Chemoselective aromatic C-H insertion of α-diazo-β-ketoesters catalyzed by dirhodium(II) carboxylates.

The ability of α-diazo-β-ketoesters bearing a substituent on the benzylic position to undergo aromatic C-H insertion is described. Good to excellent yields of the aromatic C-H insertion products were observed with Rh(2)(tpa)(4) or Rh(2)(esp)(2) catalysts. This is an attractive strategy to prepare tetralins carrying a methyl group on the benzylic position, a structural motif found in several types of natural products.