Rhodium/copper-catalyzed annulation of benzimides with internal alkynes: indenone synthesis through sequential C-H and C-N cleavage.

Doubled up: a rhodium(III)/copper(II) system co-catalyzes the annulation of benzimides with internal alkynes for the synthesis of indenones (see scheme; Cp*=C(5) Me(5)). The reaction involves an uncommon nucleophilic addition of a transition-metal-carbon bond to an imide moiety. This novel reaction provides a facile route to synthesize indenones from readily available benzimides and internal alkynes.