A novel approach for construction of the naturally occurring dihydroagarofuran sesquiterpene skeleton

A general and efficient approach for the synthesis of a kind of dihydrofuran sesquiterpenes extensively present in the Celastraceae family of plants has been developed by a series of transformations from santonin. The key creative and versatile steps involve the strategic acid-catalyzed double-bond shifting affording 6, the novel base-promoted epoxide rearrangement of 7 generating two key functions (the C5-OH and the Delta(7,11) double bond) and the stereoselective construction of a tetrahydrofuran moiety without particularly controlling the stereochemistry of C7. In particular, this approach can introduce any number of hydroxyls at the required positions for synthesis of many natural dihydroagarofuran sesquiterpenes. (C) 2002 Elsevier Science Ltd. All rights reserved.