Enantioselective Synthesis of Tertiary α,α-Diaryl Carbonyl Compounds Using Chiral <i>N,N′</i>-Dioxides under Umpolung Conditions
作者:Tae-Woong Um、Girim Lee、Seunghoon Shin
DOI:10.1021/acs.orglett.0c00333
日期:2020.3.6
addition of the chiral N,N'-dioxide into ynamides generated enolonium ions in situ which underwent enantioselective alkylation by indoles, pyrroles, and phenols, without racemization of the formed tertiary center. This external oxidant approach allows for the use of unmodified nucleophiles and does not leave trace groups from the oxidant, which significantly increases the synthetic efficiency and the
A General Organocatalytic System for Electron Donor–Acceptor Complex Photoactivation and Its Use in Radical Processes
作者:Eduardo de Pedro Beato、Davide Spinnato、Wei Zhou、Paolo Melchiorre
DOI:10.1021/jacs.1c05607
日期:2021.8.11
variety of radical precursors. Excitation with visible light generates open-shell intermediates under mild conditions, including nonstabilized carbon radicals and nitrogen-centered radicals. The modular nature of the commercially available xanthogenate and dithiocarbamate anion organocatalysts offers a versatile EDA complex catalytic platform for developing mechanistically distinct radical reactions
Copper-Catalyzed Fluoroolefination of Silyl Enol Ethers and Ketones toward the Synthesis of β-Fluoroenones
作者:Yanlin Li、Jing Liu、Shuang Zhao、Xuzhao Du、Minjie Guo、Wentao Zhao、Xiangyang Tang、Guangwei Wang
DOI:10.1021/acs.orglett.7b03700
日期:2018.2.16
A general and facile synthetic method for β-fluoroenones from silylenolethers or ketones, with a copper–amine catalyst system, has been developed. The reaction proceeded by a tandem process of difluoroalkylation–hydrolysis–dehydrofluorination. This method is characterized by high yields, excellent Z/E ratios, a low-cost catalyst, and a broad substrate scope. The synthetic potential of β-fluoroenones
A new catalytic asymmetric tandem α‐alkenyl addition/proton shift reaction of silyl enol ethers with ketimines was serendipitously discovered in the presence of chiral N,N′‐dioxide/ZnII complexes. The proton shift preferentially proceeded instead of a silyl shift after α‐alkenyl addition of silyl enol ether to the ketimine. A wide range of β‐amino silyl enol ethers were synthesized in high yields with
N-Aminopyridinium salts generate nitrogen-centered radicals by means of photoredox catalysis. Herein, we report that they can be trapped by enol equivalents to give α-amino carbonyl compounds in excellent yields. The broad syntheticutility of this method is demonstrated by functionalization of ketones, aldehydes, esters enol equivalents, vinyl ethers, and 1,3-diketones without the need for prior conversion