GB716327A — New heterocyclic compounds

USPTO Abstract

The invention comprises pyrazolo-pyrimidines (tetra-aza-indenes) of the formula <FORM:0716327/IV (b)/1> where R1 is hydrogen or amino, R2 is alkyl and R3 is amino, alkylamino, dialkylamino or hydroxy. These are made by the action of hydrazine on 4-alkylthio-6-alkyl-5-formyl- or 5-cyano-pyrimidines; when R3 is hydroxy it can also be produced by hydrolysis of an amino group. Examples show the production of the 6-amino-4-methyl and 3 : 6-diamino-4-methyl compounds, the latter being hydrolysed to the 3-amino-4-methyl-6-hydroxy compound. The pyrimidines used as starting materials are prepared as follows: 2-amino-4-methylthio-5-nitro-6-methylpyrimidine is made from the 4-chloro compound and methanethiol and the nitro group then reduced. The resulting 2 : 5-diamino-4-methylthio-6-methylpyrimidine is diazotized and treated with (1) formaldehyde, sodium acetate and copper sulphate to give 2 - amino - 5 - formyl - 4 - methylthio - 6 - methylpyrimidine, and (2) sodium cyanide and nickel sulphate, yielding 2-amino-5-cyano-4-methylthio-6-methylpyrimidine.