DE2618373A1 - PROCESS FOR PREPARING ALKYL 3- (2-QUINOXALINYLMETHYLENE) CARBAZATE 1,4-DIOXIDES - Google Patents

Description

GLAWE ₁ DELFS, MOLL & PARTNER

PATENT LAWYERS

DR.-ING. RICHARD GLAWE, MÖNCHEN DIPL-ING. KLAUS DELFS, HAMBURG DIPL.-PHYS. DR. WALTER MOLL, MUNICH DIPL.-CHEM. DR. ULRICH MENGDEHL, HAMBURG

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2 HAMBURG 13 POST BOX 2570 ROTHENBAUM-CHAUSSEE 58 TEL. (040) 4 10 20 08 TELEX 21 29 21

HAMBURG

η 7978/76 M / sp

INDUSTRIA CHIMICA ^P ROPOTTI FRANCIS SpA, Via Origgio 23, Caronno ^p ertusella (Varese, Italy)

A process for the preparation · of Alkvl-3- (2-methylene chinoxalinvl) -c arbazat-1, ² I- (Ji oxides

The invention relates to a process · for the preparation · of alkyl-3- (2-chinoxalinvl-methvlen) -carbazat-l, ⁱ l-dioxides, particularly the Methvlesters of formula (I)

- CH

= N-NH-C-

OCH.

(D

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BANK: DRESDNER BANK, HAMBURG, 4 030 448 (BLZ 200 BOO00) POST CHECK: HAMBURG 147607-200 TELEGRAM: SPECHTZIES

Of the Schiff ¹ bases of 2-formyl-quinoxaline-l, ⁱ J-dioxide, from the point of view of their applicability, methyl 3- (2-quinoxaline-methylene) -carbazate-l, U-dioxide is the most important.
This compound, according to the U.S. Patent No. 3,371,090 by reacting the 2-Formylchinoxalin-l, ¹ <+ -dioxids methyl carbazate or according to German Offenlegungsschrift 1,927,337 from the acetal of 2-Pormylchinoxalin-1, Jj-dioxide with methyl carbazate can be obtained.

The preparation takes place according to the following reaction scheme

- CHO + NH ₂ -NH-COOCH ₃ = + (I)

The production takes place in organic solvents, e.g. of methanol in the presence of acids.

If the condensation reaction is carried out using the aldehyde, it must be obtained from the acetal be, because the synthesis of the aldehyde described in the literature takes place first, via the production of the acetal, the is then converted to the aldehyde.

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+ with -i

This hydrolysis reaction results in yield losses and a brown discoloration of the product, which has to be recrystallized for the subsequent reactions with a corresponding increase in production costs. Palis, the acetal is used for the condensation, this must be formed "in situ" by acid hydrolysis in the presence of methyl carbazate. The latter product is also hydrolyzed with corresponding losses. It has now been found that the preparation of (I) can be carried out in an advantageous manner, if not 2-Formylchinoxalin-l, ¹ l-dioxide, but the hydrazone (II)

- CH = N-NH,

(II)

or its symmetrical hydrazone (III)

-CH = N-N = CH -

(III)

is reacted with methyl carbazate.

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The process of the invention can also be carried out in a simple manner and with high yields in water as the solvent.

The intermediates (II) and (III) formed in the process of the invention are new compounds.

According to the method of the invention it is not even necessary that the hydrazone (II) or the symmetrical hydrazone (III) is isolated, because they can be in the reaction mixture in which they have been produced, react with methyl carbazate even in a heterogeneous stage. Considering the reactivity of the hydrazone (II) the reaction between this and methyl chloroformate takes place just as well, whereby the compound (I), i.e. methyl 3- (2-quinoxalinyl-methylene-carbazate) -l, 4-dioxide forms.

Similarly, further, particularly lower alkyl esters of 3- (2-Chinoxalinvl-methylene) carbazate-l, ¹ J-dioxide may be prepared.

example 1
Hydrazone of 2-Pormylchinoxalin-l, ^1-dioxide 4

1.5 g of 2-pormylquinoxaline-l, M-dioxide are suspended in 15 ml of ethanol, 0.56 g of hydrazine hydrate are added and the mixture is kept at 20 ° C. for 2 hours. The hydrazone (II) is obtained in a yield of 93% (1 > 5 g), which is washed with a little alcohol and isolated.

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It melts at 195 ° C with decomposition.

Analysis: C 52 H 3.89 N 26.99 * (found)

52.9 ¹ Y 3.9t 27.13 (calc.)

Example 2
Met hy 1-3- (2-quinoxalinyl-methylerf-carbazate -1, M-dioxide (I)

1 g of hydrazone (II) is dissolved in 5 ml of water with 0.5 g of methyl carbazate suspended and kept for 1 hour at 25 ° C, after adding 1 ml of hydrochloric acid (36?) 1.15 g of (I) with a yield from 9QiS.

