Enzymatic resolution of α-hydroxyphosphinates with two stereogenic centres and determination of absolute configuration of stereoisomers obtained

The use of quinine as a chiral solvating agent allows us to determine a tentative absolute configuration at the phosphorus atom of hydroxyphosphinates with two stereogenic centres (at the phosphorus and α-carbon atoms). Two ethyl butyryloxyalkane( P -phenyl)phosphinates were hydrolysed using various lipases. In all cases isomers possessing α-carbon atom with an ( S )-configuration were hydrolysed preferentially. The absolute configuration of both chiral centres of obtained α-hydroxyphosphinates was determined by using ( S )-(+)-MTPA-Cl and quinine. The mode of chiral discrimination of α-hydroxyphosphinates by quinine was studied by means of computational chemistry, which confirmed the experimental findings that the signals in 31 P NMR spectra of compounds with an ( R P )-configuration are situated upfield when compared with the respective ( S P ) isomers.