pH-Selective Synthesis of Amino Acids Catalyzed by a Water-Soluble Iridium Hydride Complex

摘要

pH-Selective catalytic synthesis of natural a-amino acids with non-polar side chains,a polar uncharged side chain,and a polar charged side chain has been achieved by reductive amination of commercially available alpha-keto acids with a transition metal catalyst and HCOONH_4.The catalyst is a water-soluble mononuclear iridium hydride complex [Cp*Ir~III(bpy)H]_2(SO_4)(1,Cp* = rf-QMe,,bpy = 2,2'-bipyridine).HCOONH_4 is utilized as an amine donor(NH_4~+)as well as a hydrogen donor(HCOO~-)in aqueous media.The selective synthesis of a-amino acids without formation of a-hydroxy carboxylic acids as a by-product has been made poss1ble under the optimized pH conditions.