Step‐Economical Synthesis of 2,4‐Disubstituted Phthalazinones via a t ‐ BuONa ‐Promoted One‐Pot Reaction

A t ‐BuONa‐promoted, one‐step synthesis of 2,4‐disubstituted phthalazinones from 3‐ylidenephthalides under mild reaction conditions has been developed. The reaction shows broad scope for both alkyl and aryl substituents that can be readily introduced at the N2 position. Moreover, the protocol is compatible with a broad range of substrates and facilitates late‐stage functionalization, demonstrating its general applicability in synthetic and medicinal chemistry.