SUBSTITUTED PYRIMIDONES

1294626 1 - Benzyl - 3,4,5,6 - tetrahydro - 2- (1H)-pyrimidones NORWICH PHARMACAL CO 19 April 1971 [5 March 1970] 22882/71 Heading C2C Novel 1 - benzyl - 3,4,5,6 - tetrahydro - 2(1H)- pyrimidones of the general formula wherein (a) R1 is a hydrogen atom and R2 is a hydrogen or halogen atom or an amino, acetylamino, hydroxy, phenyl or methoxy group, (b) R2 is a hydrogen atom and R1 is a hydrogen or fluorine atom or a nitro group and (c) both R1 and R2 are chlorine atoms, are prepared (i) by reaction of 2-hydroxypyrimidine hydrochloride with a benzyl halide of the general formula wherein X is a chlorine or bromine atom and R1 and R2 are as defined above, exceptt hat R2 may additionally be a nitro or benzyloxy group when R1 is a hydrogen atom, in the presence of a base and catalyst and hydrogenation of the resulting 1-benzyl-2(1H)pyrimidone in the presence of platinum oxide or palladium-on-carbon; (ii) by reaction of 3,4,5,6-tetrahydro-2(1H)- pyrimidone with a benzyl halide of the second general formula above wherein R1 and R2 are as defined for the first general formula above and X is a halogen atom, in the presence of a base and catalyst; and (iii) when R2 is an acetylamino group, by acetylation of the corresponding compound in which R2 is an amino group. Dimethyl bis-(m-nitrobenzyl) ammonium iodide is obtained as a by-product in the reaction of 3,4,5,6-tetrahydro-2(1H)-pyrimidone with mnitrobenzyl chloride in the presence of K 2 CO 3 , KI and dimethylformamide. Pharmaceutical compositions having central nervous system stimulant and mydriatic activity comprise, as active ingredient, a 1-benzyl-3,4,5, 6 - tetrahydro - 2(1H)-pyrimidone of the first general formula above, together with an inert, physiologically acceptable carrier.