Catalytic Asymmetric C
−H Functionalization under Photoredox Conditions by Radical Translocation and Stereocontrolled Alkene Addition
Chuanyong Wang
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
Search for more papers by this authorDr. Klaus Harms
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
Search for more papers by this authorCorresponding Author
Prof. Dr. Eric Meggers
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
Search for more papers by this authorChuanyong Wang
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
Search for more papers by this authorDr. Klaus Harms
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
Search for more papers by this authorCorresponding Author
Prof. Dr. Eric Meggers
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
Search for more papers by this authorGraphical Abstract
The light combo: Through radical translocation, a photoredox-mediated C(sp3)−H activation was combined with asymmetric catalysis. Upon irradiation with visible light, α,β-unsaturated N-acylpyrazoles react with N-alkoxyphthalimides in the presence of a rhodium-based chiral Lewis acid catalyst and the photosensitizer fac-[Ir(ppy)3] to provide a C−C bond-formation product with high enantioselectivity and, where applicable, with some diastereoselectivity.
Abstract
This work demonstrates how photoredox-mediated C(sp3)−H activation through radical translocation can be combined with asymmetric catalysis. Upon irradiation with visible light, α,β-unsaturated N-acylpyrazoles react with N-alkoxyphthalimides in the presence of a rhodium-based chiral Lewis acid catalyst and the photosensitizer fac-[Ir(ppy)3] to provide a C−C bond-formation product with high enantioselectivity (up to 97 % ee) and, where applicable, with some diastereoselectivity (3.0:1 d.r.). Mechanistically, the synthetic strategy exploits a radical translocation (1,5-hydrogen transfer) from an oxygen-centered to a carbon-centered radical with a subsequent stereocontrolled radical alkene addition.
Supporting Information
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