Alkylzinc Bromides Research Articles

Multicomponent synthesis of α-branched amines using organozinc reagents generated from alkyl bromides.

The use of alkylzinc bromides in the multicomponent Mannich reaction is described. Heteroleptic organozinc compounds were obtained in THF or 2-MeTHF by direct insertion of zinc dust into the C-Br bond of alkyl bromides. It was found that the presence of a stoichiometric amount of LiCl was essential for the efficiency of the subsequent three-component coupling with aldehydes and amines. A variety of primary, secondary, and tertiary organozinc reagents as well as secondary amines and aromatic aldehydes could be used for the straightforward preparation of α-branched amines. Interestingly, whereas previously reported work describing the preparation and reaction of organozinc iodides in acetonitrile showed higher reactivity of secondary organozinc reagents over primary ones, reactions in THF in the presence of LiCl led to opposite results, with higher reactivity of primary organozinc reagents.

Terminal‐Selective Functionalization of Alkyl Chains by Regioconvergent Cross‐Coupling

AbstractHydrocarbons are still the most important precursors of functionalized organic molecules, which has stirred interest in the discovery of new C−H bond functionalization methods. We describe herein a new step‐economical approach that enables C−C bonds to be constructed at the terminal position of linear alkanes. First, we show that secondary alkyl bromides can undergo in situ conversion into alkyl zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross‐coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross‐coupling then provided access to the corresponding linear arylation product in only two steps.

Terminal-Selective Functionalization of Alkyl Chains by Regioconvergent Cross-Coupling.

Hydrocarbons are still the most important precursors of functionalized organic molecules, which has stirred interest in the discovery of new C-H bond functionalization methods. We describe herein a new step-economical approach that enables C-C bonds to be constructed at the terminal position of linear alkanes. First, we show that secondary alkyl bromides can undergo in situ conversion into alkyl zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross-coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross-coupling then provided access to the corresponding linear arylation product in only two steps.

Glucosides with cyclic diarylpolynoid as novel C-aryl glucoside SGLT2 inhibitors

Novel C-aryl glucoside SGLT2 inhibitors containing cyclic diarylpolynoid motif were designed and synthesized for biological evaluation. Alkylzinc bromides have been efficiently prepared by the direct insertion of zinc metal into alkyl bromides. The organozinc reagents underwent smooth Pd-catalyzed cross-coupling reactions. Subsequent ring closing metathesis using 2nd generation Grubbs catalyst successfully generated novel class of ansa-compounds. These glucosides with cyclic diarylpolynoids demonstrated moderate in vitro inhibitory activity against SGLT2 in this series to date (IC(50)=59.5-103 nM).

ChemInform Abstract: Preparation of Alkylzinc Bromides Using a New Mn/Cu Catalyzed Bromine- Zinc Exchange Reaction.

The reaction of functionalized primary alkyl bromides with Et2Zn in DMPU in the presence of a catalytic mixed metal system constituted of MnBr2 (or FeCl3) and CuCl provides functionalyzed alkylzinc bromides (> 80 % yield). In the presence of PdCl2(dppf) or CuCN·2LiCl, these organozinc species reach with a range of electrophiles providing various polyfunctional molecules in good yields.

Synthesis of 5′-functionalized nucleosides: S-Adenosylhomocysteine analogues with the carbon-5′ and sulfur atoms replaced by a vinyl or halovinyl unit

Adenosine and uridine analogues functionalized with alkenyl or fluoroalkenyl chain at C5′ were prepared employing cross-metathesis, Negishi couplings, and Wittig reactions. Metathesis of the protected 5′-deoxy-5′-methyleneadenosine or uridine analogues with six-carbon amino acids (homoallylglycines) in the presence of Grubbs catalysts gave nucleoside analogues with the C5′–C6′ double bond. Alternatively, the Pd-catalyzed cross-coupling between the protected 5′-deoxy-5′-(iodomethylene) nucleosides and suitable alkylzinc bromides also provided analogues with alkenyl unit. Stereoselective Pd-catalyzed monoalkylation of 5′-(bromofluoromethylene)-5′-deoxyadenosine with alkylzinc bromides afforded adenosylhomocysteine analogues with a 6′-(fluoro)vinyl motif. The vinylic adenine nucleosides produced time-dependent inactivation of the S-adenosyl- l-homocysteine hydrolases.

S-Ribosylhomocysteine analogues with the carbon-5 and sulfur atoms replaced by a vinyl or (fluoro)vinyl unit

Treatment of the protected ribose or xylose 5-aldehyde with sulfonyl-stabilized fluorophosphonate gave (fluoro)vinyl sulfones. Stannyldesulfonylation followed by iododestannylation afforded 5,6-dideoxy-6-fluoro-6-iodo- d- ribo or xylo-hex-5-enofuranoses. Coupling of the hexenofuranoses with alkylzinc bromides gave 10-carbon ribosyl- and xylosylhomocysteine analogues incorporating a fluoroalkene. The fluoroalkenyl and alkenyl analogues were evaluated for inhibition of Bacillus subtilis S-ribosylhomocysteinase (LuxS). One of the compounds, 3,5,6-trideoxy-6-fluoro- d- erythro-hex-5-enofuranose, acted as a competitive inhibitor of moderate potency ( K I = 96 μM).

