最初提出的 (±)-烟内酯 A 结构的合成是一种具有三个连续手性中心的强效抗病毒木脂素,从丙烯酸甲酯开始分 5 步合成。合成的关键步骤包括 In 催化的区域选择性烯丙基化和 Mn 催化的 Mukaiyama 水合反应。我们的合成策略还使我们能够获得其他三种差向异构体并研究构效关系。合成化合物的核磁共振数据与分离样品的核磁共振数据不匹配,表明烟内酯 A 的结构仍有待重新分配。评估了所有合成目标化合物的抗烟草花叶病毒 (anti-TMV) 活性。生物测定结果表明,(±)-8-去甲基烟内酯 A 显示出与市售药物宁南霉素相似的抗 TMV 活性,
Novel Isomerically Pure Tetrasubstituted Allylboronates: Stereocontrolled Synthesis of α-Exomethylene γ-Lactones as Aldol-Like Adducts with a Stereogenic Quaternary Carbon Center
作者:Jason W. J. Kennedy、Dennis G. Hall
DOI:10.1021/ja016391e
日期:2002.2.1
1-alkoxycarbonyl vinylcopper(I) intermediates from the conjugate addition of organocuprates onto acetylenic esters were trapped with very high cis-addition selectivity with iodomethylboronic esters in the presence of HMPA. The resulting isomerically pure 3,3-disubstituted allylboronates react with aldehydes in a highly diastereo- and enantioselective manner, providing α-exomethylene γ-lactones with a stereogenic
Lewis Acid Catalyzed Allylboration: Discovery, Optimization, and Application to the Formation of Stereogenic Quaternary Carbon Centers
作者:Jason W. J. Kennedy、Dennis G. Hall
DOI:10.1021/jo049773m
日期:2004.6.1
A full account of the development of the first catalytic manifold for the additions of allylboronates to aldehydes is described. The thermal additions (both diastereospecific and enantioselective) of 2-carboxyester 3,3-disubstituted allylboronates 1 to both aromatic and aliphatic aldehydes give biologically and synthetically important exo-methylene butyrolactones 2 containing a β-quaternary carbon
Enantioselective addition of β-functionalized allylboronates to aldehydes and aldimines. Stereocontrolled synthesis of α-methylene-γ-lactones and lactams
We report results regarding the development of condensations of chiral β-alkoxycarbonylallylboronates on aldehydes and imines. These allylboronates add in a highly enantioselective and diastereospecific manner to afford biologically and synthetically useful chiral α-methylene-γ-butyrolactones and lactams. The nature of the electrophile (aldehyde vs imine) is shown to have a dramatic influence on the
[reaction; see text] A general and practical procedure for the highly diastereoselective preparation of either the cis- or trans-beta,gamma-disubstituted-gamma-butyrolactones by appropriate choice of Lewis or Bronsted acid catalysts during crotylboration or lactonization is reported. The cis-stereochemistry of the Z-crotylboration product can be inverted with strong acids during lactonization. A carbocation
Triflic Acid-Catalyzed Additions of 2-Alkoxycarbonyl Allylboronates to Aldehydes. Study of Scope and Mechanistic Investigation of the Reaction Stereochemistry
作者:Tim G. Elford、Yuichiro Arimura、Siu Hong Yu、Dennis G. Hall
DOI:10.1021/jo062151b
日期:2007.2.1
The substrate scope and the effect of substrate on the observed inversion of stereoselectivity in the triflic acid-catalyzed allylboration reaction between 2-alkoxycarbonyl allylboronates and aldehydes are presented. A mechanisticinvestigation is described so as to confirm the involvement of a carbocation intermediate as the source of stereochemical inversion. This methodology allows a facile access