CS252341B1 - 0.N-substituted 4,9-dihydro-6-hydroxy-1,3-dimathyl-4-oxo-1H-pyrazolo (3,4-b) quinolines - Google Patents

Abstract

The solution relates to 0,N-substituted 4,9-dihydro-6-hydroxy-1,3-dimethyl-4-oxo-1H-pyrazolo[3,4-b]quinolines of the general formula I O (i) 1 2 where R and R are hydrogen atoms or methyl groups. These new, previously undescribed substances are useful as intermediates for the preparation of substances exhibiting significant biological effects, effects, especially antiviral and antitumor

Description

The present invention relates to O, N-substituted 4,9-dihydro-6-hydroxy-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinolines of formula I

O

H ² CH ₃ (1) wherein R ¹ and R ² are hydrogen or methyl.

These novel substances, which have not been described yet, are useful as intermediates for the preparation of substances having significant biological effects, in particular antiviral and antitumor activity.

2

The compound of formula (I) wherein R is methyl and R is hydrogen may be prepared by acid hydrolysis of 4-chloro-6-methoxy-1,3-dimethyl-1H-pyrazolo [3,4-b] quinoline by boiling with dilution hydrochloric acid. A compound of formula I wherein R 1 and R 2 is methyl can be prepared by methylation of the sodium salt of 4,9-dihydro-6-methoxy-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline according to the invention methyl iodide in dimethylformamide at room temperature. A compound of formula I wherein R is hydrogen and R is methyl may be prepared according to the invention from 4,9-dihydro-6-methoxy-1,3,9-trimethyl-4-oxo-1H-pyrazolo / 3,4- b) quinoline by demethylation with azeotropic hydrobromic acid.

The process for preparing the substances is simple and provides the desired products in satisfactory yields. The products obtained are directly usable for further use. Further details are given in the following examples. The examples given are merely illustrative and not limiting

Example 1

4,9-Dihydro-6-methoxy-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline

A mixture of 4-chloro-6-methoxy-1,3-dimethyl-1H-pyrazolo [3,4-b] quinoline (2.6 g of 10 mmol) and 2M hydrochloric acid (25 ml) was refluxed for 6 hours. After cooling, the insoluble material was aspirated and recrystallized from ethanol. 1.95 g (75%) of m.p. 306 DEG-310 DEG

Example 2

4.9-Dihydro-6-methoxy-1,3,9-trimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline

To a stirred suspension of 4,9-dihydro-6-methoxy-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline (16.6 g, 68 mmol) in dimethylformamide (330 mL) was added 80% sodium hydride (2.2 g, 73 mmol) was added and the mixture was stirred under nitrogen for 1 hour. After the dropwise addition of methyl iodide (14.5 g, 0.1 mol), the mixture was stirred at room temperature for 4 hours, then the mixture was poured into water, the insoluble material was filtered off with suction and recrystallized from ethanol. o tt Mp 227-228 ° C

Example 3.

4.9-Dihydro-6-hydroxy-1,3,9-trimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline

A mixture of 4,9-dihxdro-6-methoxy-1,3,9-trimethyl-4-oxo-1H-parazolo [3,4-b] quinoline (2.6 g, mmol) and azeotropic hydrobromic acid (35 ml) was refluxed for 16 hours. After cooling, the insoluble material was aspirated and crystallization from ethanol gave 1.95 g (80%) of m.p. 336 DEG-340 DEG.

Claims (1)

SUBJECT OF THE INVENTION O, N-substituted 4,9-dihydro-6-hydroxy-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinolines of formula I RO -CH 1/1, 2 CH, Wherein R and R are hydrogen or methyl.