10.1021/jo990412u.s001 Claus-Dieter Graf Claus-Dieter Graf Christophe Malan Christophe Malan Klaus Harms Klaus Harms Paul Knochel Paul Knochel New Homochiral Ligands Bearing Nonstereogenic Chirotopic Centers. Lithiated <i>N</i>,<i>N</i><i>‘</i>-Dialkylureas as Chiral Bases and Sterically Crowded Phosphines for Asymmetric Catalysis American Chemical Society 1999 ureas 2 ee C 2 monophosphine 3 Chiral Bases Lithiated N ligand ketone New Homochiral Ligands Bearing Nonstereogenic Chirotopic Centers nonstereogenic chirotopic center achiral sterically enantiomeric type 1 alkylation synthesis alkyl diphosphine 23 allylation Sterically Crowded Phosphines dimethyl malonate Dialkylurea Asymmetric Catalysis homochiral enantioselective deprotonation Pd 1999-06-24 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/New_Homochiral_Ligands_Bearing_Nonstereogenic_Chirotopic_Centers_Lithiated_i_N_i_i_N_i_i_i_-Dialkylureas_as_Chiral_Bases_and_Sterically_Crowded_Phosphines_for_Asymmetric_Catalysis/3718164 The synthesis of new homochiral pseudo-<i>C</i><i><sub>2</sub></i>-symmetrical ligands of type <b>1</b> bearing a nonstereogenic chirotopic center is reported. Two such structural units are combined in the ureas <b>2</b> and <b>10</b>, which proved to be useful for enantioselective deprotonation and alkylation of ketones (up to 88% <i>ee</i>). The monophosphine <b>3</b> induced a high enantiomeric excess in the Pd-catalyzed allylation of dimethyl malonate (up to 73% <i>ee</i>). Furthermore, we have shown that the achiral sterically crowded alkyl diphosphine <b>23</b> efficiently stabilized Pd(0) at high temperatures.