DE1921522A1 - 2,4-disubst 1,3,4-oxadiazol-5-ones with tuber - culostatic, analgesic antipyretic, dielectric - Google Patents

Abstract

2-R-4-R'-1,3,4-oxadiazol-5-ones (where R and R' are opt. subst. alkyl, aryl or heterocyclic residues) are prepd. by treating corr. 5-imino-1,3-4-oxadiazolines with nitrite-contng. solns. in acidic medium to give corr. 5-nitrosoimino-1,3,4-oxadiazolines which, without isolation, are converted into the corr. 1,3,4-oxadiazol-5-ones by adding a solvent (pref. a lower alcohol, acetone or dioxan), optionally initially with slight heating. Advantages are that use of phosgene is avoided, yields (80%) and purity of products are good, elevated temps. are not used, reaction times are short, and intermediate nitroso cpds. are not isolated.

Description

Process for the preparation of substituted 1,3,4-oxdiazolones- (5) Die The invention relates to a process for the preparation of 2,4-disubstituted 1,3,4-oxdiazolones (5) according to patent application P 16 95 600.6.

2,4-disubstituted 1,3,4-oxdiazolones- (5) are essentially so far only accessible by reacting suitable derivatives of hydrazine with phosgene. Known have also become the implementation of monosubstituted 1,3,4-oxdiazolones (5) (prepared by reaction of acylhydrazines with phosgene) with alkylating agents or with Formaldehyde and amines under the conditions of the Mannich reaction.

Working with is a disadvantage of the processes that have become known the highly toxic phosgene and the associated technical expenses. aside from that the processes are not always universally applicable or the yields due to formation of by-products low. The reaction times are for the known methods long. It is often necessary to work at an elevated temperature.

The invention is based on the object, starting from the 5-imino-1,3,4-oxdiazolines, to produce certain substituted 1, 3,4-0xdiazolone- (5) in a simple way.

In the further development of the process mentioned in the main patent, it has now been found that, contrary to the previous assumption, the process can also be extended to the production of heterocyclically substituted 1,3,4-oxdiazolones (5) of the general formula where R and R 'denote alkyl, aryl and heterocyclic radicals, which could optionally also be substituted # if one treats correspondingly 2,4-disubstituted 5-imino-1,3,4-oxdiazolines in an acidic medium with a nitrithaltic solution and the resulting nitroso compounds are not isolated, but by adding a suitable solvent (preferably lower alcohols, dioxane, acetone) to the reaction mixture, if necessary with initially gentle warming, immediately converting them to the corresponding 2,4-disubstituted 1,3,4-oxdiazolones ( 5) transferred.

This method is characterized by the fact that it works with the highly poisonous phosgene is confined to the devestment (by 80%), the products incurred in good purity and the reaction times and the outlay on equipment are low. It does not work at an elevated temperature.

Compared to the procedure mentioned in the main patent, there is a further simplification, since the isolation of the nitroso compound occurring as an intermediate product ceases to exist.

The compounds show tuberculostatic, analgesic, antipyretic, diuretic, bactericidal, herbicidal, fungicidal and insecticidal properties.

The process is explained in more detail in the following examples: Example 1: 5 g of 2- [thienyl- (2)] -4-methyl-5-imino-1,3,4-oxdiazoline are in a mixture of 60 ml of water and 5 ml of concentrated hydrochloric acid below OOC with stirring slightly more than the stoichiometric Amount of a nitrite, dissolved treated in water.

Then 30 ml of alcohol are added. Under intense warming, stormy continues Nitrogen evolution one. 4.3 g of the oxdiazolone separate from the cooled solution from (85% of theory).

Mp 93 ° C N calc .: 15.4% found: 15.7% Example 2 t 5 g of 2-phenyl-4- [furyl- (2)] - 5-imino-1,3,4-oxdiazoline are in a mixture of 60 ml of water and 5 ml of concentrated hydrochloric acid below OOC with stirring with a little more than the stoichiometric amount of a nitrite, dissolved treated in water. Then 30 ml of methanol are added. Under intense warming and nitrogen evolution, the nitroso compound goes into solution.

On cooling, 4.0 g of oxdiazolone separate out (81% of theory).

Fp .: 114 ° N calc .: 12.3% found: 12.5%

Claims (1)

Claims: Process for the preparation of substituted 1,3,4-oxdiazolones- (5) of the general formula where B and R 'denote alkyl, aryl and heterocyclic radicals, which can optionally also be substituted, according to patent application P 16 95 600.6, characterized in that corresponding 5-imino-1,3,4-oxdiazolines are obtained by treatment with nitrite-containing solutions in an acidic medium into the associated 5-nitrosimino-1,3,4-oxdiazolines and these, without isolating them, possibly with gentle warming at the beginning, by adding a solvent (preferably lower alcohols, acetone, dioxane) to the corresponding 1,3,4-Oxdiazolone- (5) transferred.