10.1021/ja8001343.s006 Peng Fu Peng Fu Marc L. Snapper Marc L. Snapper Amir H. Hoveyda Amir H. Hoveyda Catalytic Asymmetric Alkylations of Ketoimines. Enantioselective Synthesis of <i>N</i>-Substituted Quaternary Carbon Stereogenic Centers by Zr-Catalyzed Additions of Dialkylzinc Reagents to Aryl-, Alkyl-, and Trifluoroalkyl-Substituted Ketoimines American Chemical Society 2008 esters Ketoimine alkylation ketoimine chiral 2 Zn quaternary carbon stereogenic center Catalytic Asymmetric Alkylations Substituted Quaternary Carbon Stereogenic Centers Et 2 Zn 2008-04-23 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Catalytic_Asymmetric_Alkylations_of_Ketoimines_Enantioselective_Synthesis_of_i_N_i_Substituted_Quaternary_Carbon_Stereogenic_Centers_by_Zr_Catalyzed_Additions_of_Dialkylzinc_Reagents_to_Aryl_Alkyl_and_Trifluoroalkyl_Substituted_Ketoimines/2943166 Catalytic enantioselective alkylations of three classes of ketoimines are reported. Reactions are promoted in the presence 0.5–10 mol % of a Zr salt and a chiral ligand that contains two inexpensive amino acids (valine and phenylalanine) and involve Me<sub>2</sub>Zn or Et<sub>2</sub>Zn as alkylating agents. Requisite aryl- and alkyl-substituted α-ketoimine esters, accessed readily and in >80% yield on gram scale through a two-step sequence from the corresponding ketones, undergo alkylation to afford quaternary α-amino esters in 79–97% ee. Aryl-substituted trifluoroketoimines are converted to the corresponding amines by reactions with Me<sub>2</sub>Zn, catalyzed by a chiral complex that bears a modified <i>N</i>-terminus. The utility of the catalytic asymmetric protocols is illustrated through conversion of the enantiomerically enriched alkylation products to a range of cyclic and acyclic compounds bearing an <i>N</i>-substituted quaternary carbon stereogenic center.