A new and efficient process for the preparation of lamotrigine and related 3,5-diamino-6-substituted-1,2,4-triazines

摘要

A process for the manufacture of 3,5-diamino-6-substituted-1, 2, 4- triazines of formula(I) is disclosed: which comprises the steps of: (a) reacting a compound of formula(II) with aminoguanidine in the presence of an organic sulphonic acid in an organic solvent under anhydrous conditions to form a cyanohydrin of formula (III); (b) dehydrating the cyanohydrin of formula (III) to form a compound of formula (IV) by using a dehydrating reagent; and (c) cyclization of the compound of formula IV into a 3,5-diamino-6- substituted-1, 2,4-triazine compound of formula I or into a hydrated form thereof, wherein R is optionally substituted C1-C4 alkyl or aryl group.