Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Rhodium-catalysed ortho-alkynylation of nitroarenes.

ABSTRACT: The ortho-alkynylation of nitro-(hetero)arenes takes place in the presence of a Rh(iii) catalyst to deliver a wide variety of alkynylated nitroarenes regioselectively. These interesting products could be further derivatized by selective reduction of the nitro group or palladium-catalysed couplings. Experimental and computational mechanistic studies demonstrate that the reaction proceeds via a turnover-limiting electrophilic C-H metalation ortho to the strongly electron-withdrawing nitro group.

SUBMITTER: Tan E

PROVIDER: S-EPMC8597868 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Rhodium-catalysed ortho-alkynylation of nitroarenes.

Tan Eric E Montesinos-Magraner Marc M García-Morales Cristina C Mayans Joan Guillem JG Echavarren Antonio M AM

Chemical science 20211011 44

The ortho-alkynylation of nitro-(hetero)arenes takes place in the presence of a Rh(iii) catalyst to deliver a wide variety of alkynylated nitroarenes regioselectively. These interesting products could be further derivatized by selective reduction of the nitro group or palladium-catalysed couplings. Experimental and computational mechanistic studies demonstrate that the reaction proceeds via a turnover-limiting electrophilic C-H metalation ortho to the strongly electron-withd ...[more]

PMID: 34820088

Similar Datasets

Addition of arylstannanes to alkynes giving ortho-alkenylarylstannanes catalysed cooperatively by a rhodium complex and zinc chloride.

Project description:The reaction of arylstannanes ArSnR3 with unfunctionalised alkynes was found to proceed in the presence of a rhodium catalyst and a catalytic amount of zinc chloride to give ortho-alkenylarylstannanes with high selectivity in high yields. The catalytic cycle is very unique, consisting of three transmetalation steps, from Sn to Rh, Rh to Zn, and Zn to Sn, in addition to arylrhodation of alkyne followed by 1,4-migration of Rh from 2-arylalkenyl carbon to ortho-alkenylaryl carbon.

| S-EPMC6182567 | biostudies-literature

Copper-catalysed photoinduced decarboxylative alkynylation: a combined experimental and computational study.

Project description:Redox-active esters (RAEs) as alkyl radical precursors have demonstrated great advantages for C-C bond formation. A decarboxylative cross-coupling method is described to afford substituted alkynes from various carboxylic acids using copper catalysts CuCl and Cu(acac)2. The photoexcitation of copper acetylides with electron-rich NEt3 as a ligand provides a general strategy to generate a range of alkyl radicals from RAEs of carboxylic acids, which can be readily coupled with a variety of aromatic alkynes. The scope of this cross-coupling reaction can be further expanded to aliphatic alkynes and alkynyl silanes using a catalytic amount of preformed copper-phenylacetylide. In addition, DFT calculations revealed the favorable reaction pathway and that the bidentate acetylacetonate ligand of the copper intermediate plays an important role in inhibiting the homo-coupling of the alkyne.

| S-EPMC8159226 | biostudies-literature

An Adaptive Rhodium Catalyst to Control the Hydrogenation Network of Nitroarenes.

Project description:An adaptive catalytic system that provides control over the nitroarene hydrogenation network to prepare a wide range of aniline and hydroxylamine derivatives is presented. This system takes advantage of a delicate interplay between a rhodium(III) center and a Lewis acidic borane introduced in the secondary coordination sphere of the metal. The high chemoselectivity of the catalyst in the presence of various potentially vulnerable functional groups and its readiness to be deployed at a preparative scale illustrate its practicality. Mechanistic studies and density functional theory (DFT) methods were used to shed light on the mode of functioning of the catalyst and elucidate the origin of adaptivity. The competition for interaction with boron between a solvent molecule and a substrate was found crucial for adaptivity. When operating in THF, the reduction network stops at the hydroxylamine platform, whereas the reaction can be directed to the aniline platform in toluene.

| S-EPMC9544374 | biostudies-literature

Ruthenium-Catalyzed Peri- and Ortho-Alkynylation with Bromoalkynes via Insertion and Elimination.

Project description:The alkynylation of naphthols takes place with total regiocontrol at the peri position of the hydroxyl group in the presence of [RuCl2(p-cymene)]2 as the catalyst. This reaction features high functional group tolerance. The related ortho-alkynylation of benzoic acids proceeds under similar conditions and also shows wide functional group tolerance. Both reactions proceed through metalation, insertion of the alkyne, and bromide elimination.

| S-EPMC5679662 | biostudies-literature

Synthesis of P-Stereogenic Benzoazaphosphole 1-Oxides via Alkynylation of P-Stereogenic ortho-Aurated and ortho-Iodo Phosphinic Amides.

Project description:An efficient methodology for the synthesis of P-stereogenic dihydrobenzoazaphosphole 1-oxides via intramolecular 5-exo-dig alkyne hydroamination promoted by tetrabutylammonium fluoride is herein described. The required chiral o-alkynylphosphinic amide starting materials were prepared in high yields under very mild reaction conditions through alkynylation of P-stereogenic (O^C)-cyclometalated (phosphinic amide)dichlorogold(III) complexes and Sonogashira cross-coupling of ortho-iodo P-stereogenic phosphinic amide.

| S-EPMC6641963 | biostudies-literature

Amide synthesis via nickel-catalysed reductive aminocarbonylation of aryl halides with nitroarenes.

