Optisch aktive aromatische Spirane, 13. Mitt.

Several optically active title compounds were obtained from the 4′-acetyl-4-carboxylic acid2 or the 4,4′-diacetyl derivative4. (−)-2 was accessible by optical resolutionvia its (−)-α-phenethylamine salts, (+)- and (−)-4 as well as the enantiomeric methylesters3 (of2) were obtained by chromatography on triacetylcellulose in ethanol. The enantiomeric purities were established either from the chromatographic results or from the1H-NMR spectra of the phenethyl-amine saltes (via the diastereotopic acetyl protons).