Cyclic Diaryl λ -Bromanes as Original Aryne Precursors.

Despite the widespread application of hypervalent iodines, the corresponding λ -bromanes are less explored. Herein we report a general, safe, and high-yielding strategy to access cyclic diaryl λ -bromanes. These unique compounds feature reactivity that is appealing and complementary to that of λ -iodanes, generating arynes under mild reaction conditions and in the presence of a weak base. Accordingly, formal meta-selective transition-metal-free C-O and C-N couplings may be achieved. Mechanistic studies unambiguously support the aryne generation mechanism.