4-Dimethylaminopyridine-catalyzed dynamic kinetic resolution in asymmetric synthesis of P-chirogenic 1,3,2-oxazaphospholidine-2-oxides

Abstract

Excellent diastereoselectivity (dr value up to 100 : 0) was achieved in DMAP-catalyzed P–N bond formation in the synthesis of P-chirogenic organophosphines from phenylphosphonic dichloride (PhP(O)Cl₂) and (S)-2-pyrrolidinemethanol derivatives. Investigations using NMR spectroscopy and calculations revealed the formation of a bimolecular complex from (PhP(O)Cl₂) and revealed DMAP as an ‘active phosphonyl’ that was converted to the P–N bonded compound with a significant preference for one of two diastereomers through dynamic kinetic resolution. These results present for the first time the mechanism of conversion from an achiral phosphorus centre to a P-stereogenic centre by direct stereoselective reaction at the phosphorus centre.