of fused bicyclic ring systems via intramolecular C–H insertion reaction of σ-symmetric α-alkyl-α-diazoesters is described. With dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh2(S-PTTL)4, the C–H insertion proceeded in a chemoselective manner to give methyl bicyclo[3.3.0]oct-7-ene-2-carboxylate and methyl bicyclo[4.3.0]nonane-7-carboxylate derivatives with up to 99% ee and perfect cis diastereoselectivity