Asymmetric Intramolecular C−H Insertions of Aryldiazoacetates
摘要:
[GRAPHICS]The enantioselectivity of Rh-2(SDOSP)(4) catalyzed C-H insertion of aryldiazoacetates is very dependent on the site of the C-H insertion. The highest enantioselectivity is obtained for insertion into methine C-H bonds.
[GRAPHICS]The enantioselective intramolecular C-H insertion reaction of aryldiazoacetates has been explored with use of dirhodium(II) carboxylate catalysts, which incorporate N-phthaloyl- or N-benzene-fused-phthaloyl-(S)-amino acids as chiral bridging ligands. Dirhodium tetrakis[N-phthaloyl-(S)tert-leucinate], Rh-2(S-PTTL)(4), has proven to be the catalyst of choice for this process, providing exclusively cis-2-aryl-3-methoxycarbonyl-2,3-dihydobenzofurans in up to 94% ee.