Iridium-Catalyzed Annulation of o-Carboranyl Carboxylic Acids with Alkynes: Synthesis of Carborano-Isocoumarins

An efficient iridium-catalyzed formal [4+2] annulation of carboranyl carboxylic acids with alkynes is developed, resulting in the facile synthesis of a new class of carborano-isocoumarin derivatives. The carboxyl group not only serves as a directing group to control the regioselectivity but also ingeniously becomes a part of the final products. The reaction mechanism involves sequential carboxyl-directed B(4)-H metalation, alkyne insertion, and reductive elimination.

Automated summary

An efficient iridium-catalyzed formal [4+2] annulation of carboranyl carboxylic acids with alkynes has been developed, allowing for the facile synthesis of a new class of carborano-isocoumarin derivatives. The carboxyl group not only acts as a directing group for regioselectivity control but also cleverly becomes a part of the final products. The reaction mechanism involves sequential carboxyl-directed B(4)-H metalation, alkyne insertion, and reductive elimination.