Chromatographic enantiomer separation and absolute configuration of spiro[benzo-1,3-dioxole-2,9′-bicyclo[3.3.1]nonan]-2′-one and the corresponding diastereomeric hydroxy acetals

The enantiomers of spiro[benzo-1,3-dioxole-2,9'-bicyclo[3.3.1]nonan]-2'-one 2 and the corresponding diastereomeric exo-2'- and endo-2'-hydroxy acetals 3a,b obtained from this monoacetal were solved by HPLC on a swollen microcrystalline triacetylcellulose column. The absolute configuration of the enantiomers of 2 and 3a,b was assigned based on the signs of the Cotton effect and employing the octant rules for the carbonyl and the aromatic chromophores The low intensity of the band at 290 nm in the CD spectrum of monoacetal 2 was accounted far by the interaction of the carbonyl and aromatic chromophores.