Effective enantiomeric separations of racemic primary amines by the isopropyl carbamate-cyclofructan6 chiral stationary phase

A new chiral stationary phase (CSP) was developed by bonding isopropyl-carbamate functionalized cyclofructan6 (IP-CF6) to the silica gel. It was evaluated by injecting 119 racemic primary amine-containing compounds. This CSP showed pronounced enantioselectivity toward all types of primary amines, separating 93% of all tested compounds. Baseline separation was achieved even for some simple aliphatic racemic amines that contained no other functionality. The polar organic mode was shown to be the effective mobile phase owing to higher efficiency. This new chiral stationary phase showed great potential for preparative-scale separations. It is also interesting that the chiral selector, R-naphthylethyl-carbamate functionalized CF6 (RN-CF6), was found to provide complementary selectivity for the relatively few amine analytes that did not separate on IP-CF6. Thus between the two CSPs, 98% of attempted amine compounds were separated.