Facile separation of the enantiomers of diethyl N-(aryl)-1-amino-1-arylmethanephosphonates on a rationally designed chiral stationary phase

Separation of the enantiomers of each member of a series of diethyl N-(aryl)-1-amino-1-arylmethanephosphonates is easily accomplished by HPLC using a WHELK-O column. This totally synthetic chiral stationary phase (CSP 1) is designed to utilize specifiable interactions to differentiate between enantiomers. The structural features of these phosphonates suggested that CSP 1 would be applicable to the separation of the enantiomers of this class of compounds even though there was an element of uncertainty owing to the presence of two pi-basic interaction sites, one on either side of the stereogenic center. The structures of the pi-basic N-aryl and C-aryl substituents have been varied, the structure of the latter being found to have the greatest effect on retention and enantioselectivity.