The present invention provides compounds of the formula (I): ##STR1## and the pharmaceutically acceptable salts thereof, wherein R is C.sub.3 -C.sub.7 cycloalkyl, aryl or C.sub.1 -C.sub.6 alkyl, said C.sub.1 -C.sub.6 alkyl being optionally substituted by fluoro, --COOH, --COO(C.sub.1 -C.sub.4) alkyl, C.sub.3 -C.sub.7 cycloalkyl, adamantyl, aryl or het.sup.1, and said C.sub.3 -C.sub.7 cycloalkyl being optionally substituted by 1 or 2 substituents each independently selected from C.sub.1 -C.sub.4 alkyl, C.sub.3 -C.sub.7 cycloalkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, fluoro, fluoro(C.sub.1 -C.sub.4) alkyl and fluoro(C.sub.1 -C.sub.4)alkoxy; R.sup.1 is phenyl, benzyl, naphthyl, thienyl, benzothienyl or indolyl, each optionally substituted by 1 or 2 substituents each independently selected from C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, halo and trifluoromethyl; R.sup.2 represents various groups; X is C.sub.1 -C.sub.4 alkylene; and X.sup.1 is a direct link or C.sub.1 -C.sub.6 alkylene. Such compounds and salts are useful as tachykinin antagonists.