Project description:Aminocarbonylation of aryl halides is one of the most useful methods in amide synthesis, but nitroarenes have not been used as a nitrogen source in this method even though they are more economical and accessible than anilines. Reported here is the development of nickel catalysis for the first three-component reactions of aryl halides, Co2(CO)8, and nitroarenes under reductive conditions to produce aryl amides. A wide range of (hetero)aryl iodides and bromides as well as nitro(hetero)arenes are suitable reaction partners, and high functional group compatibility has been achieved. The method might be used for the streamlined synthesis of aryl amides.

| S-EPMC5869604 | biostudies-literature

Amine synthesis via iron-catalysed reductive coupling of nitroarenes with alkyl halides.

Project description:(Hetero)Aryl amines, an important class of organic molecules in medicinal chemistry, are most commonly synthesized from anilines, which are in turn synthesized by hydrogenation of nitroarenes. Amine synthesis directly from nitroarenes is attractive due to improved step economy and functional group compatibility. Despite these potential advantages, there is yet no general method for the synthesis of (hetero)aryl amines by carbon-nitrogen cross-coupling of nitroarenes. Here we report the reductive coupling of nitroarenes with alkyl halides to yield (hetero)aryl amines. A simple iron catalyst enables the coupling with numerous primary, secondary and tertiary alkyl halides. Broad scope and high functional group tolerance are demonstrated. Mechanistic study suggests that nitrosoarenes and alkyl radicals are involved as intermediates. This new C-N coupling method provides general and step-economical access to aryl amines.

| S-EPMC4990657 | biostudies-literature

Rhodium-catalysed tetradehydro-Diels-Alder reactions of enediynes via a rhodium-stabilized cyclic allene.

Project description:Efficient methods for the synthesis of fused-aromatic rings is a critical endeavour in the creation of new pharmaceuticals and materials. A direct method for preparing these systems is the tetradehydro-Diels-Alder reaction, however this is limited by the need for harsh reaction conditions. A potential, but underdeveloped, route to these systems is via transition metal-catalysed cycloaromatisation of ene-diynes. Herein, tethered unconjugated enediynes have been shown to undergo a facile room-temperature RhI-catalysed intramolecular tetradehydro-Diels-Alder reaction to produce highly substituted isobenzofurans, isoindolines and an indane. Furthermore, experimental and computational studies suggest a novel mechanism involving an unprecedented and complex RhI/RhIII/RhI/RhIII redox cycle involving the formation of an unusual strained 7-membered rhodacyclic allene intermediate and a RhIII-stabilized 6-membered ring allene complex.

| S-EPMC8162385 | biostudies-literature

Rhodium-catalysed syn-carboamination of alkenes via a transient directing group.

Project description:Alkenes are the most ubiquitous prochiral functional groups--those that can be converted from achiral to chiral in a single step--that are accessible to synthetic chemists. For this reason, difunctionalization reactions of alkenes (whereby two functional groups are added to the same double bond) are particularly important, as they can be used to produce highly complex molecular architectures. Stereoselective oxidation reactions, including dihydroxylation, aminohydroxylation and halogenation, are well established methods for functionalizing alkenes. However, the intermolecular incorporation of both carbon- and nitrogen-based functionalities stereoselectively across an alkene has not been reported. Here we describe the rhodium-catalysed carboamination of alkenes at the same (syn) face of a double bond, initiated by a carbon-hydrogen activation event that uses enoxyphthalimides as the source of both the carbon and the nitrogen functionalities. The reaction methodology allows for the intermolecular, stereospecific formation of one carbon-carbon and one carbon-nitrogen bond across an alkene, which is, to our knowledge, unprecedented. The reaction design involves the in situ generation of a bidentate directing group and the use of a new cyclopentadienyl ligand to control the reactivity of rhodium. The results provide a new way of synthesizing functionalized alkenes, and should lead to the convergent and stereoselective assembly of amine-containing acyclic molecules.

| S-EPMC4636455 | biostudies-literature

Rhodium catalysed C-3/5 methylation of pyridines using temporary dearomatisation.

Project description:Pyridines are ubiquitous aromatic rings used in organic chemistry and are crucial elements of the drug discovery process. Herein we describe a new catalytic method that directly introduces a methyl group onto the aromatic ring; this new reaction is related to hydrogen borrowing, and is notable for its use of the feedstock chemicals methanol and formaldehyde as the key reagents. Conceptually, the C-3/5 methylation of pyridines was accomplished by exploiting the interface between aromatic and non-aromatic compounds, and this allows an oscillating reactivity pattern to emerge whereby normally electrophilic aromatic compounds become nucleophilic in the reaction after activation by reduction. Thus, a set of C-4 functionalised pyridines can be mono or doubly methylated at the C-3/5 positions.

| S-EPMC8163342 | biostudies-literature