Weisi Guo

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Dual photoredox−transition-metal catalysis has emerged as a powerful tool for the development of chemical transformations. However, its application in the selective difunctionalization of 1,3-dienes remains essentially unexploited. By the synergistic action of photoredox and copper catalysts, we report herein an enantioselective 1,2-amidocyanation of 1,3-dienes. Visible-light irradiation of a chloroform solution of conjugated dienes, N-Boc-amidopyridinium salts, and TMSCN in the presence of a catalytic amount of fac-Ir(ppy)3, Cu(OTf)2·xH2O, and a chiral Box ligand affords three-component adducts in good to high yields with high regio- and enantioselectivities. A L*CuCN complex, fully characterized spectroscopically and confirmed by X-ray crystallographic analysis, is able to catalyze the transformation, therefore supporting an inner-sphere cyanide transfer pathway.

2023

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The generation of heteroatom-centred radicals (X), followed by intramolecular 1,5-hydrogen atom transfer (1,5-HAT) and the functionalisation of the translocated carbon-centred radicals, is the basic mechanism of the classic Hofmann-Loffler-Freytag (HLF) reaction and the Barton reaction. The chemoselectivity of the 1,5-HAT process is different from that of the transition metal-catalysed counterpart, providing, therefore, a complementary tool for remote C(sp(3))-H bond functionalisation. There is a recent resurgence in this research field due to the emergence of visible light photocatalysis. This tutorial review summarises the recent progress in the remote functionalisation of C-H bonds featuring a key 1,5-HAT step with particular focus on photoredox-catalyzed remote C-H functionalisation.

2021

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Copper-Catalyzed Cyanoalkylative Aziridination of N-Sulfonyl Allylamines

Weisi Guo, Minh Tu Ha, Qian Wang, Jieping Zhu

Reaction of N-arylsulfonyl allylamines with alkyl nitriles in the presence of di-tert-butyl peroxide (DTBP) and a catalytic amount of copper salt afforded homologated aziridines in 43-86% yield. A sequence involving addition of the in situ generated cyanomethyl radical to the double bond followed by a copper-mediated intramolecular C-N bond formation accounted for the reaction outcome. 2,3-Disubstituted allylamines were converted to trisubstituted aziridines in a stereoselective manner. Starting from enantioenriched allylamines, chiral aziridines were obtained diastereoselectively.

WILEY-V C H VERLAG GMBH2020

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