Iron(iii) halide or iodine-promoted synthesis of 3-haloindene derivatives from o-alkynylarene chalcones

Abstract

o-Alkynylarene chalcones, when treated with ferric halides/iodine, undergo cyclization to give synthetically important 3-haloindene derivatives in good yields. The reactions proceed through Lewis acid-promoted intramolecular nucleophilic addition of the alkyne unit to the enone moiety followed by halide capture of the resulting vinyl carbocation intermediate. The reactions are operationally simple, require only inexpensive and environmentally friendly reagents and are applicable to a range of substrates.