Secondary phosphine oxides: tautomerism and chiral recognition monitored by multinuclear NMR spectroscopy of their Rh2[(R)-MTPA]4 adducts.
Six secondary phosphine oxides and their tautomeric equilibria as free ligands and in the presence of an equimolar amount of the chiral dirhodium complex Rh* are described and discussed. Discrimination of enantiomers is easily possible by inspecting the (31)P NMR resonances; some (1)H and (13)C NMR resonances are useful as well. H/D exchange of the acidic protons in the phosphine oxides takes place with acetone-d(6), the solvent additive, after some hours but does not obscure the chiral recognition experiment. (103)Rh,(31)P coupling constants are discussed briefly. Decomposition of ligand molecules in 1:1-Rh*-adducts occurs slowly but completely.
Magiera
Damian
D
Universität Hannover, Institut für Organische Chemie, Hannover, Germany.
Szmigielska
Anna
A
Pietrusiewicz
K Michal
KM
Duddeck
Helmut
H