Process for preparing a pharmaceutically active compound and for preparing its intermediate

1. A process for preparing the intermediate 2-(2,3-dichlorophenyl)-2-(aminoguanidine)acetonitrile, of formula (II):

which comprises the reaction of 2,3-dichlorobenzoyl cyanide with aminoguanidine bicarbonate, wherein it is carried out in non-aqueous medium in the presence of methanesulphonic acid as the only reaction medium; and wherein once the reaction has finished, the process further comprises the steps of:

i) adding water;

ii) adjusting the pH of the medium to a pH higher than the pKa of hydrogen cyanide; and

iii) isolating intermediate of formula (II).

2. Process according to claim 1 , wherein said reaction is carried out within a temperature range of 20 to 80° C.

3. Process according to claim 2 , wherein said reaction is carried out within a temperature range of 30 to 60° C.

4. Process according to claim 1 , wherein in ii), said adjustment of the pH is carried out by adding a sodium hydroxide solution.

5. Process for preparing the 3,5-diamino-6-(2,3-dichlorophenyl)- 1,2,4-triazine, of formula (I):

or a pharmaceutically acceptable salt thereof, which comprises the following steps:

a) preparation of the intermediate 2-(2,3-dichlorophenyl)-2-(aminoguanidine)acetonitrile, of formula (II), according to claim 1 ;

b) cyclisation of said intermediate of formula (II) in an aliphatic alcohol or in an aliphatic alcohol/water solution under reflux; and, if desired, obtaining a pharmaceutically acceptable salt thereof.

6. Process according to claim 5 , wherein said aliphatic alcohol used in step b) may be chosen from between ethanol and isopropanol.