RESUMO
The gold-catalyzed hydroamination of 2-(arylethynyl)pyridines with anilines affords stereoselectively Z-enamine products with excellent regioselectivity. The reaction proceeds with moderate to excellent yields and accommodates a diverse range of functional groups on alkynes (ether, bromo, trifluoromethyl, acetyl, and carbomethoxy) and anilines (ether, bromo, chloro, and carbethoxy). The stereochemistry of the obtained enamines is complementary to that reported in previous studies. A plausible explanation for the observed selectivity was attained by means of NMR experiments.
RESUMO
An efficient strategy for the synthesis of 6-unsubstituted indolo[1,2-c]quinazolines is described. The Pd-catalyzed reaction of o-(o-aminophenylethynyl) trifluoroacetanilides with Ar-B(OH)2 afforded 2-(o-aminophenyl)-3-arylindoles, that were converted to 12-arylindolo[1,2-c]quinazolines by adding dimethylformamide dimethyl acetal (DMFDMA) to the reaction mixture after extractive work-up. This reaction outcome is different from the previously reported Pd-catalyzed sequential reaction of the same substrates with Ar-I, Ar-Br and ArN2+BF4-, that afforded 12-arylindolo[1,2-c]quinazolin-6(5H)-ones. Moreover, 12-unsubstituted indolo[1,2-c]quinazolines can be obtained both by reacting 2-(o-aminophenyl)indoles with DMFDMA or by sequential Pd-catalyzed reaction of o-(o-aminophenylethynyl)aniline with DMFDMA.
RESUMO
A novel palladium-catalyzed approach to 2-(aminomethyl)indoles from 3-(o-trifluoroacetamidoaryl)-1-propargylic alcohols and amines has been developed.
Assuntos
Alcinos/química , Indóis/síntese química , Paládio/química , Propanóis/química , Catálise , Indóis/química , Estrutura Molecular , EstereoisomerismoRESUMO
Applications of the cascade cyclocarbopalladation reaction followed by Suzuki-Miyaura coupling reactions of the readily available aryl-substituted propargylic aryl ethers with arylboronic acid and potassium trans-ß-styryltrifluoroborate accomplish a new versatile entry in the synthesis of benzofuran derivatives. Notably, a new approach to the challenging synthesis of C3 functionalized 2-unsubstituted benzofurans has been developed by a cyclocarbopalladation/cross-coupling/aromatization process.
Assuntos
Benzofuranos/síntese química , Compostos de Boro/química , Hidrocarbonetos Bromados/química , Paládio/química , Alcinos/química , Benzofuranos/química , Catálise , Ciclização , Éteres/química , Estrutura Molecular , Compostos Organometálicos/químicaRESUMO
Free NH 2-substituted 3-arylindoles have been prepared usually in good to high yields through the palladium-catalyzed reaction of readily available 2-alkynyltrifluoroacetanilides with arylboronic acids under oxidative conditions. The reaction tolerates a variety of useful functional groups both in the arylboronic acid and in the alkyne, including chloro, formyl, and ester groups.
Assuntos
Acetanilidas/química , Ácidos Borônicos/química , Indóis/química , Paládio/química , Catálise , Ciclização , OxirreduçãoRESUMO
Free NH 3,3-diarylacrylamides are cyclized to substituted 2-quinolones in the presence of CuI, PPh(3), and KO-t-Bu in o-xylene at 100 °C. The reaction proceeds through a C-H functionalization/C-N bond formation process. With unsymmetrical 3,3-diarylacrylamides, high selectivity is observed using substrates where the aromatic ring trans to the amide group bears o-methyl, -chloro, or -bromo substituents.
Assuntos
Amidas/química , Cobre/química , Hidroxiquinolinas/síntese química , Iodetos/química , Quinolonas/síntese química , Catálise , Ciclização , Hidroxiquinolinas/química , Estrutura Molecular , Quinolonas/químicaRESUMO
The palladium-catalyzed cyclization of 2-(2-bromoaryl)-3-arylindoles provides a new versatile approach to dibenzo[a,c]carbazoles. The reaction tolerates a variety of useful substituents including chloro, nitro, ether, cyano, keto, and ester groups.
Assuntos
Carbazóis/síntese química , Indóis/síntese química , Paládio/química , Acetanilidas/química , Catálise , Ciclização , Estrutura MolecularRESUMO
The scope and the generality of gold versus silver catalyzed intramolecular hydroarylation reactions of 3-[(3-arylprop-2-ynyl)oxy]benzene derivatives in terms of rings substitution were investigated. Only products deriving from 6-endo cyclization were exclusively formed. The features of substituents had a considerable effect on the reaction outcome in the presence of silver catalysis, whereas gold catalysis revealed a unique blend of reactivity and selectivity and represented the only choice for the intramolecular hydroarylation reaction of the starting substrates bearing electron deficient arenes.
Assuntos
Derivados de Benzeno/química , Benzopiranos/síntese química , Técnicas de Química Sintética/métodos , Ouro/química , Prata/química , Benzopiranos/química , Catálise , Ciclização , Estrutura MolecularRESUMO
A novel palladium-catalyzed approach to 2-amino ketones from arylpropargylic carbonates bearing neutral, electron-rich, and electron-poor aromatic rings and cyclic secondary amines containing useful functional groups such as cyano, chloro, and bromo substituents has been developed.
