Alkylmagnesium Bromides Research Articles

An Effective System to Synthesize Hypolipidemic Active α‐Asarone and Related Methoxylated (E)‐Arylalkenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Nickel-Catalyzed Cross-Coupling of Neopentyl Arenesulfonates with Methyl and Primary Alkylmagnesium Bromides

[reaction: see text] Neopentyl arenesulfonates were reacted with methyl and primary alkylmagnesium bromides in the presence of dppeNiCl(2), via the nucleophilic aromatic substitution of neopentyloxysulfonyl groups by the primary alkyl nucleophiles, to produce the corresponding alkylarenes in good yields. This result shows that the alkyloxysulfonyl group might be a suitable alternative to halides and triflate in some circumstances.

An Effective System to Synthesize Hypolipidemic Active α-Asarone and Related Methoxylated (E)-Arylalkenes

Abstract Methoxylated (E)-arylalkenes (1a–1k) were prepared in two steps by an improved Grignard reaction comprising the reverse addition of alkylmagnesium bromide to benzaldehydes (2a–2k) in anhydrous ether and toluene into arylalkanols (3a–3k) in high yield, followed by dehydration with silica gel under microwave irradiation for 3–12 min, depending upon the substituents attached to the aromatic ring to afford hypolipidemic active α-asarone (1a) and related methoxylated (E)-arylalkenes (1b–1k).

Conjugate Additions of Carbon Nucleophiles to Cyclopentadienones.

[reaction: see text] Reactions of cyclopentadienones 1 with alkylmagnesium bromides were investigated and gave 1,4 adduct and/or 1,2 adduct.

Cross‐Coupling of (Z)‐1,2‐Bis(ethylseleno)ethene with the Grignard Reagents.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Convenient Synthesis of 4(5)‐Alkylacyl‐1H‐imidazoles from 4(5)‐Imidazolecarboxaldehyde.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Conjugate additions of carbon nucleophiles to cyclopentadienones.

[reaction: see text] Reactions of cyclopentadienones 1 with alkylmagnesium bromides were investigated and gave 1,4 adduct and/or 1,2 adduct.

Cross-coupling of ( Z)-1,2-bis(ethylseleno)ethene with the Grignard reagents

The nickel-catalyzed cross-coupling of ( Z)-1,2-bis(ethylseleno)ethene with the alkyl magnesium bromides proceeds with substitution of both ethylseleno groups to afford symmetrical alkenes, ( Z)-RCHCHR, in high yield with complete retention of configuration. In the case of phenyl magnesium bromide the monoarylation occurs to form ( Z)-2-ethylseleno styrene, EtSeCHCHPh.

A Convenient Synthesis of 4(5)-Alkylacyl-1H-imidazoles from 4(5)-Imidazolecarboxaldehyde

A convenient synthesis of 4(5)-acyl-1H-imidazoles from 4(5)-imidazolecarboxaldehyde without N-protecting group is described. 4(5)-Cyanoimidazole could be synthesized from commercially available 4(5)-imidazolecarboxaldehyde in one-pot. Treatment of 4(5)-cyanoimidazole with various alkylmagnesium bromides followed by addition of aqueous sulfuric acid afforded 4(5)-acyl-1H-imidazoles in good yield.

An unexpected participation of oxygen in a novel synthesis of [2,2′-bi-1 H-indene]-3,3′-dialkyl-3,3′-dihydroxy-1,1′-diones

This paper describes, for the first time, a short synthetic procedure for [2,2′-bi-1 H-indene]-3,3′-dialkyl-3,3′-dihydroxy-1,1′-diones ( 1a– f ). The key feature of this synthetic method lies in the participation of oxygen when the intermediate arises from the nucleophilic addition of alkylmagnesium bromide to 2,2′-biindanylidene-1,1′,3,3′-tetraone. The background leading to the development of this synthesis is discussed, together with the proposal of a novel reaction mechanism. The structures of all the new compounds have been determined by X-ray crystallography.

