Ga(OTf)3-mediated synthesis of substituted benzofurans

A synthetic procedure, for the synthesis of a series of functionalized benzofurans 3-5 and benzonaphthofurans 6, starting from intermolecular O-alkylation of alpha-bromoaryl ketones 2 with potassium oxygenated phenoxides 1 followed by Ga(OTf)(3)-catalyzed direct intramolecular cyclodehydration of the resulting alpha-aryloxyaryl ketones, has been developed. The use of various metal triflates was investigated for a facile approach and efficient transformation. Pentacyclic benzophenanthrofurans 7 were prepared via photolytic annulations of 5. (C) 2016 Elsevier Ltd. All rights reserved.