Oxidative C-H/C-H Annulation of Imidazopyridines and Indazoles through Rhodium-Catalyzed Vinylene Transfer

Transition-metal-catalyzed C−H activation followed by oxidative annulation with alkynes has been an efficient syn-thetic tool for the assembly of various poly-aromatic scaffolds. Despite the substantial progress in this field, it is still a significant challenge to achieve the synthesis of non-substituted vinylene-fused compounds. In this contribution, we report a Rh-catalyzed C−H/C−H vinylene cyclization adopting vinylene carbonate as a “vinylene transfer” agent. This protocol achieves the direct annula-tive π-extension of imidazole- and pyrazole-fused aromatics.Ghosh K., Nishii Y., Miura M.. Oxidative C-H/C-H Annulation of Imidazopyridines and Indazoles through Rhodium-Catalyzed Vinylene Transfer. Organic Letters. 22(9), 3547-3550, (2020), 1 May 2020; ©2020 American Chemical Society. https://doi.org/10.1021/acs.orglett.0c00975