Fluorenyl Carbanions Research Articles

Synthesis Of New Cyclopentadienyl-, Indenyl- And Fluorenylphosphanes By The Reaction Of Carbanions Of The Cyclopentadienyl Type With Alkyl(Aryl)Chloro-N,N-Dialkylaminophosphanes

A number of alkyl(aryl)chloro-N,N-dialkylaminophosphanes RP(Cl)NR1R2 (1a-o ) were synthesized starting from alkyl(aryl)dichlorophosphanes RPCl2 and amines by a convenient procedure with nearly quantitative yields. The reactivity of alkyl(aryl)-N,N-dialkylamino(halogeno) phosphanes RP(Hal)NR1R2 (Hal = Cl, I) with cyclopentadienyl, bis(cyclopentadienyl), indenyl, bis(indenyl) and fluorenyl carbanions has been investigated. The new aminocyclopentadienylphosphanes R„Cp(R)PNR1R2 2a-f and 3a-c (R„Cp = Ind, Flu, Cp2CMe2, Ind2CEt2, Ind2(CH2)2) were characterized by spectroscopic techniques and elemental analyses. Flu(t-Bu)PN(H)t-Bu (2f) was characterized by X-ray diffraction analysis

ChemInform Abstract: Axially Chiral Cyclopentadienyl Ligands: Stereoselective Synthesis of 1‐Substituted‐9‐(1′‐naphthyl)fluorenes and Retention of Axial Chirality in the Fluorenyl Carbanions.

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Axially chiral cyclopentadienyl ligands: stereoselective synthesis of 1-substituted-9-(1′-naphthyl)fluorenes and retention of axial chirality in the fluorenyl carbanions 1

1-(tert-Butyl- or 1-(p-tolyl-sulfinyl)naphthalene-2-carboxylate esters undergo coupling reactions with fluorenyllithiums substituted at the 1-position, providing 1-(1′-substituted-fluoren-9′-yl)naphthalene-2-carboxylate esters as single rotamers where the naphthalene ester substituent is syn to the fluorene 9-H. The stereoselectivity of the coupling reaction, with respect to asymmetric induction at the fluorene 9-C, varies from 21–95% (ee or de) dependant on the sulfoxide, ester and fluorene substituents, and the reaction temperature. The stereomutation of +ac(R)-1-methyl-9-(2′-methoxymethyl-1′-naphthyl)fluorene 33 into ent-33 was achieved through thermal atropisomerisation of 33 to the –sc(R)-rotamer 34, followed by lithiation of 34 and then reprotonation of the resultant fluorenyllithium 35, demonstrating the retention of axial chirality in the fluorenyl carbanion.

ChemInform Abstract: Asymmetric 9‐(1′‐Naphthyl)fluorenes: Enantioselective Synthesis, Determination of Absolute Configuration and Retention of Axial Chirality in the Fluorenyl Carbanions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Asymmetric 9-(1′-naphthyl)fluorenes: enantioselective synthesis, determination of absolute configuration and retention of axial chirality in the fluorenyl carbanions

The rotamers of 1-methyl-9-[2′-(methoxymethyl)-1′-naphthyl]fluorene 10 and 11 were synthesised enantioselectively via ligand coupling reactions of 1-(alkyl or arylsulfinyl)naphthalene-2-carboxylate esters with 1-methylfluorenyllithium and the absolute configurations established by a single crystal X-ray study of the (1R)-menthyl ester 4; deprotonation of 10 and 11 affords fluorenyl carbanions, ent-12 and 12, respectively, which retain axial chirality.

Anisotropy and asymmetry of diamagnetic susceptibility, quadrupole coupling constants and molecular motion of fluorene and the fluorenyl carbanion

Fluorene and the fluorenyl carbanion, both perdeuterated, have been studied by 2H N.M.R. at 11·7 Tesla. From deuteron splittings and spin-spin relaxation times, information is obtained about the anisotropy and asymmetry of the diamagnetic susceptibility, the quadrupole coupling constants of the different deuterium nuclei and the rotational diffusion constants of the two species.

