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1.
Chem Commun (Camb) ; 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33724282

RESUMO

Herein, we report on selectivity control in C-H activations with alkylidenecyclopropanes (ACPs) for the chemo-selective assembly of cyclopropanes or dienes. Thus, unprecedented rhodaelectro-catalyzed C-H activations were realized with diversely decorated ACPs with a wide substrate scope and electricity as the sole oxidant.

2.
Chemistry ; 26(69): 16450-16454, 2020 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-32596872

RESUMO

C-H hydroxylation of aryl acetamides and alkyl phenylacetyl esters was accomplished via challenging distal weak O-coordination by versatile ruthenium(II/IV) catalysis. The ruthenium(II)-catalyzed C-H oxygenation of aryl acetamides proceeded through C-H activation, ruthenium(II/IV) oxidation and reductive elimination, thus providing step-economical access to valuable phenols. The p-cymene-ruthenium(II/IV) manifold was established by detailed experimental and DFT-computational studies.

3.
Angew Chem Int Ed Engl ; 59(14): 5551-5556, 2020 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-31793169

RESUMO

Nitrogen-doped polycyclic aromatic hydrocarbons (aza-PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza-PAHs was developed via a rhodium-catalyzed cascade C-H activation and alkyne annulation. A multifunctional O-methylamidoxime enabled the high chemo- and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C-H activation steps. In addition, the metalla-electrocatalyzed multiple C-H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups.

4.
Org Lett ; 21(2): 571-574, 2019 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-30604972

RESUMO

Low-valent manganese-catalyzed C-H alkylation of pyridine derivatives with both primary and challenging secondary alkyl halides was established by amide assistance. The strategy provided expedient access to alkylated pyridines with wide functional group tolerance and ample scope through weak chelation. Mechanistic studies provided strong support for a rate-determining C-H activation and a SET-type C-X scission.

5.
Beilstein J Org Chem ; 14: 1546-1553, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30013681

RESUMO

Versatile C-H amidations of synthetically useful ferrocenes were accomplished by weakly-coordinating thiocarbonyl-assisted cobalt catalysis. Thus, carboxylates enabled ferrocene C-H nitrogenations with dioxazolones, featuring ample substrate scope and robust functional group tolerance. Mechanistic studies provided strong support for a facile organometallic C-H activation manifold.

6.
Chemistry ; 23(48): 11524-11528, 2017 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-28704583

RESUMO

C-H alkylations with challenging ß-hydrogen-containing alkyl halides were accomplished with sustainable MnCl2 as the catalyst under phosphine-ligand-free conditions. The proximity-induced benzamide C-H activation occurred with ample substrate scope through rate-determining C-H metalation, also setting the stage for manganese-catalyzed oxidative C-H methylations.

7.
Org Lett ; 19(14): 3795-3798, 2017 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-28686458

RESUMO

The design of trisubstituted triazoles set the stage for proximity-induced iron-catalyzed C-H activation of benzyl and aryl amines with ample scope. Thereby, C-H alkylations and C-H arylations proved viable with high levels of chemo and positional selectivities by means of racemization-free iron catalysis with the reusable triazole being removed in a traceless fashion.

8.
Angew Chem Int Ed Engl ; 56(1): 350-353, 2017 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-27910194

RESUMO

Oxidative ring contraction of cyclic α-formyl ketones was facilitated by the action of H2 O2 under operationally simple and environmentally benign reaction conditions. The process was highly regioselective and enables stereospecific construction of contiguous quaternary all-carbon centers from stereodefined all-substituted all-cyclic ketones. The asymmetric syntheses of (+)-cuparene and (+)-tochuinyl acetate were also successively achieved by taking advantage of this novel protocol.

9.
Org Lett ; 18(1): 80-3, 2016 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-26654658

RESUMO

Relying on the nucleophilicity of silanol for building up silicon-incorporated scaffold with an enantiopure tetrasubstituted carbon center remains elusive. In this report, asymmetric bromo-oxycyclization of olefinic silanol by using chiral anionic phase-transfer catalyst is described. This protocol provided a facile entry to a wide arrangement of enantiopure benzoxasilole in moderate to excellent enantioselectivities depending on the unique reactivity of bromine/N-benzyl-DABCO complex.


Assuntos
Hidrocarbonetos Bromados/química , Silanos/síntese química , Alcenos/química , Catálise , Ciclização , Estrutura Molecular , Silanos/química , Silício/química , Estereoisomerismo
10.
Org Biomol Chem ; 13(19): 5381-4, 2015 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-25881571

RESUMO

The first direct access to unprotected amino-pyrroloindoline via aminocyclization of tryptamine and tryptophan has been described. A variety of structurally diverse amino-pyrroloindolines are furnished by the use of O-(2,4-dinitrophenyl)hydroxylamine (DPH) as the nitrogen source in the presence of catalytic Rh2(esp)2.


Assuntos
Aminas/síntese química , Indóis/síntese química , Pirróis/síntese química , Triptaminas/síntese química , Alcaloides/química , Aminas/química , Ciclização , Indóis/química , Pirróis/química , Triptaminas/química
11.
Chem Sci ; 6(12): 6986-6990, 2015 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29861937

RESUMO

By designing a novel chiral ion-pair organocatalyst composed of chiral phosphate and DABCO-derived quaternary ammonium, highly enantioselective 3-exo iodo-cycloetherification of allyl alcohols was achieved using NIS as a halogen source. Based on this reaction, one-pot asymmetric 3-exo iodo-cycloetherification/Wagner-Meerwein rearrangement of allyl alcohols en route to enantioenriched 2-iodomethyl-2-aryl cycloalkanones was subsequently developed. Due to the participation of adjacent iodine, the Wagner-Meerwein rearrangement of 2-iodomethyl-2-aryl epoxide proceeds with unusual retention of stereoconfiguration.

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