Gas chromatography–mass spectrometry of the stereoisomers of heterocyclic compounds. Part 3.† Perhydro-4-thia-s-indacene

Abstract

A gas chromatographic-mass spectrometric study of mixtures of the stereoisomers of perhydro-4-thia-s-indacene (PHTI) has been carried out. Separation has been accomplished on a column packed with graphitized thermal carbon black (GTCB) and on a capillary column of high efficiency. In addition to the known cis-syn-cis isomer, five novel diastereomers have been found. The stereospecificity of their fragmentation under electron impact appeared to be quite distinct and mass spectra (70 eV) of cis-cis, trans-cis and trans-trans conjugated isomers were distinguished. An important part in the structural elucidation of the novel isomers is played by molecular statistical calculations of the thermodynamic parameters of their adsorption on GTCB, which were performed on the basis of hypothetical molecular structures of these compounds optimized by molecular mechanics. Evidence for the existence of cis-cis isomers with the middle ring in a boat conformation obtained from these data is discussed.

Molecular statistical calculation of thermodynamic characteristics of adsorption of O-, S-, and Se-containing heteroadamantanes on graphitized thermal carbon black

“…25 For example, the conformational composition, separation on the GTC, and identification by chromatography coupled with mass spec trometry of stereoisomeric perhydrothioxanthenes, per hydroxanthenes, and perhydro 4 thia s indacenes have been studied earlier. 24,[33][34][35] Good agreement between the experimental and theoretically calculated TCA values (in particular, К 1,С and q -dif,1 ) for diverse stereoisomers was established 24,33-35 when the earlier 27,28 determined AAP parameters were used in the form of Eq. (2).…”

“…Therefore, the structures of oxa , thia , and selenaadamantanes can include both substituted and unsubstituted cyclohexane moieties, whose ratio is determined by the number and position of hetero atoms in the molecule. Since in perhydroxanthenes and perhydro 4 thia s indacenes the oxygen and sulfur atoms also substitute the СН 2 groups in the saturated cyclo hexane ring, our molecular statistical calculations of the TCA of heteroadamantanes are based on the AAP param eters known from the literature 34, 35 (see Table 1). In addi tion, we used the AAP parameters for the selenium atoms calculated earlier 36 and approved by us for molecules of tetrahydroselenophene, selenophene, and benzo selenophene.…”