The research focuses on the inversion of configuration at C3 of 1,2-O-isopropylidene-d-arabinofuranoside and d-ribofuranoside promoted by DAST. Both the initial configuration and the presence of C5 acyl group in d-furanosides are the key factors for this inversion due to the formation of cyclic oxonium ion intermediates. This inversion of configuration has been successfully applied to scalable synthesis of d-lyxose and 2′,5′-di-O-benzoyl-3′-fluoro-3′-deoxy-β-d-ribofuranosyl-7-halogen-7-deazapurine.

中文翻译：

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DAST氟化1, 2-O-异亚丙基D-呋喃戊糖的研究及其规模化应用

该研究重点是DAST促进的1,2- O-异丙叉-d-阿拉伯呋喃糖苷和d-呋喃核糖苷C3构型反转。由于环状氧鎓离子中间体的形成，d-呋喃糖苷中的初始构型和C5酰基的存在是这种转化的关键因素。这种构型反转已成功应用于d-来苏糖和2',5'-二-O-苯甲酰基-3'-氟-3'-脱氧-β- d-呋喃核糖基-7-卤素-7-的大规模合成去氮嘌呤。