Optically Active Spiranes, XI: Syntheses of Optically Active Mono to Heptasubstituted 5-Methyl and Ethyl-2,2'-Spirobiindanes and Related Naphthalene Derivatives of Known Chirality and Enantiomeric Purity

Article abstract of DOI:10.1007/BF00899783

Starting from optically active 5,5'-dimethyl, diethyl, and 5-ethyl-5'-methyl-2,2'-spirobiindane as well as from 5'-ethyl-spirobiindane-5-carboxylic ester of known enantiomeric purity and configuration 75 mono to polysubstituted 2,2'-spirobiindanes have been prepared.Amongst these are several compounds with rings anellated in the 6,7 (and 6',7') positions, especially a spirohydrocarbon 4x with orthogonal naphthalene units the circular dichroism of which is reported and discussed.Several mono and disubstituted 5-methyl and ethylindanes (1, 2) have been prepared as models for synthetic transformations in the spirobiindane series.From the molar rotations of symmetrically diacylated 5,5'-dimethyl and diethyl spirobiindanes (4a, 7b, 7c) empirical ligand parameters λ for acetyl and methoxycarbonyl were determined which gave much better results in the calculation of the rotations of appropriate spirobiindanes (with the "shortened polynomal Ansatz") than the λ-values deduced previously from 5,5'-disubstituted spirobiindanes.The significance of these results is briefly discussed. - Keywords: Chirality function; Circular dichroism; Ligand parameters; 5-Methyl and ethylindanes; 1H-NMR spectra