Abstract: The invention relates to compounds of the formula in which: Y is --CH-- or --N--; R.sub.1 is hydrogen, a halogen or a CF.sub.3, (C.sub.1 -C.sub.4)alkyl or (C.sub.1 -C.sub.4)alkoxy group; R.sub.2 is a methyl or ethyl group; R.sub.3 and R.sub.4 are each hydrogen or a (C.sub.1 -C.sub.3)alkyl; and X is:(a) a (C.sub.1 -C.sub.6)alkyl, a (C.sub.1 -C.sub.6)alkoxy, a (C.sub.3 -C.sub.7)carboxyalkyl, a (C.sub.1 -C.sub.4)alkoxy-carbonyl(C.sub.1 -C.sub.6)alkyl, a (C.sub.3 -C.sub.7)carboxyalkoxy or a (C.sub.1 -C.sub.4)alkoxycarbonyl-(C.sub.1 -C.sub.6)alkoxy;(b) a radical selected from (C.sub.3 -C.sub.7)cycloalkyl, (C.sub.3 -C.sub.7)cycloalkoxy, (C.sub.3 -C.sub.7)-cycloalkylmethyl, (C.sub.3 -C.sub.7)cycloalkylamino and cyclohexenyl, it being possible for said radical to be substituted by a halogen, hydroxyl, (C.sub.1 -C.sub.4)-alkoxy, carboxyl, (C.sub.1 -C.sub.4)alkoxycarbonyl, amino or mono- or di-(C.sub.1 -C.sub.4)-alkylamino; or(c) a group selected from a phenyl, phenoxy, phenylamino, N-(C.sub.1 -C.sub.