Synthesis of the Multisubstituted Halogenated Olefins via Cross‐Coupling of Dihaloalkenes with Alkylzinc Bromides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis of the multisubstituted halogenated olefins via cross-coupling of dihaloalkenes with alkylzinc bromides.

[reaction: see text] The 1-fluoro-1-haloalkenes undergo Pd-catalyzed Negishi cross-couplings with primary alkylzinc bromides to give multisubstituted fluoroalkenes. The alkylation was trans-selective giving pure Z-fluoroalkenes in most cases. The highest yields were obtained with Pd2(dba)3 and PdCl2(dppb) catalysts but the best stereochemical outcome was obtained with less reactive Pd(PPh3)4. The tertiary alkylzincs also produced desired fluoroalkenes in high yields. Coupling of beta,beta-dichlorostyrene with organozinc reagent resulted in the formation of monocoupled product.

Highly Efficient, General Procedure for the Preparation of Alkylzinc Reagents from Unactivated Alkyl Bromides and Chlorides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly Efficient, General Procedure for the Preparation of Alkylzinc Reagents from Unactivated Alkyl Bromides and Chlorides

[reaction: see text] Alkylzinc bromides have been efficiently prepared by the direct insertion of zinc metal (dust, powder, granule, shot), activated with 1-5 mol % I(2), into alkyl bromides in a polar aprotic solvent. The zinc reagents thus formed undergo Ni- and Pd-catalyzed cross-coupling with aryl halides to produce functionalized alkylarenes in excellent yields.

ChemInform Abstract: Direct Formation of Secondary and Tertiary Alkylzinc Bromides and Subsequent Cu(I)‐Mediated Couplings.

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: 1,4‐Addition of Secondary and Tertiary Alkylzinc Bromides to α,. beta.‐Unsaturated Ketones Without a Copper Catalyst.

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.

Direct Formation of Secondary and Tertiary Alkylzinc Bromides and Subsequent Cu(I)-Mediated Couplings.

Secondary and tertiary alkylzinc bromides can be generated from the direct oxidative addition of Rieke zinc to secondary and tertiary alkyl bromides in high yield. These organozinc reagents have been found to undergo copper-catalyzed conjugate addition, cross-coupling with acid chlorides, and carbocupration to activated alkynes.

1,4-Addition of secondary and tertiary alkylzinc bromides to .alpha.,.beta.-unsaturated ketones without a copper catalyst.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT1,4-Addition of secondary and tertiary alkylzinc bromides to .alpha.,.beta.-unsaturated ketones without a copper catalyst.M. V. Hanson and R. D. RiekeCite this: J. Am. Chem. Soc. 1995, 117, 43, 10775–10776Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://doi.org/10.1021/ja00148a033RIGHTS & PERMISSIONSArticle Views724Altmetric-Citations40LEARN 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 (235 KB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: Direct Formation of Secondary and Tertiary Alkylzinc Bromides.

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.

Direct formation of secondary and tertiary alkylzinc bromides

The direct formation of secondary and tertiary alkylzinc bromides can be accomplished under mild conditions from the direct oxidative addition of Rieke zinc to secondary and tertiary alkyl bromides including remote functionalized halides.

Preparation of alkylzinc bromides using a new Mn/Cu catalyzed bromine-zinc exchange reaction

The reaction of functionalized primary alkyl bromides with Et 2Zn in DMPU in the presence of a catalytic mixed metal system constituted of MnBr 2 (or FeCl 3) and CuCl provides functionalyzed alkylzinc bromides (> 80 % yield). In the presence of PdCl 2(dppf) or CuCN·2LiCl, these organozinc species reach with a range of electrophiles providing various polyfunctional molecules in good yields .

ChemInform Abstract: Synthesis and Reactivity of Some Organozinc Compounds in Solvents Unusual in Organometallic Chemistry.

AbstractThe alkyl bromides (I) react with freshly prepared active zinc (II)/ copper couple in diethyl carbonate to form the alkylzinc bromides (III) which are treated with acetyl chloride (IV), yielding the methyl ketones (V).

Sytnhèse et réactivite de quelques organozinciques dans des solvants peu courants en chimie organométallique

The use of solvents strange to organometallic chemistry viz. carbonic or phosphoric esters, or sulfolane allows zinc to react with organic halides, which are unusually unreactive towards this metal. The reactions of the organozinc compounds thus synthesised (alkylzinc bromides, n-octylzinc chloride, phenylzinc iodide) have been studied.