DD288601A5 - PROCESS FOR THE PREPARATION OF 2,3-DIARYLAMINOCHIOXALINES - Google Patents

Abstract

The invention relates to a process for the preparation of 2,3-Diarylaminochinoxalinen, which can be used as Antileprotica and as intermediates for dyes. The 2,3-diarylaminoquinoxalines can be described by the following general formula wherein R 1 and R 2 are the same or different and are hydrogen, alkyl, alkoxy, halogen, carbalkoxy or nitro. Formula {quinoxalines; Oxalsaeureimidchloride; o-phenylenediamines; Cycloacylierung; Dye intermediates; Antileprotica}

Description

wherein R ¹ and R ^{2 are the} same or different and represent a hydrogen atom, an acrylic radical, an alkoxy radical, a halogen atom, a carbalkoxy radical or a nitro group.

Characteristics of the known prior art

2,3-Diarylamlnochinoxaline were previously produced only by nucleophilic substitution of 2,3-dichloroquinoxalines using substituted anilines. Due to the irr, aromatic Heterocycius strongly lowered Eiectrophiiie positions 2 and it was necessary to always work at temperatures above 160 ° C; see. S. D. Carter u. G.W.H. Cheeseman, Tetrahedron 34 (1978). As a result of these reactions, which are relatively drastic with respect to the high temperatures, it has always been difficult to eliminate deep-colored impurities in the course of side reactions. In the case of reaction with anilines containing one or more acceptor groups, the yields of final product are greatly reduced or no reaction takes place.

Object of the invention

The ziol of the invention is to make the 2,3-diarylaminoquinoxalines available as biologically active substances such as antileprotica and as intermediates for dyes based on domestic raw materials.

Explanation of the essence of the invention

The object of the invention is to represent 2,3-Diarylaminochlnoxaline with a defined substituent pattern and in high purity, which can be used as Antileprotica and as intermediates for dyes use. According to the invention the object is achieved in that industrially readily available o-phenylenediamines reacted with Oxalsäurabis [arylimidchloriden] in the course of a cycloacylation to the 2,3-Diarylaminochinoxalinen v / earth. The addition of a tertiary amine as HCI scavenger proves to be advantageous.

The radicals R 'and R ² may be identical or different and denote a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a carbalkoxy group or a nitro group. The reactions are carried out in solvents such as acetone or acetonitrile, hydrocarbons such as benzene or toluene and Halogenkohlenwasserstnffen such as carbon tetrachloride or chloroform, preferably at temperatures between 60 ° C and 9O ⁰ C. To simplify the workup, the 2,3-diarylaminoquinoxalines are precipitated from the reaction solutions in the form of their hydrochlorides. Particular advantages of the method are:

1. In contrast to examples described in the literature, the reactions proceed consistently under relatively mild conditions, in cheap solvents and give good yields of final product. By precipitating the 2,3-Diarylaminochinoxaline in the form of their hydrochlorides complicated Fieltigungsoperationen unnecessary.

2. The resulting 2,3-Diarylaminochlnoxaline are characterized by a wide range of applications. Thus, they can be used as biologically active substances such as antileprotica and as starting materials for Farbstoffsynthessn.

Ausführungsbelspiele example 1

C, 1 mol (10.8 g) of o-phenylenediamine are refluxed together with 0.1 mol (27.7 g) of oxalic acid bis [phenyl imide chloride] and 0.2 mol (23 ml) of triethylamine in 250 ml of acetonitrile for one hour. After cooling, the solvent is removed in vacuo, the residue of dark brown color in about 80ml of methanol and taken with about 15ml cone. Hydrochloric acid added. Within a short time precipitates an intense yellow precipitate, which is sucked sharp after cooling and washed with a little ice-cold methanol. The 2,3-diphenylaminochinoxaline hydrochloride, which is sufficiently pure for further reactions, can be further purified by recrystallization from methanol / acetone; yellow-green crystals, F 196-198 ° C, yield 84% d. Th.

Example 2 Analogously to Example 1, from 0.1 mol (12.2 g) of 4-methyl-o-phenylenediamine and 0.1 mol (27.7 g) of oxalic acid bis-phenyl-imidyl chloride]

87% d. Th. 2,3-Diphenylamino-6-methyl-quinoxaline hydrochloride in the form of yellow crystals, F198-204 ⁰ C.

Example 3

Analogously to Example 1, from 0.1 mol (13.8 g) of 4-methoxy-o-phenylenediamine and 0.1 mol (27.7 g) Oxalsäurebistphenylimidchlorid] 78% d. Th. 2,3-Diphonylamino-6-methoxy-quinoxaline hydrochloride in the form of yellow-green crystals, F 132-134 ⁰ C.

