JP2773362B2 - Quinoxaline-palladium complex and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a compound of the formula (I) (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. R ⁵ , R
^6, R ⁷ is an alkyl group, X represents a halogen atom. n is 1
These values are shown. ) And a method for producing the quinoxaline-palladium complex.

<Prior Art and Problems to be Solved by the Invention> A palladium complex in which three molecules of cyclohexyl isocyanide are inserted into a methyl-palladium bond has been known.

However, there is no known quinoxaline-palladium complex in which 1,2-diisocyanobenzenes are inserted to form a quinoxaline skeleton.

In addition, the present inventors have found that 1,2-diisocyanobenzenes are polymerized by an organozinc compound to produce a quinoxaline polymer, but the complex was unstable and could not be isolated.

<Means for Solving the Problems> The inventors of the present invention have conducted intensive studies on the reaction between 1,2-diisocyanobenzenes and transition metals, and as a result, have found that the reaction with a specific alkylpalladium complex has -It has been found that a quinoxaline-palladium complex in which two adjacent isocyano groups are continuously inserted into a palladium bond to form a heteroaromatic ring and a quinoxaline skeleton can be obtained.

Further, when an excess of diisocyanobenzenes is present, the polymerization reaction proceeds to give a polymer while forming a oxaline skeleton, and the isolated quinoxaline-palladium complex is not only stable in air but also stable. When a diisocyanobenzene is further acted on, the living polymerization reaction proceeds to form a polymer having a higher degree of polymerization while forming an xaline skeleton, and a hydride or an alkylating agent is acted on the palladium complex. And found that the group containing palladium at the terminal was easily converted to hydrogen or an alkyl group, etc., and completed the present invention.

That is, the present invention provides a compound of the formula (I) (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. R ⁵ , R
^6, R ⁷ is an alkyl group, X represents a halogen atom. n is 1
These values are shown. A quinoxaline-palladium complex represented by the formula (2): (Wherein R ¹ , R ² , R ³ , and R ⁴ represent the same meaning as described above), and a diisocyanobenzene represented by the formula (III): R ⁵ Pd (PPhR ⁶ R ⁷ ) ₂ X ( III) wherein R ⁵ , R ⁶ and R ⁷ are an alkyl group or an aralkyl group, and X is a halogen atom. Wherein the quinoxaline-palladium complex ( Production method of I), and (3) Formula (IV) (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ have the same meanings as described above. M represents a numerical value satisfying 1 ≦ m.) -A palladium complex and one mole of the diisocyanobenzenes (I
Formula (V) characterized by reacting I) (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ have the same meaning as described above. M is a number satisfying 1 ≦ m, l is a positive number and 1 <M +
1).

A method for producing a quinoxaline-palladium complex represented by
And (4) a quinoxaline represented by the above formula (I)
Palladium complex and metal hydride compound or MR ⁸ _pq
Y _q (M is a metal of Group IA to IIIA or IIB in the periodic table, p is a valence of M, q is a number satisfying 0 ≦ q <p, R ⁸ is an alkyl group, a haloalkyl group, a trialkylsilylmethyl A group, an aralkyl group, an aryl group, and Y represent a halogen atom or an alkoxy group.) (Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and n mean the same as above. R ⁹ means hydrogen or the same as R ⁸ above.) Is provided.

The quinoxaline-palladium complex of the present invention is a pharmaceutical,
It is useful as an intermediate of an electric / electronic material. For example, by reduction, a low molecular weight material can be derived into a raw material or a semiconductor material of a quinomycin-based drug, and a high molecular weight material can be derived into a conductive polymer material.

 Hereinafter, the present invention will be described in detail.

The diisocyanobenzenes used as a raw material in the present invention have the formula (II) (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. ), Preferably the above-mentioned alkyl group,
The alkoxy group, haloalkyl group, and alkoxycarbonyl group preferably have 1 to 6 carbon atoms, particularly 1 to 2 carbon atoms, and specifically include methyl, ethyl, propyl, trifluoromethyl, difluoromethyl, monofluoromethyl, and trifluorocarbon. The alkyl of the ethyl or trialkylsilylmethyl group is preferably a methyl or ethyl group. These diisocyanobenzenes can be produced by a known method such as the method described in JP-A-1-143850.

The palladium complex is represented by the general formula (III) R ⁵ Pd (PPhR ⁶ R ⁷ ) ₂ X (III) (wherein R ⁵ , R ⁶ , and R ⁷ represent an alkyl group or an aralkyl group, and X represents a halogen atom. A palladium complex represented by the formula: wherein R ⁵ is methyl,
An alkyl group having 1 to 5 carbon atoms such as an ethyl group, and R ⁶ and R ^{7 each} include a 1 carbon atom such as a methyl, ethyl, propyl and hexyl group.
~ 6 alkyl groups are preferred.

