Reaction Of Dianion Research Articles

Synthesis and reactivity of allenes substituted by selenenyl groups at 1- and 3-positions.

1,3-Bis(methylseleno)- and 1,3-bis(benzylseleno)-1,3-diphenylpropadienes were synthesized by reaction of Ph(2)C(3) dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with dimethyl diselenide or benzylselenocyanate in the presence of TMEDA, and reaction of the dianion with a mixture of dimethyl diselenide and benzylselenocyanate yielded 1-benzylseleno-3-methylselenoallene along with the symmetric allenes. Diselenocyclic allenes and tetraselenocyclic bisallenes were also obtained by reacting the dianion with corresponding alkane diselenocyanates. The thermal reaction of the 1,3-bis(alkylseleno)allenes mainly afforded enediynes through radical pathway, and the nine-membered cyclic allene provided intramolecular cyclization product via an intramolecular rearrangement. Heating of the cyclic bisallenes gave compounds derived from intramolecular cyclization products together with a small amount of the enediynes. Irradiation of allenes caused rearrangement of the selenenyl group to give alkynes, and the alkynes also reacted photochemically to yield the enediynes.

REACTION OF THE 2,3'-BIQUINOLYL DIANION WITH BENZOATE - A RARE CASE OF ACYLATION OF AROMATIC DIANIONS

In a continuation of a study of the properties of the 2,3'-biquinolyl dianion (1), for which a convenient method of generation was proposed in our previous work [1], we investigated the acylation of this species by alkyl benzoates. As a rule, acylation products are not formed in the reactions of dianions of aromatic compounds [2]. We have shown that 2,3'-biquinolyl dianion obtained from 2,3'-biquinolyl and three equivalents of metallic lithium in absolute THF forms the benzoylation product at C(4') upon stirring with a two-fold molar excess of methyl benzoate (dried by distillation over CaH2) at room temperature for 2 h, namely, 4'-benzoyl-1,4'dihydro-2,3'-biquinolyl (2), in 61% yield. This product was isolated analogously to the procedure used for the arylation products of this dianion [3].

Reaction of dianions of acetoacetic esters with epibromohydrin derivatives: a novel synthesis of tetrahydrofuran derivatives and tetrahydropyran derivatives

The dianion of the acetoacetic ester reacts with epibromohydrin derivatives to afford a mixture of ( Z)-2-alkoxycarbonylmethylidenetetrahydrofuran derivative and ( E)-2-alkoxycarbonylmethylidenetetrahydropyran derivative. The selective formation of the tetrahydrofuran derivative is achieved by the use of LiClO 4 as the additive.

Gas phase reactions of dianions. 2. The effect of a second charge on S N2 potential energy surfaces: an ab initio study

Ab initio calculations have been used to investigate the S N 2 reactions of model dianions with methyl bromide. Two dianion models were used. Model A consists of a series of ω-alkoxy carboxylates with charge separations of 5, 10, and 15 Å. Model B employs complexes of acetate and fluoride where the two anions are held at fixed separations of 5, 10, 15, 20, 25, and 30 Å. In each case, the carboxylate is used as the nucleophile in the S N 2 process. The results indicate that for initial charge separations of 15 Å or more, the second charge has only a modest effect on the barrier (<2.5 kcal/mol) and geometry (<0.04 Å) of the S N 2 transition state relative to a singly charged analog (acetate + methyl bromide). Consequently, dianions with moderately long initial charge separations provide S N 2 reactivity that is very similar to that of singly charged analogs. In contrast, large effects (barrier reductions >10 kcal/mol) are seen in the reactions of dianions with short charge separations (<10 Å).

