Compounds of formula (I): ##STR1## in which: R.sup.1 is aryl or aromatic heterocyclic; R.sup.2 and R.sup.3 are hydrogen, alkyl, alkoxy, halogen, phenyl, phenoxy, C.sub.1 -C.sub.6 alkylthio, phenylthio, C.sub.1 -C.sub.6 haloalkyl, cyano or nitro, or together are alkylene optionally containing oxygen; R.sup.4 is hydrogen, aliphatic acyl, cycloalkylcarbonyl, cycloalkoxycarbonyl, aromatic acyl, alkoxycarbonyl or benzyloxycarbonyl; R.sup.5 and R.sup.6 are alkyl; and X is oxygen, sulfur or methylene, have calcium channel blocking activity and can serve for the treatment or prophylaxis of cardiovascular diseases and disorders. They may be prepared by reacting a corresponding compound where R.sup.4 is hydrogen and the aminoethyl group is replaced by hydrogen with a compound providing the aminoethyl group and the, if required, acylating the product.