Synlett 2004(6): 975-978  
DOI: 10.1055/s-2004-820044
LETTER
© Georg Thieme Verlag Stuttgart · New York

Photochemical Ring Opening of Tricyclic Hemiketals: Diastereoselective Construction of Functionalized Medium-Sized Carbocycles and a Diquinane

Namakkal G. Ramesha, Alfred Hassner*b
a Department of Chemistry, Indian Institute of Technology - Delhi, Hauz Khas, New Delhi, 110 016, India
b Department of Chemistry, Bar-Ilan University, Ramat Gan, 52900, Israel
Fax: +972(3)5351250; e-Mail: hassna@mail.biu.ac.il;
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Publikationsverlauf

Received 31 December 2003
Publikationsdatum:
25. März 2004 (online)

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Abstract

A facile stereoselective construction of functionalized medium-sized carbocycles and a diquinane from bicyclo[3.n.1]alkanones is reported. The key step is the hypervalent iodine mediated photochemical ring opening of tricyclic hemiketals, formed by dihydroxylation of methylene-bicyclo[3.3.1]nonan-9-one and methylene-bicyclo[3.2.1]octan-8-one, to afford eight- and seven-membered carbocyclic rings, respectively. Subsequent transformation of the cyclooctane into a diquinane was achieved using LDA. The reaction was also extended to the synthesis of a fused bicylic system.