JPS62205080A - Production of n,n'-dimethyldihydropyrrolopyrrole - Google Patents

Abstract

PURPOSE:N,N'-Dialkoxycarbonyl of dihydropyrrolopyrrole is used as a feedstock to effect reduction whereby the titled compound which is used as a starting compound for electric or electronic materials is obtained advantageously with reduced by-products through a step-shortened process. CONSTITUTION:An N,N'-dialkoxycarbonyl of formula I (R1 is H, alkyl, trialkylsilyl; R2 is alkyl) is subjected to reduction reaction to give a compound of formula II. In the reaction, a metal hydride is used as a reducing agent and tetrahydrofuran, as a solvent. The reaction temperature usually ranges from 0 deg.C - the boiling point of the solvent. The metal hydride is, e.g., a mixture of lithium aluminum hydride and aluminum chloride or bis(2-methoxyethoxy) aluminum sodium hydride and the amount of the reducing agent is more than stoichimetic one calculated as hydrogen atoms effective in reduction.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention provides a general formula (Il (wherein R represents a hydrogen atom, an alkyl group, or a trialkylsilyl group) that is useful as a raw material for electrical and electronic materials. The present invention relates to a method for producing N, dimethyldihydropyrrolopyrroles represented by

<Prior Art> As a method for producing N,d-dimethyldihydropyrrolopyrroles, a method for producing a compound in which R is hydrogen in general formula (1) is known.

Method for thermally decomposing zatris-5-homobenzene (An
gew, Chem, , Int, Ed, Engl
, .

Dan, 847 (1975)).

(b) A cell method in which dihydropyrrolopyrrole is treated with methyl iodide (Tetrahdron Lett, 2003).

25, 5669 (1984)).

\, \, \1, \, 2 U <Problem to be solved by the invention> The method (a) above uses cyclohexane-1,4- as the raw material.
Since it is obtained from a diene through a seven-step polycyclic reaction, it has the major disadvantage that it requires a large number of steps to produce the raw material and the operations are extremely complicated.

On the other hand, the method (b) above is a method recently proposed by the present inventors, in which the raw material can be obtained from p-dichlorobenzene in as few steps as 4 steps, and the steps for obtaining the raw material are significantly shortened. has been done. However, since not only N-methylation but also C-methylation occurs in the methylation reaction, the yield of the target product was not fully satisfactory.

Means for Solving the Problems> The present inventors have further studied the method for producing N,N'-dimethyldihydrorobiroles, and found that N,N'- They discovered that the desired product could be obtained efficiently by using a dialkoxycarbonyl compound and reducing it, and after conducting further studies, they completed the present invention.

That is, the present invention provides reduction of an N,N'-dialkoxycarbonyl compound represented by the general formula (n) (wherein R represents a hydrogen atom, an alkyl group, or a trialkylsilyl group, and R2 represents an alkyl group). General formula+I) (wherein, R
1 represents the same meaning as above. ) denoted by N, N
The present invention provides a method for producing '-dimethyldihydropyrrolobyroles.

The method of the present invention has the advantage that by-products are significantly reduced and the target product can be obtained in good yield, and furthermore, the precursor equivalent of the raw material in the method (b) ° can be used as a raw material (in). This brings about various advantages, such as the ability to further shorten the manufacturing process for raw materials.

Next, the method of the present invention will be explained in detail.

In the compound represented by the general formula (II), which is a raw material of the present invention, R atoms include, for example, hydrogen atom, methyl, ethyl,
Examples thereof include alkyl groups such as propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, and octyl, and trialkylsilyl groups such as trimethylsilyl, triethylsilyl, tripropylsilyl, and tributylsilyl.

Examples of R8 include the same alkyl groups as exemplified for R, with methyl and ethyl being particularly preferred.

Such raw material compounds of the present invention can be prepared by known methods such as Tet.
rahedron Lett,, 25 5669 (1
984), Chem, Lett, 1984208
B and Chem, Lett, 198g
'148 etc. can be manufactured by reference.

The method of the present invention is characterized by directly reducing the alkoxycarbonyl group on the nitrogen atom on the N,N'-dialkoxycarbonyl compound side to a methyl group. A method using chemical compounds is adopted.

Metal hydrides include aluminum hydride and its derivatives, such as lithium aluminum hydride (LAH
) and aluminum chloride, sodium bis(2-methoxyethoxy)aluminum hydride, etc. are preferred.

The amount of metal hydride used is usually greater than the theoretically required amount in terms of hydrogen atoms effective for reduction. Also, when using LAH, aluminum chloride is usually 0% relative to LAH.
．． They are used together in 2 to 0.4 moles.

Ethers such as tetrahydrofuran and diethyl ether are usually used as solvents, but these can be mixed with benzene,
It can also be used diluted with a hydrocarbon such as toluene.

