为了预测烷基链中1,3-二甲基取代的相对立体化学,最近提出了一种基于1 H NMR数据的简单方法。位于甲基取代的次甲基碳之间的亚甲基质子的Δδ值可以用来预测。在这里,我们将这种经验性的“基因组质子规则”应用于链霉菌属的脂肽Verucopeptin 。为了确定维鲁肽中1,3,5-三甲基取代的烷基链的绝对立体化学,我们通过氧化裂解将相应的烷基链转化为羧酸。双子质子规则清楚地预测了相对立体化学为31 S *,33 S *,35 R*。通过合成四种可能的非对映异构体并比较其NMR光谱,可以肯定地证实了这一预测。此外,我们使用报道的化合物和我们合成的化合物重新研究了双子质子规则。我们的结果强烈表明,该规则是可靠的,至少对于预测2,4-二甲基化和2,4,6-三甲基化脂肪酸的立体化学而言。
Iterative Deoxypropionate Synthesis Based on a Copper-Mediated Directed Allylic Substitution: Formal Total Synthesis of Borrelidin (C3–C11 Fragment)
作者:Christian Herber、Bernhard Breit
DOI:10.1002/chem.200600343
日期:2006.8.25
alkylation strategies such as enolate reactivity as well as costs and problems associated with the chiral auxiliary. Practicability of this new method is demonstrated through application in natural product syntheses. Thus, an efficient synthesis of the northern part of the angiogenesis inhibitor borrelidin (28), the deoxypropionate building block 27, could be devised, representing a formal total synthesis