preferably particularly preferably from 20 to 80 ° C, in particular from 40 to 60 ° C. The present preference is from 0.1 to 1 bar, particularly preferably from 0.5 to 5 bar, in particular from 0.8 to 1.5 bar. The reaction is carried out for a time of preference from 10 minutes to 100 hours, particularly preferably from 1 hour to 10 hours. The molar ratio of both ligands L 1 and L 2 as a sum to the ruthenium salt used is preferably 2-20: 1, particularly preferably 2-5: 1. After the reaction in step (a), the reaction mixture is reacted with 1-alkyl, preferably from -80 to 100 ° C, particularly preferably from -40 to 50 ° C, in particular from -30 to -30 ° C. 20 ° C. In this reaction, the molar ratio of the ruthenium salt originally used to 1-alkyne is preferably from 1: 1 to 1:10. Preferably, the reaction is carried out at a pressure from 0.1 to 10 bar, particularly preferably from 08 to 1.5 bar, in particular from 1 to 1.4 bar, for a time preferably from 30 seconds to 10 hours, particularly preferably from 1 hour. minute to 1 hour.

To prepare the compounds of the formula I, the isolation of the intermediate V is not necessary, but it is possible. The other reaction in step (b) is preferably carried out in the presence of water. To prepare mixed anion complexes of the formula IV, the intermediate is isolated before the reaction in step (c), ie the reaction with HY, [HL 1] Y or [HL 2] Y, preferably HY. Typically, the reaction is then completed from 1 to 100 hours, preferably from 3 to 10 hours, and gives catalysts for metathesis in yields up to 95%, based on the ruthenium salt used. Suitable reactors are glass or steel vessels in general, which may have to be resistant to pressure. The reaction mixture obtained is preferably worked by removing the volatile constituents under reduced pressure and extracting the solid residue with an organic solvent such as pentane. In the ruthenium complexes of formulas I and IV, X is a monodentate anionic ligand, for example, halogen, pseudo halogen, carboxylate, diketonate. X is particularly preferably halogen, in particular bromine or chlorine, especially chlorine. Particular preference is given to the use of RuCl3'3H20 in the reaction.

In the ruthenium complexes of formula IV, Y may be the same ligand as X. Preferably it is a halogen different from X or a carboxyl group that is attached to a polymer or a support, thus making it possible to fix the catalyst to a support . In the case of the intermediates of the formula V, the ligand X can also be substituted by means of metathesis of the salt with MY, where M is an alkali metal or ammonium, preferably potassium. This also makes it possible to obtain mixtures of the product. L 1 and L 2 are neutral electron donating ligands. Examples of these ligands are amines, phosphines, arsines and stibams, preferably phosphines. L 1 and L 2 are preferably selected from the phosphines of the formula III. where R 1 and R 2 are independently phenyl radicals or 3 organic radicals with spherical hindrance. And R is hydrogen, a substituted or unsubstituted C 1 -C 20 alkyl radical or C 6 -C 20 aryl radical or is as defined for R. for the purposes of the present invention, a "spherically hindered radical" is a radical having a bulky structure. Examples of these radicals are i-propyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl or menthyl. Preference is given to the use of a hexyl cyclo radical as a spherically hindered radical. Particularly preferably, the three radicals R 1, R 2 and R 3 are spherically hindered radicals or phenyl radicals, in particular cyclohexyl radicals. The radicals R 1, R 2 and R 3 can each carry suitable substituents. Examples of these substituents are C 1 -C 3 alkyl radicals, preferably C 1 -C 3 alkyl radicals, C 1 -C 3 fluoroalkyl radicals, halogen atoms, nitro groups, amino groups, ester functions and acid functions, -OH, alkoxy groups, C? -C6 or sulfonate groups. Preferably the radicals are unsubstituted. The radical R is hydrogen or a C 1 -C 20 alkyl radical, preferably C 1 -C 6 substituted or unsubstituted, or C 6 -C 20 aryl radical, preferably C 1 -C 6. With respect to the substituents, what was said in the above is applied.

Particularly preferred ruthenium complexes of the formula I are RuCl2 (= CH-CH3) (PCy3) 2 and RuCl2 (= CH-CH2Ph) (PCy3) 2 where Cy is a cyclohexyl radical and Ph is a phenyl radical.

The ruthenium complexes prepared according to the present invention can be used as catalysts for metathesis. The invention is illustrated by means of the following examples.

