DD209459A1 - PROCESS FOR PREPARING SUBSTITUTED PYRAZOLO (3,4-B) -PYRIDINES - Google Patents

Abstract

The aim of the invention is to develop a process for the preparation of 3-amino-4aryl-bromo-6-methylthio-1H-pyrazolo (3,4-b) pyrides. The substituted pyrazolo (3,4-b) pyridines of the general formula II in which R is an optionally alkoxy-, alkyl- or halogen-substituted phenyl radical can be prepared by reacting the pyridinecarbonitriles of the general formula I in which R has the above meaning, be prepared with hydrazine hydrate. These substituted pyrazolo (3,4-b) pyridines are suitable as organic intermediates for further syntheses. They can be used in particular for the preparation of further derivatives of pyrazolo (3,4-b) pyridienes.

Description

Process for the preparation of substituted

 • PyrazoloPjj ^ -bJpyridines. ... .. ·

Field of application of the invention ,:: _ _. ".

The invention "relates to a Verfahreni'sur

of 3-amino-4-aryl-5'-urom-6-methyltiiio-iH-pyrazolo [^ 3,4-b pyridines.

These substituted pyrazoles j ~ 3,4-b] pyridines are suitable as organic intermediates for further syntheses. They can be used in particular for the preparation of further derivatives of Eyrazolo [3, 4-bipyridines.

Characteristic of the known technical solutions

3-Amino-4-aryl-5-bromo-6-methylthio-1H-pyrazolo pyridines are not yet known: -.

Object of the invention

The aim of the invention is to develop a process for the preparation of 3-imino-4-aryl-5-bromo-6-ethylthio-1H-pyrazolo [3,4-bpyridines. ,

Explanation of the reading of the invention

The substituted Pyrazölop3,4-b] pyridines of the general formula II, - in the .-. E for an optionally - ',', alkoxy-j alkyl- or halogen-substituted Vbienylrest. can, by reacting the Pyridincarbonitrrile

The general formula I, in which H has the above meaning, can be prepared with hydrazine hydrate. The reactions are carried out in an organic solvent, preferably in alcohols, with an excess of hydrazine hydrate. The reaction temperatures are at the boiling points of the solvents used. The reaction times are two to eight hours. After cooling, the ßeaktionsmischungen 20 ⁰ O substituted] fall? Yrazolo- [3 »4-kj pyridine in very good purity from" Another Heini ceremony can be performed by recrystallization from alcohols or glacial acetic acid.

Embodiments Example 1

pyridine

0.005 mol of 2,5-dibromo-6-methylthio-4-phenyl-pyridine-3-carbonitrile are heated in 20 ml of ethanol with 0.02 mol of 85% strength hydrazine hydrate for four hours with reflux cooling, for example by boiling. The mixture is allowed to cool to 20 ⁰ G, filtered from the precipitate, washed with a little cold ethanol and crystallized from ethanol

Yield: 83% of theory Schmp. 239-240 ⁰ O

O ₁₃ H ₁₁ ErI ₄ S (335,2) Ber. 0 46.57 H 3.03 H 16.71

Gef. 0 46.70 H 3.30 N 16.98

EXECUTIVE SUMMARY 2 . ·

3-Amino-5-bromo-4- (p-chlorophenyl) -6-methylthio-1H-pyrazolo [3,4-bJ pyridine

0.005 mol of 2,5-dibromo-4- (p-chloro-phenyl) -6-methylthiopyridine-3-carbonitrile and 0.02 mol of 85% hydrazine hydrate are reacted in 20 ml of ethanol, as under

- Embodiment-1 described «-.- ··· ··· ···

Yield: 89% d. Schmp. 237-238 ⁰ G

₃ S (369.7) Ber. G -42,23 Ή 2,91 ^ 15,17

Gef. C 42.12 H 2.40 N 15.33

IS (Hu3ol): HH, HH ₂ 3230, 5330, 3470 cm- ¹ ; ~ ^'1 H-HMH. (Acetone-d ₆ ): - SGH ₃ V 2.50 ^ -HSg ^, 57, ^ B. 11 _f S2 \ - ^; :: 'aroma protons 7.33 ppm ·

E ι

.σ

C-Be

C-SCE

-HBr

S-H

C-Br

C-SGEL

II

Claims (1)

Erf indan gsansprucn, ...; - ... .....: .-- .: Process for the preparation of substituted pyrazolyl-3,4-bj pyridines; the general formula II, -invaer-S "" stands for an optionally alkoxy-, alkyl- or halogen-substituted phenyl radical, characterized in that lyridincarbonitrile of the general formula I, in which H has the above meaning, is reacted with Eydrazinhydrat For this 1 sheet of formulas