Compounds for use in imaging, diagnosing and/or treatment of diseases of the central nervous system or of tumors

A compound of formula Ia

• wherein
• W is —C(U1)(U2)—C≡CH,
• U1 and U2 are each independently hydrogen or deuterium, wherein at least one of U1 and U2 is deuterium,
• A is substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, (C1-C10)alkyl, G4-(C2-C4)alkynyl, G4-(C1-C4)alkoxy, (G4-(C1-C4)alkyl)aryl, (G4-(C1-C4)alkoxy)aryl, (G4-(C1-C4)alkyl)aryl, or (G4-(C1-C4)alkoxy)aryl,
• G1, G2, G3 and G4 are independently and individually, at each occurrence, selected hydrogen, (C1-C4)alkyl, L, and —(C1-C6)alkyl-L,
• with the proviso that exactly one of G1-G4 is L or —(C1-C6)alkyl-L,
• L is a leaving group, or L is F,
• n is an integer from 0 to 6,
• m is an integer from 0 to 4,
• including all isomeric forms of said compound, including but not limited to enantiomers and diastereoisomers as well as racemic mixtures,
• and any pharmaceutically acceptable salt, ester, amide, complex or prodrug thereof.