u00b0 26 6 g of 5 6 diamino 4 butylamino 2 methylpyridine 3 carboxylic acid ethyl ester 0 1 mol are dissolved in 150 ml of toluene 9 g of diacetyl are added and the mixture is refluxed while the water formed is removed by a water separator after about 5 hours the theoretical amount of water is separated and the solution is evaporated to dryness the dark oily residue is extracted twice with 100 ml portions of gasoline and addition of activated charcoal the gasoline extracts are combined and concentrated to about 100 ml 8 butylamino 2 3 6 trimethylprido 2 3 b pyrazine 7 carboxylic acid ethyl ester crystallizes on cooling yield 21 g 66 m p 97 u00b0 99 u00b0 13 3 g of 5 6 diamino 4 butylamino 2 methylpyridine 3 carboxylic acid ethyl ester 0 05 mol of example 1 d and 4g of glyoxal monohydrate dissolved in 100 ml of toluene are refluxed while the water formed is removed by means of a water separator after about 3 hours the reaction is complete and the solution is concentrated the remaining oily residue is extracted twice with 50 ml portions of gasoline and addition of activated charcoal the gasoline extracts are cooled and the crystalline 8 butylamino 6 methylpyrido 2 3 b pyrazine 7 carboxylic acid ethyl ester is filtered off yield 70 m p 56 u00b0 58 u00b0 by substituting ethylamine for the butylamine in the procedure of example 1 b 6 chloro 4 ethylamino 2 methyl 5.