Nucleosides. 121. Improved and General Synthesis of 2'-Deoxy C-Nucleosides. Synthesis of 5-(2-Deoxy-β-D-erythro-pentofuranosyl)uracil, -1-methyluracil, -1,3-dimethyluracil, and -isocytosine

Article abstract of DOI:10.1021/jo00342a022

5-(2-Deoxy-β-D-erythro-pentofuranosyl)-1,3-dimethyluracil (6a), -1-methyluracil (6b), -uracil (6c), and -isocytosine (6d) were synthesized.Compounds 6b-d are C-nucleoside isosteres of thymidine, 2'-deoxyuridine, and 2'-deoxycytidine, respectively. 1,3-Dimethylpseudouridine (1a), 1-methylpseudouridine (1b), pseudouridine (1c), and pseudoisocytidine (1d) were treated with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane in pyridine to afford the corresponding 3',5'-tetraisopropyldisiloxanyl derivatives 2 which were converted into the respective 2'-O-<(imidazol-1-yl)thiocarbonyl> C-nucleosides 3.Compounds 3a,b were converted directly into the corresponding 2'-deoxy β-C-nuleosides 5a,b exclusively by reduction with n-Bu3SnH.For the synthesis of 2'-deoxy β-C-nucleosides 5c,d, the intermediates 3c,d were trimethylsilylated prior to n-Bu3SnH treatment.Deprotection of 5a-d was effected by treatment with n-Bu4NF, and the corresponding free 2'-deoxy β-C-nucleosides 6a-d were obtained in good yields.