Dong Z, Li J, Yao T, Zhao C. Palladium-Catalyzed Enantioselective C-H Olefination to Access Planar-Chiral Cyclophanes by Dynamic Kinetic Resolution.
Angew Chem Int Ed Engl 2023:e202315603. [PMID:
37919238 DOI:
10.1002/anie.202315603]
[Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 10/31/2023] [Accepted: 11/02/2023] [Indexed: 11/04/2023]
Abstract
Planar-chiral cyclophanes have received increasing attention for drug discovery and catalyst design. However, the catalytically asymmetric synthesis of planar-chiral cyclophanes has been a longstanding challenge. We describe the first Pd(II)-catalyzed enantioselective C-H olefination of prochiral cyclophanes. The low rotational barrier of less hindered benzene ring in the substrates allows the reaction to proceed through a dynamic kinetic resolution. This approach exhibits broad substrate scope, providing the planar-chiral cyclophanes in high yields (up to 99 %) with excellent enantioselectivities (up to >99 % ee). The ansa chain length scope studies reveal that the chirality of the cyclophanes arises from the bond rotation constraint of the benzene ring around the macrocycle plane, rather than the C-N axis. The C-H activation approach is also applicable to the late-stage modification of bioactive molecules and pharmaceuticals.
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