Friedel-Crafts Alkylation with Carbenium Ions Generated by Electrochemical Oxidation of Stannylmethyl Ethers
作者:Anna Lielpetere、Aigars Jirgensons
DOI:10.1002/ejoc.202000568
日期:2020.8.9
Friedel–Crafts alkylation of electron rich arenes can be achieved by stabilized carbenium ions which are generated by single cell anodic oxidation of stannylmethyl ethers at low potential. The use of NaHCO3 as an additive ensures close‐to‐neutral conditions enabling the reaction with arenes bearing acid‐sensitive groups such as O‐TBS, O‐Tr, O‐MOM, O‐THP.
5-Substituted 2-tributylstannylfurans which were synthesized by the reaction of corresponding 5-substituted 2-lithiofurans with tributylstannyl chloride, were treated with two equimolar amounts of lead tetraacetate at room temperature to give corresponding 5-substituted 5-acetoxy-2(5H)-furanones in good yields. The 5-acetoxy-2(5H)-furanone was heated at 80 °C in acetic acid-acetic anhydride containing
Highly selective one-pot conversion of THP and MOM ethers to acetates by indium triiodide-catalysed deprotection and subsequent transesterification by ethyl acetate
作者:Brindaban C. Ranu、Alakananda Hajra
DOI:10.1039/b104055n
日期:——
A simple and efficient method is developed for the chemoselective one-pot conversion of tetrahydropyranyl (THP) and methoxymethyl (MOM) ethers of primary alcohols to the corresponding acetates by indium triiodide-catalysed deprotection and subsequent acetylation by ethyl acetate through a transesterification process.
A Relative Organolithium Stability Scale Derived from Tin−Lithium Exchange Equilibria. Substituent Effects on the Stability of α-Oxy- and α-Aminoorganolithium Compounds
作者:Paula Graña、M. Rita Paleo、F. Javier Sardina
DOI:10.1021/ja025552r
日期:2002.10.1
Quantitative thermodynamic stability scales of organolithiumcompounds can be derived from measurements of tin−lithium exchange equilibria. A ΔGeq scale of α-oxy- and α-aminoorganolithium compounds was established, and quantitative stabilization effects of O-alkyl, O-alkoxyalkyl, O-carbamoyl, N-carbamoyl, and O-carbonyl groups of the α-carbanion are presented. It has been found that an α-oxycarbanion
有机锂化合物的定量热力学稳定性标度可以从锡-锂交换平衡的测量中推导出来。建立了α-氧基-和α-氨基有机锂化合物的ΔGeq标度,并给出了α-碳负离子的O-烷基、O-烷氧基烷基、O-氨基甲酰基、N-氨基甲酰基和O-羰基的定量稳定作用。已经发现,α-氧碳负离子通过作为 O-取代基的羰基比通过烷基或烷氧基烷基更好地稳定,而不同的 O-羰基取代基的阴离子稳定效果是可比的。发现 N-氨基甲酰基比其 O-氨基甲酰基对应物具有更高的稳定作用。提供的 NMR 数据表明,苄基 N 或 O 取代的碳负离子具有高度平面化的结构,其中负电荷高度离域。从锡-锂交换中获得的稳定性数据可以轻松转换为“有效 pK”数据,这些数据可用于预测酸...
Copper-Catalyzed Direct C-2 Difluoromethylation of Furans and Benzofurans: Access to C-2 CF<sub>2</sub>H Derivatives
We report herein the first copper-catalyzed C-2 difluoromethylation of furans and benzofurans. The developed methodology allows the selective introduction of the CF2CO2Et moiety at C-2 using CuI as a catalyst. This process was applied to a broad range of furans and benzofurans, giving the functionalized products in moderate to good yields. The resulting products were then decarboxylated to afford the highly valuable C-2-CF2H-substituted furans and benzofurans in good yields.