Sugar derived hexacoordinated phosphates: chiral anionic auxiliaries with general asymmetric efficiency.
Mannose-derived hexacoordinated phosphate anions, prepared in as few as two steps from methyl-alpha-D-mannopyranoside and tris(dimethylamino)phosphine, are chiral anionic auxiliaries with broad asymmetric efficiency. These chemically robust anions are effective NMR chiral solvating agents and efficient asymmetry-inducers, able to control the configuration of conformationally labile C2-symmetric monomethinium cations (organic, helical, charge 1+, P or M enantiomers) and D3-symmetric iron(II) trisdiimine complexes (metallo-organic, octahedral, charge 2+, Delta or Lambda enantiomers). Diastereomeric control with often unmatched selective levels was achieved with the help of mannopyranoside backbone of the anions and the substituents on the [1,3]dioxane ring that play a key role in the recognition process, something not obvious at first sight.
Pérollier
Céline
C
Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland.
Bernardinelli
Gérald
G
Lacour
Jérôme
J