Enantioselective Synthesis of 1,5-<i>anti</i>- and 1,5-<i>syn</i>-Diols Using a Highly Diastereoselective One-Pot Double Allylboration Reaction Sequence
作者:Eric M. Flamme、William R. Roush
DOI:10.1021/ja028055j
日期:2002.11.1
gamma-boryl-substituted allylborane reagents 4 and 11 were generated in situ by the hydroboration of allenes 3 and 10 with diisopinocampheylborane. The keys to the success of this method are the excellent stereocontrol in the allylboration step leading to 5 and the corresponding substituted methallylboronate derived from 11, the stereospecificity of the subsequent allylboration reaction of the substituted
1,5-二取代 (E)-1,5-anti-pent-2-endiols 1 和 (Z)-1,5-syn-pent-2-endiols 2 的高度非对映选择性和对映选择性合成已通过两种不同的醛与 (E)-γ-(1,3,2-二氧杂硼烷基)-烯丙基]二异松蒎基硼烷 (4) 或 (E)-γ-(4,4,5,5-四苯基-分别为 1,3,2-二氧杂硼烷基)烯丙基]二异松蒎基硼烷 (11)。在所有情况下,以 63-95% 的产率获得指定的二醇 1 和 2,具有 89-96% ee 和 >/=20:1 的非对映选择性。双功能 γ-硼基取代的烯丙基硼烷试剂 4 和 11 是通过丙二烯 3 和 10 与二异松蒎基硼烷的硼氢化反应原位生成的。该方法成功的关键是烯丙基硼化步骤中出色的立体控制导致 5 和相应的取代的甲基烯丙基硼酸酯衍生自 11,