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Synlett 1990; 1990(2): 103-105
DOI: 10.1055/s-1990-21001
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Asymmetric Synthesis of C2-Symmetric Annulated Bicyclooctylcyclopentadienes

Zhuoliang Chen* , Ronald L. Halterman
  • *Department of Chemistry, Boston University, Boston, MA 02215, USA
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Publikationsdatum:
08. März 2002 (online)

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The efficient asymmetric preparation of the C2-symmetric annulated cyclopentadienes, (+)-(1R,7R,8R,10R)-8, 10-diisopropyltricyclo[5.2.2.02,6]undeca-2,5-diene (1) and (-)-(1S,7S,8R,10R)-8,10-dimethyltricyclo [5.2.2.02,6]undeca-2,5-diene(2) is described. The key step in these syntheses is an asymmetric dihydroboration of 1,4-dialkyl-1,4-cyclohexadienes using enantiomerically pure isopinocamphenylborane. The overall yield of enantiomerically enriched 1 or 2 is 27% and 20%, respectively, for the five-step synthesis (Birch reduction of 1,4-dialkylbenzene, asymmetric dihydroboration-oxidation, bis(methanesulfonate) formation, bisalkylation of cyclopentadiene, and [1,5]-sigmatropic rearrangement). The formation of chiral titanocene dichlorides is described.