Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Nickel-catalyzed, carbonyl-ene-type reactions: selective for alpha olefins and more efficient with electron-rich aldehydes.

ABSTRACT: Described are several classes of unusual or unprecedented carbonyl-ene-type reactions, including those between alpha olefins and aromatic aldehydes. Catalyzed by nickel, these processes complement existing Lewis acid-catalyzed methods in several respects. Not only are monosubstituted alkenes, aromatic aldehydes, and tert-alkyl aldehydes effective substrates, but monosubstituted olefins also react faster than those that are more substituted, and large or electron-rich aldehydes are more effective than small or electron-poor ones. Conceptually, in the presence of a nickel-phosphine catalyst, the combination of off-the-shelf alkenes, silyl triflates, and triethylamine functions as a replacement for an allylmetal reagent.

SUBMITTER: Ho CY

PROVIDER: S-EPMC3148195 | biostudies-literature | 2006 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Nickel-catalyzed, carbonyl-ene-type reactions: selective for alpha olefins and more efficient with electron-rich aldehydes.

Ho Chun-Yu CY Ng Sze-Sze SS Jamison Timothy F TF

Journal of the American Chemical Society 20060401 16

Described are several classes of unusual or unprecedented carbonyl-ene-type reactions, including those between alpha olefins and aromatic aldehydes. Catalyzed by nickel, these processes complement existing Lewis acid-catalyzed methods in several respects. Not only are monosubstituted alkenes, aromatic aldehydes, and tert-alkyl aldehydes effective substrates, but monosubstituted olefins also react faster than those that are more substituted, and large or electron-rich aldehydes are more effective ...[more]

PMID: 16620106

Similar Datasets

Bronsted-Acid-Catalyzed Intramolecular Carbonyl-Olefin Reactions: Interrupted Metathesis vs Carbonyl-Ene Reaction.

Project description:Lewis acid catalysts have been shown to promote carbonyl-olefin metathesis through a critical four-membered-ring oxetane intermediate. Recently, Brønsted-acid catalysis of related substrates was similarly proposed to result in a transient oxetane, which fragments within a single elementary step via a postulated oxygen-atom transfer mechanism. Herein, careful quantum chemical investigations show that Brønsted acid (triflic acid, TfOH) instead invokes a mechanistic switch to a carbonyl-ene reaction, and oxygen-atom transfer is uncompetitive. TfOH's conjugate base is also found to rearrange H atoms and allow isomerization of the carbocations that appear after the carbonyl-ene reaction. The mechanism explains available experimental information, including the skipped diene species that appear transiently before product formation. The present study clarifies the mechanism for activation of intramolecular carbonyl-olefin substrates by Brønsted acids and provides important insights that will help develop this exciting class of catalysts.

| S-EPMC8117943 | biostudies-literature

Nickel-catalyzed Heck-type reactions of benzyl chlorides and simple olefins.

Project description:Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives are described. A wide range of both the benzyl chloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including ethylene), proceed at room temperature, and provide 1,1-disubstituted olefins over the more commonly observed 1,2-disubstituted olefins with very high selectivity.

| S-EPMC3226728 | biostudies-literature

Organocatalyzed Intramolecular Carbonyl-Ene Reactions.

Project description:An organocatalyzed intramolecular carbonyl-ene reaction was developed to produce carbocyclic and heterocyclic 5- and 6-membered rings from a citronellal-derived trifluoroketone and a variety of aldehydes. A phosphoramide derivative was found to promote the cyclization of the trifluoroketone, whereas a less acidic phosphoric acid proved to be a superior catalyst for the aldehyde substrates.

| S-EPMC6272844 | biostudies-other

Nickel-catalyzed Suzuki-Miyaura cross-couplings of aldehydes.

Project description:Transition-metal-catalyzed cross-couplings have been extensively used in the pharmaceutical and agrochemical industries for the construction of diverse C-C bonds. Conventional cross-coupling reactions require reactive electrophilic coupling partners, such as organohalides or sulfonates, which are not environmentally friendly and not naturally abundant. Another disadvantage associated with these transformations is the need for an exogenous base to facilitate the key transmetalation step, and this reagent inevitably induces side reactions and limits the substrate scope. Here, we report an unconventional Suzuki-type approach to the synthesis of biaryls, through nickel-catalyzed deformylative cross coupling of aldehydes with organoboron reagents under base-free conditions. The transformation tolerates structurally diverse (hetero)aryl substituents on both coupling partners and shows high reactivity and excellent functional group tolerance. Furthermore, the protocol was carried out on gram scale and successfully applied to the functionalization of complex biologically active molecules. Mechanistic investigations support a catalytic cycle involving the oxidative addition of the nickel into the aldehyde C(acyl)-H bond with subsequent hydride transfer, transmetalation, decarbonylation and reductive elimination processes.

| S-EPMC6488620 | biostudies-literature

Iron-Catalyzed Meerwein Carbooxygenation of Electron-Rich Olefins: Studies with Styrenes, Vinyl Pyrrolidinone, and Vinyl Oxazolidinone.

