Catalyst-Free Green Synthesis of Phthalazinones at Room Temperature

An efficient catalyst-free synthesis of phthalazinones from 2-formyl/acetyl/benzoylbenzoic acids and substituted hydrazines is described. The direct cyclocondensation of a series of aryl/alkylhydrazines and various 2-formyl/acetyl/benzoylbenzoic acids was performed at room temperature to afford the corresponding phthalazinones in very high isolated yields. The gram-scale reaction and application in the biological activity phthalazinone derivative demonstrated its practical potential. The plausible reaction mechanism was proposed based on the corresponding DFT calculations.