Inclusion compounds of a borneol dumb-bell host with methylcyclohexanones and 2-butanols: structures and resolutions

Abstract

The host 2,2′-(benzene-1,4-diyl-diethynylene) diborneol has been employed to resolve racemic methylcyclohexanones and 2-butanol. For 2-methylcyclohexanone, the resultant inclusion compound yielded an enantiomeric excess of 72% (S) while with 3-methylcyclohexanone the enantiomeric excess was 57% (S). The host failed to resolve (R,S)-2-butanol, and the inclusion compounds derived from the (R,S)-, (R)- and (S)-2-butanol are isostructural, being dominated by a stable framework of host⋯host hydrogen bonds. The non-templating effect of the 2-butanol was explained in terms of the secondary interactions occurring in these structures which were also analysed by the program CrystalExplorer.