ABSTRACT
An approach for the ligand-free Pd-catalyzed C-H activation/[5 + 1] cyclization carbonylation by employing readily available ClCF2COONa as a carbonyl source via difluorocarbene transfer and hydrolysis has been developed. The current protocol enables us to obtain a series of carbonylation cyclization product benzopyranone and phenanthridinone derivatives in up to 91% yield with excellent functional group compatibility. This protocol has the advantages of mild reaction conditions, wide applicable substrates, and simple and safe operation and provides a new method for the synthesis of complex lactam and lactone compounds.
ABSTRACT
A ligand-free palladium-catalyzed and norbornadiene-mediated annulation reaction of iodoarenes with methyl 2-haloarenecarboxylates is reported. The sequentially accomplished reaction comprises intermolecular C-H arylation, followed by intramolecular decarboxylative annulation, affording various valuable phenanthrenes. This reaction protocol could be expanded to triphenylene syntheses whereby norbornene was the cocatalyst. Interestingly, the decarboxylation of methyl esters was accomplished via solvent-mediated CMe-O bond cleavages.
ABSTRACT
An efficient synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols under heating conditions is described. The method is characterized by mild conditions, simple operation, metal-free catalysis and good functional group tolerance. Mechanistic studies suggest that the reaction involves a radical pathway and an isomerization process.
ABSTRACT
A novel Pd-catalyzed assembly of N-substituted phthalimides by merging of [4+1] cycloaddition and difluorocarbene transfer carbonylation from 2-iodo-N-phenylbenzamides and difluorocarbene precursors is disclosed. Difluorocarbene acts as a carbonyl source and simultaneously forms one C-C bond, one C-N bond and one CîO bond to produce N-substituted phthalimides in high yields.
ABSTRACT
An efficient visible-light-assisted, copper-catalyzed tandem radical cyclization of N-propargylindoles with cyclic ethers is established. A series of 2-oxoalkyl-9H-pyrrolo[1,2-a]indol-9-ones with potential biological activities were synthesized in moderate yields by using a dual catalytic system with copper acetate as a transition metal catalyst and eosin Y as a visible light catalyst. The investigation of reaction mechanism shows that it goes through a cascade oxoalkyl radical addition, cyclization, and oxidation process.
ABSTRACT
A metal-free method for the regioselective synthesis of 2-thiolated quinolines from quinoline N-oxides in water at room temperature is developed. The reaction is conducted using benzenethiols as thiolation reagents in the presence of p-toluenesulfonyl chloride via p-toluenesulfonyl chloride-assisted tandem C-H bond activation, nucleophilic addition, deoxygenation and aromatization processes. This method does not require the use of metal catalysts and oxidants. It shows the advantages of wide functional group tolerance, short reaction times and simple operation.
Subject(s)
Oxides , Quinolines , Oxides/chemistry , Quinolines/chemistry , MetalsABSTRACT
A Pd-catalyzed annulation between 1-(2-iodophenyl)-1H-indoles and sodium difluorochloroacetate has been developed to synthesize 10H-indolo[1,2-a]indol-10-one derivatives via C-H bond activation and difluorocarbene transfer. Our route enables facile access to the targeted products with various substituents in moderate to high yields. This method features high reactivity, good functional group tolerance, a simple operation procedure, and mild reaction conditions. The reaction can be carried out on a gram scale.
Subject(s)
Indoles , Palladium , Palladium/chemistry , Catalysis , Molecular Structure , Indoles/chemistry , SodiumABSTRACT
In the past decade, visible light photoredox catalysis has been established as a gentle and powerful strategy for the activation of organic molecules. As an important part of this, organic photocatalysts are widely used in chemical synthesis due to their attributes, such as cheapness and relatively high redox potential. In this article, we review the related organic reactions promoted by visible light in the presence of various organic photocatalysts over the past 5 years. The reaction mechanisms involving single electron transfer, energy transfer and proton-coupled electron transfer are also discussed. The recovery and reuse of some supported organic photocatalysts are highlighted. Moreover, prospects for the development of organic photocatalysts are emphasized.
Subject(s)
Light , Catalysis , Electron TransportABSTRACT
In this paper, regiospecific, double intraannular C-N bond cleavages of N-alkyl 4-oxopiperidinium salts are presented. The reaction sequence involves a charge-transfer complex, in situ formed between sulfonyl chloride and N-methylmorpholine, which induces S-Cl bond homolysis of sulfonyl chloride, yielding a reactive sulfonyl radical that further induces the double C-N bond cleavages of N-alkyl 4-oxopiperidinium salt. The secondary amine thus produced was trapped by sulfonyl chloride to yield the desired sulfonamide product. The key feature of this protocol is that two intraannular C-N bonds of the 4-oxopiperidine ring are cleaved in one step under metal- and oxidant-free conditions.
