fused-ring-system formation oxacycle synthesis Allan-Robinson flavone synthesis Allan-Robinson isoflavone synthesis Allan-Robinson reaction RXNO RXNO:0000475 Reaction of ortho-hydroxyaryl ketones with aromatic acid anhydrides to yield a flavone or isoflavone. https://www.rsc.org/Merck-Index/reaction/r6/ https://www.wikidata.org/wiki/Q3046015