PREPARATION OF MILLIGRAMS OF PURE ENANTIOMERS USING ANALYTICAL-SCALE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Pure enantiomers of an agrochemical process intermediate, (RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)-pentan-3-one (1), have been prepared on the milligram scale under overload chromatographic conditions on an analytical chiral column (250 x 4.6 mm i.d.). The effects of variation of temperature and mobile phase composition on retention factor, separation factor, and peak resolution have been investigated. Effects,of now rate, enantiomer ratio, sample concentration, and column load on productivity are also studied. Seven milligrams of the less retained (+)-enantiomer and 5 mg of the (-)-enantiomer were obtained from a single injection of 21 mg of (RS)-1. (C) 1994 Wiley-Liss, Inc.