title: Synthesis of 3'-C-substituted thymidine derivatives by free-radical techniques: scope and limitations.
abstract: The scope and limitations of radical-mediated 3'-C-substitution of pyrimidine nucleosides was evaluated with 5'-O-(tert-butyldimethylsilyl)thymidine or its tert-butyldiphenylsilyl analogue having thionoester or thionoamide groups at O-3', including (methylthio)thiocarbonyl, (phenoxy)thiocarbonyl, (pentafluorophenoxy)thiocarbonyl, and (1-imidazolyl)thiocarbonyl. Their reaction with acrylonitrile, methyl acrylate, and allyltributyltin under radical-generating conditions affords corresponding 3'-C-alkylated products, together with the product of simple deoxygenation at C-3'. The conditions for optimizing the yield of 3'-C-substituted product are presented.
authors.affiliation: Department of Chemistry, American University, 4400 Massachusetts Avenue, Washington, DC 20016, USA. carbchm@american.edu
authors.forename: Derek
authors.initials: D
authors.lastname: Horton
authors.forename: Kuangmin
authors.initials: K
authors.lastname: Chen
authors.forename: Zaesung
authors.initials: Z
authors.lastname: No
authors.forename: Howard C
authors.initials: HC
authors.lastname: Lee
mesh_terms: D005609:Free Radicals / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011741:Pyrimidine Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D013854:Thioamides / Q000737:chemistry; D013936:Thymidine / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D011741:Pyrimidine Nucleosides; D013854:Thioamides; D013936:Thymidine