The present disclosure relates to a series of 2-substituted-di- tri or tetra-hydro-8H-cyclopentaoxazolo[3,2-a]pyrimidin-8-ones and 2-substituted-di-, tetra-, or hexa-hydro-cyclohexaoxazolo[3,2-a]pyrimidin-9-ones of formula (I): wherein p, n, A, B, X, Y, R1, R2, R3, R4, R5, R6, R7 and R8 are as defined herein. This invention also relates to methods of making these compounds including novel intermediates. The compounds of this invention are modulators of metabotropic glutamate receptors (mGluR), particularly, mGluR2 receptor. Therefore, the compounds of this invention are useful as pharmaceutical agents, especially in the treatment and/or prevention of a variety of central nervous system disorders (CNS), including but not limited to acute and chronic neurodegenerative conditions, psychoses, convulsions, anxiety, depression, migraine, pain, sleep disorders and emesis.