Synthesis of enantiomerically pure dissymmetric 2,2′-disubstituted 9,9′-spirobifluorenes

Racemic dissymmetric 2,2'-dihydroxy-9,9'-spirobifluorene was prepared and resolved by clathrate formation with (R,R)(+)-2,3-dimethoxy-N,N,N',N'-tetracyclohexylsuccindiamide, giving rise to both enantiomers in very good yields. The absolute stereochemistry of the resolved Material could be assigned by an X-ray structure analysis of single crystals of the clathrate. Enantiomerically pure diols could be transformed into the corresponding ditriflates, which were then used as starting materials in different cross-coupling procedures to provide a number of new enantiomerically pure spiro compounds bearing versatile functional groups suitable for further elaboration, as demonstrated by some examples. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheirn, Germany, 2005)