Synthesis of bifunctionally modified hexofuranosides of thymine and uracil

The glycosylation of bis(trimethylsilyl) derivatives of uracil and thymine by bifunctionally modified derivatives of D-glucofuranose in the presence of SnCl₄ as the condensing agent was studied. It is shown that the anomers of D-glucofuranose derivatives with a 1,2-trans orientation of the OAc groups undergo condensation more readily than the anomers. Both anomers give a mixture of and nucleosides with significant preponderance of the latter due to the primary formation of a 1,2-acetoxonium ion. It is assumed that the formation of nucleosides is due to the competitive coparticipation of other groups and/or more remote acetyl groups.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 542–548, April, 1982.