126002-58-2Relevant articles and documents
Alkyl-GeMe3: Neutral Metalloid Radical Precursors upon Visible-Light Photocatalysis
Wei, Li-Pu,Xiao, Bin,Xu, Qing-Hao
, (2022/02/17)
Single-electron transfer (SET) oxidation of ionic hypervalent complexes, in particular alkyltrifluoroborates (Alkyl-BF3?) and alkylbis(catecholato)silicates (Alkyl-Si(cat)2?), have contributed substantially to alkyl radical generation compared to alkali or alkaline earth organometallics because of their excellent activity–stability balance. Herein, another proposal is reported by using neutral metalloid compounds, Alkyl-GeMe3, as radical precursors. Alkyl-GeMe3 shows comparable activity to that of Alkyl-BF3? and Alkyl-Si(cat)2? in radical addition reactions. Moreover, Alkyl-GeMe3 is the first successful group 14 tetraalkyl nucleophile in nickel-catalyzed cross-coupling. Meanwhile, the neutral nature of these organogermanes offset the limitation of ionic precursors in purification and derivatization. A preliminary mechanism study suggests that an alkyl radical is generated from a tetraalkylgermane radical cation with the assistance of a nucleophile, which may also result in the development of more non-ionic alkyl radical precursors with a metalloid center.
A General Organocatalytic System for Electron Donor-Acceptor Complex Photoactivation and Its Use in Radical Processes
De Pedro Beato, Eduardo,Melchiorre, Paolo,Spinnato, Davide,Zhou, Wei
supporting information, p. 12304 - 12314 (2021/08/20)
We report herein a modular class of organic catalysts that, acting as donors, can readily form photoactive electron donor-acceptor (EDA) complexes with a 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, encompassing redox-neutral and net-reductive processes. Mechanistic investigations, by means of quantum yield determination, established that a closed catalytic cycle is operational for all of the developed radical processes, highlighting the ability of the organic catalysts to turn over and iteratively drive every catalytic cycle. We also demonstrate how the catalysts' stability and the method's high functional group tolerance could be advantageous for the direct radical functionalization of abundant functional groups, including aliphatic carboxylic acids and amines, and for applications in the late-stage elaboration of biorelevant compounds and enantioselective radical catalysis.
Catalyst-Free Decarboxylation of Carboxylic Acids and Deoxygenation of Alcohols by Electro-Induced Radical Formation
Chen, Xiaoping,Luo, Xiaosheng,Peng, Xiao,Guo, Jiaojiao,Zai, Jiantao,Wang, Ping
, p. 3226 - 3230 (2020/02/27)
Electro-induced reduction of redox active esters and N-phthalimidoyl oxalates derived from naturally abundant carboxylic acids and alcohols provides a sustainable and inexpensive approach to radical formation via undivided electrochemical cells. The resulting radicals are trapped by an electron-poor olefin or hydrogen atom source to furnish the Giese reaction or reductive decarboxylation products, respectively. A broad range of carboxylic acid (1°, 2°, and 3°) and alcohol (2° and 3°) derivatives are applicable in this catalyst-free reaction, which tolerated a diverse range of functional groups. This method features simple operation, is a sustainable platform, and has broad application.
