Direct Transition-Metal Free Benzene C-H Functionalization by Intramolecular Non-Nitroarene Nucleophilic Aromatic Substitution of Hydrogen to Diverse AIEgens.

Direct C(sp )-H functionalization through nitroarene-triggered nucleophilic aromatic substitution of hydrogen (SNAr ) has attracted growing attention, owing to its high efficiency and low carbon footprint. In this study, non-nitro-group-assisted S Ar has been developed for direct benzene functionalization in one pot under mild conditions. The electron-withdrawing carbonyl group and the halide or trifluoromethyl group on the phenyl ring enable the σ adduct formation to fulfill the intramolecular C(sp )-C(sp ) bond construction. Notably, the cyano group serves as both the electron-withdrawing group to activate the C(sp )-H bond and the leaving group to fulfill the β-elimination. Three series of pyrrolo[1,2-b]isoquinolinones, as well as unexpected rearrangement products 3-(1H-pyrrol-2-yl)-1H-inden-1-ones are regioselectively obtained through a simple and efficient base-catalyzed one-pot strategy. Mechanistic studies indicate that the σ adduct from carbanion addition to hydrogen serves as the sole intermediate for all of the aforementioned transformations. These molecules show intense luminescence and the subsequent one-step structural modification results in the aggregation-induced emission (AIE) derivatives with redshifted full-color tunable fluorescence, large Stokes shifts, and good quantum yields. Further living cell imaging investigations suggest their potential application as specific bioprobes for lipid droplet localization and visualization.