Separation and absolute configuration of the enantiomers of a degradation product of the new inhalation anesthetic sevoflurane

In a rebreathing anesthesia circuit, the inhaled anesthetic sevoflurane deg rades into at least two products, termed "compound A" and "compound B." The enantiomer separation of the chiral compound B (1,1,1,3,3-pentafluoro-2-(f luoromethoxy)-3-methoxypropane) by capillary gas chromatography (cGC) using heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-beta -cyclodextrin a s chiral selector was studied. With this cyclodextrin derivative diluted in the polysiloxane PS 86, an unprecedented high separation factor alpha of 4 .1 (at 30 degreesC) was found. Consequently, the enantiomers of compound B were isolated by preparative GC and their specific rotations were measured. In addition, their absolute configurations were determined by X-ray crysta llography. To collect the X-ray data, single crystals of both enantiomers w ere grown in situ on the diffractometer. The levorotatory enantiomer B(-) h as the R-configuration while the dextrorotatory enantiomer B(+) has the S-c onfiguration. The elution order of the compound B enantiomers on heptakis(2 ,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-beta -cyclodextrin is R before S. (C) 2000 Wiley-Liss, Inc.