Die Reaktion von 3-Benzoylchromon mit Diphenylketen. 28. Mitt. über Untersuchungen an 4-Pyronen

The Reaction of 3-Benzoylchromone with Diphenylketene By action of diphenylketene on 3-benzoylchromone ( 3 ) two products are obtained. The result depends on the reaction conditions: 1,4-cycloaddition yields 2-oxo-2H-pyrano-chromanone 6 , while decarboxylation gives triphenylethenyl-chromone 11 , which can be converted into the corresponding 4-thiochromone 15 or into an acetophenone derivative 16 .