JPH0370718B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a cobalt complex by applying a new production method. The complex obtained here is a new substance having the structure of dimethoxycarbonylcyclopentadienyl cobalt polyene. Furthermore, the present invention relates to an improved production method for producing pyridine derivatives from alkynes and nitriles using the complex obtained here as a catalyst. A method for producing a substituted pyridine from a cyclopentadienyl cobalt cyclic diene complex and an alkyne and a nitrile using the complex as a catalyst is already known. For example, it is known that using a cycloalkadienyl cobalt cycloalkadiene complex and the same as a catalyst, two molecules of alkyne and one molecule of nitrile are bonded and cyclized at their triple bonds to obtain a substituted pyridine (Japanese Patent Application Laid-Open No. 50−135084,
JP 52-25780, U.S. Patent No. 4267329). However, it has been extremely difficult to synthesize a di-substituted cyclopentadienyl cobalt polyene complex compound in which two electron-withdrawing groups are bonded to cyclopentadiene. The present invention provides a complex in which two methoxycarbonyl groups are bonded to a cyclopentadienyl ring, a method for producing the same, and use as a catalyst. That is, the present invention solves this difficulty by a new production method and discloses a method for obtaining η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex in good yield. The obtained η ⁵ −
All of the dimethoxycarbonylcyclopentadienyl cobalt polyene complexes are new substances that have not been described in any literature, and were synthesized for the first time by the method of the present invention. The η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex according to the present invention can be produced by the following route. [In the formula (), _M is an alkali metal,
It is a substituted polyene having ~4 substituents (the substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group). However, R ₁ excludes polyenes consisting only of aromatic rings. ] The starting material here, dimethoxycarbonylcyclopentadienyl alkali metal complex, can be obtained by the reaction of monomethoxycarbonylcyclopentadienyl alkali metal complex with dimethyl chloride, but it can also be obtained by the method by D. Peters ( J.Chem.
Soc., 1959 , 1757, (1959]). The present inventors have improved this method and found a process that allows for higher yield and easier production. This process is However, higher yields can be obtained by using a monomethoxycarbonylcyclopentadienyl alkali metal complex as starting material. In addition, Peters' method uses an extremely complicated method to separate the product, but he discovered a method in which the alkali metal complex is precipitated and dried from the reaction product solution and used as it is in the next step, the reaction with cobalt. By applying these methods, it has become possible to easily obtain the compounds of the present invention. Among the tristophenylphosphine cobalt monohalogenides, for example, tristophenylphosphine cobalt monochloride can be easily obtained by reacting cobalt chloride and triphenylphosphine in the presence of a reducing agent [Inorg .Chim.Acta, 3 , 227 (1969)]. The reaction of formula () is carried out by adding about the equivalent molar amount or a slight excess of dimethoxycarbonylcyclopentadienyl sodium in a solvent at a temperature of 0°C to 80°C.
This can be carried out by reacting for 0.1 to 24 hours. The reaction product obtained here can be isolated and purified, but it can also be used as it is for the next reaction. For the reaction of formula (), add a polyene corresponding to the target substance to the reaction solution of formula (), and
