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Enantioselective Reductive Homocoupling of Allylic Acetates Enabled by Dual Photoredox/Palladium Catalysis: Access to C2‑Symmetrical 1,5-Dienes

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journal contribution
posted on 05.08.2021, 19:03 by Hong-Hao Zhang, Menghan Tang, Jia-Jia Zhao, Changhua Song, Shouyun Yu
Transition-metal-catalyzed reductive coupling reactions have emerged as powerful protocols to construct C–C bonds. However, the development of enantioselective C­(sp3)–C­(sp3) reductive coupling remains challenging. Herein, we report a highly regio-, diastereo-, and enantioselective reductive homocoupling of allylic acetates through cooperative palladium and photoredox catalysis using diisopropylethylamine or Hantzsch ester as a homogeneous organic reductant. This straightforward protocol enables the stereoselective construction of C­(sp3)–C­(sp3) bonds under mild reaction conditions. A series of C2-symmetrical chiral 1,5-dienes were easily prepared with excellent enantioselectivities (up to >99% ee), diastereoselectivities (up to >95:5 dr), and regioselectivities (up to >95:5 rr). The resultant chiral 1,5-dienes can be directly used as chiral ligands in asymmetric synthesis, and they can be also transformed into other valuable chiral ligands.

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