C‐5′‐Substituted Cinchona Alkaloid Derivatives Catalyse the First Highly Enantioselective Dynamic Kinetic Resolutions of Azlactones by Thiolysis

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AbstractThe highly enantioselective dynamic kinetic resolution (DKR) of azlactones by thiolysis has been achieved for the first time. Although both the parent alkaloid quinine and known C‐5′‐urea derivatives fail to promote the reaction effectively, a new class of C‐5′‐hydroxylated catalysts proved capable of catalysing the DKR of a range of azlactones derived from both unbranched‐ and, previously challenging, branched‐chain amino acids in 84–92 % ee, including an example of the synthesis of an enantioenriched N‐protected thioester derived from an extraterrestrial amino acid isolated from the Murchison meteorite.