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Abstract: Two synthetic strategies were developed to obtain isonucleosides 2a and 2b. Starting from the known compound 4, an extension of one carbon unit at sugar 6-terminal was achieved by Wittig reaction and Stannyl-desulfonylation reaction. After oxidation of the double bond, the isonucleosides with elongated side chain 2a and 2b were synthesized. For the synthesis of isonucleosides containing different bases, an epoxide intermediate approach was developed. Isonucleosides 2a and 2b were synthesized by regioselective epoxide opening reaction of 18 in good yield. [Copyright &y& Elsevier]

Abstract: Our studies of the TIBAL-promoted Claisen rearrangement reaction and ring-closing metathesis (RCM) resulted in the development of an efficient synthetic route to polyfunctional seven-membered carbasugar synthons from d-arabinose. Moreover, the construction of 8-oxa-bicyclo[3.2.1]octane derivatives 10 and 13 was achieved by BCl3 or iodide-promoted intramolecular electrophilic addition reactions, which were regio- and stereoselective. [Copyright &y& Elsevier]