Regioselective lithiation of silyl phosphine sulfides: asymmetric synthesis of P-stereogenic compounds.
Starting from a trimethylsilyl-substituted phosphine sulfide of 99:1 er (generated by n-BuLi/(-)-sparteine-mediated asymmetric lithiation of a dimethylphosphine sulfide), a two-step process of regioselective lithiation-trapping and silyl group removal has been used to prepare a range of P-stereogenic compounds, including precursors to diphosphine ligands (e.g., Mini-PHOS). This two-step protocol delivers products with the opposite configuration to that obtained by direct asymmetric lithiation-trapping of a dimethylphosphine sulfide using n-BuLi/(-)-sparteine.
Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
Jonathan J
JJ
Gammon
Peter
P
O'Brien
Brian
B
Kelly