Phosphothreonine as a Catalytic Residue in Peptide‐Mediated Asymmetric Transfer Hydrogenations of 8‐Aminoquinolines

Phosphothreonine (pThr) was found to constitute a new class of chiral phosphoric acid (CPA) catalyst upon insertion into peptides. To demonstrate the potential of these phosphopeptides as asymmetric catalysts, enantioselective transfer hydrogenations of a previously underexplored substrate class for CPA‐catalyzed reductions were carried out. pThr‐containing peptides lead to the observation of enantioselectivities of up to 94:6 e.r. with 2‐substituted quinolines containing C8‐amino functionality. NMR studies indicate that hydrogen‐bonding interactions promote strong complexation between substrates and a rigid β‐turn catalyst.