RESUMO
The metal-free cyclization of allenyl ketones and p-toluenesulfonylmethyl isocyanide (TosMIC), promoted by Cs2CO3, provides a convenient access to tetrasubstituted pyrroles in which an acyl group undergoes 1,2-migration. This tandem Michael addition/annulative migration synthetic strategy is general and high-yielding for various substituted allenyl ketones. Moreover, a phosphoryl or ester moiety is also a suitable functionality to enable such migration.
RESUMO
A rhodium-catalyzed formal [4 + 1]-cyclization reaction of aryl substituted pyrazoles with cyclopropanols via C-H bond activation/cyclization processes to selectively construct a series of carbonyl functionalized pyrazolo[5,1-a]isoindoles is described. The reaction features good functional group compatibility and a broad substrate scope with respect to both cyclization components with up to 84% yields. Mechanistic studies indicated that the C-H cleavage might be the rate-determining step in this transformation.
RESUMO
An effective rhodium(III) catalysis for the construction of valuable tetracyclic compounds is described herein. This domino process involving the C-H activation/[3 + 2] annulation/intramolecular Friedel-Crafts reaction sequences of simple and readily available N-Boc hydrazones and propargylic monofluoroalkynes afforded fused tetracyclic spiro[cyclobutane-1,9'-indeno[1,2-a]indenes] in moderate to good yields, featuring three C-C bond formation. Moreover, control experiments indicated that the C-H activation might be involved in the rate-determining step.
Assuntos
Ciclobutanos , Indenos , Ródio , Catálise , Ciclização , Hidrazonas/química , Indenos/química , Estrutura Molecular , Ródio/químicaRESUMO
Silver-catalyzed stereoselective synthesis of polysubstituted ( Z)-1,2-dihydrobenzo[ cd]indoles from 8-ethynylnaphthalen-1-amines is reported. In this protocol, a series of nitrogen-containing heterocyclic compounds were synthesized by silver-catalyzed α-addition of an alkyne bond with high selectivity and high yields. The synthesized polysubstituted 1,2-dihydrobenzo[ cd]indoles could be easily converted to benzo[ cd]indol-2(1 H)-ones, and both 1,2-dihydrobenzo[ cd]indoles and benzo[ cd]indol- 2(1 H)-ones are biological and pharmaceutical cores.
RESUMO
An electrocatalytic reductive amination of electron-deficient aldehydes/ketones was developed, which could be used in the synthesis of functionalized tertiary amines and large scale preparation of racemic clopidogrel. A plausible mechanism involving an iminium cation intermediate was proposed.
Assuntos
Aldeídos/química , Clopidogrel/química , Eletrólise , Cetonas/química , Aminação , Transporte de Elétrons , Química Verde , EstereoisomerismoRESUMO
A palladium and iodine-cocatalyzed 5-exo-dig aza-thiocyclization of 8-alkynylnaphthalen-1-amines for the synthesis of (E)-2-alkylene-1,2-dihydrobenzo[cd]indole thioethers is reported. As a result of broad reaction scope, simple operation, mild conditions, and high stereoselectivity and regioselectivity, this reaction should have potential utility in organic synthesis.
RESUMO
A facile protocol for the synthesis of polysubstituted 1,2-dihydrocyclobuta[b]naphthalenes and 1,2-dihydrocyclobuta[b]anthracenes was developed via a sequence of base-promoted 1,5-H shift, intramolecular [2 + 2] cycloaddition, and aromatization. The synthesized 1,2-dihydrocyclobuta[b]anthracenes exhibited bright blue emissions in solution and strong yellow emissions in solid, which made them possible candidates for optoelectronic conjugated materials.
RESUMO
We report an electrophilic cyclization of alkynyl imines to afford polysubstituted 3-haloquinolines using CuX-activated N-halosuccinimdes (NXS) as electrophiles. Control experiments demonstrated that the NXS/CuX system might be more active than single NXS and could be applied in the electrophilic cyclization of electron- deficient substrates.
RESUMO
An efficient base-catalyzed protocol for the synthesis of benzothiophene is described. The reaction proceeds via base-promoted propargyl-allenyl rearrangement followed by cyclization and allyl migration. Phosphine-substituted indoles can be synthesized by a similar strategy.
RESUMO
Acene derivatives as a class of polycyclic aromatic hydrocarbons have attracted considerable interest because of their outstanding semiconductor properties. We developed a one-pot synthesis for fully conjugated tetraphene via a sequence of propargyl-allenyl isomerization, phosphine addition, intramolecular Wittig reactions, and Diels-Alder cyclization reactions. The derivative-conjugated aromatic compounds including carbazole or triphenylamine have been constructed via Pd-catalyzed coupling reaction with dibromotetraphene. These compounds show superior photophysical and electrochemical properties, which make them possible candidates for optoelectronic conjugated materials.
