Three-component cascade carbopalladation/Heck cyclization/borylation: facile access to boryl-functionalized indenes

Abstract

A mild Pd-catalyzed three-component cascade cyclization functionalization of o-iodostyrenes, internal alkynes and boron reagents is presented. The transformation is driven by a controlled reaction sequence of intermolecular carbopalladation, intramolecular Heck-type cyclization, and a borylation process to give versatile boryl-functionalized indene skeletons in a selective fashion. Significantly, (Bpin)₂, (Bneop)₂ and CH₂(Bpin)₂ as boron sources are all tolerated. Additionally, the synthetic utility of this approach is demonstrated by gram-scale synthesis and synthetic transformations.