This can be carried out by reacting at ℃ for 0.5 to 24 hours. The polyenes used here can be selected from a wide range of sources, such as butadiene, isoprene, substituted or unsubstituted cyclopentadiene, dicyclopentadiene, hexadiene, norbornadiene, indene, cyclooctadiene, cyclooctatetraene, azulene, cyclododecatriene or , alkyl or phenyl substituted products thereof, and cyanomethylene substituted products. However, it does not react with polyenes that only have aromatic rings, such as benzene, toluene, and xylene. All reactions are preferably carried out in an inert atmosphere free of moisture, oxygen, carbon gas, etc. After the reaction product liquid is concentrated, it can be separated and purified by applying column chromatography. The obtained η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex is relatively stable in air. A feature of the present invention is that an excellent method for producing a dimethoxycarbonylcyclopentadienyl alkali metal complex is developed as a starting material, and this is reacted with tristriphenylphosphincobalt monohalogenide. The point is that the reaction product liquid is immediately reacted with the corresponding polyene. ()
Examples of the reaction of the formula using cyclopentadienyl sodium as a starting material are known, but the present invention is the first example using dimethoxycarbonylcyclopentadienyl sodium as a starting material, and furthermore, this reaction product The reaction between polyene and polyene is also completely unknown. The product obtained by formula () is a complex in which a dimethoxycarbonylcyclopentadienyl group is bonded to a cobalt atom in the form of η ⁵ , and furthermore, the polyene defined by R ₁ has a cobalt atom arrangement in the diene moiety. It has a position-bonded structure. That is, this complex has the formula () [In the formula (), R ₁ is an unsubstituted polyene having 2 to 4 double bonds and a carbon number of 4 to 12 or a substituted polyene having 1 to 4 substituents, and the cobalt atom is a cobalt atom in the polyene. (The substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group) which has a coordinate bond at the diene moiety. However, R ₁ excludes polyenes consisting only of aromatic rings. ]. All of these substances are new substances, and their structures were determined using elemental analysis, infrared absorption, NMR, etc. The η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex shown in the present invention has been found to have extremely high activity when used as a catalyst in the reaction of alkynes and nitriles to produce substituted or unsubstituted pyridines. Ta. Cycloalkadienyl cobalt complexes generally have catalytic activity in the synthesis of pyridine derivatives using a co-cyclization reaction product of alkynes and nitriles, but substituted cyclopentadienyl cobalt complexes in which cyclopendadiene is substituted with an electron-absorbing group It is even more active. In particular, the η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex disclosed in the present invention exhibits extremely excellent catalytic performance. The amount of catalyst used is calculated in terms of cobalt atoms in the reaction system.
It is effective at a concentration of 0.1 mmol/or higher.
And it is usually not necessary to increase the amount to 100 m mol/or more. As for the reaction raw materials, even if the above catalyst is used, it can be applied to a wide range of alkynes and nitriles as in the prior art. Alkynes include terminal alkynes such as acetylene, alkyl-, alkenyl- and allyl-acetylenes, disubstituted acetylenes such as dialkyl-, diallyl-, alkylalkenyl-acetylenes and alkylaryl-acetylenes; these alkynes may be of different types. It may also be a mixture of alkynes. Further, ether or alcohol derivatives of these alkynes may be used. On the other hand, as the nitriles, mononitriles such as hydrogen cyanide, alkyl-, allyl-, and alkenyl-nitriles, and polyfunctional nitriles in which a plurality of nitrile groups are present can be suitably used. The molar ratio of alkyne to nitrile can be appropriately selected within the range of 0.01 to 100. However, in order to reduce by-products, it is better to have an excess of nitrile than alkyne. The method of the present invention involves adding a catalyst and optionally a solvent to an excess of nitrile in the presence or absence of a solvent, and proceeding with the reaction by adding an alkyne at a temperature of 15 to 200°C. I can do it. As the solvent, saturated hydrocarbons, aromatic hydrocarbons, alcohols, amines, ethers, esters, alkylcarboxamides, etc. can be widely used, although their use is not essential. Furthermore, the complex compound obtained in the present invention can of course be used immediately for the synthesis