POLY(N(5)-BENZYL-L-GLUTAMINE)-COATED SILICA-GELS AS CHIRAL STATIONARY-PHASE FOR DIRECT RESOLUTION OF HYDANTOINS

Poly(N5-benzyl-L-glutamine) (PNLG), poly[N5-(+)-1-phenylethyl-L-glutamine] [P(+)NLG], and poly[N5-(+/-)-1-phenylethyl-L-glutamine) [P(+/-)NLG] were synthesized from poly [gamma-(beta-chloroethyl)-L-glutamate], which, in turn, was obtained by ester exchange of poly(gamma-methyl-L-glutamate) with 2-chloroethanol. The PNLG was found to exist mainly in an alpha-helical conformation in the film state by using circular dichroic and infrared spectra. Moreover, the PNLG, P(+)NLG, and P(+/-)NLG have been coated on macroporous silica gels (10 mum) and packed as chiral stationary phases for direct chromatographic resolution of 10 hydantoins. The column bearing PNLG resolved satisfactorily four hydantoins (alpha = 1.34-1.73), and the enantioselectivity (alpha) increased with the bulkiness of 5-substituent in hydantoins. On the other hand, an increase in 2-propanol concentration of the eluent (2-propanol/hexane) resulted in a smooth decrease of the capacity factor. However, the selectivity (alpha) increased slightly, indicating that the alpha-helix of PNLG plays an important role in chiral resolution. From these results, it is concluded that the main chiral recognition force is the steric hindrance between the 5-substituents of hydantoin and the side chains of PNLG. The temperature effect on the resolution of the hydantoins by PNLG was also investigated. (C) 1993 John Wiley & Sons, Inc.