Process for the preparation of 2-amino-[1,2,4]triazolo[1,5-a]pyrimidines

1. A process for the preparation of unsubstituted or substituted 2-amino-[1,2,4]triazolopyrimidines which comprises combining A) a 2-amino-pyrimidine with an alkyloxycarbonyl isothiocyanate or an aryloxycarbonyl isothiocyanate and B) with a hydroxyl ammonium salt and a base wherein the reactions are carried out in a carboxylic acid ester solvent in the temperature range of from 40 to 150° C.

2. The process according to claim 1 wherein the pH value in step B) is increased over time and finally maintained in the range of from 5.5 to 7.5.

3. The process according to claim 1 , wherein the hydroxylammonium salt is hydroxylammonium sulfate.

4. The process according to claim 1 wherein the 2-amino-pyrimidine is described by formula I

and the 2amino-[1,2,4]triazolopyrimidine is described by formula IV

wherein the variables have the following meaning:

E =independently the same or different are 0, S, N, P;

R =independently the same or different are C 1-10 -alkyl; C 6-20 -aryl; C 7-20 -arylalkyl; C 7-20 -alkylaryl which each of those may be substituted with one or more of the following groups: F, Cl, Br, I, C 1-20 -alkoxy, C 6-20 -aryloxy, non substituted or preferably substituted amino; F, Cl, Br, I;

n =0 or 1

m =1 for E =O, S

m =2 for E =N, P

p =0, 1,2 or 3.

5. The process according to claim 1 , wherein the process is conducted without isolation of intermediates.

6. The process according to claim 1 wherein the 2-amino-pyrimidine is 2-amino-4,6-dimethoxypyrimidine and the 2-amino-[1,2,4]triazolopyrimidine is 2-amino-5,7-dimethoxy [1,2,4]triazolo[1,5]-alpyrimidine.