Regiospecific Synthesis of 4-Deoxy-D-threo-hex-3-enopyranosides by Simultaneous Activation–Elimination of the Talopyranoside Axial 4-OH with the NaH/Im2SO2 System: Manifestation of the Stereoelectronic Effect
作者:Emanuele Attolino、Giorgio Catelani、Felicia D’Andrea
DOI:10.1002/ejoc.200600526
日期:2006.12
of 4-deoxy- and 2,4-dideoxy-2-acetamido-β-D-threo-hex-3-enopyranosides has been developed. The process involves a simultaneous activation–elimination of the OH-4 group of β-D-talopyranosides and 2-acetamido-2-deoxy-β-D-talopyranosides, mediated by the NaH/N,N′-sulfuryldiimidazole system at –30 °C. The same reaction applied on the analogous β-D-galactopyranosides takes place without any regioselectivity
开发了一种用于区域选择性制备 4-deoxy- 和 2,4-dideoxy-2-acetamido-β-D-threo-hex-3-enopyranosides 的新的高产方法。该过程包括同时激活-消除 β-D-talopyranosides 和 2-acetamido-2-deoxy-β-D-talopyranosides 的 OH-4 基团,在 –30 时由 NaH/N,N'-sulfuryldiimidazole 系统介导℃。应用于类似的 β-D-吡喃半乳糖苷的相同反应在没有任何区域选择性的情况下发生,提供 hex-3- 和 hex-4-enopyranosides 的混合物。对于甲基 2,3,6-tri-O-benzyl-α-D-talo- 和 α-D-吡喃半乳糖苷,可以通过在 –30 °C 下淬灭反应来分离相应的 4-O-imidazylates . 将这些粗产物加热至室温后,α