RESUMO
A rhodium-catalyzed efficient method for the synthesis of 2,3-dihydro-1H-indazoles is described. The reaction of arylhydrazines with olefins results in the corresponding 2,3-dihydro 1H-indazoles with exclusive regioselectivity via C-H bond activation. The utility of the methodology is illustrated by a rapid synthesis of 1H-indazoles under mild reaction conditions in half an hour.
Assuntos
Hidrazinas/síntese química , Indazóis/síntese química , Ródio/química , Alcenos/química , Catálise , Hidrazinas/química , Indazóis/químicaRESUMO
Palladium(II)-catalyzed arylation of arenes with aryl boronic acids and a free amine as directing group in aqueous medium has been developed. High reactivity and chemoselectivity for the formation of carbon-carbon bonds were achieved by the use of soluble silver salts. The addition of water is crucial to improve the arylation yield.
RESUMO
A novel protocol for palladium-catalyzed arylation of the C(sp(2))-H bond directed by a N,N-dimethylaminomethyl group in the presence of AgOAc and Cu(OAc)2·H2O is described. Various aryl iodides proved to be efficient coupling partners, furnishing the corresponding ortho monoarylated or diarylated arenes in moderate to good yields. Cu(OAc)2·H2O is found to be the important additive to improve the yields in this transformation.
RESUMO
Pd(OAc)2-catalyzed oxidative acetoxylation of benzylic C-H bonds utilizing a bidentate system has been explored. A variety of picolinoyl- or quinoline-2-carbonyl-protected toluidine derivatives react with PhI(OAc)2 in the presence of Pd(OAc)2 to afford the acetoxylated products in synthetically useful yields. A broad of functionalities, such as CH3, F, Cl, Br, I, COCH3, CO2Et, SO2CH3, and NO2, were tolerated. This transformation provides easy access to 2-hydroxymethylaniline derivatives.
Assuntos
Compostos de Anilina/síntese química , Compostos de Benzil/química , Paládio/química , Compostos de Anilina/química , Catálise , Ligação de Hidrogênio , OxirreduçãoRESUMO
The unprecedented dimerizations of 2H-azirines have been developed under the catalysis of palladium and silver. Upon changing the reaction conditions, the fully aryl-substituted pyrrole and pyrimidine derivatives were furnished in moderate yields with regiospecificity, respectively. Control experiments uncovered distinct catalytic effects of two transition metals, and the proposed catalytic cycles plausibly rationalized the chemodivergence and regioselectivity.
RESUMO
We have disclosed a Rauhut-Currier reaction of γ-alkyl-substituted allenoate, catalyzed by L-valine-derived amide phosphine, to form trisubstitued allenoate, which was trapped by maleimide or DMAD via the Diels-Alder reaction. Exo-bicyclic succinimide derivatives including three continuous stereocenters with an exo-carbon-carbon double bound were constructed in up to quantitative yields with high stereospecificity.
RESUMO
An efficient method for the construction of various 3,4,5-trisubstituted phenol derivatives has been achieved via the Rh(III)-catalyzed coupling of phosphonium cations with internal alkynes. This protocol shows good substrate compatibility, as an array of structurally and electronically diverse phosphonium compounds react efficiently with up to 87% yield.
RESUMO
In this article, a practical and metal-free method for the synthesis of poly-functionalized 3-selenyl/sulfenyl/telluriumindoles from o-alkynyl arylamines has been achieved. In this protocol, the in situ formation of selenenyl chloride, sulfenyl chloride or tellurenyl chloride is considered as the key intermediate and the 3-selenyl/sulfenyl/telluriumindoles can be obtained in good to excellent yields. Furthermore, the product 2-phenyl-3-(phenylselanyl)-1-tosyl-1H-indole can be selectively oxidized to compounds 2-phenyl-3-(phenylseleninyl)-1-tosyl-1H-indole and 2-phenyl-3-(phenylselenonyl)-1-tosyl-1H-indole in good yields.
RESUMO
The in situ formed furan-fused cyclobutenes via Cu(I)-catalyzed cycloisomerization of readily available allenyl ketones bearing a cyclopropyl moiety are a highly reactive and powerful species, which undergo annulative fragmentation with terminal ynones to afford a wide variety of functional furans in moderate to high yields. This ring-distortion protocol features an unprecedented strain-controlled cycloisomerization/Diels-Alder/retro-Diels-Alder (CDRD) sequence under mild conditions.
RESUMO
Construction of a new benzene via the electrocyclization of diene-allene is an efficient protocol to access polysubstituted benzenes from simple, readily available starting materials. In this paper, we present a comprehensive study of a heteroatom-promoted propargyl-allenyl isomerization and electrocyclization for the facile and efficient synthesis of polyfunctionalized benzenes and naphthalenes. As a result of the readily accessible starting materials, simple operation, and mild conditions, this reaction should be an appealing strategy in organic synthesis.