Fused Heteroaromatic Rings via Metal-Mediated/Catalyzed Intramolecular C-H Activation: A Comprehensive Review.

The present review highlights the most important recent contributions toward the synthesis of functionalized fused heteroaromatic rings via intramolecular C-H activation mediated or catalyzed by transition metals. This type of reaction constitutes a versatile strategy to obtain a great variety of fused heterocyclic systems through the formation of carbon-carbon (C-C) and C-heteroatom bonds from direct coupling between two adjacent C-H bonds or C-H/H-X bonds. The  revision is focused on the synthesis of fused heterocycles through two chemical processes: (1) metal-catalyzed intramolecular oxidative C-H activation, and (2) intramolecular C-H activation mediated by metallic Lewis acids.