Described are novel heterocyclic compounds of the general formula (I), their derivatives, analogs, tautomeric forms, stereoisomers, polymorphs, hydrates, solvates, pharmaceutically acceptable salts, pharmaceutical compositions, metabolites and prodrugs thereof. These compounds are useful in the treatment of immunological diseases, inflammation, pain disorder, rheumatoid arthritis; osteoporosis; multiple myeloma; uveititis; acute and chronic myelogenous leukemia; atherosclerosis; cancer; cachexia; ischemic-induced cell damage; pancreatic beta cell destruction; osteoarthritis; rheumatoid spondylitis; gouty arthritis; inflammatory bowel disease; ARDS; psoriasis; Crohn's disease; allergic rhinitis; ulcerative colitis; anaphylaxis; contact dermatitis; muscle degeneration; asthma; COPD; bone resorption diseases; multiple sclerosis; sepsis; septic shock; toxic shock syndrome and fever. More particularly these compounds are useful as PDE4 inhibitors and are useful for treating PDE4 mediated diseases.