Novel organoiron compounds resulting from the attempted syntheses of dibenzofulvalene complexes

Thermal reaction of 2,2′-biindenyl with Fe(CO) 5 generates (η 4-2,2′-biindenyl)Fe(CO) 3 and a ferrole isomer of (μ,η 3:η 3-dibenzo[b,e]fulvalene)Fe 2(CO) 6. Reaction of the dianion of dibenzo[b,e]fulvalene with iron carbonyls produced a novel cyclized acyliron complex, whose structure was proven by X-ray crystallography; a mechanism is proposed for its formation. Reaction of the same dianion with (η 5-cyclopentadienyl)Fe(CO) 2Br generated another novel cyclic compound (C 18H 12)Fe(CO) 2(C 5H 4), probably via intramolecular radical attack on the η 5-bound cyclopentadienyl ring. Treatment of dibenzo[a,d]fulvalene with Fe 2(CO) 9 generates (η 2-dibenzo[a,d]fulvalene)Fe(CO) 4, (μ,η 2:η 2-dibenzo[a,d]fulvalene)Fe 2(CO) 8, and two compounds with bis(η 5) structures. These appear to have CO and Fe(CO) 4 groups inserted into the reactive Fe–Fe bond of (μ,η 5:η 5-dibenzo[a,d]fulvalene)Fe 2(CO) 4.

The Gas-Phase Reactions of Dianions with Alkyl Bromides: Direct Identification of SN2 and E2 Products

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTThe Gas-Phase Reactions of Dianions with Alkyl Bromides: Direct Identification of SN2 and E2 ProductsAdeliza E. Flores and Scott GronertView Author Information Department of Chemistry and Biochemistry San Francisco State University San Francisco, California 94132 Cite this: J. Am. Chem. Soc. 1999, 121, 11, 2627–2628Publication Date (Web):March 3, 1999Publication History Received12 November 1998Published online3 March 1999Published inissue 1 March 1999https://doi.org/10.1021/ja983922zCopyright © 1999 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views499Altmetric-Citations51LEARN 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 Read OnlinePDF (53 KB) Get e-AlertsSUBJECTS:Alkyls,Anions,Ions,Kinetic parameters,Substitution reactions Get e-Alerts

A concise synthesis of (−)-mesembrine

(−)-Mesembrine 11 was synthesized in 7 steps, in 19.4% overall yield and with ee>95%. The key step of the sequence is a stereoselective alkylation reaction of dianion derived from C 2 symmetric imidazolines allowing efficient formation of quaternary benzylic center. Chiral auxiliaries derived from ( S,S)-1,2-diamino-1,2-diphenylethane 1a and ( S,S)-1,2-diaminocyclohexane 1b were compared. This synthesis provided unambiguous correlation of the newly formed stereocenter.

Dissection of Nucleophilic and General Base Roles for the Reaction of Phosphate with p-Nitrophenyl Thiolacetate, p-Nitrophenyl Thiolformate, and Phenyl Thiolacetate.

Phosphate buffers are well-known to catalyze the decomposition of various active acyl compounds. This study was undertaken to determine the extent to which it acts as a nucleophile and general base toward some activated esters and thiolesters. Thus, the hydrolyses of p-nitrophenyl acetate (3a), p-nitrophenyl thiolacetate (3b), phenyl acetate (4a), phenyl thiolacetate (4b), and p-nitrophenyl thiolformate (5) have been studied in aqueous phosphate, &mgr; = 1.0 (K(2)SO(4)). Both phosphate monoanion and dianion are reactive toward the thiolesters 3b, 4b, and 5. For 3b, reaction of the dianion exhibits a solvent kinetic isotope effect (SKIE) of 1.00 +/- 0.11 while that for the monoanion is 2.13 +/- 1.1. For the reaction of phosphate dianion with 5, the SKIE is 0.8 +/- 0.2 and that for the monoanion at pH 3.05 is roughly 1.5. Phosphate dianion reacts with each thiolacetate and its oxygen analogue at comparable rates: the reactivity ratio of the formyl to acetyl thiolesters, 5:3b, toward phosphate dianion is 685. (1)H NMR analysis of the 3b hydrolysis mixtures in H(2)O and D(2)O containing phosphate shows the transient formation, and subsequent hydrolysis, of acetyl phosphate. Analysis of the kinetics of these processes indicates that in H(2)O at pH = 8.5, phosphate dianion functions as both a nucleophile and general base toward 3b, the nucleophilic role comprising 80-93% of the reaction. In D(2)O, the process is entirely nucleophilic. For the reaction of phosphate dianion with 4b, the (1)H NMR analysis indicates that the nucleophilic role comprises 40-50% of the reaction, the general base role being 50-60%. The reaction of phosphate dianion with 5 is entirely nucleophilic, while the monoanion reacts as a general base. The data are interpreted in terms of standard carbonyl addition/elimination mechanisms in which the ability of the attacking phosphate di- or monoanion to displace a given leaving group is tied to the pK(a) of the conjugate acids of the nucleophile and leaving groups.