The reaction is as shown in the following formula: Ortho R ⁵ -Pd binding - 2 di isocyanoacetate benzene compound
The polymerization reaction proceeds while two adjacent isocyano groups are successively inserted to form a heteroaromatic ring and a quinoxaline skeleton. The growing end is a palladium complex attached to the quinoxaline skeleton and can be isolated.

Further, when the above quinoxaline-palladium complex is reacted with diisocyanobenzenes, as shown by the following formula, Polymerization further proceeds in the same manner as described above, and a quinoxaline-palladium complex having a larger number of quinoxaline chains (degree of polymerization) can be obtained.

These reaction behaviors indicate that the polymerization is living polymerization.

The reaction temperature is not particularly limited, but is usually
The temperature is preferably from room temperature to 150 ° C and the boiling point of the solvent or lower, more preferably from 30 to 120 ° C.

As the reaction solvent, a solvent which usually dissolves the 1,2-diisocyanobenzene compound, the above-mentioned palladium complex and the produced palladium complex and can be used without any particular limitation as long as it does not react with these can be used. And ethers such as tetrahydropyran and ethylene glycol dimethyl ether; aromatic hydrocarbons such as toluene and xylene; and halogenated hydrocarbons such as chloroform, chlorobenzene and methylene chloride.

Further, since the reaction between quinoxaline and the palladium complex is a living polymerization reaction, the average degree of polymerization of the quinoxaline in the obtained quinoxaline-palladium complex is almost proportional to the molar ratio of 1,2-diisocyanobenzene compound / palladium complex. Therefore, the molar ratio of quinoxaline to palladium complex can be appropriately determined according to the desired degree of polymerization. For example, when obtaining a quinoxaline-palladium complex having a quinoxaline chain number of 1 to 200 on average, the molar ratio is selected in the range of 1 to 200.

However, depending on the type of substituent, the higher the degree of polymerization becomes, the more insoluble in the solvent, the product is deposited, and the degree of polymerization may not be so large.In particular, R ¹ and R ⁴ may be trialkyl. Since a polymer having a silylmethyl group has high solubility in an organic solvent, a palladium complex having quinoxaline having a higher polymerization degree can be obtained.

The quinoxaline-palladium complex of the present invention is stable even in the air, and is easily isolated. In addition, even if it is isolated, it is dissolved in a solvent and has the ability to restart polymerization when a 1,2-diisocyanobenzene compound is present, in which case the degree of polymerization of quinoxaline is higher than that of quinoxaline. -A palladium complex is obtained.

Therefore, when a quinoxaline-palladium complex having a polymerization degree of l and a 1,2-diisocyanobenzene compound is reacted to obtain a quinoxaline-palladium complex having an average quinoxaline chain number of m + 1, the quinoxaline having a quinoxaline chain number of m is obtained. -One mole of 1,2-diisocyanobenzene compound may be used per mole of palladium complex.

Further, the quinoxaline-palladium complex of the present invention can be prepared by using a metal hydride compound or MR ⁸ _pq X _q (M is the periodic table I)
A to IIIA, IIB metals, p is valence of M, q is 0 ≦ q <
R ⁸ represents an alkyl group, a haloalkyl group, or a trialkylsilylmethyl group, and X represents a halogen atom or an alkoxy group. ) By reacting with an organometallic compound represented by
Pd (PPhR ⁶ R ⁷⁾ a ₂ X -R ⁹ can be converted into (hydrogen or the R ^8).

Here, specific examples of R ⁸ include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-
Butyl, pentyl, hexyl, pentadecyl, etc.
-20 alkyl groups, and their halogen-substituted compounds, and trialkylsilylmethyl groups.

Examples of the hydride compound include NaBH ₄ , LiAlH _{4, and the} like, and the above-mentioned organometals are Grignard reagents (R ⁸ Mg
Br (R ⁸ is as defined above)], AlR ⁸ _3, organic aluminum such as AlR ⁸ ₂ Cl, organoboronic such as BR ⁸ _3, organolithium such as LiR ^8, ZnR ⁸ ₂ organozinc such like Is exemplified.

For example by reduction with NaBH _4, the terminal -Pd (PPh
R ⁶ R ⁷ ) ₂ X to -H and Grignard reagent (R ⁸ MgCl: R
⁸ is an alkyl group, trimethylsilylmethyl group, an aralkyl group, a -R ⁸ by reduction with haloalkyl group),
For example, by reducing with (CH ₃ ) ₃ SiCH ₂ MgCl, −CH ₂ Si
(CH ₃ ) ₃ can be converted.

(Effect of the Invention) The quinoxaline-palladium complex of the present invention is a pharmaceutical,
It is useful as an intermediate of electric and electronic materials. For example, by reduction, low molecular weight compounds can be derived into raw materials and semiconductor materials of quinomycin-based drugs, and high molecular weight compounds can be converted into conductive polymers.

