Chemoselective Isomerization of Secondary-Type Propargylic Alcohols to Propargylic/Allenic Bromides, and Brominated Dienes with Appel-Type Reaction Conditions
作者:Norio Sakai、Tsukasa Maruyama、Takeo Konakahara
DOI:10.1055/s-0029-1217701
日期:2009.8
Herein is described the chemoselective isomerization of secondary-type propargylicalcohols to allenic bromides, propargylicbromides and brominated dienes under Appel-type reaction conditions containing Ph 3 P, CBr 4 and additives.
Overriding the alkynophilicity of gold: catalytic pathways from higher energy Au(i)–substrate complexes and reactant deactivation via unproductive complexation in the gold(i)-catalyzed propargyl Claisen rearrangement
作者:Dinesh V. Vidhani、John W. Cran、Marie E. Krafft、Igor V. Alabugin
DOI:10.1039/c2ob27231h
日期:——
Computational and experimental analysis of unusualsubstituenteffects in the Au-catalyzed propargyl Claisen rearrangement revealed new features important for the future development of Au(I) catalysis. Despite the higher stability of Au–alkyne complexes, they do not always correspond to the catalytically active compounds. Instead, the product emanates from the higher energy Au(I)–oxygen complex reacting
The combination of H-3[PW12O40]center dot nH(2)O (1 mol %) and Et3SiH led to the direct catalytic deoxygenation of propargyl alcohols, in which proper solvent selection Cl(CH2)(2)Cl vs CF3CH2OH was the key to obtaining better product yields. Under similar conditions, the deoxygenation of allyl alcohols proceeded to give thermodynamically stable alkenes with migration of the double bonds in good yields.
Synthesis of tetrasubstituted furans via In-catalyzed propargylation of 1,3-dicarbonyl compounds-cyclization tandem process
An efficient method to synthesize tetrasubstituted furans using simple starting materials such as propargylic alcohols and 1,3-dicarbonyl compounds has been developed. It was discovered that InCl3 could catalyze this transformation efficiently while other simple iron, copper and silver salts were proven to be ineffective. (C) 2008 Elsevier Ltd. All rights reserved.
Heteropoly Compound Catalyzed Synthesis of Both Z- and E-α,β-Unsaturated Carbonyl Compounds
An EZ switch: The cationic species of the heteropoly compounds has a critical impact on the Z/E selectivity of the Meyer–Schuster rearrangement of propargyl alcohols (see scheme). The isolation of the thermodynamically unfavorable Z‐α,β‐unsaturatedcarbonylcompounds is notable. The high Z selectivities were obtained at a reaction temperature as high as 50 °C.
一个 EZ 开关:杂多化合物的阳离子物质对一个临界冲击ž / é炔丙基醇的迈耶-舒斯特重排反应的选择性(见方案)。分离出热力学上不利的Z -α,β-不饱和羰基化合物。在高达 50°C的反应温度下可获得较高的Z选择性。