Example 1 Synthesis of ethylidene complex RUCI2 (= CH-CH3) (PCY3) 2 from RuCl3 * 3H20 and acetylene 50 mmol of activated magnesium were placed in 20 ml of THF abs. After the addition of 8 mmol of RuCl3'3H20, 31 mmol of tricyclohexylphosphine and 80 ml of THF, the reaction mixture was stirred at 60 ° C under a bar of hydrogen for 6.5 hours. After cooling the reaction mixture to -30 ° C, acetylene was introduced for about 10 seconds and the mixture was stirred for another 5 minutes. The reaction mixture was then mixed with 0.5 ml of water, warmed to room temperature, the solvent was removed under reduced pressure, the solid residue was transferred to an extraction funnel and extracted with 20 ml of pentane in a Soxhlett extractor. The yield of the analytically pure red-violet solid, isolated, was 5.3 g (88% of theory).

Example 2 Synthesis of the RuCl2 complex (= CH-CH2-Ph) (PCy3) 2 from RuCl3'3H2? and phenylacetylene After the addition of 1.9 mmol of RuCl'3H2 ?, 8 mmol of tricyclohexylphosphine and 0.5 ml of CICH2CH2CI to 50 mmol of activated magnesium in 25 ml of abs THF, the reaction mixture was stirred at 60 ° C under 1 bar of hydrogen for 6.5 hours. After the reduction, the reaction mixture was cooled to -40 ° C and 1.9 mmol of phenyl acetylene were added dropwise with vigorous gas evolution. After stirring for 20 minutes at -40 ° C, the cooling was removed and, at about 0 ° C, 7 mmol of water was added. After heating to room temperature, stirring was continued for another 10 minutes, then the solvent was removed under reduced pressure and the residue was extracted with 60 ml of toluene. The extract was evaporated to dryness, the remaining crimson solid was washed four times in succession with 10 ml each of pentane and then twice with 40 ml of methanol each time and dried under reduced pressure. The yield of the analytically pure, isolated crimson solid was 1.2 g (76% of theory).

Claims (2)

1. A process for the preparation of ruthenium complexes of the formula I RuXY (= CH-CH2R) LXL2 (I) wherein X is an anionic ligand, R is hydrogen or a substituted or unsubstituted C1-C20 alkyl radical or aryl radical of C6-C20 / YL1 and L2 are, independent of each other, electron-donating ligands without charge, per 1 2 (a) the RU 3 reaction with L and L in an inert solvent in the presence of a reducing agent and hydrogen and, without isolation of the intermediates, (b) the subsequent reaction with the compounds of the formula II R-C = CH (II) where R is as defined above, in the presence or absence of water.

2. The process for preparing ruthenium complexes of formula IV. RuXY (= CH-CH2R) L1! 2 (IV) where X, Y are the same or different anionic ligands, R is hydrogen or a substituted or unsubstituted C1-C20 alkyl radical or aryl radical of Cd-C2o > And L 1, L 2 are, independent of each other, electron donating ligands, uncharged, by (a) the reaction RUX 3 with L 1 and L 2 in an inert solvent in the presence of a reducing agent and hydrogen with compounds of the formula II R-C = CH (II) where R is as already defined, in the presence or absence of water, to form a compound of the formula V. RuXH (= C-CHR) LXL2 (V) where X, R, L 1, L 2 are as already defined, (b) the separation of the compound of formula V from the reaction mixture and the subsequent reaction with HY, (HL 1) Y or (HL 2) Y in an inert solvent with compounds of formula II. R-C == € H (II) where R is as already defined, in the presence or absence ua, and (c) the subsequent reaction with HY, [HL] Y or [HL2] Y. The process as recited in claim 1 or 2, wherein L 1 and L 2 are selected from among phosphines of formula III. wherein R 1 and R 2 are independently phenyl or spherically hindered, organic radicals and R 3 is hydrogen, a substituted or unsubstituted C 1 -C 3 alkyl radical or C 6 -C 20 aryl radical or is as defined for R. The process as recited in claim 3, wherein R 1 and R 2 are selected from i-propyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl or menthyl. The process as recited in any of claims 1 to 4, wherein X is halogen and Y is the same halogen or different or is a carboxyl group that is attached to a polymer or a support. The process as mentioned in any of claims 1 to 5, wherein the reduction with hydrogen is carried out in the presence of a metallic or non-metallic reducing agent. The process as recited in claim 6, wherein the reducing agent used is magnesium which is activated by contact with an organic solvent containing chlorine. 8. The process as mentioned in any of claims 1 to 7, wherein the reaction in step (a) it is carried out at a pressure in the range from 0.1 to 100 bar and in step (b) it is carried out at a pressure in the range of 0.1 to 10 bar. The process as mentioned in any of claims 1 to 8, wherein the reaction in step (a) is carried out from 0 to 100 ° C and in step (b) it is carried out from -80 to 100 ° C. The process as mentioned in any of claims 1 to 9, wherein the solvent is selected from aromatic, heteroaromatic, cyclic or acyclic ethers. The process as recited in any of claims 1 to 10, wherein the ruthenium complexes of formula I or IV are, after removing the volatile constituents of the reaction mixture, isolated in analytically pure form by extraction with an organic solvent.