Pyrrolidine oxadiazole- and thiadiazole oxime derivatives being oxytocin receptor antagonists

A compound according to formula I:

• a geometrical isomer thereof, an optically active form thereof, an enantiomer thereof, a diastereomer thereof, a racemate thereof, or a pharmaceutically acceptable salt thereof, wherein:
• A is selected from the group consisting of —(C═O)—, —(C═O)—O—, —SO2—, —SO2NH—, and —CH2—;
• B is an unsubstituted or substituted oxadiazole or unsubstituted or substituted thiadiazole ring;
• R1 is selected from the group consisting of C1–C6-alkyl, C2–C6-alkenyl, C2–C6-alkynyl, aryl, heteroaryl, C1–C6 alkyl aryl, and C1–C6 alkyl heteroaryl, wherein R1 can form with the O atom to which it is attached a 3–8 membered, saturated or unsaturated heterocyclic ring which may contain 1–2 further heteroatoms selected from the group consisting of N, S and O and which is optionally fused with an aryl, heteroaryl or 3–8 membered saturated or unsaturated cycloalkyl ring;
• R2 is selected from the group consisting of C1–C6-alkyl, C2–C6-alkenyl, C2–C6-alkynyl, aryl, heteroaryl, heteroarylalkyl, 3–8-membered cycloalkyl, acyl, C1–C6-alkyl aryl, and C1–C6-alkyl heteroaryl, wherein said cycloalkyl or aryl or heteroaryl groups may be fused with 1–2 further cycloalkyl or aryl or heteroaryl groups;
• R3, R4, R5 and R6 are independently selected from the group consisting of hydrogen, halogen, C1–C6-alkyl and C1–C6-alkoxy.