RESUMEN
Magnetic Cu-MOF-74 (Fe3O4@SiO2@Cu-MOF-74) was synthesized for the first time by grafting MOF-74 (copper as the metal center) on the surface of core-shell magnetic carboxyl-functionalized silica gel (Fe3O4@SiO2-COOH), which was prepared by coating core Fe3O4 nanoparticles with hydrolyzed 2-(3-(triethoxysilyl)propyl)succinic anhydride and tetraethyl orthosilicate. The structure of Fe3O4@SiO2@Cu-MOF-74 nanoparticles was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe3O4@SiO2@Cu-MOF-74 nanoparticles could be applied as a recyclable catalyst to the synthesis of N-fused hybrid scaffolds. 2-(2-Bromoaryl)imidazoles and 2-(2-bromovinyl)imidazoles were coupled and cyclized with cyanamide in DMF in the presence of a catalytic amount of Fe3O4@SiO2@Cu-MOF-74 along with a base to give imidazo[1,2-c]quinazolines and imidazo[1,2-c]pyrimidines, respectively, in good yields. The Fe3O4@SiO2@Cu-MOF-74 catalyst could be easily recovered by a super magnetic bar and recycled more than four times while almost maintaining catalytic activity.
RESUMEN
2-(2-Bromoaryl)imidazoles react with cyclohexane-1,3-diones in the presence of a catalytic amount of recyclable Fe3O4@SiO2@MOF-199 and a base to give the corresponding C-C coupled and cyclized products 6,7-dihydroimidazo[1,2-f]phenanthridin-8(5H)-ones in high yields. The magnetic MOF catalyst could be easily recovered and reused four times without any significant loss of catalytic activity. The coupled and cyclized scaffolds were aromatized to imidazo[1,2-f]phenanthridines in high yields by a one-pot sequential procedure including reduction, dehydration, and oxidation. The present protocol could be applied to the synthesis of Zephycandidine A, which is known to exhibit anti-tumor activity.
RESUMEN
A class of trinuclear imidazole-fused hybrid scaffolds was constructed by the reaction of 2-(2-bromoaryl)- and 2-(2-bromovinyl)imidazoles with 2-aminobenzimidazoles as building blocks in the presence of a base under microwave irradiation. A nucleophilic aromatic substitution followed by cyclization is proposed as a reaction pathway of this green process.
RESUMEN
A class of binuclear N-fused hybrid scaffolds was constructed by the reaction of 2-(2-bromoaryl)- and 2-(2-bromovinyl)benzimidazoles with aryl isocyanates as building blocks in the presence of a base under microwave irradiation. A nucleophilic addition followed by an unprecedented transition-metal-free C(sp2)-N coupling is proposed as a reaction pathway of this green process.
RESUMEN
Aryl 2-bromobenzoates and aryl 2-bromocyclohex-1-enecarboxylates are cyclized by microwave irradiation in dimethylformamide in the presence of K2CO3 to give the corresponding 6 H-benzo[ c]chromen-6-ones and their 7,8,9,10-tetrahydro analogues, respectively, in 50-72% yields. Aryl 3-bromoacrylates are also converted into 2 H-chromen-2-ones under the employed conditions.
RESUMEN
ß-Bromo-α,ß-unsaturated aldehydes and 2-bromobenzaldehydes react with 4,7-dimethoxy-1H-benzo[d]imidazole-2-amine by microwave irradiation in dimethylformamide in the presence of a base to give the corresponding dimethoxy-substituted benzo[4,5]imidazo[1,2-a]pyrimidines and benzo[4,5]imidazo[1,2-a]quinazolines, respectively, in moderate to good yields. Oxidation of such N-fused hybrid scaffolds by aqueous ceric ammonium nitrate affords pyrimidine- and quinazoline-fused benzimidazole-4,7-diones in high yields.