ABSTRACT
A novel charge-transfer complex triggered sulfonylation of 1,4-diazabicyclo[2.2.2]octane (DABCO) with mild reaction conditions has been developed. The formation of a charge-transfer complex between electron-withdrawing (hetero)aryl sulfonyl chloride and DABCO allows the synthesis of N-ethylated piperazine sulfonamide in good yields. The reaction has a high functional group tolerance. Spectroscopic studies confirmed the charge-transfer complex formation between sulfonyl chlorides and DABCO, which facilitates the C-N bond cleavage of DABCO.
ABSTRACT
Sulfonyl chlorides were reduced to anhydrous sulfinate salts with magnesium under sonication. These sulfinates were alkylated to sulfones with alkyl chlorides in the presence of catalytic sodium iodide under sonication. A variety of aliphatic sulfones was efficiently prepared by this one-pot two-step procedure.
ABSTRACT
A magnesium salt promoted synthesis of ketones via tandem nucleophilic addition-Oppenauer oxidation of aldehydes using organozinc chemistry was demonstrated. Magnesium salts concomitantly generated via magnesium metal mediated organohalide zincation exhibit high efficacy for nucleophilic addition of organozinc reagents to aromatic aldehydes and thereafter Oppenauer oxidation whereby ketones are formed in high to excellent yields.
ABSTRACT
In this study, a facile CuI catalyzed synthesis of sulfones involving a nucleophilic addition of functionalized organozinc reagents to organic sulfonyl chlorides is realized. This reaction proceeds efficiently at room temperature, giving rise to various functional group substituted sulfones, generally in moderate to high yields. The method provides a novel, simple, and promising strategy for functionalized sulfone synthesis in the research field of sulfur chemistry.
Subject(s)
Copper/chemistry , Halogens/chemistry , Iodides/chemistry , Organic Chemicals/chemistry , Sulfones/chemistry , Zinc/chemistry , Catalysis , Oxygen/chemistryABSTRACT
The title compound, C20H20Br4N2, is a product of the condensation reaction of 4,6-di-bromo-2,3-di-methyl-aniline and butane-2,3-dione. The mol-ecule has a center of symmetry at the mid-point of the central C-C bond. The dihedral angle between the benzene ring and the 1,4-di-aza-butadiene plane is 78.3â (2)°. Niether hydrogen bonding nor aromatic stacking is observed in the crystal structure.
ABSTRACT
The title compound, C30H18ClNO, is a product of the condensation reaction of acenaphthyl-ene-1,2-dione and 5'-chloro-1,1':3',1''-terphenyl-4'-amine. The acenaphthyl-ene fragment and two terminal phenyl rings are rotated relative to the central benzene ring by 72.2â (3), 43.2â (3) and 41.2â (3)°, respectively. This mol-ecular conformation is supported by weak C-Hâ¯π inter-actions. In the crystal, mol-ecules form centrosymmetric dimers by the stacking inter-actions between two neighboring acenaphthyl-ene fragments, with an inter-planar distance of 3.365â (3)â Å. The dimers are bound to each other by weak C-Hâ¯N and C-Hâ¯π inter-actions, forming a three-dimensional framework.
ABSTRACT
In the presence of pinacolone, the in situ prepared triorganoaluminium reagents reacted with aromatic aldehydes to give ketones in moderate to high yield. We propose that the products are formed via a tandem organoaluminium reagents addition-Oppenauer oxidation sequence.
Subject(s)
Aldehydes/chemistry , Aluminum/chemistry , Hydrocarbons, Aromatic/chemistry , Ketones/chemistry , Butanones/chemistry , Ketones/chemical synthesis , Oxidation-ReductionABSTRACT
[RhCp*Cl(2)](2) can catalyze the oxidative coupling of secondary isonicotinamides with activated olefins using Cu(OAc)(2) as an oxidant. The selectivity can be controlled by the solvent. In MeCN, the mono-olefination and two-fold oxidation reaction is the major pathway, while in THF this reaction gave mostly diolefination products. In both cases, the coupled products contain an exocyclic C=C bond.
ABSTRACT
[RhCp*Cl(2)](2) can catalyze the oxidative coupling of N-aryl and N-alkyl benzamidines with alkynes to give N-substituted 1-aminoisoquinolines in high selectivity.
Subject(s)
Isoquinolines/chemical synthesis , Organometallic Compounds/chemistry , Rhodium/chemistry , Catalysis , Crystallography, X-Ray , Isoquinolines/chemistry , Models, Molecular , Molecular Structure , Oxidation-Reduction , StereoisomerismABSTRACT
Rh(III)-catalyzed oxidative coupling reactions between isoquinolones with 3-aryl groups and activated olefins have been achieved using anhydrous Cu(OAc)(2) as an oxidant to give tetracyclic products. The nitrogen atom acts as a directing group to facilitate ortho C-H activation. This reaction can be one-pot starting from methyl benzohydroxamates, without the necessity of the isolation of isoquinolone products. A broad scope of substrates has been demonstrated, and both terminal and internal activated olefins can be applied. In the coupling of N-methylmaleimide, a Wacker-like mechanism was proposed, where backside attack of the NH group in isoquinolones is suggested as a key step. Selective C-H activation has also been achieved at the 8-position of 1-naphthol, leading to an olefination product.