Progress toward the Total Synthesis of Bielschowskysin: A Stereoselective [2 + 2] Photocycloaddition
摘要:
The tetracyclic core of the diterpene bielschowskysin has been prepared as a single enantiomer via a stereoselective intramolecular [2 + 2] photocycloaddition of 5-alkylidene-2(5H)-furanone 3.
The First Synthesis and Reaction of β-Ethoxy-α-fluoro-α-(phenylselanyl)ethene: Scandium or Lanthanum Triflate Catalyzed α-Fluoroformylalkenylation of Aldehydes
We describe the first preparation of the hitherto unknown β-ethoxy-α-fluoro-α-(phenylselanyl)ethenes and the successful Lewis acid catalyzed α-fluoroformylalkenylation of non-enolizable aldehyde acetals to provide α,β-unsaturated aldehydes or acetals exclusively.
Development of Enantioselective Synthetic Routes to (−)-Kinamycin F and (−)-Lomaiviticin Aglycon
作者:Christina M. Woo、Shivajirao L. Gholap、Liang Lu、Miho Kaneko、Zhenwu Li、P. C. Ravikumar、Seth B. Herzon
DOI:10.1021/ja307497h
日期:2012.10.17
cyclization, and diazo transfer provided the advanced diazofluorene 63, which was elaborated to (-)-kinamycin F (9) in three steps. The diazofluorene 87 was converted to the C(2)-symmetric lomaiviticinaglycon precursor 91 by enoxysilane formation and oxidative dimerization with manganese tris(hexafluoroacetylacetonate) (94, 26%). The stereochemical outcome in the coupling is attributed to the steric
Direct Manipulation of Metal Imido Geometry: Key Principles to Enhance C–H Amination Efficacy
作者:Yunjung Baek、Elisabeth T. Hennessy、Theodore A. Betley
DOI:10.1021/jacs.9b09015
日期:2019.10.23
Multinuclear NMRspectroscopy and solid-state magnetic susceptibility measurements were used to determine that (TrL)Co(NAd) exhibits a low-spin CoIII electronic configuration. Exposure of 1-10 mol% of (TrL)Co to linear alkyl azides (RN3) resulted in catalytic formation of substituted N-heterocycles via intramolecular C-H amination of a range of C-H bonds, including primary C-H bonds. The mechanism of the
我们报告了由具有空间阻碍的三苯甲基取代基(TrL)(TrL = 5-mesityl-1,9-(trityl)dipyrrin 的二吡咯-亚甲基配体支持的可分离 CoIII 亚胺复合物(TrL)Co(NR)介导的催化 CH 胺化)。(TrL)Li 与 CoCl2 在 THF 中的金属化提供了一种独特的三角锥几何形状的高自旋 (S = 3/2) 三配位配合物 (TrL) CoCl,显示了钴和其中之一之间的 η1-芳烃相互作用。来自三苯甲基侧翼基团的邻碳。(TrL)CoCl 与钾石墨的化学还原产生高自旋 (S = 1) CoI 合成子 (TrL)Co,其通过与三苯甲基部分苯基取代基之一的分子内 η6-芳烃相互作用稳定。用化学计量的 1-叠氮金刚烷 (AdN3) 处理 (TrL)Co 提供了三配位 CoIII 酰亚胺 (TrL)Co(NAd),如单晶 X 射线衍射所证实。有趣的是,(TrL)Co(NAd)
Total synthesis of erythromycin B
作者:Philippe Breton、Paul J. Hergenrother、Tsuneaki Hida、Anne Hodgson、Andrew S. Judd、Erica Kraynack、Philip R. Kym、Wen-Cherng Lee、Michael S. Loft、Masayuki Yamashita、Stephen F. Martin
DOI:10.1016/j.tet.2007.02.044
日期:2007.6
We report the details of the first totalsynthesis of erythromycin B using two different strategies for the end game. The first of these follows a classical approach in which the desosamine and cladinose residues are sequentially appended to a macrocyclic lactone, which was formed by cyclization of a seco acid derivative, to give a bis-glycosylated macrolide intermediate that is converted into erythromycin
Iron(III) chloride-catalyzed effective allylation reactions of acetals with allyltrimethylsilane proceeded smoothly in high to excellent yields. In addition, this method could be applied to the one-pot synthesis of homoallyl benzyl ethers by a combination of dibenzyl acetalization of aldehydes and consecutive allylation of dibenzyl acetals.