Example 4

0.02mcl (2.16g) of o-phenylenediamine and 0.02mol (5.54g) of oxalic acid bis [phonylimidchloride] are stirred together with 0.04mol (5.6ml) of triethylamine in 100ml of dry toluene at 80 ° C for one hour. After cooling, the triethylamine hydrochloride is filtered off with suction, concentrated in vacuo to about 50 ml and for a short time passed dry HCl gas through the solution. After a short time, the desired 2,3-diphenylaminoquinoxaline hydrochloride precipitates in the form of lemon yellow crystals. Yield 92% d. Th., F 196-198 ⁰ C.

Example 5

From Example 4 is obtained from 0.02 mol (2.16 g) of o-phenylenediamine and 0.02 mol (6.10 g) of oxalic acid bis [4-methviphenylimidchlorid] 88% d. Th. 2 ₍ 3-bis (4-methylphenylamino) quinoxaline hydrochloride in the form of yellow crystals, F * 230-238 ° C (MeCN / DMF).

Example 6 Analogously to Example 4, from 0.02 mol (2.44 g) of 4-methyl-o-phenylenediamine and 6.10 g (0.02 mol) of oxalic acid bis [2-

methylphenylimide chloride] 87% d. Th. 2,3-bis [2-methylphenylamino] -6-methylquinoxaline hydrochloride as yellow crystals, F

Example 7

0.01 mol (1.08 g) of o-phenylenediamine and 0.01 mol (4.21 g) of oxalic acid bis [4-carboethoxyphenylimide chloride are refluxed with 0.02 mol (2.8 ml) of triethylamine in 60 ml of acetonitrile for 30 minutes heated. After cooling, add approx. 5 ml of cone. Hydrochloric acid and placed overnight in the refrigerator. The resulting yellow crystal mass is then filtered off with suction, washed with a little ice-cold methanol and ethanol / acetonitrile! recrystallized. Is obtained 2,3-bis- [4-carboethoxyphenylamino] quinoxaline as a bright yellow crystals, F 208-219 ⁰ C (from 135 ⁰ C sintering), yield 77%. Th.

Example 8 Analogously to Example 7, from 0.01 mol of o-phenylenediamine and 0.01 mol (3.46 g) of oxalic acid bis [4-chlorophenylimidchlorid] 90% d. Th. 2,3-bis [4-chlorophenylamino] quinoxaline hydrochloride in the form of sulfur yellow crystals, F 232-235 ⁰ C. Example 9

0.04 moles (6.12 g) of 4-nitro-o-phenylenediamine are refluxed in 160 ml of acetone for 4 hours along with O, 4 moles (11.08 g) of oxalic acid bis [phenylimidchloride] and 0.08 moles (11.2 ml) of triethylamine. After cooling, the solvent is removed in vacuo, the brown residue in about 50 ml of methanol and stored overnight in the refrigerator. The mixture is then filtered off with suction, washed with methanol and recrystallized from acetonitrile. The desired 2,3-diphenylamino-6-nitro-quinoxaline is obtained as free base in the form of bright orange crystals, F 239-241 ⁰ C, yield 76% of theory. Th.

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Claims (4)

claims: 1. A process for the preparation of 2,3-Diarylarninochinoxalinen the general formula: where R ¹ and R ^{2 are} identical or different and denote a hydrogen atom, an alkyl radical, an alkoxy radical, a halogen atom, a carbalkoxy radical or a nitro group, characterized in that industrially readily accessible o-phenylenediamines with oxalic acid bis [arylimidchloriden] in the course of a cycloacylation to the 2,3-Diarylaminochinoxalinen be implemented. 2. The method according to claim 1, characterized in that it is carried out in the presence of a tertiary amine as HCI scavenger. 3. The method according to claim 1, characterized in that the reaction in solvents such as acetone or acetonitrile, in hydrocarbons such as benzene and toluene and in halogenated hydrocarbons such as carbon tetrachloride or chloroform are preferably carried out at temperatures between 60 ⁰ C and 9O ⁰ C. 4. The method according to claim 1, characterized in that to simplify the work-up after the reaction, the resulting 2,3-Diarylaminochinoxaline be precipitated as hydrochlorides and thus are easily separable and easy to clean. For this 1 page formulas Field of application of the invention The invention relates to a process for the preparation of 2,3-Diarylaminochinoxalinen which can be used as Antileprotica and as intermediates for dyes. The 2,3-diarylaminoquinoxalines can be described by the following general formula: