RESUMEN
We describe the transition-metal-free coupling for polyfluoroalkoxy arenes using polyfluoroalkoxy borates, which serve as counterions to diaryliodonium salts and transferring mediators of polyfluoroalkoxy groups. This strategy demonstrates high functional group compatibility owing to the low nucleophilicity of the borate mediator, thus offering a practical approach for synthesizing diverse polyfluoroalkoxy arenes.
RESUMEN
α-Fluorinated aryl esters pose a challenge in synthesis via O-arylation of α-fluorinated carboxylates owing to their low reactivities. This limitation has been addressed by combining a silver catalyst with aryl(trimethoxyphenyl)iodonium tosylates to access α-fluorinated aryl esters. We envision that the catalytic system involves high-valent aryl silver species generated via the oxidation of silver(I) salt. The present method provided a synthetic protocol for various α-fluorinated aryl esters including fluorinated analogs of drug derivatives.
RESUMEN
Decarboxylative arylation of α,α-difluoro-ß-ketoacid salts with diaryliodonium(III) salts has been developed to synthesize α-aryl-α,α-difluoromethyl ketones, which are attractive synthetic intermediates for various difluorobenzyl units. This additive-free arylation represents an alternative approach to conventional synthetic methods that rely on transition metal catalysts and/or organometallic compounds. The reaction involves sequential ligand exchange of difluoroketoacid with tosylate ligand of diaryliodonium salt, followed by decarboxylative ligand coupling. Various functional groups, including ester, nitro, cyano, heteroarenes, and aryl halide groups, were tolerated during the present reaction. The resulting α-aryl-α,α-difluoromethyl ketones can be transformed into the corresponding esters, amides, and difluoromethyl compounds, which are commonly found in biologically active compounds.
Asunto(s)
Compuestos Organometálicos , Sales (Química) , Ligandos , Metales , Cetonas , ÉsteresRESUMEN
The chemistry of polyvalent iodine compounds has piqued the interest of researchers due to their role as important and flexible reagents in synthetic organic chemistry, resulting in a broad variety of useful organic molecules. These chemicals have potential uses in various functionalization procedures due to their non-toxic and environmentally friendly properties. As they are also strong electrophiles and potent oxidizing agents, the use of hypervalent iodine reagents in palladium-catalyzed transformations has received a lot of attention in recent years. Extensive research has been conducted on the subject of C-H bond functionalization by Pd catalysis with hypervalent iodine reagents as oxidants. Furthermore, the iodine(III) reagent is now often used as an arylating agent in Pd-catalyzed C-H arylation or Heck-type cross-coupling processes. In this article, the recent advances in palladium-catalyzed oxidative cross-coupling reactions employing hypervalent iodine reagents are reviewed in detail.
Asunto(s)
Yodo , Paladio , Catálisis , Indicadores y Reactivos , Yoduros , Yodo/química , Oxidantes , Oxidación-Reducción , Paladio/químicaRESUMEN
High reactivity of trimethoxyphenyl (TMP)-iodonium(III) acetate for phenol O-arylation was achieved. It was first determined that the TMP ligand and acetate anion cooperatively enhance the electrophilic reactivity toward phenol oxygen atoms. The proposed method provides access to various diaryl ethers in significantly higher yields than the previously reported techniques. Various functional groups, including aliphatic alcohol, boronic ester, and sterically hindered groups, were tolerated during O-arylation, verifying the applicability of this ligand- and counterion-assisted strategy.
RESUMEN
Since the 1950s, diaryliodonium(III) salts have been demonstrated to participate in various arylation reactions, forming aryl-heteroatom and aryl-carbon bonds. Incorporating the arylation step into sequential transformations would provide access to complex molecules in short steps. This focus review summarizes the double functionalization of carbon-iodine(III) and ortho carbon-hydrogen bonds using diaryliodonium(III) salts. This involves arylation/intramolecular rearrangement, arylation followed by electrophilic aromatic substitution, three-component [2 + 2 + 2] cascade annulation, sequential metal-catalyzed arylations, and double functionalization via aryne formation.
Asunto(s)
Yodo , Sales (Química) , Carbono/química , Catálisis , Yoduros , Yodo/química , Sales (Química)/químicaRESUMEN
Benzolactams have unique biological activity and high utility in the synthesis of valuable compounds with direct applicability to oxindole alkaloids and antibacterial agents. Despite recent advances in organic chemistry and the growing number of reported methods for synthesizing benzolactams, their preparation still requires a multistep process. C-H amination reactions can convert aromatic C(sp2)-H bonds directly to C(sp2)-N bonds, and this direct approach to C-N bond formation offers effective access to benzolactams. Hypervalent iodine reagents are promising tools for achieving oxidative C-H amination. Motivated by our ongoing research efforts toward the development of useful hypervalent-iodine-mediated oxidative transformations, we herein describe an effective intramolecular oxidative C-H amination reaction based on µ-oxo hypervalent iodine catalysis for the synthesis of benzolactams bearing various functional groups.
Asunto(s)
Benzodiazepinonas/química , Carbono/química , Hidrógeno/química , Yodo/química , Aminación , Benzodiazepinonas/síntesis química , Catálisis , Ciclización , Oxidación-ReducciónRESUMEN
Functionalized nucleobases are utilized in a wide range of fields; therefore, the development of new synthesis methods is essential for their continued application. With respect to the C6-arylation of halopurines, which possess a substituent at the N7-position, only a small number of successful cases have been reported, which is predominately a result of large steric hinderance effects. Herein, we report efficient and metal-free C6-arylations and SNAr reactions of N7-substituted chloropurines in aromatic and heteroatom nucleophiles promoted by triflimide (Tf2NH) in fluoroalcohol.
Asunto(s)
Ciclohexanonas/química , Purinas/química , Antivirales/síntesis química , Antivirales/química , Purinas/síntesis química , EstereoisomerismoRESUMEN
Nucleophilic aromatic substitution (SNAr) reactions can provide metal-free access to synthesize monosubstituted aromatic compounds. We developed efficient SNAr conditions for p-selective substitution of polyfluoroarenes with phenothiazine in the presence of a mild base to afford the corresponding 10-phenylphenothiazine (PTH) derivatives. The resulting polyfluoroarene-bearing PTH derivatives were subjected to a second SNAr reaction to generate highly functionalized PTH derivatives with potential applicability as photocatalysts for the reduction of carbon-halogen bonds.
Asunto(s)
Carbono/química , Fluorenos/química , Hidrocarburos Aromáticos/química , Fenotiazinas/química , Fenómenos Químicos OrgánicosRESUMEN
In organic synthesis, due to their high electrophilicity and leaving group properties, halogens play pivotal roles in the activation and structural derivations of organic compounds. Recently, cyclizations induced by halogen groups that allow the production of diverse targets and the structural reorganization of organic molecules have attracted significant attention from synthetic chemists. Electrophilic halogen atoms activate unsaturated and saturated hydrocarbon moieties by generating halonium intermediates, followed by the attack of carbon-containing, nitrogen-containing, oxygen-containing, and sulfur-containing nucleophiles to give highly functionalized carbocycles and heterocycles. New transformations of halogenated organic molecules that can control the formation and stereoselectivity of the products, according to the difference in the size and number of halogen atoms, have recently been discovered. These unique cyclizations may possibly be used as efficient synthetic strategies with future advances. In this review, innovative reactions controlled by halogen groups are discussed as a new concept in the field of organic synthesis.
Asunto(s)
Halógenos/química , Compuestos Heterocíclicos/síntesis química , Ciclización , Compuestos Heterocíclicos/química , Estructura MolecularRESUMEN
Trifluorovinylzinc is a common synthetic intermediate for trifluorovinyl derivatives, including α,ß,ß-trifluorostyrenes and hexafluorobutadiene. Here, we report a novel synthetic approach for the formation of trifluorovinylzinc chloride via a C-F bond activation of tetrafluoroethylene (TFE), which is an industrially cost-effective bulk feedstock with a negligible GWP. The present system provides a practical synthetic route to various trifluorovinyl derivatives with very low energy consumption.
RESUMEN
Various aryl-substituted purine derivatives were synthesized through the direct arylation of halopurines with aromatic compounds, facilitated by the combination of triflic acid and fluoroalcohol. This metal-free method is complementary to conventional coupling reactions using metal catalysts and reagents for the syntheses of aryl-substituted purine analogues.
Asunto(s)
Hidrocarburos Fluorados/química , Purinas/química , Purinas/síntesis química , Catálisis , EstereoisomerismoRESUMEN
The data in this article are related to research article ''Efficient N-arylation of azole compounds utilizing selective aryl-transfer TMP-iodonium (III) reagents (Koseki et al., 2019). For the title compound, phenyl(2,4,6-trimethoxyphenyl)iodonium(III) acetate (Ph(TMP)IOAc), the single-crystal X-ray diffraction measurement together with NMR analysis, like also the method of synthesis and crystallization are presented. The X-ray structure analysis has revealed that the two types of geometries regarding the acetate anion attached to phenyl (TMP)iodonium (III) cation are found in the crystal states.
RESUMEN
The Cu(I)-catalyzed pentafluoroethylation of iodoarenes via the fluorocupration of tetrafluoroethylene (TFE) is disclosed. The active species, (phen)CuC2 F5 , was isolated and its molecular structure confirmed by a single-crystal X-ray diffraction analysis. The key to the successful suppression of the competing oligomerization of TFE is to refrain from stirring the reaction mixture. A mechanistic study clearly discarded the possibility that the catalytic reaction proceeds via a radical pathway.
RESUMEN
A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CSN Ar) process.
RESUMEN
The copper(I)-mediated generation of -OCF2 CF2 - moieties by the oxycupration of tetrafluoroethylene (TFE) using either copper aryloxides or alkoxides is disclosed. The key intermediates, 2-aryloxy-1,1,2,2-tetrafluoroethyl and 2-alkoxy-1,1,2,2-tetrafluoroethyl copper complexes, were obtained from the reaction of the corresponding aryloxy and alkoxy copper complexes with TFE, and their structures in solution and in the solid state were unambiguously determined by multinuclear NMR spectroscopy and X-ray diffraction analysis. These copper complexes subsequently reacted with aryl iodides (ArI) to afford ROCF2 CF2 Ar (R=aryl or alkyl) in high yields.
RESUMEN
The development and optimization of a palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enone conjugate acceptors is described. These reactions employ air-stable and readily-available reagents in an operationally simple and robust transformation that yields ß-quaternary ketones in high yields and enantioselectivities. Notably, the reaction itself is highly tolerant of atmospheric oxygen and moisture and therefore does not require the use of dry or deoxygenated solvents, specially purified reagents, or an inert atmosphere. The ring size and ß-substituent of the enone are highly variable, and a wide variety of ß-quaternary ketones can be synthesized. More recently, the use of NH4PF6 has further expanded the substrate scope to include heteroatom-containing arylboronic acids and ß-acyl enone substrates.
RESUMEN
In the presence of a catalytic amount of Ni(cod)2 and IPr (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), a cross-trimerization reaction of tetrafluoroethylene (TFE), ethylene, and aldehydes proceeded in a selective manner to afford a variety of 4,4,5,5-tetrafluoro-1-pentanone derivatives in good to excellent yields. The present system involves a five-membered nickelacycle key intermediate generated via the oxidative cyclization of TFE and ethylene.
RESUMEN
We have synthesized a new nickel enolate [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] featuring fluorine atoms on the enolate moiety via B(C6F5)3-promoted C-F bond activation of α,α,α-trifluoroacetophenone. X-ray diffraction study of [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] revealed that the complex had adopted an η(3)-oxallyl coordination mode in the crystal lattice. The reaction of (t)BuNC with [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] resulted in the coordination of isocyanide to the nickel center to form a C-bound enolate complex. The reactions of [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] with aldehydes gave insertion products quantitatively which were fully characterized by NMR spectroscopy. Furthermore, we established unique catalytic applications for [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] toward a Tishchenko reaction, along with a highly selective crossed-esterification of α,α,α-trifluoroacetophenones with aldehydes.
RESUMEN
The bromination of hydrocarbons with CBr4 as a bromine source, induced by light-emitting diode (LED) irradiation, has been developed. Monobromides were synthesized with high efficiency without the need for any additives, catalysts, heating, or inert conditions. Action and absorption spectra suggest that CBr4 absorbs light to give active species for the bromination. The generation of CHBr3 was confirmed by NMR spectroscopy and GC-MS spectrometry analysis, indicating that the present bromination involves the homolytic cleavage of a C-Br bond in CBr4 followed by radical abstraction of a hydrogen atom from a hydrocarbon.