Collect. Czech. Chem. Commun. 2006, 71, 1611-1626

Hydroboration of 1,1'-Bi(cyclopent-1-ene) and 3,3'-Biindene: Experimental and Theoretical Study

Jaroslav Kvíčala*, Ondřej Baszczyňski, Alena Krupková and Denisa Stránská

Department of Organic Chemistry, Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic


Hydroboration of bi(cyclopent-1-ene) (1) or 3,3'-biindene (2) with borane, thexylborane or (-)-isopinocampheylborane afforded, regardless of reaction conditions, meso-isomers of polycyclic 1,4-diols 3a, 4a as the main products. No reaction was observed with 9-BBN. The structure of the major product 4a, as well as of the minor racemic product 4b was assigned based on 1H NMR spectra of the corresponding Mosher's diesters 5a-5c. Finally, the stereochemistry of the product 4a was confirmed by a single-crystal X-ray analysis of the corresponding dimesylate 6. To elucidate preferential formation of the meso-isomers, complexes of monohydroborated intermediate with borane were studied theoretically by DFT methods.

Keywords: Dienes; Asymmetric hydroboration; Boranes; Chiral diols; Mosher's esters; Absolute configuration; DFT calculations; X-Ray diffraction.

References: 31 live references.