Synthesis of 3′,7′-anhydrooctose nucleosides related to the ezomycins and the octosyl acids

Abstract

Several novel 3′,7′-anhydrooctose nucleosides, including a 3′,7′-anhydroocturonic acid nucleoside, namely l-(3,7-anhydro-5,6-dideoxy-β-D-allo-octofuranosyluronic acid)-3-methyluracil (40), have been synthesized. The synthetic sequence leading to 40 consists of three key steps: preparation of an octose nucleoside by a chain extension of an uridine derivative using a Wittig reaction, conversion of the octose nucleoside into a bicyclic-octose nucleoside by an intramolecular cyclization, and elaboration of a carboxylic acid function at the C-8′ position of the bicyclic-octose nucleoside. The structures of the 3′,7′-anhydrooctose nucleosides have been established by their uv, 1Hmr, 13Cmr, and mass spectral data.