Novel Syntheses of alpha,beta-Unsaturated Esters, alpha,beta-Unsaturated gamma-Lactones, and 2-Alkoxypyrroles via 1,2,4-Triazole-Stabilized Allenic Anions.

The dianion 12 (right harpoon over left harpoon 13) of 1-(1,2,4-triazol-1-yl)phenylpropargyl ethyl ether 11(readily prepared from phenylpropargylaldehyde diethyl acetal 8 and 1,2,4-triazole) reacts with alkyl halides, aldehydes, ketones, and alpha,beta-unsaturated ketones to give exclusively gamma-substituted allenic products of type 10. These adducts underwent mild in situ hydrolysis enabling convenient syntheses of alpha,beta-unsaturated esters 9a-c and alpha,beta-unsaturated gamma-lactones 16, 18, 20, and 22. Reactions of dianion 13 with imines generated the 1,3,4-trisubstituted 2-alkoxypyrroles 27, 30, and 31 in high yields. The alkyl-substituted analog 34 underwent similar reactions to give predominantly the gamma-products 39,40, and 42 along with a small proportion of alpha-analogs.

ChemInform Abstract: Reaction of Dianions of Acyclic β‐Enamino Ketones with Electrophiles. Part 7. Synthesis of 5‐(Monoalkylamino)‐3‐oxo γ,. delta.‐Unsaturated Acids and Esters and of 3‐(Monoalkylamino)‐5‐oxo . beta.,γ‐Unsaturated Esters.

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Reaction of dianions of acyclic β-enamino ketones with electrophiles. 8. Synthesis of trialkylsilylenaminones and α′-silylated β-diketones

α′- and γ-Dianions of β-(monoalkylamino) α,β-unsaturated ketones react with trialkylchlorosilanes leading to α′- and γ-trialkylsilylenaminones. Conversely from trimethylchlorosilane, the reaction between dianions of 3-( N-isopropylamino)-1-arylbut-2-en-1-ones and t-butyldimethylchlorosilane or triisopropylchlorosilane leads to the corresponding 4-trialkylsilyl derivatives. An explanation of these findings is reported. Hydrolysis of these compounds affords the until now unknown α′ silylated β-diketones.

Dithio and Thiono Esters, 62. Reactions of Alkanedithioic Acid Dianions with Iodine, Sulfur, and Tin Compounds

AbstractThe monoanion of the alkanedithioic acid 1a is oxidized with hypervalent iodine compounds to form the 1,2‐dithiine 6, the monoanion of 1b yields the 1,2,4‐trithiolane 7 and the dianions 2b, c furnish the 1,2,4,5‐tetrathianes 3b, c. With diphenyltin or dimethyltin dichlorides 8 the monoanions of 1b, c afford the monothioacyl or bisthioacyl organotin sulfides 10a–c or 11a, b respectively. When treated with lithium hexamethyldisilazane, 10b undergoes an intramolecular cyclization to the 1,3,2‐dithiastannetane 9b; 10a is deprotonated by triethylamine to the 1,3,5‐trithia‐2‐stanninane 13. The dianion 2c reacts with diphenyltin dichloride 8 to yield the 1,3,2‐dithiastannetane 9d, with dimethyltin dichloride the 1,2,4‐trithiolane 16 is formed. 9d is cleaved by thionyl chloride, sulfur dichloride, and disulfur dichloride to give a complex mixture of the 1,2,4,5‐tetrathiane 3c and the cyclic polysulfides 1,2,3,4,5,6‐hexathiepane 18, 1,2,3,5,6,7‐hexathiocane 19 and the 1,2,3,5,6‐pentathiepane 20 in varying amounts. Reaction of the dianion 2b with thionyl chloride leads to the formation of the 1,2,4,5‐tetrathiane 3b as main product; byproducts are cyclic polysulfides, the 1,2,3,5,6‐pentathiepane 21 and the 1,2,3,4,5,6‐hexathiepane 22.

