Triazolopyrimidines their preparation and use in medicine

s-triazolo(1,5-a)pyrimidine compounds of the Formula (I> wherein R2 and R3 are the same or different and represent an H atom, a C1 to C3 alkyl group or a halogen atom; R4 represents a straight-chain or branched-chain C4 to C9 alkyl group, an aralkyl group substituted by one or more C1 to C3 alkoxy or alkyl groups; 2,5-dioxaheptyl or 3-oxahexyl residues; R5 represents an H atom, a C1 to C3 alkyl group, a hydroxyethyl group or a hydroxypropyl group; R6 and R7 are the same or different and represent an H atom, a straight-chain or branched-chain C1 to C5 alkyl group, or R6 and R7 together complete a cycloaliphatic ring, the substituents in positions 5 and 7 optionally being mutually exchanged, and the pharmaceutically acceptable salts thereof, their preparation and pharmaceutical compositions comprising them are disclosed as therapeutic aids for cardio-circulatory disorder.