Efficient Chemoenzymatic Synthesis of Chiral Pincer Ligands

Chiral, nonracemic pincer ligands based on the 6-phenyl-2-aminomethylpyridine and 2-aminomethylbenzo[h]quinoline scaffolds were obtained by a chemoenzymatic approach starting from 2-pyridyl and 2-benzoquinolyl ethanone. In the enantiodifferentiating step, secondary alcohols of opposite absolute configuration were obtained by Baker’s yeast reduction of the ketones and by lipase mediated dynamic kinetic resolution of the racemic alcohols. Their transformation into homochiral 1-methyl-1-heteroarylethanamines occurred without loss of optical purity giving access to pincer ligands, used in enantioselective catalysis