Purine nucleosides XXVIII. The synthesis of 7-(2′-deoxy-α- and β-d-ribofuranosyl)purines from 2′-deoxyribofuranosylimidazoles. Preparation of the 2′-deoxy derivative of the nucleoside from pseudovitamin B12 factor G

The synthesis of 1-(2′-deoxyribofuranosyl)imidazoles have been achieved for the first time via the fusion method of glycosidation. 4-Amino-5-carboxamido-1-(2′-deoxy-α-D-ribofuranosyl)-imidazole ( 8 ) and 4-amino-5-carboxamido-1-(2′-deoxy-β-D-ribofuranosyl)imidazole ( 10 ) have been obtained and their structures established by spectroscopic methods. The first examples of 7-(2′-deoxyglycosyl)purines 7-(2′-deoxy-α-D-ribofuranosyl)hypoxanthine ( 6 ) and 7-(2′-deoxy-β-D-ribofuranosyl)hypoxanthine ( 11 )] have been obtained from the requisite 2′-deoxyribofuranosylimidazoles. The preparation of 6 has furnished the 2′-deoxy derivative (α-configuration) of the nucleoside from pseudovitamin B₁₂ Factor G, which constitutes the first 2′-deoxy derivative of any nucleoside isolated from the various naturally occurring pseudovitamin B₁₂ factors.