Catalytic Asymmetric C
−H Functionalization under Photoredox Conditions by Radical Translocation and Stereocontrolled Alkene Addition |
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Authors: | Chuanyong Wang Dr. Klaus Harms Prof. Dr. Eric Meggers |
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Affiliation: | Fachbereich Chemie, Philipps-Universit?t Marburg, Marburg, Germany |
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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. |
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Keywords: | asymmetric catalysis C− H activation photochemistry radicals rhodium |
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