Iridium-Catalyzed Enantioconvergent\nConstruction of\nPiperidines and Tetrahydroisoquinolines from Racemic 1,5-Diols

We report herein a one-step synthesis of valuable enantioenriched\npiperidines and tetrahydroisoquinolines from readily available racemic\n1,5-diols. Key to the success is the development of new iridacycle\ncatalysts that enable efficient redox-neutral construction of two\nC–N bonds between diols and amines in an enantioconvergent\nfashion. Mechanistic studies identified an intriguing preferential\noxidation of secondary versus primary alcohol in the diol substrate\nby the iridacycle catalyst, which set a challenging intermolecular\namination of aryl–alkyl-substituted alcohol as the enantiodetermining\nstep for this catalytic <i>N</i>-heterocycle synthesis.\nApplication of this catalytic method to the preparation of important\ndrugs and bioactive compounds is also demonstrated.