Synthesis of 5H-Dibenzo[c,g]chromen-5-ones via FeCl3-Mediated Tandem C–O Bond Cleavage/6π Electrocyclization/Oxidative Aromatization

A novel and expedient method for transformation of readily available 1-isochromanones bearing a diaryl allenic moiety at the C4-position to functionalized 5H-dibenzo[c,g]chromen-5-ones under mild conditions is developed. This strategy is based on the dual abilities of iron(III) chloride to promote selective C–O bond cleavage/6π electrocyclization and an oxidative aromatization sequence.