四氧化钌催化的直接氧化环化是一种强大的合成方法,可从简单的非手性1,5-二烯起始原料中非对映选择性地制备THF二醇,与目标定向和天然产物的合成具有显着的相关性。我们在这里报告老化的预催化剂溶液表现出异常高的反应性。因此,即使在催化剂负载量为50 ppm的情况下,对于在此单步转化中建立的四个立体异构中心,也获得了令人印象深刻的结果,具有良好的高收率和出色的非对映选择性。周转次数高达15000,周转频率高达3660 h -1获得了。用光谱法分析了老化效果,并给出了解释该反应性的初步假设。最后,通过使用一组具有不同取代模式和不同反应双键几何形状的底物,证明了这种效应在氧化环化化学中的普遍性。
In Situ Generation of Ylides for Tandem Oxidation-Olefination Reactions of Unactivated Diols
作者:Andrew Graham、David Phillips
DOI:10.1055/s-2008-1042799
日期:——
An efficient desymmetrization of diols is achieved using phosphonium salts which undergo deprotonation in the presence of a hindered amine base and manganese dioxide to produce α,β-unsaturated hydroxy esters in good yields.
Synthetic studies on amphidinolides C and F: synthesis of the C18–C29 segment of amphidinolide F
作者:Alan Armstrong、Constantina Pyrkotis
DOI:10.1016/j.tetlet.2009.02.093
日期:2009.7
The C18–C29 segment of amphidinolideF is synthesised in 12 steps from 1,4-butanediol. Key steps include a mono-Sharpless dihydroxylation of a dienoate, iodocyclisation to construct the trans-THF ring and an E-selective Wittig reaction to introduce the C25–C26 olefin.
Coibacins A and B: Total Synthesis and Stereochemical Revision
作者:Vânia M. T. Carneiro、Carolina M. Avila、Marcy J. Balunas、William H. Gerwick、Ronaldo A. Pilli
DOI:10.1021/jo402339y
日期:2014.1.17
The interface between synthetic organic chemistry and natural products was explored in order to unravel the structure of coibacin A, a metabolite isolated from the marine cyanobacterium cf. Oscillatoria sp. that exhibits selective antileishmanial activity and potent anti-inflammatory properties. Our synthetic plan focused on a convergent strategy that allows rapid access to the desired target by coupling of three key fragments involving E-selective Wittig and modified Julia olefinations. CD measurements and comparative HPLC analyses of the natural product and four synthetic stereoisomers led to determination of its absolute configuration, thus correcting the original assignment at C-5 and unambiguously establishing those at C-16 and C-18. Additionally, we synthesized coibacin B on the basis of the assignment of configuration for coibacin A.