trans-Diastereoselective Ru(II)-Catalyzed Asymmetric Transfer Hydrogenation of α‑Acetamido Benzocyclic Ketones via Dynamic Kinetic Resolution

A highly efficient enantio- and diastereoselective catalyzed asymmetric transfer hydrogenation via dynamic kinetic resolution (DKR–ATH) of α,β-dehydro-α-acetamido and α-acetamido benzocyclic ketones to ent-trans-β-amido alcohols is disclosed employing a new ansa-Ru­(II) complex of an enantiomerically pure syn-N,N-ligand, i.e. ent-syn-ULTAM-(CH₂)₃Ph. DFT calculations of the transition state structures revealed an atypical two-pronged substrate attractive stabilization engaging the commonly encountered CH/π electrostatic interaction and a new additional OSO···HNAc H-bond hence favoring the trans-configured products.