Compounds of the formula (I): Ar.sub.1 --CH(OH)--CH.sub.2 --NH--CH.sub.2 --X--CH.sub.2 --E--(CH.sub.2).sub.n --Y--Ar.sub.2, in which the substituents and symbols have the meanings given in the description, are novel active compounds having, in particular, a broncholytic action.