The invention provides compounds having the general formula (I) wherein X is O or S； R1 is C, N, O or S； R1a is CH, CH2, N or NH； R2 is a bond, CH or CH2； m is 1, 2 or 3； n is 1 or 2； when n is 2 or m is 2 or 3, the ring containing R1 may be fused with a benzene ring； each --- represents a single or double bond provided that one double bond extends from the carbon atom to which R3-C=C- is bonded and that no ring carbon atom bears two double bonds； and R3, R4 and R5 represent a wide range of substituents. These compounds are selective for the metabotropic mGlu5 receptor. They, their solvates, hydrates, enantiomers, diastereomers, N-oxides and pharmaceutically acceptable salts, and pharmaceutical compositions containing them, can be used to treat diseases or disorders of the lower urinary tract, especially neuromuscular dysfunctions of the lower urinary tract. They may also be useful for the treatment of migraine； for the treatment of gastroesophageal reflux disease (GERD)； for the treatment of anxiety disorder； for the treatment of abuse, substance dependence and substance withdrawal disorder； for the treatment of neuropathic pain disorder； and for the treatment of fragile X syndrome disorders.
