The present invention relates to compounds of formula I wherein R1 is selected from the group consisting of hydrogen and lower alkyl； each R2 is independently selected from the group consisting of hydrogen and lower alkyl； each R3 is independently selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, phenyloxy, benzyloxy, halogen and lower alkyl substituted by halogen； X is selected from the group consisting of &mdash；CH2&mdash；, &mdash；CH&mdash； and &mdash；O&mdash；； Y is selected from the group consisting of &mdash；CH2&mdash；, &mdash；CH&mdash； and a bond with the proviso that, when X is &mdash；O&mdash；, Y may not be a bond； Z is selected from the group consisting of &mdash；CH2&mdash； and &mdash；CH&mdash；； m is 0, 1 or 2； and n is 0, 1 or 2； and to pharmaceutically-acceptable acid addition salts of such compounds. The invention relates also to processes for preparing such compounds, compositions comprising such a compound or a pharmaceutically-acceptable acid addition salt thereof, and a method of treating a disease or disorder in a patient comprising administering such a compound, or pharmaceutically-acceptable acid addition salt thereof, to a patient in need of such treatment.
