Synthesis of 3′-C-substituted thymidine derivatives by free-radical techniques: scope and limitations
摘要:
The scope and limitations of radical-mediated 3'-C-substitution of pyrimidine nucleosides was evaluated with 5'-O-(tertbutyldimethylsilyl)thymidine or its tert-butyldiphenylsilyl analogue having thionoester or thionoamide groups at O-3', including (methylthio)thiocarbonyl, (phenoxy)thiocarbonyl, (pentafluorophenoxy)thiocarbonyl, and (1-imidazoiyl)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. (c) 2006 Elsevier Ltd. All rights reserved.