Example 3
Methy1-3- (2-quinoxalinvl-methvlene) carbazate-1,4-dioxide (I)

1 g of 2-Pormyl "(quinoxalinyl-methylene) -carbazat 1,4-dioxide is suspended in 10 ml of ethanol and treated with 0.375 g of hydrazine hydrate at 20 ⁰ C for 2 hours. 0.5 g of methyl carbazate is replaced and then treated with 10.6 ml of hydrochloric acid (10 *) for 2 hours at 25 ° C

1.18 g of (I) are obtained with a yield of 92 ?.

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example ¹ y

Disubstituted symmetrical hydrazone of 2-formylquinoxaline-1,11-dioxide (III)

1 g of 2-Formylchinoxalin-l, ¹ t-dioxide with 10 ml of hydrochloric acid (10?) And 0.145 g of hydrazine hydrate at 30 ° C for 30 minutes to give 0.96 g of (III) with a yield of 96? receives.

The product has a melting point of 25 ¹ J ⁰ C with decomposition.

Analysis: C. 56 , 9 * example 5 H 3 , 15 N 22 35? (found) 57 3 , 21 22 33 (ber.)

Disubstituted symmetrical hydrazone of 2-formylquinoxaline, 4-dioxide (III)

1 g of 2-Formylchinoxalin-l, ⁱ are treated with 10 ml of hydrochloric acid (10?) .For 50 ⁰ C J-dioxide-dimethylacetal. After cooling to 30 ⁰ C are employed 0.118 g of hydrazine hydrate added and holds for 30 minutes at this temperature to obtain 0.77 g (III).

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Example 6 Methyl 3- (2-quinoxalinylmethylene) carbazate 1,4-dioxide (I)

1 g of (III) is treated under reflux with 10 ml of acetic acid and 0.5 g of methyl carbazate. After the Abki 1.26 g (I) with a yield of 90 ?.

Treated methyl carbazate. After cooling to ⁰ ° C., one obtains

Example 7

Methyl 3- (2-quinoxalinylmethylene) carbazate-l, ⁱ t-dioxide (I)

1 g of 2-formylquinoxaline 1,4-dioxide is mixed with 5 ml of 10% hydrochloric acid and 0.145 g of hydrazine hydrate treated at 30 ° C. for 30 minutes.

0.8 g of methyl carbazate and 15 ml of acetic acid are added and

refluxed for 30 minutes, 1.21 g of (I) receives.

Example 8 Methyl-3- (2-quinoxaline-methylene) -carbazate-l, U-dioxide (I)

1 g (II) are suspended in 5 ml of dimethylformamide, 6 ml of pyridine and treated with O, M65 g of methyl chloroformate at ⁰ ° C. To

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1.02 g of (I) are obtained with a yield of 80% at room temperature for 12 hours.

Example 9
Methyl 3- (2-quinoxalinylmethylene) carbazate 1,4-dioxide

1 g of (II) are suspended in 5 ml of dimethylformamide in the presence of 0.5 g of sodium bicarbonate; the latter is used instead of pyridine used. Otherwise, proceed as in Example 8, a yield of 75% is obtained.

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Claims (6)

Claims 1. Process for the preparation of Alkvl-3- (2-quinoxalinylmethylene) -carbazat-l ^ -dioxiden, in particular of the formula (I) T CH = N-NH-C-OCH. (D characterized in that the hydrazone (II) or the symmetrical hydrazone (III) 1-CH = N-NH 2
(II) -CH = N-N = CH- (III) of 2-formylquinoxaline-1,4-dioxide reacts with methyl carbazate. 709838/05? ^ ... OK 2. Process for the preparation of the hydrazone of 2-formylquinoxaline-1,4-dioxide, characterized in that 2-formylquinoxaline-1,4-dioxide is added to ethanol with hydrazine hydrate converts and that the product thus obtained is then washed with alcohol. 3. Process for the preparation of the disubstituted symmetrical hydrazone of 2-formylquinoxaline-1,4-dioxide (III), thereby characterized in that 2-formylquinoxaline 1,4-dioxide with hydrazine hydrate in the presence of hydrochloric acid. H. Hydrazone of P-formylquinoxaline-lj ^ -dioxids or symmetrical hydrazone of the same according to the formulas (II, or III). 5. The method according to claim 1, characterized gekennzei chnet that one is a mixture of the hydrazone (II) and the hydrazone (III) reacts with methyl carbazate. 6. Process for the preparation of the compounds according to Claim 1, characterized in that the hydrazone is used of formula (II) with alkyl chloroformates, in particular methyl chloroformate, reacts. 709838/0528