The invention relates to compounds of formula (I) wherein R1 is hydrogen, lower alkyl, -CH2-cycloalkyl or cycloalkyl； R2 is hydrogen, lower alkyl, lower alkyl substituted by hydroxy or R1 and R2 may form together with the N and C atom to which they are attached a pyrrolidine ring optionally substituted by one or two F-atoms or by hydroxy, or may form an azetidine or a piperidine ring； R3 is hydrogen, lower alkyl, lower alkyl substituted by hydroxy, -(CH2)oNH2, benzyl optionally substituted by hydroxy, phenyl, -CH2-cycloalkyl or cycloalkyl； R3' is hydrogen or lower alkyl； n is 1； m is 0 or 1； o is 1 to 4； or to pharmaceutically acceptable acid addition salt, to a racemic mixture or to its corresponding enantiomer and/or optical isomers thereof. It has been found that the present compounds are oxytocin receptor agonists for the treatment of autism, stress, including post traumatic stress disorder, anxiety, including anxiety disorders and depression, schizophrenia, psychiatric disorders and memory loss, alcohol withdrawel, drug addiction and for the treatment of Prader-Willi Syndrom.
