Regiochemical control of the addition of aryl selenols and aryl thiols to the triple bond of arylpropiolates. Synthesis of seleno- and thioflavones and seleno- and thioaurones
two: α‐Diazocarbonyl compounds display a diverse pattern of reactivity upon palladium‐catalyzed reaction with esters. Esters bearing an alkynyl group on the carbonyl carbon atom lead to two different CC bonds at the same carbon atom in a single operation through decarboxylation and migratory insertion, whereas aromatic and benzylic acid derivatives afford aromatic and benzylic esters bearing an O‐substituted