Semi-preparative gas chromatographic separation of all-trans-perhydrotriphenylene enantiomers on a chiral cyclodextrin stationary phase

Enantiomers of all-trans-perhydrotriphenylene (PHTP) were separated by gas chromatography using heptakis(6-O-tert.-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin (TBDMS-β-CD) as the chiral selector. Conditions for semi-preparative separations were established using a 2 m×2 mm I.D. packed column and subsequently extended to a 1.8 m×4 mm I.D. column which enabled separations on a mg scale. The column packing was TBDMS-β-CD dissolved in SE-54 coated on Chromosorb P AW-DMCS 80–100 mesh. Optimization of the chromatographic conditions (oven temperature, carrier gas flow, and column load) with respect to better efficiency and peak retention resulted in a system capable of separating up to 10 mg of the racemate per day. Purities of separated enantiomers were determined by capillary gas chromatography. Yields and purities of the fractions obtained by single- and double-step separations are compared. Highly enriched enantiomers with purities of up to 99.6% (99.2% ee) were obtained by a single separation step.