102617-51-6Relevant articles and documents
Scalable Photoelectrochemical Dehydrogenative Cross-Coupling of Heteroarenes with Aliphatic C?H Bonds
Chen, Peng-Yu,Xu, Hai-Chao,Xu, Pin
, p. 14275 - 14280 (2020)
Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross-coupling of heteroarenes with aliphatic C?H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross-coupling of heteroarenes and C(sp3)?H donors through H2 evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp3)?H donor is converted to a nucleophilic carbon radical through H-atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl2 from Cl?. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products.
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.
Microtubing-Reactor-Assisted Aliphatic C?H Functionalization with HCl as a Hydrogen-Atom-Transfer Catalyst Precursor in Conjunction with an Organic Photoredox Catalyst
Deng, Hong-Ping,Zhou, Quan,Wu, Jie
supporting information, p. 12661 - 12665 (2018/09/20)
Chlorine radical, which is classically generated by the homolysis of Cl2 under UV irradiation, can abstract a hydrogen atom from an unactivated C(sp3)?H bond. We herein demonstrate the use of HCl as an effective hydrogen-atom-transfer catalyst precursor activated by an organic acridinium photoredox catalyst under visible-light irradiation for C?H alkylation and allylation. The key to success relied on the utilization of microtubing reactors to maintain the volatile HCl catalyst. This photomediated chlorine-based C?H activation protocol is effective for a variety of unactivated C(sp3)?H bond patterns, even with primary C(sp3)?H bonds, as in ethane. The merit of this strategy is illustrated by rapid access to several pharmaceutical drugs from abundant unfunctionalized alkane feedstocks.
