PURPOSE: To obtain the titled substance useful as an antimicrobial agent in high yield, by thermally decomposing a 2-piperazinylpyridopyrimidine compound containing a hydrazine residue at the 4-position.
CONSTITUTION: A compound shown by formula I (R3 is acyl, etc.,; X is halogen is reacted with an alkoxymethylene malonic diester to give a compound shown by formula II (R2 is lower alkyl), which is subjected to ring closure under heating to give a compound shown by formula III, which is alkylated and reacted with a hydrazine compound or treated in the reverse order to give a compound shown by formula IV (Y is hydrazine residue; R1 is lower alkyl), which is hydrolyzed to give a compound, which is heated to 200°C or heated in an aqueous solution of a basic compound at reflux temperature and the hydrazine residue is eliminated to give a compound shown by formula V.
SATO SHOGO
TAKAHASHI YOSHIO
TAMURA TOSHIAKI
