Sulfonamides as N-Centered Radical Precursors for C-N Coupling Reactions To Generate Amidines.

Nitrogen-centered radicals (NCRs) are valuable intermediates for the construction of C-N bonds. Traditional methods for the generation of NCRs employ toxic radical initiators, transition metal catalysts, photocatalysts, or organometallic reagents. Herein, we report a novel strategy for the generation of NCRs toward the construction of C-N bonds under transition-metal-free conditions. Thus, super-electron-donor (SED) 2-azaallyl anions undergo single-electron transfer (SET) with sulfonamides, forming aminyl radicals (R2N•, R = alkyl) and culminating in the generation of amidines bearing various functional groups (33 examples, up to 96% yield). Broad substrate scope and gram-scale telescoped preparation demonstrate the practicality of this method. Radical clock and electron paramagnetic resonance (EPR) experiments support the proposed radical coupling pathway between the generated N-centered radical and the C-centered 2-azaallyl radical.

Aryl acrylonitriles synthesis enabled by palladium-catalyzed α-alkenylation of arylacetonitriles with vinyl halides/triflates.

Aryl acrylonitriles are an important subclass of acrylonitriles in the medicinal chemistry and pharmaceutical industry. Herein, an efficient synthesis of aryl acrylonitrile derivatives using a Palladium/NIXANTPHOS-based catalyst system was developed. This approach furnishes a variety of substituted and functionalized aryl acrylonitriles (up to 95% yield). The scalability of the transformation and the synthetic versatility of aryl acrylonitrile were demonstrated.