Results: The new chiral derivative cis - (+) - N-allyl-4 - (3, 4-dimethoxyphenyl) - 4a, 5, 6, 7, 8, 8a-hexahydro-2H-phthalazin-1-on was successfully synthesized which had anti-inflammatory activity in mice at dose of 60 mmol / kg after 5 hours.