Substituent-Controlled\nCopper-Catalyzed Trifluoromethylation\nof 1,7-Dienes: Synthesis of Mono- and Bis-trifluoromethylated Benzoxepines

A copper-catalyzed trifluoromethylation of benzene-linked\n1,7-dienes\nwith 1-trifluoromethyl-1,2-benziodoxole via a radical cascade cyclization\nprocess for the synthesis of mono- and bis-trifluoromethylated benzoxepines\nis developed. The selectivity depends on substituents on the double\nbond of the allyl group in 1,7-dienes. The large-scale operation and\nlate-stage functionalization of bioactive molecules reveal the promising\nutility of this protocol.