engleski

Mechanochemical catalyst- and additive-free halogenation and imidation of azobenzenes with strong electron-donating substituents

Halogenated arenes are important precursors in cross-coupling reactions and components of numerous organic and natural compounds, pharmaceuticals, new materials, etc. Although ball milling methods are widely used for the synthesis of various classes of compounds, their application in the synthesis of halogenated arenes is still scarce. In this work, we present a catalyst- and additive- free protocol for the halogenation of 4, 4’- functionalized electron-rich azobenzenes in a ball mill under NG conditions, using N-halosuccinimides as a halogen source. These transformations resulted in the products halogenated in ortho- position to the electron-donating groups, while the reactions of azobenzenes containing dimethylamino group as substituent with NIS led to imidation products. The protocols described above provide a mild and environmentally friendly approach for the halogenation of Csp2–H bonds and the imidation of Csp3–H bonds of azobenzenes with electron-donating substituents by electrophilic activation using N-halosuccinimides.

mechanochemistry ; halogenation ; imidation ; catalyst-free ; additive-free

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