Ag-Catalyzed Domino Decarboxylative Alkylation/Dearomative Annulation: Entry to Fused-Pyrido[4,3-]Indolones.

Here we report the development of unprecedented silver-catalyzed intramolecular annulations of -acrolyl-2-(3-indolyl) benzimidazoles with alkyl carboxylic acids to construct complex fused-pentacyclic alkaloid scaffolds. Divergent reactivities are noticed with altered groups at C2-indole of the substrate. The reaction proceeds through decarboxylative alkylation, followed by dearomative annulation in a domino manner with excellent diastereoselectivity. Owing to the reactivity of the -OH group, these aza-enriched scaffolds can be further functionalized.