查看更多>>摘要：Aldehydes are abundant chemical motifs presented in natural products and pharmaceuticals. As a radical precursor, its application is limited. Dihydropyridines (DHPs) can act as masked aldehydes, providing alkyl radicals under the activation of Lewis acid, heat, SET oxidant and light irradiation. Herein, we report the direct activation of 4-alkyl DHPs via single electron transfer at the anode. C-C bond homolysis at the C4-position of DHP generated the corresponding alkyl radical, which was captured subsequently by 2-phenyl and 2-ethoxy carbonyl allyl bromide. The following intramolecular elimination reaction afforded 20 different radical allylation products bearing various alkyl substituents with yields up to 92%. (C) 2022 Elsevier Ltd. All rights reserved.
Forni, Jose A.Czyz, Milena L.Polyzos, AnastasiosLupton, David W....
5页
查看更多>>摘要：Reported here is a regioselective C(sp(3))-C(sp(2)) cross coupling reaction between inert gamma-C(sp(3))-H bonds in aliphatic amines and cyanoarenes under electrochemical conditions in flow. The developed methodology takes advantage of a removable redox active auxiliary, which triggers selective 1,7-hydrogen atom transfer to functionalise an aliphatic C-H bond at the gamma-position of an alkyl amine. In this reaction, a cyanoarene radical anion functions as both a selective arylating reagent and a redox active mediator, enabling the controlled one electron reduction of the redox active auxiliary. This strategy offers a new approach towards gamma-C(sp(3))-H bond functionalisation allowing generation of, amongst others, sterically crowded carbon centres under mild reaction conditions and in the absence of additional catalysts or radical initiators. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A simple and mild approach to access polycyclic 8H-indolo[3,2,1-de]phenanthridin-8-ones through a visible-light induced free radical cyclization of (2-bromophenyl)(9H-carbazol-9-yl)methanones using benzothiadiazole-containing photocatalyst is reported. This transition metal free method can be utilized for the synthesis of 7H-thieno[2',3':4,5]pyrido[3,2,1-jk]carbazol-7-one, 14H-isoquinolino[4,3,2-kl]phenoxazin-14-one, 14H-isoquinolino[4,3,2-kl]phenothiazin-14-one, and 10,11,12,13-tetrahydro-8H-indolo [3,2,1-de]phenanthridin-8-one. Moreover, some products were found to emit strong blue or green fluorescence. (C) 2022 Elsevier Ltd. All rights reserved.
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Elsevier