of pyridine and its derivatives without being separated and purified. This process is an advantageous choice for industrial use as a catalyst. The method of the present invention is characterized by strong catalytic activity and high reaction rate. Another major feature is that aromatic hydrocarbons produced as by-products along with the production of pyridine and its derivatives can be significantly reduced. As a result, industrially satisfactory productivity and product concentration can be easily obtained. In particular, when a lower alkyne such as acetylene is used as a raw material, the reaction can proceed at a sufficiently practical rate at a much lower pressure than in known systems. This fact is extremely important from a practical standpoint, considering that lower alkynes have an extremely high risk of decomposition and explosion due to pressurization. It can be said that, for the first time, the present invention has made it possible to industrially easily produce, for example, industrially important products such as vinylpyridine, α-picoline, pyridine, etc. from acetylene and nitrile. Aspects of the present invention will be described below with reference to Examples, but the scope of the present invention is not limited by these aspects. Example 1 Preparation of ^η4-1,5 -cyclooctadiene- ^η5 -dimethoxycarbonylcyclopentadienyl cobalt. A solution of cyclopentadienyl sodium in tetrahydrofuran (10 mmol/
ml solution (10ml) to dimethyl carbonate (8ml)
is added, sealed in a nitrogen atmosphere, and heated at 100°C for 20 hours. The resulting reaction solution was mixed with tristriphenylphosphine cobalt monochloride (3.08 g,
3.5 mmol) of benzene (20 ml) is added to the suspension. The mixture immediately becomes a red liquid, which is stirred occasionally to complete the reaction, then 1,5-cyclooctadiene (1 ml) is added, and the mixture is stirred overnight at room temperature. Pass the insoluble material through a short alumina column and collect the red-orange liquid that elutes with benzene. The solvent is concentrated under reduced pressure and heated, the precipitated triphenylphosphine is removed by decantation, and the mixture is subjected to alumina chromatography. The solvent is distilled off under reduced pressure from the two yellow liquid bands flowing out with benzene/hexane (1:1), and the residue is heated and dissolved in hexane and left in a refrigerator to obtain reddish brown crystals. [First crystal] Yield 61 mg (yield 5%), melting point 115
~116℃, elemental analysis value C: 58.71%, H: 6.09%,
Calculated value as C ₁₇ H ₂₁ O ₄ Co C: 58.63%, H:
6.08%. IR (Nujol) 1725, 1710 cm ^-1 (C=O).
NMR (CDCl ₃ ); δ1.7, 2,4, 3.6 (C ₈ H ₁₂ ); 3.96
(OCH ₃ ); 4.54 (t, 1H), 4.92 (d, 2H)
_{( C5H3} ). [Second crystal] Yield 108 mg (yield 9%), melting point 99
~100°C, elemental analysis values C: 58.63%, H: 6.08%.
IR (Nujol) 1730, 1710 cm ^-1 (C=O). NMR
(CDCl ₃ ); δ1.7, 2,4, 3.6 (C ₈ H ₁₂ ); 3.85
(OCH ₃ ); 4.94 (d, 2H), 5.16 (t, 1H)
_{( C5H3} ). Both are isomers of the title compound, the former having η ⁴ −
1,5-cyclooctadiene-η ⁵ -1,3-dimethoxycarbonylcyclopentadienyl cobalt (complex), the latter is η ⁴ -1,5-cyclooctadiene-η ⁵ -1,2-dimethoxycarbonylcyclopenta It was identified as dienyl cobalt (complex). Example 2 Preparation of ^η4 -norbornadiene- ^η5 -dimethoxycarbonylcyclopentadienyl cobalt. A bistriphenylphosphine-η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt solution was prepared from dimethoxycarbonylcyclopentadienyl sodium and tristriphenylphosphine cobalt monochloride in the same manner as in Example 1, and norbornadiene (2 ml) was added. After that, leave it at room temperature for 1 day. Two types of isomers were obtained by treatment in the same manner as in Example 1. [1,2-isomer (complex)] Reddish brown crystals,
Yield 12%, melting point 142-145°C. NMR ( _CDCl3 );
0.8, 3.0, 3.2 (C ₇ H ₈ ); 3.87 (OCH ₃ ); 5.16 (d,
2H), 5.28(t, 1H) (C ₅ H ₃ ). [1,3-isomer (complex)] Orange oil, yield 12%. NMR ( _CDCl3 ); δ, 0.8, 3.0, 3.2
(C ₇ H ₈ ); 3.83 (OCH ₃ ); 5.00 (t, 1H), 5.10 (d,
2H) ( _{C5H3 )} . Example 3 A solution of methyl chloroformate in tetrahydrofuran (2 g/30 ml) was added to a solution of sodium methoxycarbonylcyclopentadienyl in tetrahydrofuran (28 m mol/28 ml) prepared by Rausch's method.
