Abstract
Gas chromatographic separations of the stereoisomers of menthol derivatives, important intermediates in the synthesis of physiologically active natural products, were carried out on several substituted β-cyclodextrin (CD) columns, including per-O-methyl-β-cyclodextrin (PME-β-CD), heptakis(2,3-di-O-acetyl-6-tert-butyldimethylsilyl)-β-CD (DIAC-6-TBDS-β-CD), and heptakis(2,3-di-O-methyl-6-tert-butyldimethylsilyl)-β-CD (DIME-6-TBDS-β-CD) as chiral stationary phases (CSPs). With the DIME-6-TBDS-β-CD column, a separation of the Z- and E-isomers of methylidenementhol was accomplished; no separation was achieved with the other columns. The stereoisomers of methylidenementhol and the corresponding tert-butyldimethylsilyl (TBS) ether were separated on both the β-CD and the heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TME-β-CD) columns by high-performance liquid chromatography (HPLC) with a mobile phase involving acetonitrile and H2O. For the separation of the Z- and E-isomers of methylidenementhol, the TME-β-CD column was superior. In contrast, the β-CD column was preferable in the case of the corresponding TBS ether.
