5-Noraristeromycin C-Nucleosides Based on Imidazo[1,2-a]pyrazine.

The preparation of two C-5'-nor-3-deazaaristeromycin diastereomeric analogues possessing a bridgehead nitrogen is described from (3aR,4R,65,6a5)-2,2-dimethyl-6-vinyltetrahydro-3aH-cyclopenta[ d][1,3]dioxol-4-ol that served as the cyclopentyl unit of the target carbocyclic nucleosides and as the scaffold upon which the compounds were built. The process evolved via a de novo approach for constructing the requisite fused imidazo unit between the aforementioned cyclopentyl ring and a readily available 2,3-dichloropyrazine. The syntheses were accomplished in 11 and 8 steps depending on the diastereomer sought. [ABSTRACT FROM AUTHOR]