IMPROVED PROCESS FOR PRODUCING 2,4-DIAMINO-5-BRACKET-3-COMMA ABOVE, 4-COMMA ABOVE,5-COMMA ABOVE-TRIMETHOXY-BENZYL-BRACKET CLOSED-PYRIMIDINE

The invention relates to an improved process for the preparation of 2,4-diamino-5-(3',4',5'-trimethoxy-benzyl)-pyrimidine of the general formula I by reacting a compound of the general formula II (wherein R is an alkyl group having 1-4 carbon atoms) with guanidine, which comprises preparing the said compound of the general formula II by reacting alpha -(3,4,5-trimethoxy-benzal)- beta -methoxy-propionitrile of the formula III with ethylene glycol monoalkylether of the general formula IV HO-CH2-CH2-OR (IV> (wherein R as as stated above) in the presence of an alkali metal alkoxide at a temperature between 60 DEG and 90 DEG and reacting the compound of the general formula II thus obtained - if desired without isolation - with guanidine in the presence of an alkanol having 4-8 carbon atoms. The advantage of the process is that it is economical and can be carried out with high yields even on industrial scale and provides a product of high purity. The compound of the formula I obtained is a known chemotherapeutical drug.