Cyclic Diaryl λ3 -Bromanes as Original Aryne Precursors

Abstract

Despite the widespread application of hypervalent iodines, the corresponding λ³ -bromanes are less explored. Herein we report a general, safe, and high-yielding strategy to access cyclic diaryl λ³ -bromanes. These unique compounds feature reactivity that is appealing and complementary to that of λ³ -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.

Keywords: arynes; hypervalent bromine; hypervalent iodine; metal-free coupling; λ3-bromanes.