Assuntos
Aminas/química , Carbonatos/química , Cetonas/síntese química , Paládio/química , Catálise , Estrutura MolecularRESUMO
Novel palladium-catalyzed reactions of arenediazonium tetrafluoroborates with N,N-diprotected allylamines are presented. The reaction of arenediazonium tetrafluoroborates with N,N-(Boc)(2) allylamine allows for an easy approach to cinnamylamines whereas using 2-alkynyl-N-(allyl)trifluoroacetanilides and 2-iodo-N-(allyl)trifluoroacetanilide the reaction provides a useful tool for appending indole rings to aniline fragments.
Assuntos
Alilamina/química , Compostos Azo/química , Indóis/síntese química , Propilaminas/síntese química , Catálise , Estrutura Molecular , Paládio/químicaRESUMO
This perspective reports on some of the main copper-catalyzed routes to the construction of the pyrrole and furan rings incorporated into the indole and benzo[b]furan systems, respectively. The first part illustrates the synthesis of indoles through cyclizations of 2-alkynylanilid(n)es, preformed or generated in situ, and cyclizations via intramolecular N-arylation, N-vinylation, and C-C bond forming reactions. The second part illustrates the synthesis of benzo[b]furans through cyclizations of preformed 2-alkynylphenols, domino synthesis of 2-alkynylphenols/cyclization processes, and cyclizations via intramolecular O-arylation reactions.
Assuntos
Benzofuranos/química , Cobre/química , Indóis/química , Catálise , LigantesRESUMO
The palladium-catalyzed reaction of (hetero)aryl bromides, chlorides, and nonaflates with α-allyl-ß-ketoesters provides ready efficient access to functionalized 2,3-dihydrofurans. The reaction tolerates several useful substituents including chloro, fluoro, ether, ketone, ester, cyano, and nitro groups.
Assuntos
Ésteres/química , Furanos/síntese química , Cetonas/química , Paládio/química , Catálise , Furanos/química , Estrutura Molecular , EstereoisomerismoRESUMO
The reaction of readily available (5R)-5-but-3-en-1-ylpyrrolidin-2-one with aryl bromides, chlorides, or triflates in the presence of Pd(2)(dba)(3), Xphos, and Cs(2)CO(3) in 1,4-dioxane at 120 degrees C affords (5R,7aR)-5-aryl hexahydropyrrolizidin-3-ones in good to high yields through a diastereoselective carboamination reaction. Aryl iodides are less successful substrates than bromides and chlorides.
Assuntos
Paládio/química , Pirrolidinas/síntese química , Pirrolidinonas/síntese química , Aminação , Catálise , Pirrolidinas/química , Pirrolidinonas/química , EstereoisomerismoRESUMO
A novel palladium-catalyzed synthesis of arylphosphonates from arenediazonium tetrafluoroborates and triethylphosphite or diethylphosphite is presented. The reaction tolerates useful substituents including bromo, chloro, nitro, ether, cyano, keto, and ester groups, can be performed as a one-pot process from anilines omitting the isolation of arenediazonium salts, and can be extended to the preparation of arylphosphine oxides and arylphosphines.
Assuntos
Ácidos Bóricos/química , Compostos de Diazônio/química , Paládio/química , Fosfinas/síntese química , Boratos , Catálise , Óxidos/química , Fosfinas/químicaRESUMO
The utilization of perfluoro-tagged palladium nanoparticles immobilized on fluorous silica gel through fluorous-fluorous interactions (Pd(np)-/FSG) or linked to silica gel by covalent bonds (Pd(np)-) in the alkynylation of terminal alkynes with aryl halides under aerobic, copper- and phosphine-free conditions in water, and their recovery and re-utilization, is described.
Assuntos
Alcinos/síntese química , Derivados de Benzeno/síntese química , Halogênios/síntese química , Nanopartículas Metálicas/química , Paládio/química , Alcinos/química , Derivados de Benzeno/química , Catálise , Halogênios/química , Dióxido de Silício/química , Água/químicaRESUMO
N-Propargylic beta-enaminones have been used as common intermediates for the synthesis of polysubstituted pyrroles and pyridines. Best results have been obtained using DMSO as solvent. In the presence of Cs(2)CO(3) N-propargylic beta-enaminones are cyclized to pyrroles in good to high yields, whereas omitting bases and using CuBr leads to the selective formation of pyridines.
RESUMO
The palladium-catalyzed hydroarylation of arenediazonium tetrafluoroborates with alkynes in the presence of triphenylsilane affords stereoselectively hydroarylation products in moderate to high yields. The reaction tolerates a variety of substituents including keto, ester, cyano, and nitro groups and can be performed as a one-pot procedure generating the arenediazonium salt in situ. With ethyl phenylpropynoate as the starting alkyne, the hydroarylation affords ethyl (Z)-2-arylcinnamates stereo- and regioselectively.
Assuntos
Alcinos/química , Compostos de Diazônio/química , Paládio/química , CatáliseRESUMO
The immobilization of phosphine-free perfluoro-tagged palladium nanoparticles Pd-1 on fluorous silica gel (FSG) and their utilization in the Heck reaction have been investigated. High yields of vinylic substitution products have been obtained. Recycling studies have shown that the solid-supported palladium catalyst can be readily recovered and reused several times without significant loss of activity. Reactions and recovery of the solid-supported palladium catalyst system can be carried out in the presence of air, without any particular precaution.
RESUMO
2-Substituted 3-aroylquinolin-4(1H)-ones, prepared through a palladium-catalyzed carbonylative cyclization of N-(2-iodoaryl)enaminones, proved to inhibit efficiently the Hedgehog pathway through direct antagonism of the wild-type and drug-resistant form of the Smoothened receptor. Notably, these compounds repressed the Hh-dependent growth events and the proliferation of tumor cells with aberrant activation of the Hh pathway, which plays a crucial role in development and tumorigenesis.