The invention relates to heterocyclic compounds useful as phosphodiesteraseinhibitors(PDEs) in particular phosphodiesterase type 4 (PDE-4) and type 10 inhibitors(PDE-10)represented by formula (I), tautomeric forms, stereoisomers, diastereomers,enantiomers,appropriate N-oxides, pharmaceutically acceptable salts, pharmaceuticallyacceptable hydrates,pharmaceutically acceptable solvates, pharmaceutically acceptable compositionscontaining themand their use in treating allergic and inflammatory diseases and forinhibiting the production ofTumor Necrosis Factor (TNF-.alpha.).The compounds represented by general formula I are useful in the treatment ofallergicand inflammatory diseases including asthma, COPD, allergic rhinitis, allergicconjunctivitis,respiratory distress syndrome, chronic bronchitis, nephritis, rheumatoidspondylitis,ostheoarthritis, atopic dermatitis, eosinophilic granuloma, psoriasis,rheumatoid septic shock,ulcerative colitis, parkinson's disease； multiple sclerosis, chronicinflammation, Crohn'ssyndrome and other inflammatory conditions of lungs, eyes, joints, bowels,skin, heart andcentral nervous system (CNS).The invention also relates to a process for preparing the heterocycliccompounds of thegeneric formula (I).
