Stereoselective Synthesis and Conformational Study of Novel 2′,3′-Didehydro-2′,3′-dideoxy-4′-selenonucleosides

Stereoselective synthesis of novel 2′,3′-didehydro-2′,3′-dideoxy-4′-selenonucleosides
(4′-seleno-d4Ns) 4a−c was
accomplished via 4′-selenoribofuranosyl pyrimidines 11a−c, as key intermediates. 4′-Selenoribofuranosyl
pyrimidines 11a−c were efficiently
synthesized from d-ribose or d-gulonic γ-lactone
using a Pummerer-type condensation as a key step. Introduction of
2′,3′-double bond was achieved by treating cyclic 2′,3′-thiocarbonate
with 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine.

以4'-硒代呋喃核糖基嘧啶类化合物11a-c作为关键中间体，完成了新型2',3'-双脱氢-2',3'-双脱氧-4'-硒代核苷（4′-seleno-d4Ns）4a-c的立体选择性合成。4'-硒代呋喃核糖基嘧啶类化合物11a-c可由D-核糖或D-古洛糖酸γ-内酯出发，以帕默尔型缩合（Pummerer-type condensation）作为关键步骤高效合成。通过将环状2',3'-硫代碳酸酯与1,3-二甲基-2-苯基-1,3,2-二氮杂磷杂环戊烷反应，成功引入2',3'-双键。