Ring Opening of Phthalimide Derivatives with Benzylamine: Formation of Carboxamides and their Pharmacological Evaluation

The ring opening of phthalimide derivatives viz N-cyclopentylphthalimide (1a), N-benzylphthalimide (1b), Nprop-2-ynylphthalimide (1c), 1-phthloylamino-3-[4-(2-methoxyphenyl)-piperizin-1-yl]-propane(1d) and 1­ phthloylamino-4-[4-(2-methoxyphenyl)-piperizin-1-yl]-butane (1e) was accomplished using benzylamine in dimethylformamide (DMF) at room temperature to afford the corresponding carboxamides: benzamido­ cyclopentane-2-(N-benzyl)-carboxamide (3a) benzamido-1-phenylmethylene-2-(N-benzyl)-carboxamide (3b) and 3-benzamido-prop-2-yne-2-(N-benzyl)carboxamide (3c) and were unequivocally characterized by infrared, nuclear magnetic resonance, mass spectrometer and elemental analyses. The products obtained were screened for antiinflammatory and analgesic properties using carrageenan-induced rat paw oedema assay and acetic acid-induced writhing test, respectively. The most active compound was 3b for the antiinflammatory activity assay and for the analgesic activity test the most active compound was 3a. The activities were dose-dependent. All the compounds tested showed better analgesic activity than acetylsalicylic acid.