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1.
Nature ; 575(7782): 336-340, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31723273

RESUMO

Organoboron reagents are important synthetic intermediates that have a key role in the construction of natural products, pharmaceuticals and organic materials1. The discovery of simpler, milder and more efficient approaches to organoborons can open additional routes to diverse substances2-5. Here we show a general method for the directed C-H borylation of arenes and heteroarenes without the use of metal catalysts. C7- and C4-borylated indoles are produced by a mild approach that is compatible with a broad range of functional groups. The mechanism, which is established by density functional theory calculations, involves BBr3 acting as both a reagent and a catalyst. The potential utility of this strategy is highlighted by the downstream transformation of the formed boron species into natural products and drug scaffolds.


Assuntos
Compostos de Boro/química , Compostos de Boro/síntese química , Boro/química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Teoria da Densidade Funcional , Descoberta de Drogas , Indóis/química , Compostos Organometálicos/química , Preparações Farmacêuticas/síntese química , Preparações Farmacêuticas/química
2.
Nature ; 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31569198

RESUMO

Organoboron reagents are important synthetic intermediates that play a key role in the construction of natural products, pharmaceuticals, and organic materials.1 The discovery of simpler, milder and more efficient approaches to organoborons opens a route to diverse substances.2-5 Here we show a general method of directed C-H activation for site-selective C-H borylation of arenes and heteroarenes avoiding the use of metal catalysts. C7 and C4-borylated indoles are produced by a mild approach with broad functional group compatibility. The mechanism involves BBr3 as both reagent and catalyst and is established with DFT calculations. Downstream transformation of the formed boron species to natural products and drug scaffolds highlights the potential utility of this strategy.

3.
J Org Chem ; 84(16): 10145-10159, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31313585

RESUMO

A practical single-electron-transfer-induced selective C(sp3)-N coupling of cycloketoximes with anilines via C-C bond cleavage under copper-catalytic and synergetic photoredox/copper-catalytic reaction systems has been uncovered. These two powerful and simple protocols demonstrated excellent selectivity and good functional group compatibility without any base or ligand control. Preliminary mechanistic experiments indicated that a radical-mediated process was involved in these transformations.

4.
Angew Chem Int Ed Engl ; 58(28): 9448-9452, 2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31058401

RESUMO

A series of in situ formed alkenyl diboronate complexes from alkenyl Grignard reagents (commercially available or prepared from alkenyl bromides and Mg) with B2 Pin2 (bis(pinacolato)diboron) react with diverse alkyl halides by a Ru photocatalyst to give various gem-bis(boryl)alkanes. Alkyl radicals add efficiently to the alkenyl diboronate complexes, and the adduct radical anions undergo radical-polar crossover, specifically, a 1,2-boryl-anion shift from boron to the α-carbon sp2 center. This transformation shows good functional-group compatibility and can serve as a powerful synthetic tool for late-stage functionalization in complex compounds. Measurements of the quantum yield reveal that a radical-chain mechanism is operative in which the alkenyl diboronates acts as reductive quencher for the excited state of the photocatalyst.

5.
Chem Commun (Camb) ; 55(13): 1971-1974, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30681675

RESUMO

The first example of intramolecular ring-opening and reconstruction of cyclobutanone oxime esters via selective C-C bond cleavage leading to the synthesis of 3,4-dihydronaphthalene-2-carbonitriles in the presence of a cheap copper catalyst has been reported. The protocol is distinguished by mild and safe reaction conditions that exclude ligands, oxidants, bases, toxic cyanide salts and tolerates a wide scope of cyclobutanones without compromising their efficiency and scalability. The alternative visible-light-driven photoredox process for this coupling reaction was also uncovered.

6.
Angew Chem Int Ed Engl ; 56(41): 12727-12731, 2017 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-28861945

RESUMO

The first example of intermolecular olefination of cyclobutanone oximes with alkenes via selective C-C bond cleavage leading to the synthesis of nitriles in the presence of a cheap copper catalyst is reported. The procedure is distinguished by mild and safe reaction conditions that avoid ligand, oxidant, base, or toxic cyanide salt. A wide scope of cyclobutanones and olefin coupling components can be used without compromising efficiency and scalability. The alternative visible-light-driven photoredox process for this coupling reaction was also uncovered.

7.
Chem Rec ; 16(2): 886-96, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26968749

RESUMO

In the past decade, transition-metal-catalyzed C-H activations have been very popular in the research field of organometallic chemistry, and have been considered as efficient and convenient strategies to afford complex natural products, functional advanced materials, fluorescent compounds, and pharmaceutical compounds. In this account, we begin with a brief introduction to the development of transition-metal-catalyzed C-H activation, especially the development of transition-metal-catalyzed chelation-assisted C-H activation. Then, a more detailed discussion is directed towards our recent studies on the transition-metal-catalyzed chelation-assisted oxidative C-H/C-H functionalization of aromatic substrates bearing directing functional groups.

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