Metal-Free Arylation-Lactonization Sequence of γ-Alkenoic Acids Using Anilines as Aryl Radical Precursors

Article abstract of DOI:10.1002/ejoc.201901679

The presence of salicylic acid (10 mol-%) and H₂O (10 equiv.) significantly improves the arylation-lactonization sequence of γ-alkenoic acids with in situ formed diazonium salts (from bench stable anilines). The reaction is finished in less than 5 h without thermal or photochemical activation, giving access to a variety of γ,γ-disubstituted butyrolactones. The protocol is user-friendly and can be used at gram-scale or adapted to transform alkenols into phthalanes. Control experiments revealed that aryl radicals participate in the reaction and a plausible mechanism is proposed to include this and other mechanistic investigations, for the catalyzed and the background reaction.