Electrophilic Cyclizations of Diaryl-2,3-allenyl Ethers with N‑Bromosuccinimide: En Route to 2‑Bromonaphthalenes

The reaction of diaryl-2,3-allenyl ethers with N-bromosuccinimide in a mixed solvent of CH₃NO₂/EtOH affords highly functionalized 2-bromonaphthalenes in 21–66% yields. The electronic effect on the aryl is important to the selectivity of the reaction: when 4-(trifluoromethyl)­phenyl or 1-naphthyl was applied as one of the two aryl groups, the regioselectivity was practical, affording the products with the other relatively electron-rich phenyl ring or the non-1-naphthyl group being cyclized as the major, respectively.