A Pd-catalyzed decarboxylative dearomatization reaction of a heterocyclic substrate enables access to an uncommon reaction intermediate that rearomatizes in the presence of amine bases in a net C-H functionalization sequence. The dearomatized benzo[b]thiophene intermediate bears an exocyclic alkene that can be functionalized through cycloaddition and halogenation reactions to deliver complex heterocyclic products.
Keywords: C–H functionalization; Dearomatization; Decarboxylation; Heterocycles; Transition-metal.