HPLC SEPARATION OF THE ZZ, ZE, EZ, AND EE GEOMETRIC ISOMERS AND EE ISOMER ENANTIOMERS OF A SUBSTITUTED PENTADIENYL CARBOXAMIDE USING ACHIRAL CHIRAL COLUMN-SWITCHING/

The four geometric isomers of a substituted pentadienyl carboxamide we re separated on an achiral aminopropyl column coupled with a silica pr ecolumn. The R and S enantiomers of the biologically active EE isomer (RO 24-0238 and RO 24-2099) were resolved (R(s) 1.65) on a cellulose-b ased chiral stationary phase (Chiracel OF). The coupled silica and ami nopropyl columns were connected to the Chiralcel OF column through a s ix port switching valve that enabled transfer to the EE isomer to the chiral phase for enantiomer resolution. By examining the selectivity f or separation of the geometric isomers of various achiral stationary p hases using hexane-isopropanol mobile phases, a method was developed w hich linked the achiral separation of the geometric isomers with the c hiral separation of the EE enantiomers.