Add under ice cooling. After the mixture reaches room temperature, it is concentrated under reduced pressure and then methylene chloride is added to precipitate a pale pink precipitate. This was separated and dried to obtain 1.23 g of dimethoxycarbonylcyclopentadienyl sodium. When 0.6 g of this solid is dissolved in water and mixed with a benzene suspension of tristriphenylphosphine cobalt monohalogenide [1.76 g (2 mmol/)], the benzene phase becomes reddish brown. To this mixture was added 1,5-cyclooctadiene (2 ml) and stirred for a further 2 hours, the organic phase was separated, dried over sodium sulfate and filtered through a short column of alumina. Separation and purification was performed by the method of Example 1, and η ⁴
-1,5-cyclooctadiene- ^{η 5} -1,3-dimethoxycarbonylcyclopentadienyl cobalt and η ⁴ -1,5-cyclooctadiene-η ⁵ -1,
2-dimethoxycarbonylcyclopentadienyl cobalt was obtained at a production ratio of 1:3.5 (total yield 360 mg, yield 52%). Example 4 A synthetic reaction of dimethoxycarbonylcyclopentadienyl sodium was carried out using cyclopentadienyl sodium and chloroformic acid ester according to the method of D. Peters. From this reaction solution, the precipitate was separately dried according to the method of Example 3, and 0.4 g of dimethoxycarbonylcyclopentadienyl sodium powder was obtained.
I got it. Furthermore, by the method of Example 3, η ⁴ −1,5
-Cyclooctadiene-η ⁵ -Crystals of a mixture of dimethoxycarbonylcyclopentadienyl cobalt
0.19g was obtained (yield 55%). Example 5 Two types of η ⁴ produced by the method of Example 1 in a 100 ml stainless steel autoclave under an argon atmosphere
-1,5-cyclooctadiene-η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt (complex and) 45 mg (0.13 mmol) was added to 30 ml of toluene.
Dissolve and prepare, and add 10g of acrylonitrile.
I prepared it. After the autoclave was replaced with acetylene and heated from normal pressure to 150° C., acetylene was constantly supplied at a rate of 13 kg/cm ² G. 60
2-vinylpyridine was synthesized by reacting for a minute, and the reaction solution was analyzed by gas chromatography. The reaction results are shown in Table 1. Example 6 Two types of η ⁴ produced by the method of Example 2 as catalysts
The reaction was carried out in the same manner as in Example ⁵ , except that 77 mg (0.23 mmol) of a 1:1 mixture of -norbornadiene-η 5 -dimethoxycarbonylcyclopentadienyl cobalt (complex and), 17.8 g of acrylonitrile and 54 ml of toluene were used. The reaction pressure is 13
It was Kg/cm ² G. The reaction results are shown in Table 1. Comparative Examples 1-3 The same operations as in Example 5 were repeated using known catalysts. As catalysts, biscyclopentadienyl cobalt (complex), η ⁴ -1,5-cyclooctadiene- ^{η 5} -cyclopentadiene cobalt (complex) and η ⁴ -1-exo-cyanomethylcyclopentadiene-η ⁵ -cyclo Pentadienyl cobalt (complex) was added in an amount of 0.26 mmol, which is equivalent to the complex. 5.0 g of acrylonitrile and 80 ml of toluene were charged as a solvent. Acetylene was supplied and the reaction was carried out at a reaction pressure of 13 kg/cm ² G. The results of these reactions are shown in Table 1.

【table】

[Table] Example 7 η ⁴ -1,5-cyclooctadiene- as a catalyst
8.7 mg η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt (1:1 mixture with complex)
(0.025 mmol), 4 g of methylacetylene, 12 g of acetonitrile and 50 ml of benzene were charged into an ampoule and reacted at a temperature of 95°C for 29 hours. As a result of analyzing the product by gas chromatography, 2, 3, 6
-Trimethylpyridine 9.3m mol, 2,4,6
-9.9m mol of trimethylpyridine was produced, total
The catalytic efficiency was 770 mol/Co g atom. For comparison, η ⁴ −1,5-cyclooctadiene−η ⁵ −
When cyclopentadienyl cobalt (complex) is used, the total catalyst efficiency is 250 mol/Co g atom, η ⁴ -dimethyldibutylcyclopentadienone-η ⁵ -cyclopentadienyl cobalt (complex,
When using cyclopentadienyl cobalt carbonyl and heptine-2)
It was 160 mol/Co g atom. Example 8 Acetylene and hydrogen cyanide were reacted using the method of Example 5. The amount charged was 2.5 ml of hydrogen cyanide and 43 ml of toluene, and the reaction was carried out for 60 minutes at a reaction pressure of 16 kg/cm ² G. Gas chromatographic analysis of the products yielded the complexes, 0.6 g and 0.9 g of pyridine, respectively, with catalytic efficiencies of 29 and 45 mol/Co.