〔Example〕

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Example 1 The following formula (1a) 3,4,5,6-tetramethyl-1,2-diisocyanobenzene (2a) is heated to 60 ° C. in tetrahydrofuran (THF) in an equimolar amount with the methylpalladium complex (1 mmol) represented by The reaction was completed in a few hours.

The obtained quinoxaline-palladium complex was isolated and subjected to elemental analysis. As a result, C: 52.55%, H: 5.67%, N: 4.24
% (Calculated value of the following structure (3a): C: 52.62%, H: 5.63%,
N: 4.23%).

When H ¹ NMR (200 MHz, CDCl ₃ ) measurement was performed,
δ: 2.68, 2.57, 2.41, 2.37 and 2.29 (S, 3H × 5, Ph-C
H ₃ ), 7.10 to 7.45 (m, P-Ph, 10H), 1.52 (t, 6H, J _PH :
Peaks appeared at 3.6 Hz) and 1.48 (t, 6H, J _PH : 3.6 Hz).

From the above results, this quinoxaline-palladium complex (3a) Was confirmed.

Example 2 The THF solution containing 0.5 mmol of (3a) obtained in Example 1 was added to 0
℃ to cool, was added dropwise 0.4ml with _{(CH 3) 3 SiCH 2 MgCl} (1.4M, diethyl ether solution) syringe. After the dropwise addition, the reaction solution was heated to reflux THF, and reacted for 30 minutes. Excessive Grignard reagent was quenched by adding 12 ml of pH 7 buffer, and extracted with chloroform. The organic layer was dried over anhydrous sodium sulfate, and the precipitated Pd powder was removed with a short column of silica gel. The solvent was removed by an evaporator and distilled off to obtain a solid.

When this solid was subjected to H ¹ NMR (200 MHz, CDCl ₃ ) measurement, δ: 0.09 (S, 9H, Si (CH ₃ ) ₃ ), 2.52 (S, 2H, Ar-CH ₃ )
_{3), 2.41 (S, 6H} , Ar-CH 3), 2.67,2.71,2.73 (S, 3H, A
peak appeared in the r-CH _3).

From now on, this compound (4a) Was confirmed.

Thereby, this palladium complex (3a) can be easily converted to (CH
₃ ) It turns out that it reacts with ₃ SiCH ₂ MgCl and the terminal can be converted to CH ₂ Si (Me) ₃ .

Example 3 The same operation as in Example 1 was performed except that 3,4,5,6-tetramethyl-1,2-diisocyanobenzene (2a) was used twice in mole per methyl palladium complex (1 mmol). . After completion of the reaction, quinoxaline obtained by liquid chromatography
The palladium complexes were separated and two of them were analyzed.

Product 5-a-1: H ¹ NMR (200 MHz, CDCl ₃ ) δ: 1.4 to 1.6 (m, 12H, P-CH ₃ ) 1.71,2.11,2.45 ^* 2.26,2.39,2.41,2.49 ^* , 2.65,
2.72,2.81,3.18, (s, 3H × 9,6H × 2 ^* , Ar-CH ₃ ) 6.7-6.8,7,3-7.4 (m, 10H, P-Ph) Elemental analysis Measured value H: 6.06, C : 61.69, N: 8.07 calculated H: 5.97, C: 61.78, N: 8.16 · product ^{5-a-2: H 1} NMR (200MHz, CDCl 3) δ: 1.2~1.3 (m, 6H, P-CH _{3) 1.43~1.56 (m, 6H,} P-CH 3) 1.71,2.11,2.45 * 2.26,2.39,2.41,2.49 *, 2.65,
2.72,2.81,3.18, (s, 3H × 7,6H × 1 ^* , Ar-CH ₃ ) 6.7-6.8,7,3-7.4 (m, 10H, P-Ph) From the above results, two kinds of products Is (Product 5-a-1 was n = 3 and 5-a-2 was n = 2).

Example 4 24.5 mg (0.13 mmol) of 3,4,5,6-tetramethyl-1,2-diisocyanobenzene (2a) and a methylpalladium complex (1
a) 20.2 mg (0.042 mmol) was dissolved in ₄ ml of THF dried with LiAlH ₄ under a nitrogen atmosphere, and this solution was heated to reflux THF and reacted for 15 minutes. The reaction solution was cooled to 0 ° C., and 0.2 ml (0.28 mmol) of Grignard reagent [(CH ₃ ) ₃ SiCH ₂ MgCl] (1.4 M diethyl ether solution) was added dropwise with a syringe. Then, the reaction solution was heated to reflux THF, and reacted for 30 minutes.

