C−H Methylation of Iminoamido Heterocycles with Sulfur Ylides**

Asymmetric transformations from sulfoxonium ylides

Sulfoxonium ylides are important surrogates for diazo compounds, and their use in industry as safer alternatives has been evaluated during recent years. Beyond the known classical transformations, these ylides have also been used in a surprising plethora of novel and intrinsic chemical reactions, especially in recent years. Bench stability and handling are also an advantage of this class of organosulfur molecules. Despite this, efficient asymmetric transformations, specifically catalytic enantioselective versions, have only recently been reported, and there are specific reasons for this. This perspective article covers this topic from the first studies up to the latest advances, giving personal perspectives and showing the main challenges in this area in the coming years.

Iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabled aldehyde C-H methylation

A practical and general iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabling aldehyde C-H methylation for the synthesis of methyl ketones has been developed. This mild, operationally simple method uses ambient air as the sole oxidant and tolerates sensitive functional groups for the late-stage functionalization of complex natural-product-derived and polyfunctionalized molecules.

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

Direct C(sp² )-H functionalization through nitroarene-triggered nucleophilic aromatic substitution of hydrogen (SNAr^H ) has attracted growing attention, owing to its high efficiency and low carbon footprint. In this study, non-nitro-group-assisted S_N Ar^H 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^H adduct formation to fulfill the intramolecular C(sp² )-C(sp³ ) bond construction. Notably, the cyano group serves as both the electron-withdrawing group to activate the C(sp³ )-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^H 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.