Enantioselective Desymmetrization of Diphenylphosphinamides via (-)-Sparteine-Mediated Ortho-Lithiation. Synthesis of P-Chiral Ligands

Asymmetric ortho-lithiation of N-dialkyl-P, P-diphenylphosphinamides using [n-BuLi.(-)-sparteine] is described as an efficient method for the synthesis of P-chiral ortho-functionalized derivatives in high yields and ee's from 45 to >99%. The method allows access to new enantiomerically pure P-chiral phosphine and diimine ligands.