The present invention relates to a compound represented by formula I : wherein: R1 is hydrogen halogen lower alkyl or cyano Ring A is an optionally substituted heterocyclic group Ring B is an optionally substituted 3 to 6-membered monocyclic group and Y is optionally substituted amino optionally substituted cyclic amino optionally substituted aliphatic 3 to 6-membered monocyclyloxy optionally substituted lower alkyl or optionally substituted lower alkyl-O- or a pharmaceutically acceptable salt thereof and to their use as PDE10 inhibitor.
