A One-Pot Method to Prepare 4,5-Benzotropones and 2,3,4,5-Dibenzotropones

Abstract An extremely simple method is developed to prepare 4,5-benzotropones and 2,3,4,5-dibenzotropones via one-pot cycloaddition reactions of alkynes with naphthoquinones and dibenzoquinones mediated by BF3·Et2O. Various mono- and disubstituted phenylacetylenes, multisubstituted 1,2-naphthoquinones and dibenzoquinone substrates are investigated. In addition, a scale-up synthesis of 7-phenyl-5H-dibenzo[a,c][7]annulen-5-one and further derivation of 7-(4-fluorophenyl)-5H-dibenzo[a,c][7]annulen-5-one are explored.