The reaction temperature and time vary depending on the substrate to be reduced, the reducing agent, the solvent, etc., and are usually selected from the range of θ°C to the boiling point of the solvent, but the reaction proceeds satisfactorily even at room temperature. The reaction time is usually
It takes about several hours to more than ten hours. The progress of the reaction can be monitored by an appropriate method, such as TLC.

The desired product can be efficiently separated from the reaction mixture by conventional operations such as extraction and distillation. Further, it can be further purified by operations such as recrystallization and hammer chromatography.

<Effects of the Invention> According to the method of the present invention, the amount of by-products is significantly reduced, the target product can be obtained in a good yield, and the production and process steps can be shortened.

Next, examples will be shown to explain the present invention in more detail.
The present invention is not limited to these in any way.

<Example> Example 1 (8,6-bis(trimethylsilyl)-1,4-dimethyldihydropyrrolo(8,2-b)pyrrole) Lithium aluminum hydride in anhydrous diethyl ether 250 under a nitrogen atmosphere 600 l19 (18.2 mmol) and 780 μm (5.4 mmol) of anhydrous aluminum chloride were added with stirring, and the mixture was stirred at room temperature for 15 minutes.

Then 8,6-bis(trimethylsilyl)-1°4-di(methoxycarbonyl)dihydropyrrolo(8,2-b)
Add 502 kg of pyrrole (7 mmol of IJ) and
Stirred for 8 hours. Next, 100% of water was added to the reaction mixture, and the ether layer was separated. The aqueous layer was extracted twice with 100% ether. The resulting ether solution was mixed, washed with water,
After drying, concentrate under reduced pressure to give a light brown color, mp, 178~
Crystal 85B''P was obtained at 175°C (dec).pm
The purity by r was 96% and the pure yield was calculated to be 89%.

When recrystallized from ethanol, mp is 174-175℃.
Colorless plate-like crystals of (dec) were obtained. This crystal was confirmed to be 8,6-bis(trimethylsilyl)-1,4-dimethyldihydropyrrolo(8,2-b)pyrrole.

Elemental analysis (as C engineering 4H26N2""@) CHN analysis value (%) 60.58 9,55 9.
89 calculated value C%) 60.36 9.40 1
0.05 mass analysis: 278 (M+, 100%)
pmr (CDCJ,) δppm: 0-8 (18
H*s)*8.77(6H,S), 6.49(2)I
, 5) UV (sic o hexa:, z): λmax
264 nm (a 17.050) Example 2 (8,6-di-t-butyl-1,4-dimethyldihydro(8,2-b)pyrrole) Hydrogen in 100% of anhydrous diethyl ether under a nitrogen atmosphere Lithium aluminum chloride 2
48 M? (6,40t mol) and 780'f anhydrous aluminum chloride (2,22t mol) were added,
Stirred at 20°C for 15 minutes. To the resulting solution was added 2,5-di-t-butyl-1,4-dimethoxycarbonyldihydropyrrolo(8,2-b)pyrrole 204 (0,611 mmol) at 20°C, and further at the same temperature Stir for hours.

Next, 100 g of water was slowly added to the reaction mixture, and the ether layer was separated. The aqueous layer was extracted twice with 100-pentane. The resulting ether solution and pentane solution were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. Then, it was concentrated under reduced pressure to obtain mp.

Colorless crystals 145119 at 202-808°C (yield 97
%)was gotten. The kernel one is 8.6-di-t-butyl-
It was identified as 1,4-dimethyldihydropyrrolo (1,2-b).

Elemental analysis (as C□6H2aN2) HN Analysis value example) '77.78 10.45 11
．． 82 calculated value C%) 78.00 10.68
11.87 mass analysis: 246 (M”, 59%)
pmr (CDCJ3) δppm: 1.8B (
18H, s).

8.78 (6H, s), 6.02 (2H, 5) Uv
(Cyclohexane) AmaX: 260 nm (
Example 8 (1,4-dimethyldihydropyrrolo[8°2-b]pyrrole) A toluene solution (7%) of sodium bis(methoxyethoxy)aluminum hydride in 200 w of anhydrous tetrahydrofuran (THF). ) 9.82 m (8,2
1, obtained according to Reference Example 1 by dissolving 8 mmol)
4-di(methoxycarbonyl)dihydropyrrolo[8゜2
-b] After adding 60 μm (0.27 mmol) of pyrrole at room temperature, heating under reflux was continued for 12 hours.

After adding 100% of water to the reaction mixture, the TiIF layer was separated. The aqueous layer was extracted twice with 50 mj of ether. The resulting THF solution and ether solution were combined, washed with saturated saline, dried, and then concentrated under reduced pressure to obtain an oil with a weight of 81.2"P. Results of LC analysis and PMR analysis. , this oil contains 27.5F (yield 76%) of 1,4-dimethyldihydropyrrolo(8,2
-b) It was found that pyrrole was included. Note that the compound obtained in Reference Example 2 was used as a standard sample.

