DD143778A1 - PROCESS FOR PREPARING PYRAZOLO SQUARE BRACKET ON 5.1-B SQUARE BRACKET TO THIAZOLENE - Google Patents

Abstract

The aim of the invention is to provide a process for the production of 5-Aroyl-6-imino-5,6-dihydro-pyrazolo [5,1-b] thiazole-7-carboxylic acid esters and derivatives thereof develop. The pyrazolo [5,1-bithiazoles of the general formula III in which R is an alkyl radical, R 1 is a hydrogen, a halogen atom, an alkyl group or an alkoxy group, R2 represents a hydrogen atom, an acyl group or a carbalkoxy group and R3 represents a hydrogen atom, an alkyl group or a Aryl radical can, by reaction of the pyrazole derivatives of the general formula I in which R and R1 as defined above, with carbonyl compounds of the general formula II in which R2 and R3 are the above X is a halogen atom and Y is an oxygen atom or two alkoxy groups, getting produced. The pyrazolo [5,1-b] thiazoles of general formula III can be used as organic Intermediates can be used for further syntheses. They are in particular for illustration novel heterocyclic compounds suitable. - Formulas I to III

Description

Process for the preparation of pyrazolep, 1-bithiazoles Field of application of the invention

The invention relates to a process for the preparation of 5-aroyl-6-imino-5,6-dihydro-pyrazoloQ, 1-bthiazole-7-carboxylic acid esters and derivatives thereof These pyrazolo [5,1-b] thiazoles can be described as organic intermediates are used for further syntheses · They are particularly suitable for the preparation of novel heterocyclic compounds.

Characteristics of the known technical solutions

5-Aroyl-6-imino-5,6-dihydro-pyrazo-1-yl-yl, 1-b] t hiazo 1-7-carboxylic acid esters and their derivatives are not yet known «

Object of the invention

The aim of the invention is a process for the preparation of these 5-aroyl-6-imino-5,6-dihydro-pyrazolo _. 1 ~ bJthiazol-7-carboxylic acid esters and their derivatives to develop.

Provision of the knowledge of the invention

The pyrasolo [p, .1-b] thiazoles of the general formula III in which R is an alkyl radical, R ^{1 is} a hydrogen atom, a halogen atom, an alkyl radical or an alkoxy group,

R represents a hydrogen atom, an acyl group or a carbalkoxy group and Ir represents a hydrogen atom, an alkyl group or an aryl radical, can be prepared by reacting the pyrazole derivatives of the general formula I ₉ in which R and R are as defined above, with carbonyl

p compounds of general formula II, in which R and R have the above meanings, X represents a halogenator "and Y represents an oxygen atom or two alkoxy groups,

The reactions are carried out in an organic solvent, preferably in alcohols. The reaction temperatures are 20 ° to 150 ⁰ C, the reaction times are 10 minutes to 5 hours · It is necessary to carry out the reaction either in the presence of mineral acids or of bases · When using bases subsequent treatment (5 to 50 minutes) of Reaction product with carboxylic acid anhydrides in the boiling heat required to complete the dehydration

The reaction products precipitate after cooling the reaction mixtures to 20 ⁰ C from crystalline * They are further purified by recrystallization from organic solvents.

Embodiments Example 1

5-Benzoyl-6-imino-5,6-dihydro-pyrazolo [5,1-b] t hiazo1-7-carboic acid e-et hyle st er

0.01 mole of 1-benzoyl-5-imino-3-mercapto-A-pyrazole-4-carboxylic acid ethyl ester and 0.015 mole of bromoacetaldehyde diethyl acetal are dissolved in a mixture of 40 ml of ethanol, 20 ml of water and 0.5 ml of concentrated sulfuric acid 1 Heated under reflux for one hour. The mixture is allowed to cool to 20 ^° C. and the precipitate is filtered off, washed with water and then with ethanol. The crude product

is recrystallized from ethanol.

Yield: 79 $ d.Th · Melting point: 169-172 ⁰ C

Embodiment 2

5-Benzoyl-6-irino-3-ethyl-5,6-dihydro-pyrazolo [5,1-thiazole-2,7-dicarboxylic acid diethyl ester Dissolve 0.01 mol of sodium and 0.01 mol of 1- Benzoyl-5-iraino-3-mercapto-A-pyrazolin-4-carboxylic acid ethyl ester in 30 ml of absolute ethanol, added under Uraschütteln with 0.01 mol of ethyl chloroacetate and shaking the Reaktionsini se hung for 2 hours at 20 ⁰ C. The precipitate is filtered off, washed several times with water and dried. "The dried product is heated for 15 minutes in 50 ml of acetic anhydride. After cooling to 20 ⁰ C is filtered off and the residue

Ί5 recrystallized from glacial acetic acid.

Yield: 85% of theory Melting point: 191-193 ⁰ C

For this 1 page formulas

ROOC-C C-SH

+ C-H

-HX

HN = C. NH

MT

c «= o I

-H ₂ Y

HN = C N-

Il "C-R

C = O

R ¹ III

Claims (4)

Inventor sansjor uoh 1 ♦ A process for preparing τοη pyrazolo Q ?, 1-b3thiazolen of the general formula III in which R is an alkyl radical, R is a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, R is a hydrogen atom, an acyl group or a carbalkoxy group and R is a hydrogen atom, an alkyl group or an aryl radical, characterized in that pyrazole derivatives of the general formula I, wherein R and R are as defined above, with Carbonyl compounds of general formula II in which R and R have the above meanings, X represents a halogen atom and Y represents an oxygen atom or two alkoxy groups, are reacted * 2. The method according to item 1, characterized in that the reactions are carried out in the presence of mineral acids · 3. Process according to item 1, characterized in that the reactions are carried out in the presence of bases. « 4 »Process according to item 3, characterized in that the reaction products are heated with carboxylic acid anhydrides.