It was a g atom. Also, as a catalyst, η ⁴ -indene-η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt (complex, produced using indene instead of cyclooctadiene in Example 3, unpurified solution)
The catalyst efficiency for pyridine production is
It was 12 mol/Cog atom (compared to raw material cobalt). On the other hand, when the reaction was carried out using a known catalyst, the complex, the production of pyridine was trace.

Claims (1)

[Claims] 1 Formula () [In the formula (), R ₁ is an unsubstituted polyene having 2 to 4 double bonds and a carbon number of 4 to 12 or a substituted polyene having 1 to 4 substituents, and the cobalt atom is a cobalt atom in the polyene. (The substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group) which has a coordinate bond at the diene moiety. However, R ₁ excludes polyenes consisting only of aromatic rings. ] η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex. 2 A dimethoxycarbonylcyclopentadienyl alkali metal complex is reacted with tristriphenylphosphine cobalt monohalogenide, and further an unsubstituted polyene having 4 to 12 carbon atoms or 1 to 4 carbon atoms having 2 to 4 double bonds is prepared. Substituted polyene having 1 to 4 substituents [(substituents are alkyl groups having 1 to 4 carbon atoms, phenyl groups, or cyanomethylene groups).
However, polyenes consisting only of aromatic rings are excluded. ] Formula () characterized by reacting with one or more members of the group [In the formula (), R ₁ is an unsubstituted polyene having 2 to 4 double bonds and a carbon number of 4 to 12 or a substituted polyene having 1 to 4 substituents, and the cobalt atom is a cobalt atom in the polyene. (The substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group) which has a coordinate bond at the diene moiety. However, R ₁ excludes polyenes consisting only of aromatic rings. ] A method for producing a η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex. 3 Cyclopentadienyl alkali metal complex or methoxycarbonylcyclopentadienyl alkali metal complex and chloroformate are reacted, and then tristriphenylphosphincobalt monohalogenide is reacted, and two types of bonds 2 to 3 are reacted. unsubstituted polyene having 4 to 12 carbon atoms, or substituted polyene having 1 to 4 substituents [(the substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group). However, polyenes consisting only of aromatic rings are excluded. ] Formula () characterized by reacting with one or more members of the group [In the formula (), R ₁ is an unsubstituted polyene having 2 to 4 double bonds and a carbon number of 4 to 12 or a substituted polyene having 1 to 4 substituents, and the cobalt atom is a cobalt atom in the polyene. (The substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group) which has a coordinate bond at the diene moiety. However, R ₁ excludes polyenes consisting only of aromatic rings. ] A method for producing a η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex. 4 In the reaction of producing unsubstituted or substituted pyridine from alkynes and nitriles through a cyclization reaction, the formula () [In the formula (), R ₁ is an unsubstituted polyene having 2 to 4 double bonds and a carbon number of 4 to 12 or a substituted polyene having 1 to 4 substituents, and the cobalt atom is a cobalt atom in the polyene. (The substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group) which has a coordinate bond at the diene moiety. However, R ₁ excludes polyenes consisting only of aromatic rings. ] ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex is present as a catalyst. 5 formula () [In the formula (), R ₁ is an unsubstituted polyene having 2 to 4 double bonds and a carbon number of 4 to 12 or a substituted polyene having 1 to 4 substituents, and the cobalt atom is a cobalt atom in the polyene. (The substituent is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyanomethylene group) which has a coordinate bond at the diene moiety. However, R ₁ excludes polyenes consisting only of aromatic rings. ] A reaction catalyst for producing unsubstituted or substituted pyridine by a cyclization reaction from an alkyne consisting of a η ⁵ -dimethoxycarbonylcyclopentadienyl cobalt polyene complex and a nitrile.