Excessive Grignard reagent was quenched by adding 10 ml of a pH 7 buffer, extracted with 50 ml of chloroform, the organic layer was dried over anhydrous sodium sulfate, and the precipitated palladium powder was removed with a short column of silica gel. As a result of separating and purifying a solid obtained by distilling off the solvent with an evaporator using a preparative recycled GPC (solvent chloroform), 4
A seed product was obtained.

 The analysis results for each product are shown below.

H ¹ NMR (CDCl ₃ ) measurement results Product 6-a-1 δ: 0.07 (s, 9H, Si (Me ₂ ) ₃ ), 2.71 (s, 2H, CH ₂ Si) 2.44, 2.46, 2.48 ^* , 2.73,2.78,2.79,2.82 (s, 3H ×
7,6H × 1 ^* , Ar-CH ₃ ) Product 6-a-2 δ: 0.14 (s, 9H, Si (Me ₂ ) ₃ ), 3.06 (s, 2H, CH ₂ Si) 2.12,2.14, 2.20,2.21,2.32,2.33,2.52 ^* , 2.68,2.
72,2.81,2.85,3.02 (s, 3H × 1,6H × 1 ^* , Ar-CH ₃ ) Product 6-a-3 δ: 0.06 (s, 9H, Si (Me ₂ ) ₃ ), 2.68 ( s, 2H, CH ₂ Si) 1.98,2.03,2.18,2.21,2.25,2.27,2.34 ^* , 2.37 ^* ,
2.41 ^* , 2.71 ^* , 2.74 ^* , 2.75 (s, 3H × 7,6H × 5, Ar-CH ₃ ) Product 6-a-4 δ: 0.15 (s, 9H, Si (Me ₂ ) ₃ ), _{3.07 (s, 2H, CH 2} Si) 1.93 *, 2.09 *, 2.12 *, 2.16 *, 2.21,2.22,2.25,
2.26,2.34,2.36,2.41,2.43,2.74,2.76,2.80,2.83,3.05
(S, 3H × 7, 6H × 5, Ar—CH ₃ ) As a result, these compounds are represented by the following formula (6a) And the yield is n = 2 (6-a-
1) is 20%, n = 3 (6-a-2) is 49%, and n = 4 (6
-A-3) was 16%, n = 5 (6-a-4) was 2%, and the overall yield was 87%. From this result, the following equation (7a) The formation of the palladium complex of (n was 2, 3, 4, and 5) was confirmed.

Example 5 A reaction was carried out in the same manner as in Example 4 except that the reaction molar ratio of 3,4,5,6-diisocyanobenzene (2a) and methylpalladium complex (1a) was changed to the molar ratio shown in Table 1. Separated and purified.

 Table 1 shows the results.

Claims (4)

(57) [Claims] 1. A quinoxaline-palladium complex represented by the formula (I). (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. R ⁵ , R
^6, R ⁷ is an alkyl group, X represents a halogen atom. n is 1
These values are shown. ) 2. Formula (II) (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. And diisocyanobenzenes represented by the formula (III) R ⁵ Pd (PPhR ⁶ R ⁷ ) ₂ X (III) (wherein R ⁵ , R ⁶ and R ⁷ represent an alkyl group, and X represents a halogen atom) The method for producing a quinoxaline-palladium complex (I) according to claim 1, wherein the reaction is carried out with a palladium complex represented by the following formula: 3. The formula (IV) (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. R ⁵ , R
^6, R ⁷ is an alkyl group, X represents a halogen atom. m is 1
Represents a numerical value satisfying ≦ m. The formula (V), wherein the quinoxaline-palladium complex represented by the formula (I) is reacted with the diisocyanobenzenes (II) in an amount of 1 mol times in terms of palladium. (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ each have the same meaning as described above. M is a number satisfying 1 ≦ m, l is a positive number and 1
<M + 1> A method for producing a quinoxaline-palladium complex represented by the formula: 4. The following formula (I) (Wherein, R ¹ , R ² , R ³ , and R ⁴ represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxycarbonyl group, or a trialkylsilylmethyl group, provided that R ¹ , R ⁴ Are not both hydrogen atoms, and R ² ,
R ³ may combine to form a naphthalene ring. R ⁵ , R
^6, R ⁷ is an alkyl group, X represents a halogen atom. n is 1
These values are shown. A quinoxaline-palladium complex represented by the following formula and a metal hydride compound or MR ⁸ _pq Y _q (M is a metal in the periodic table IA to IIIA or IIB, p is a valence of M, and q satisfies 0 ≦ q <p) R ⁸ represents an alkyl group, a haloalkyl group, a trialkylsilylmethyl group, an aralkyl group, an aryl group, and Y represents a halogen or an alkoxy group.) (R ¹ , R ² , R ³ , R ⁴ , R ⁵ and n mean the same as above. R ⁹ means hydrogen or the same as R ⁸ above.) .