Enantio- and Diastereoselective Synthesis of <i>cis</i>-2-Aryl-3-methoxycarbonyl-2,3-dihydrobenzofurans via the Rh(II)-Catalyzed C−H Insertion Process

Abstract

[formula: see text] 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], Rh2(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.