Studies on the carbanions affected by neighboring sulfur groups. 1. Effect of the oxidation number of sulfur atom on ion pairing and electron transfer of the alkali metal fluorenyl carbanions substituted in 9 position with phenyl sulfur groups

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies on the carbanions affected by neighboring sulfur groups. 1. Effect of the oxidation number of sulfur atom on ion pairing and electron transfer of the alkali metal fluorenyl carbanions substituted in 9 position with phenyl sulfur groupsShinichi Nishi and Minoru MatsudaCite this: J. Am. Chem. Soc. 1979, 101, 16, 4632–4637Publication Date (Print):August 1, 1979Publication History Published online1 May 2002Published inissue 1 August 1979https://doi.org/10.1021/ja00510a032RIGHTS & PERMISSIONSArticle Views45Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (727 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Effect of chain length on the glyme-separated ion-pair formation in bolaform salts of ?,?-(9-fluorenyl)polymethylenes

Formation constants of tetraglyme (glyme 5) separated ion pairs of bolaform electrolytes of the type Na+,−Fl(CH2) n Fl−, Na+ (Fl− denoting a fluorenyl carbanion) were measured spectrophotometrically in tetrahydrofuran (THF) and tetrahydropyran (THP) at 25°C as a function of the chain lengthn, withn=2, 3, 4, or 6. The ratiosK 1/K 2 of the first and second glyme ion-pair separation steps were found to be equal to the statistical factor 4 in all cases except in THP for the compoundn=2, where the ratio is 15. Values ofK 1 as well as K 2 increase considerably with chain length, the former by a factor 19 asn increases from 2 to 6. The ion-pair separation with glyme 5 is easier in THP than in THF. The results are discussed in terms of differences in external cation solvation and the possible involvement of cyclized structures or curled conformations as a result of interactions between the terminal ion pairs.

Formation and ligand binding of the fluorenyl carbanion by hepatic cytochrome P450

Fluorene interacts with cytochrome P450 from phenobarbital-pretreated rats by formation of an enzyme-substrate complex. Reduction of the fluorene-cytochrome P450 complex, after short exposure to NADPH and oxygen, causes the formation of a new spectral species with absorption bands at 446, 540, and 568 nm. The following results indicate that this spectral change is due to ligand binding of the fluorenyl carbanion to reduced cytochrome P450: 1. 1. The carbanion can be identified by its characteristic absorption at 374 nm. 2. 2. 3H is incorporated into the 9-position of fluorene after incubation with microsomes, NADPH, and oxygen. 3. 3. In the presence of 14CO 2, 14C-labeled fluorenyl-9-carboxylic acid is formed. 4. 4. The formation of a carbanion and its ligand binding to reduced cytochrome P450 explains the spectral similarity to the metyrapone binding spectrum. Since metyrapone also inhibits the carbanion formation a binding to a common ligand position is very likely. This is further supported by the close quantitative correlation of the 446 nm peak heights with fluorene and metyrapone in different microsomal prepations. It is concluded that the active oxygen can abstract a proton from CH-acidic compounds. The carbanion formed is stabilized by the ferrous cytochrome P450 at the hydrophobic active site of the enzyme.

Analysis of the 1H NMR spectra of substituted fluorenyl carbanions

The 1H NMR spectra of 2-methylcarbazole nitranion, bifluorene dianion, and four substituted fluorenyl carbanions have been analyzed for chemical shifts and coupling constants. Analysis of these substituted derivatives confirm the earlier assignment of fluorenyl carbanion and carbazole nitranion. Vicinal proton-proton coupling constants for these and related anions are correlated with calculated π-bond orders. It is found that a reasonable correlation exists for ω-bond orders but not for Hückel-bond orders.

Effect of cation on the nuclear magnetic resonance spectrum of fluorenyl carbanion

Effect of cation on the nuclear magnetic resonance spectrum of fluorenyl carbanion

Solvents effects on the rates of alkylation of some fluorenyl carbanions

Depending on the substituents present, the addition of dimethyl sulphoxide to t-butyl alcohol can either increase or decrease the nucleophilic reactivity of fluorenyl carbanions.

Electrophilic substitution at saturated carbon. XXXVIII. Survey of substituent effects on stereochemical fate of fluorenyl carbanions

Electrophilic substitution at saturated carbon. XXXVIII. Survey of substituent effects on stereochemical fate of fluorenyl carbanions