ChemInform Abstract: Acetylenic Amides. Part 2. The Generation and Reactions of Dianions Derived from 2‐Propynamides.

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.

Acetylenic amides. 2. The generation and reactions of dianions derived from 2‐propynamides

AbstractThe dianion of N‐benzyl‐2‐propynamide can be generated by the treatment of 4 with two equivalents of LDA at −65° or ethylmagnesium bromide at −20°. The trilithio species 6 is readily formed using 3 equivalents of LDA. Reaction of 5 with aldehydes or ketones produce hydroxypropynamides 9 in good yields. Silation of 5a with chlorotrimethylsilane produces N‐benzyl‐3‐trimethylsilyl‐2‐propynamide (13) in high yield. Reduction of 9 furnishes either fully saturated amides 15 or partially reduced cis‐olefins 16 or 18. Compounds 16, on heating, rearrange to 4‐ketoamides 17. Carboxylation of 5a with carbon dioxide produces 3‐benzyl‐2,4‐dioxo‐5‐oxazidinylacetic acid (11). Warming 11 in dimethyl sulfoxide results in the loss of carbon dioxide and the formation of N‐benzylpyruvamide (21).

Dilithiated 2-(Chloromethyl)-3-tosylpropene: A New γ-Chlorinated Allyl Sulfone Dianion in Organic Synthesis

Dilithiation of 2-(chloromethyl)-3-tosylpropene ( 1) with n-butyllithium at −90°C in the presence of DMPU affords the allylic dianion 2 which reacts with deuterium oxide or very reactive alkylating agents to give α,α-disubstituted products 3 or 4, respectively. Monoalkylation at the α-position followed by cyclopropanation reaction takes place with n-alkyl bromides to provide tosylated methylenecyclopropanes 5. The reaction of dianion 2 with aldehydes or electrophilic olefins occurs at the α-position followed by the corresponding annulation process obtaining tosylated 2,5-dihydrofurans 6 or cyclopentenes 8, respectively. When ketones are used as electrophiles, dianion 2 reacts at the γ-position yielding 3-(tosylmethylene)tetrahydrofurans 7. Reductive desulfonylation of compounds 5-8 with sodium amalgam or samarium(II) iodide to afford the corresponding desulfonylated derivatives 22-26 has been also studied.

ChemInform Abstract: Reactions of Dianions of Acyclic β‐Enamino Ketones with Electrophiles. Part 5. Esters: Synthesis of Pyridin‐4‐one and Pyran‐4‐ one Derivatives.

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.

ChemInform Abstract: Reaction of Dianion β‐Enamino Ketones with Electrophiles. Part 4. Synthesis of β′‐ and δ‐Hydroxy‐β‐enamino Ketones.

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.

ChemInform Abstract: Reactions of Dianions Derived from o‐Toluic Acids: Facile Synthesis of 3‐Phenyl‐3,4‐dihydroisocoumarins and 8‐Oxotetrahydroprotoberberines.

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.

ChemInform Abstract: Reaction of Dianions of Acyclic β‐Enamino Ketones with Electrophiles. Part 3. Nitriles: Synthesis of Pyridine and Pyrimidine Derivatives.

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.

Reactions of dianions of acyclic β-enamino ketones with electrophiles. Part 5. Esters: synthesis of pyridin-4-one and pyran-4-one derivatives

The electrophilic attack of esters to dianions of β-monosubstituted amino-α,β-unsaturated ketones and the subsequent cyclisation of the addition product offers a valuable generalisation of the synthesis of N-substituted pyridin-4-ones and pyran-4-ones. The reaction proceeds in good to high yields with α′-dianions. A side metallation reaction is observed with aliphatic esters. Product distribution is influenced by the nucleophilic ability of nitrogen and the electrophilicity of the carbonyl group which are involved in cyclisation. The reaction of γ-dianions with esters is the first example of a reactivity of these systems which resembles alkyl organometallic reagents more than enolates. In fact the major product of this reaction is the alcohol with incorporation of two enaminone moieties.