Journal of Molecular Catalysis A-Chemical, Vol.196, No.1-2, 39-53, 2003
Synthesis and properties of pentacoordinated phospha derivatives of iso-leucinol - A rare example of using of hydrophosphoranes as ligands in asymmetric catalysis
New bicyclic (1) and tricyclic (2a) hydrophosphoranes have been synthesized from iso-leucinol. Complexation of bicyclic hydrophosphorane 1 with [PdCl2(COD)], [PdCl2(RCN)(2)] and [Pd(allyl)Cl](2) has been found to give chelate products [PdCl2(L)] and [Pd(allyl)(L)]Cl-+(-) containing an "open" form of the phosphorane. Tricyclic hydrophosphorane 2a, as well as its homologue 2b, forms metal complexes with P-monodentate binding of a hydrophosphorane, phosphoranide or "open" form of the ligand. Up to 74% ee has been achieved in the Pd-catalyzed alkylation of 1,3-diphenylallyl acetate with dimethyl malonate using 1 and 2a and 2b as chiral ligands. (C) 2002 Elsevier Science B.V. All rights reserved.