Synthesis of 5 H-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 5 H-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.