Flow‐Controlled Living Anionic Monoadditional Reaction Initiated by Flash‐Generated Benzophenone Dianions

The fast and selective generation of metal benzophenone dianions was achieved under microflow conditions using metal naphthalenides (MNp, M = Li, K) as reductants. By adjusting the stoichiometric ratio between benzophenone derivatives and LiNp, lithium benzophenone dianions were generated, which underwent highly selective 1:1 monoaddition with methacrylates within seconds. Flash‐flow mixing minimized side reactions such as the generation of benzophenone radical anions and nucleophilic ester cleavage, affording chain‐type monoaddition products in up to 96% yield. The method exhibited broad substrate scope toward various benzophenone derivatives and methacrylates. Furthermore, end functionalization and the synthesis of multicomponent coupling products were achieved through end‐capping reactions with diverse electrophiles. Sequential monomer introduction enabled the synthesis of sequence‐defined oligomers. Mechanistic studies revealed that the selective formation between chain‐ and ring‐type monoadducts was governed by the reactivity of the electrophile and the nature of the metal counterion. Thus, this method provides a versatile synthetic platform for the selective generation of benzophenone dianions and anionic monoadditions under microflow conditions.