Synthesis of Functionalized (η5 -Indenyl)rhodium(III) Complexes and Their Application to C-H Bond Functionalization.

It has been established that reductive complexation of functionalized benzofulvenes, which are readily prepared from commercially available indene and 2-methylindene, with RhCl3 in ethanol affords the corresponding indenyl-rhodium(III) dichlorides bearing substituents at the 1- (H or CO2 Et), 2- (H or Me), and 3- [CH2 Ph or CH2 (2-MeOC6 H4 )] positions. The indenyl-rhodium(III) complexes bearing one ethoxycarbonyl group showed higher thermal stability and regioselectivity than our previously reported CpE RhIII complex toward the oxidative [3+2] annulation of acetanilides with internal alkynes.