Ireland-Claisen rearrangement of secondary allyl acetate revisited: inevitable C-silylation circumvented by one-pot application of excessive LDA/TMSCl and TBAF
摘要:
Yield lowering C-silylation was found to be inevitable in all the six tested examples of stoichiometric LDA/TMSCl promoted Ireland-Claisen rearrangement of secondary allyl acetates. In order to circumvent this problem, a higher yielding protocol was devised after the isolated by-products were found to be excellent substrates for further rearrangement. Thus, excessive LDA/TMSCl was applied to achieve complete 3,3'-sigmatropic shift of the substrates, and the resulting mixtures of normal and alpha-silylated gamma,delta-unsaturated carboxylic acids was then desilylated by one-pot application of TBAF. (c) 2012 Elsevier Ltd. All rights reserved.
A general and efficient Pd/phosphoramidite thioether complex-catalyzed asymmetric N-allylic alkylation of hydrazones with allylicacetates has been developed for the first time. The reaction allows for the preparation of various valuable N-substituted hydrazones with generally good yields and excellent enantioselectivities. Minor structural modification of the ligand resulted in opposite enantiomers
Arylruthenium(III) Porphyrin-Catalyzed C–H Oxidation and Epoxidation at Room Temperature and [Ru<sup>V</sup>(Por)(O)(Ph)] Intermediate by Spectroscopic Analysis and Density Functional Theory Calculations
作者:Ka-Pan Shing、Bei Cao、Yungen Liu、Hung Kay Lee、Ming-De Li、David Lee Phillips、Xiao-Yong Chang、Chi-Ming Che
DOI:10.1021/jacs.8b04470
日期:2018.6.6
metal catalysts for efficient oxidation of hydrocarbons and identification of the reactive intermediates in the oxidation catalysis are long-standing challenges. In the rapid hydrocarbon oxidation catalyzed by ruthenium(IV) and -(III) porphyrins, the putative Ru(V)-oxo intermediates remain elusive. Herein we report that arylruthenium(III) porphyrins are highly active catalysts for hydrocarbon oxidation
An indium(III) bromide-triethylsilane reagent system promotes direct reduction of esters to produce the corresponding unsymmetrical ethers. This simple catalytic system accommodated other carbonyl compounds, such as a tertiary amide and a carboxylic acid.
Expanding the Substrate Specificity of <i>Thermoanaerobacter pseudoethanolicus</i>
Secondary Alcohol Dehydrogenase by a Dual Site Mutation
作者:Musa M. Musa、Odey Bsharat、Ibrahim Karume、Claire Vieille、Masateru Takahashi、Samir M. Hamdan
DOI:10.1002/ejoc.201701351
日期:2018.2.14
The authors acknowledge the support provided by the Deanship of Scientific Research (DSR) at King Fahd University of Petroleum and Minerals (KFUPM) for funding this work under project number IN151032. They also acknowledge the supported by baseline research fund to S.M.H. by King Abdullah University of Science and Technology.
Sterically Controlled Alkylation of Arenes through Iridium-Catalyzed CH Borylation
作者:Daniel W. Robbins、John F. Hartwig
DOI:10.1002/anie.201208203
日期:2013.1.14
one‐pot method for the site‐selective alkylation of arenes controlled by steric effects is reported. The process occurs through Ir‐catalyzed CHborylation, followed by Pd‐ or Ni‐catalyzed coupling with alkyl electrophiles. This selectivity complements that of the typical Friedel–Crafts alkylation; meta‐selective alkylation of a broad range of arenes with various electronic properties and functional