RESUMEN
2-(2-Bromovinyl)- and 2-(2-bromoaryl)-benzimidazoles, including their 4,7-dimethoxy analogs, react with primary amides by microwave irradiation (or usual heating) in dimethylformamide in the presence of a catalytic amount of CuI along with a base to give the corresponding benzo[4,5]imidazo[1,2-c]-pyrimidines and -quinazolines in good yields. Treatment of benzo[4,5]imidazo[1,2-c]-pyrimidines and -quinazolines having methoxy group on benzimidazole moiety with aqueous ceric ammonium nitrate affords unprecedented N-fused hybrid scaffolds, benzo[4,5]imidazo[1,2-c]-pyrimidin-6,9-diones and -quinazoline-8,11-diones, respectively, in high yields.
RESUMEN
Quinolin-2(1H)-ones and phenanthridin-6(5H)-ones are synthesized in high yields by K2CO3-promoted cyclization of N-aryl-ß-bromo-α,ß-unsaturated amides and N-aryl-2-bromobenzamides in dimethylformamide under microwave irradiation.
RESUMEN
2-(2-Bromovinyl)benzimidazoles and 2-(2-bromophenyl)benzimidazoles react with cyanamide by microwave irradiation in dimethylformamide in the presence of a catalytic amount of CuI along with a base to give the corresponding benzo[4,5]imidazo[1,2-c]pyrimidin-1-amines and benzo[4,5]imidazo[1,2-c]quinazolin-6-amines, respectively, in moderate to good yields. 2-(2-Bromophenyl)indoles also react with cyanamide under similar conditions to afford indolo[1,2-c]quinazolin-6-amines. The reaction pathway seems to proceed via a sequence such as intermolecular C-N coupling, C-N formative cyclization, and tautomerization.
RESUMEN
An unusually stable molecular capsule was formed by heating phenyleneurea-spanned resorcinarene cavitand with 4-methyl-N-p-tolylbenzamide. The molecular capsule behaved as a discrete molecular entity showing a cylindrical D(4d) structure and showed no guest exchange in toluene-d(8) even at 100 degrees C. [structure: see text]
RESUMEN
2-Bromobenzaldehydes react with arylhydrazines in toluene at 100 [degree]C in the presence of a catalytic amount of a palladium catalyst and phosphorus chelating ligands such as 1,1[prime or minute]-bis(diphenylphosphino)ferrocene and 1,3-bis(diphenylphosphino)propane along with NaO-t-Bu to afford 1-aryl-1H-indazoles in good yields.
RESUMEN
Activated olefins react with allyl acetates and Bu3SnH in the presence of a catalytic amount of a palladium catalyst to afford the corresponding products which construct a new C-C bond selectively at the alpha-position of Michael acceptors.
Asunto(s)
Alquenos/química , Carbono/química , Paladio/química , Compuestos Alílicos/química , Compuestos Alílicos/metabolismo , Catálisis , Fenómenos Químicos , Química , CinéticaRESUMEN
[reaction: see text] A novel C3V-symmetric scaffold, trindane 7, has been efficiently synthesized from 1,3,5-tris(bromomethyl)-2,4,6-tris(chloromethyl)benzene (1) in six steps with 47% overall yield. The control of all-syn stereochemistry in the tribenzylation step has been achieved by blocking one side of the trindane ring as metal carbonyl complexes. The potential utility of trindane 7 as a receptor skeleton has been examined with a urea derivative 12 toward several anionic guests.
Asunto(s)
Aniones/análisis , Técnicas Biosensibles/métodos , Compuestos Policíclicos/síntesis química , Receptores de Droga/química , Aniones/química , Aniones/metabolismo , Sitios de Unión , Modelos Moleculares , Conformación Molecular , Compuestos Policíclicos/química , Compuestos Policíclicos/farmacocinética , Solventes , VolumetríaRESUMEN
A new reaction: A ruthenium-catalyzed transfer of an alkyl group from a trialkylamine to the α-carbon atom of a ketone leads in good yields to α-alkylated ketones [Eq. (1)]. The reaction is applicable to a wide range of alkyl(alkyl), alkyl(aryl), and cyclic ketones, and in the case of unsymmetrical ketones it takes place regioselectively at the less hindered α-position.