Metal-free site-selective functionalization with cyclic diaryl λ3-chloranes: suppression of benzyne formation for ligand-coupling reactions

Abstract

While hypervalent halogens are versatile reagents enabling diverse reactions in organic synthesis, the utility of hypervalent chlorine compounds, particularly cyclic λ³-chloranes, remains underdeveloped despite their unique electronic properties and innate enhanced reactivity. Herein, we illustrate the elusive ligand coupling reaction of cyclic λ³-chloranes that suppresses the more facile competing reaction modality involving benzyne intermediates. The methodology can be performed in three-component as well as two-component fashions, offering direct access to a wide range of unsymmetrically substituted biaryl molecules in very high yields and excellent ortho-regioselectivity. The reactions were scalable, and the versatility was demonstrated by constructing different types of C–S and C–N bonds under mild conditions. The reaction outcomes were also compared with those of corresponding λ³-iodanes and λ³-bromanes, demonstrating the superiority of cyclic λ³-chloranes in ligand-coupling reactions under metal-free conditions.