RESUMO
Herein, we report an N-alkylation of pyrroles triggered by an unprecedented selective ring-expansive migration of the spiro-2H-pyrrole intermediates obtained via Ir-catalyzed asymmetric allylic dearomatization. The reaction affords a series of tetrahydropyrrolo[1,2-c]pyrimidine derivatives in good yields (up to 88%) with excellent enantioselectivity (up to >99% ee). The proposed reaction mechanism is supported by DFT calculations and the characterization of the key intermediate.
RESUMO
An intermolecular Pd-catalyzed allylic dearomatization reaction of polycyclic indoles with substituted allylic carbonates was realized in the presence of a newly synthesized chiral phosphoramidite ligand. Various polycyclic indoline and indolenine derivatives were successfully synthesized in excellent yields (up to 99%) with excellent enantioselectivity (up to 98% ee). The obtained products could undergo versatile transformations, increasing the application potential of the method in organic synthesis.
RESUMO
A highly efficient method for constructing C3-methyl-substituted pyrroloindolines and furoindolines via cascade dearomatization reaction of indole derivatives with methyl iodide was developed. This protocol offers a direct approach to a wide range of C3 methyl substituted pyrroloindolines under mild conditions. The utility of this method was further demonstrated in the concise synthesis of (±)-esermethol.
Assuntos
Hidrocarbonetos Iodados/química , Indóis/síntese química , Pirróis/síntese química , Furanos/química , Indóis/química , Estrutura Molecular , Pirróis/químicaRESUMO
Enantioselective synthesis of pyrrole-annulated medium-sized-ring compounds by an iridium-catalyzed allylic dearomatization/retro-Mannich/hydrolysis sequence is presented. Various substituted pyrrole-annulated seven- and eight-membered-ring products were obtained under mild reaction conditions with moderate to good yields and excellent enantioselectivity. Additionally, these products contain a scaffold widely distributed in natural products and biologically active compounds. The current method provides a convenient way for accessing such pyrrole-anuulated medium-sized-ring compounds.
RESUMO
We have developed Pd-catalyzed intermolecular Friedel-Crafts-type allylic alkylation and allylic dearomatization reactions of substituted indoles bearing a nucleophilic group with vinyloxirane, providing an efficient method to synthesize structurally diverse tetrahydrocarboline and spiroindolenine derivatives under mild conditions.
RESUMO
Bridged indoline derivatives were synthesized by an intermolecular Pd-catalyzed allylic dearomatization reaction of substituted indoles. The reaction between indoles and allyl carbonates bearing a nucleophilic alcohol side-chain proceeds in a cascade fashion, providing bridged indolines in excellent enantioselectivity.
RESUMO
The rapid and direct asymmetric synthesis of 3-(3a-indolyl)hexahydropyrroloindoline motifs is an extremely important part of the total synthesis of several alkaloid structures. Herein, an intermolecular, asymmetric cascade dearomatization reaction of indole acetamides with 3-indolylphenyliodonium salts has been developed. This protocol provides a straightforward access to 3-(3a-indolyl)hexahydropyrroloindolines bearing an all-carbon quaternary stereocenter at the C3 position of the indoline ring with high enantioselectivities. The utility of the protocol has been demonstrated by the formal asymmetric synthesis of folicanthine.
Assuntos
Acetamidas/química , Cobre/química , Indóis/química , Catálise , Estrutura Molecular , EstereoisomerismoRESUMO
A chiral iridium(I) N-heterocyclic carbene complex was reported for the first time as the catalyst in the highly enantioselective intramolecular allylic amination reaction. The current method provides facile access to biologically important enantioenriched indolopiperazinones and piperazinones in good yields (74-91 %) and excellent enantioselectivities (92-99 % ee). Preliminary mechanistic investigations reveal that the C-H activation occurs at the position ortho to the N-aryl group of the ligand.
RESUMO
Asymmetric synthesis of indole-annulated medium-sized-ring compounds is developed through an iridium-catalyzed allylic dearomatization/retro-Mannich/hydrolysis cascade reaction. The reaction features mild conditions and a broad substrate scope. Under the optimal conditions, various seven-, eight-, or nine-membered-ring compounds can be afforded in good to excellent yields and excellent enantioselectivity. The proposed mechanism is supported by capturing the dearomatized intermediate through in situ reduction.
RESUMO
A direct asymmetric dearomative amination of tryptamines with O-(2,4-dinitrophenyl)hydroxylamine (DPH) was achieved using CuBr-bisoxazoline complex as a catalyst, affording 3a-amino-pyrroloindolines in good to excellent enantioselectivity under mild reaction conditions. Furthermore, the synthetic value of this method was demonstrated in the total synthesis of (-)-psychotriasine in a highly concise manner.
