PROCESS FOR PREPARING 2,5-DISUBSTITUTED-4(3H)PYRIMIDONES HAVING HISTAMINE H2-RECEPTOR ANTAGONIST ACTIVITY AND OF PHARMACEUTICAL COMPOSITIONS CONTAINING THE SAME

Histamine H2-antagonists of the formula: wherein m is an integer of from zero to 2, inclusive; n is an integer of from 2 to 5 inclusive; Z is sulfur, oxygen or methylene; R1 is NO2 or NR2R3; R2 and R3 each are independently hydrogen or (lower)alkyl, or, when R2 is hydrogen, R3 also may be formyl, carboalkoxy, alkanoyl or benzoyl; A is phenyl, furyl, thienyl, pyridyl, thiazolyl, imidazolyl, oxazolyl, oxadiazolyl, thiadiazolyl, triazolyl, isoxazolyl, isothiazolyl, pyrimidinyl, pyrazolyl, pyridazinyl or pyrazinyl; provided that A contains one or two substituents, the first substituent being selected from and the second substituent being selected from (lower)alkyl, hydroxy, trifluoromethyl, halogen, amino, hydroxymethyl and (lower)alkoxy; q is an integer of from 0 to 6, inclusive; R4 is a hydrogen atom, a (lower)alkyl group optionally substituted by one or more halogen atoms, provided that there is no halogen atom on the carbon atom attached to the nitrogen atom, or a cyclo(lower)alkyl, cyclo(lower)alkyl(lower)alkyl, (lower)alkanoyl or benzoyl group; R6 and R7 each are independently hydrogen, (lower)alkyl, (lower)alkenyl, (lower)alkynyl, phenyl(lower)alkyl or (lower)alkoxy(lower)alkyl in which the (lower)alkoxy moiety is at least two carbon atoms removed from the nitrogen atom, or R6 and R7, taken together with the nitrogen atom to which they are attached, may be pyrrolidino, methylpyrrolidino, dimethylpyrrolidino, morpholino, thiomorpholino, piperidino, methylpiperidino, dimethylpiperidino, hydroxypiperidino, N-methylpiperazino, homopiperidino, heptamethyleneimino, octamethyleneimino or 3-azabicyclo[3.2.2]non-3-yl; or a nontoxic pharmaceutically acceptable acid addition salt thereof.