Objectives: The subject "synthesis of chiral cis - (+) - N-2-clorobenzyl phthalazinon derivatives" investigated the binding ability of 2-clorobenzyl on the frame tetrahydro and hexahydrophthalazinon, which oriented synthesis of compounds with the selective phosphodiesterase IV (PDE4) inhibitory activity having anti-inflammatory activity for the treatment of asthma and rheumatoid arthritis.