A compound of formula (I): ##STR1## in which: R represents naphthyl, 5,6,7,8-tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, thienyl, optionally substituted phenyl or (C.sub.3 -C.sub.7)cycloalkyl,n represents an integer such that 1.ltoreq.n.ltoreq.8, their enantiomers, diastereoisomers and epimers as well as their addition salts with a pharmaceutically acceptable acid or base and medicinal products containing the same are useful as antagonists of substance P.