Project description:The arylative oxygenation of the electron-rich olefins styrene, ?-methylstyrene, vinyl pyrrolidinone, and vinyl oxazolidinone was accomplished using arenediazonium salts and catalytic amounts of FeSO4 in an effective single electron transfer radical process. A broad range of aryldiazonium salts was tolerated using water, methanol, or their combination with acetonitrile to furnish the corresponding carbohydroxylated and carbomethoxylated products (42 examples), including functionalized dihydroisocoumarin and dihydrobenzofuran systems in good to excellent yields (up to 88%). The protocols developed for the Fe(II)-catalyzed carbohydroxylation were also compared to Ru(II) and Ir(III) photoredox carbooxygenations of these electron-rich olefins. The Fe(II)-catalyzed process proved to be highly competitive compared to the photoredox and the uncatalyzed processes. The proposed mechanism for the Fe(II)-catalyzed reactions involves the synergic combination with an effective Fe+2/Fe+3 redox system and a radical polar crossover mechanism featuring an unprecedented capture of the reactive N-acyliminium in the case of vinyl pyrrolidinone and vinyl oxazolidinone.

| S-EPMC6854838 | biostudies-literature

Nickel-catalyzed coupling of alkenes, aldehydes, and silyl triflates.

Project description:A full account of two recently developed nickel-catalyzed coupling reactions of alkenes, aldehydes, and silyl triflates is presented. These reactions provide either allylic alcohol or homoallylic alcohol derivatives selectively, depending on the ligand employed. These processes are believed to be mechanistically distinct from Lewis acid-catalyzed carbonyl-ene reactions, and several lines of evidence supporting this hypothesis are discussed.

| S-EPMC3148200 | biostudies-literature

Nickel-catalyzed cycloadditions of unsaturated hydrocarbons, aldehydes, and ketones.

Project description:The nickel-catalyzed cycloaddition of unsaturated hydrocarbons and carbonyls is reported. Diynes and enynes were used as coupling partners. Carbonyl substrates include both aldehdyes and ketones. Reactions of diynes and aldehydes afforded the [3,3] electrocyclic ring-opened tautomers, rather than pyrans, in high yields. The cycloaddition reaction of enynes and aldehydes afforded two distinct products. A new carbon-carbon bond is formed, prior to a competitive beta-hydrogen elimination of a nickel alkoxide, between the carbonyl carbon and either one of the carbons of the olefin or the alkyne. The steric hindrance of the enyne greatly affected the chemoselectivity of the cycloaddition of enynes and aldehydes. In some cases, dihydropyran was also formed. The scope of the cycloaddition reaction was expanded to include the coupling of enynes and ketones. No beta-hydrogen elimination was observed in cycloaddition reaction of enynes and ketones. Instead, C-O bond-forming reductive elimination occurred exclusively to afford dihydropyrans in excellent yields. In all cases, complete chemoselectivity was observed; only dihydropyrans where the carbonyl carbon forms a carbon-carbon bond with a carbon of the olefin, rather than of the alkyne, were observed. All cycloaddition reactions occur at room temperature and employ nickel catalysts bearing the hindered 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) or its saturated analogue, 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazolin-2-ylidene (SIPr).

| S-EPMC4144363 | biostudies-literature

Nickel-catalyzed synthesis of acrylamides from alpha-olefins and isocyanates.

Project description:[reaction: see text] The nickel(0)-catalyzed coupling of alpha-olefins and isocyanates proceeds in the presence of the N-heterocyclic carbene ligand IPr to provide alpha,beta-unsaturated amides. Carbon-carbon bond formation occurs preferentially at the 2-position of the olefin. The N-tert-butyl amide products can be converted to the corresponding primary amides under acidic conditions.

| S-EPMC3148187 | biostudies-literature

Directed nickel-catalyzed 1,2-dialkylation of alkenyl carbonyl compounds.

Project description:A nickel-catalyzed conjunctive cross-coupling of non-conjugated alkenes, alkyl halides, and alkylzinc reagents is reported. Regioselectivity is controlled by chelation of a removable bidentate 8-aminoquinoline directing group. Under optimized conditions, a wide range of 1,2-dialkylated products can be accessed in moderate to excellent yields. To the best of our knowledge, this report represents the first example of three-component 1,2-dialkylation of non-conjugated alkenes to introduce differentiated alkyl fragments.

| S-EPMC6001383 | biostudies-literature

Directed, nickel-catalyzed 1,2-alkylsulfenylation of alkenyl carbonyl compounds.

Project description:We report a regioselective, nickel-catalyzed syn-1,2-carbosulfenylation of non-conjugated alkenyl carbonyl compounds with alkyl/arylzinc nucleophiles and tailored N-S electrophiles. This method allows the simultaneous installation of a variety of C(sp3) and S(Ar) (or Se(Ar)) groups onto unactivated alkenes, which complements previously developed 1,2-carbosulfenylation methodology in which only C(sp2) nucleophiles are compatible. A bidentate directing auxiliary controls regioselectivity, promotes high syn-stereoselectivity with a variety of E- and Z-internal alkenes, and enables the use of an array of electrophilic sulfenyl (and seleno) electrophiles. Among compatible electrophiles, those with N-alkyl-benzamide leaving groups were found to be especially effective, as determined through comprehensive structure-reactivity mapping.

| S-EPMC9172569 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data