Assuntos
Cobre/química , Indóis/química , Triptaminas/química , Aminação , Catálise , EstereoisomerismoRESUMO
A highly efficient intermolecular cascade dearomatization of substituted indoles with benzodithiolylium tetrafluoroborate has been developed. This reaction provides a novel strategy to synthesise C3 methyl-substituted pyrroloindolines and furoindolines under mild reaction conditions, the utility of which has been demonstrated by the synthesis of esermethol and physovenine in a highly concise manner.
Assuntos
Boratos/química , Furanos/síntese química , Indóis/síntese química , Pirróis/síntese química , Catálise , Estrutura Molecular , Fisostigmina/análogos & derivados , Fisostigmina/síntese química , EstereoisomerismoRESUMO
An efficient Ru-catalyzed regioselective allylic trifluoromethylthiolation reaction of allylic carbonates was developed. The linear allylic trifluoromethyl thioethers were obtained in 52-91% yields. Mechanistic investigation revealed that this reaction proceeds via a double allylic trifluoromethylthiolation sequence.
Assuntos
Compostos Alílicos/química , Hidrocarbonetos Fluorados/química , Rutênio/química , Compostos de Sulfidrila/química , Catálise , Estrutura Molecular , EstereoisomerismoRESUMO
Spiroindolenine derivatives were synthesized by intermolecular Pd-catalyzed dearomatization of indoles. The reaction between nucleophile bearing indoles and propargyl carbonate proceeds in a cascade fashion providing spiroindolenines or spiroindolines in good to excellent yields.
Assuntos
Alcinos/química , Carbonatos/química , Indóis/química , Paládio/química , Compostos de Espiro/síntese química , Catálise , Indóis/síntese química , Estrutura Molecular , Compostos de Espiro/química , EstereoisomerismoRESUMO
Copper-catalyzed C-2 arylation and vinylation of indole derivatives with iodonium salts have been realized. This method, featuring a simple operational procedure, mild reaction conditions, and a wide substrate scope, provided versatile indole derivatives with direct and selective functionalization at the C-2 position of the indole core. In the presence of excess amounts of iodonium salts, cascade C-2 arylation and dearomatization through the C-3 arylation reaction also proceeded smoothly.
Assuntos
Cobre/química , Indóis/química , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Catálise , Ciclização , Espectroscopia de Prótons por Ressonância Magnética , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
Regio- and enantioselective synthesis of N-allylindoles was realized through an iridium-catalyzed asymmetric allylic amination reaction with 2-alkynylanilines and subsequent transition-metal-catalyzed cyclization reactions. The highly enantioenriched allylic amines prepared from Ir-catalysis were treated with catalytic amount of NaAuCl4â 2 H2O or PdCl2 providing various substituted N-allylindoles in excellent yields and enantioselectivities.
RESUMO
A new strategy for the construction of a C=C-CF3 subunit has been developed via CuBr-catalyzed domino cyclization-trifluoromethylation of homopropargyl amines with Umemoto's reagent. 4-Trifluoromethyl-2,3-dihydro-pyrroliums were produced in high yields. The usefulness of these products has been demonstrated by the transformation of them into various other trifluoromethylated molecules.
Assuntos
Aminas/química , Pirróis/síntese química , Aminas/síntese química , Brometos/química , Catálise , Cobre/química , Ciclização , Halogenação , Metilação , Pirróis/químicaRESUMO
A highly regioselective palladium-catalyzed allylic alkylation of dienyl esters with nitromethane has been developed, providing selective access to the C-5 attacked products. The structures of the ligands as well as the steric effect of the substrates are important factors in determining the regiochemical outcome of the reaction.
RESUMO
A highly enantioselective synthesis of substituted tetrahydrocarbolines via Ir-catalyzed Friedel-Crafts type intramolecular asymmetric allylic alkylation of 2-indolyl allyl carbonates has been developed. This strategy features excellent chemoselectivity and enantioselectivity, mild reaction conditions, and an easily accessed chiral ligand.
Assuntos
Carbolinas/síntese química , Indóis/química , Irídio/química , Alquilação , Compostos Alílicos/química , Carbolinas/química , Carbonatos/química , Catálise , Ligantes , Estrutura Molecular , EstereoisomerismoRESUMO
An efficient way to access functionalized methylenecyclopropanes has been developed by palladacycle-catalyzed cyclopropanation of bicyclic alkenes with propiolates in high yields. The structure of the palladacycle was kept intact in the reaction, shown by (31)P NMR spectrum studies. A rational mechanism has been proposed with a deuterium-labeled experiment. The usefulness of the functionalized methylenecyclopropanes has also been demonstrated.
Assuntos
Alcenos/química , Alcinos/química , Compostos Bicíclicos com Pontes/química , Ciclopropanos/síntese química , Compostos Organometálicos/química , Paládio/química , Propionatos/química , Catálise , Ciclopropanos/química , Estrutura MolecularRESUMO
The palladium(0)-catalyzed dearomative arylation of pyrroles has been accomplished to afford the spironaphthalenepyrrole derivatives in good to excellent yields.