Synthesis of Conformationally Locked Carbocyclic Nucleosides Built on a Thiabicyclo[3.1.0]hexane System as a Pseudosugar Surrogate
The synthesis of prototype models of purine and pyrimidine carbanucleosides built on a 6-thiabicyclo[3.1.0]hexane system as pseudosugar moiety has been investigated. These pyrimidine carbanucleosides proved to be very stable compounds, in contrast to the parent epoxy analogs, which experienced epoxide ring-opening due to intramolecular enol base attack. In addition, as the synthesis of a thiirane moiety fused to a five-membered ring is not a trivial synthetic task, validation and optimization of the existing methods for episulfide preparation were required to access the committed synthetic precursor of the title compounds: (±)-(1RS,2RS,5SR)-6-thiabicyclo[3.1.0]hexan-2-ol, compound 28. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)