Reference Example 1 (1,4-di(methoxycarbonyl)dihydropyrrolo(
8,2-b) Pyrrole) 250μI of hetrifluoroacetic acid in 100-benzene! (8.25 mmol), 8.6-
Bis(trimethylsilyl)-1,4-dimethoxycarbonyl-dihydropyrrolo(8,2-b)pyrrole 505η
(1.88 mmol) was added and heated under reflux for 6.5 hours under 3 nitrogen atmospheres. After the reaction mixture was allowed to cool, the benzene layer was separated. The aqueous layer was further extracted twice with 50 mj of benzene. The obtained benzene solution was washed with water, dried, and concentrated under reduced pressure to give pale yellow crystals (mp, 162.5-168.
5℃) 815"9 was obtained. This was subjected to silica gel column chromatography and eluted with ethyl acetate-hexane (1:2) to obtain 1,4-di(methoxycarbonyl)-dihydropyrrolo(8,2-b)pyrrole. Colorless plate crystals (rnp,
168-164°C) 810'9 was obtained.

The yield is quantitative.

Elemental analysis value (as C1oH1oN204) HN analysis i (%) 58,86 4.48 12
．． 41 calculated value C%) 54,05 4.58
12.60 mass analysis: 250 (M+, 100%
)prn r (CDCl!s)899m: 4.
00(6H,s).

6.44 (2H, d, J-11,0Hz).

7.17 (2H, d, J-LOHz) UV (cyclohexane) λmax *nm: 25
0(sh.

Ryu 8,160), 256 (t 17,100).

ε 277 (69,080), 282 (sh.

&g, 9ao), 294 (sh, (5,200) Reference Example 2 (1,4-dimethyldihydropyrrolo[8°2-b]pyrrole) Cesium fluoride 787''P into methanol 55-
(4,85 mmol) and 8,6 obtained in Example 1
-Bis(trimethylsilyl)-1,4-dimethyldihydropyrrolo[3°2-b]pyrrole 227 g (0,818
t mol) was added and the resulting suspension was stirred at room temperature under a nitrogen atmosphere for 1 hour. After methanol was distilled off from the reaction mixture at 0° C. under reduced pressure, 40° of water was added to the residue, and the mixture was extracted with pentane (60 d×8 times). After washing the pentane solution with water and drying, the pentane solution was concentrated under reduced pressure to give pale reddish-purple crystals 115■ (
mp, 108°5-105°C was obtained.

This was done by sublimation method (0-1na 14g s 40-45℃
) to obtain pale yellow crystals (109 ttq (yield 99%)). Furthermore, methanol-water (1:1
) After recrystallizing from M, M was produced by sublimation method, mp,
Colorless crystals of 1,4-dimethyl-dihydropyrrolo(8,2-b)pyrrole were obtained at 104.5-105.5°C.

Elemental analysis (as C8H1oN2) HN analysis value (96) 71,45 7.48 20
．． 69 Calculated value (%) 71,61 7.51
20.87 mass analysis: 184 (M”, 100
%) pm r (CDC1a) 899m: 8
．． 68(6H,5)C5,88(2H,d,J=2.7
Hz).

6.50 (2H, d, J-2, 7H2) UV (cyclohexane) λmax: 260 mmε (Cicada 17,800) Comparative example 1 (1,4-dimethyldihydropyrrolo[8°2-b]pyrrole) Anhydrous tetrahydrofuran 6 - 60% sodium hydrogen 4901F (12 mmol) solidified with paraffin
B111! and dihydropyrrolo (8,2-b
) add pyrrole 84'IP (0,82 momol),
The mixture was heated and stirred at 60 to 68° C. for 50 minutes under an argon stream. Methyl iodide 910119 (6,4
After dropwise addition of 50° C. remol), heating was further continued at the same temperature for 60 minutes.

After slowly adding methanol 5- to the reaction mixture that was left to cool, it was concentrated under reduced pressure to obtain a brown residue. This was purified by silica gel chromatography and diluted with ethyl acetate:hexane.
Component 38W9 eluting with was obtained. Analysis of this product using LC and PMR revealed that it was a mixture of the target product (1,4-dimethyl form, yield 40%) and a by-product (1,8,4-trimethyl form, yield 40%).

Claims (1)

[Claims] General formula (II) ▲Mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_1 represents a hydrogen atom, an alkyl group or a trialkylsilyl group, and R_2 represents an alkyl group.) General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (I) (In the formula, R_1 represents the same meaning as above. .) A method for producing N,N'-dimethyldihydropyrrolopyrroles.