New chiral stationary phases containing a phosphorus atom as an asymmetric centre : I. Synthesis and first chromatographic results

Abstract

New chiral stationary phases with an asymmetric phosphorus atom have been prepared for the resolution of enantiomers. The synthesis was carried out by bonding an optically active phosphine oxide to a microparticulate γ-aminopropylsilanized silica gel via two different spacers. A baseline resolution of N-(3,5-dinitrobenzoyl) derivatives of α-amino esters and amines into their antipodes in a normal-phase system is often achieved, with resolution factors up to 4.3. Assignment of absolute configuration of the chiral phosphine oxides was established by chemical correlation. Additionally, NMR studies were made on the chemical shifts induced specifically on each enantiomeric form of the phosphine oxides in presence of the chiral solvating agent ( R)-N-(3,5-dinitrobenzoyl)-α-phenylethylamine.