A New Short Access to Amino Acids Incorporating an Aminocyclopropyl Moiety from N,N‐Dibenzylcarboxamides

Our recently reported titanium-mediated transformation of N,N-dialkylcarboxamides to cyclopropylamines has been applied to N,N-dibenzyl-2-benzyloxyacetamide using a variety of alkylmagnesium bromides to yield 1-(benzyloxymethyl)-1-(dibenzylamino)cyclopropane (15a, 48%) and 2-substituted analogs 15b−f (33−48%). These have been transformed in just a few steps into N-Boc-protected methyl esters of 1-aminocyclopropanecarboxylic acid (1, 29% overall), coronamic acid (2, 35%) and norcoronamic acid (21%), 2,3-methanoglutamic acid (21g, 19%) and 2,3-methanoornithine (21l, 12%). Similarly, the corresponding derivatives of 3,4-methano-γ-aminobutyric acid (26, 23%) and 4-spirocyclopropane-γ-butyrolactam (32, 44%) have been synthesized.

Facile interfacial electron transfer through n-alkyl monolayers formed on silicon (111) surfaces

Electron transfer (ET) kinetics through alkyl monolayers, formed on n-type Si(111) surface by the direct reaction of alkylmagnesium bromide ( n-C n H 2 n+1 MgBr, n=2, 6, 10, and 15) with hydrogen-terminated Si(111), was investigated in acetonitrile (MeCN) with anthraquinone (AQ) as the electrochemical probe. Cyclic voltammetric measurements indicate that the ability of the monolayer to block interfacial electron transfer increases with increasing alkyl chain length. In particular, the voltammetric behavior changes from non-rectifying (i.e., chemically reversible redox couple), to rectifying (i.e., diode-like when the reverse wave is pushed into the gap) with increasing chain length. The dependence of the logarithm of the electron transfer rate constant as a function on the number of carbons in the alkyl chain is not consistent with electron tunneling through the full thickness of the film. In fact, the measured constant, 0.05 ± 0.03 per methylene, is much smaller than the well-established tunneling constant, ∼1.0/CH 2 in the closely packed alkanethiol monolayers on gold suggesting permeation of the AQ into the film.

Reversible sidewall functionalization of buckytubes

Abstract Single-wall fullerene nanotubes have been made soluble in various organic solvents, including chloroform, methylene chloride, and tetrahydrofuran by covalently attaching alkanes to their sidewalls. Sidewall-alkylated nanotubes are obtained by reacting sidewall-fluorinated nanotubes with alkyl magnesium bromides in a Grignard synthesis or by reaction with alkyllithium precursors. Covalent attachment to the sidewalls was confirmed by UV–visible spectroscopy, which is also used to show that the alkane sidewall groups can be removed by oxidizing them in air to recover pristine nanotubes.

New Synthetic Routes to Alkyl Monolayers on the Si(111) Surface1

Two new methods for the formation of Si−C monolayers from reactions with Si(111)−H are reported. Besides the photochemical method previously reported by Chidsey, Lewis acid-catalyzed hydrosilylation of alkenes and direct reaction of alkylmagnesium bromide produce a surface with similar chemical composition. These processes are demonstrated and compared using reactions of a C10 precursor. The surfaces are chemically stable and can be stored for several weeks without measurable deterioration. The availability of a variety of synthetic approaches leading to the same chemical product is key to the development of flexible surface synthetic strategies. It is expected that these approaches will underpin the development of stepwise solid-phase-like syntheses of more complex organic/bioorganic species on these surfaces.

Highly Diastereoselective Additions to Chiral α-Keto Acetals

A general synthesis of (4R*,5R*)-2-acyl-4,5-diphenyl-1,3-dioxolanes and the addition of alkylmagnesium bromides to these compounds is described. The addition reactions occur with high diastereoselectivity (typical selectivity ca. 90:10). An example addition reaction carried out on an optically active acetal proves the sense of asymmetric induction for addition of organomagnesium reagents to these α-keto acetals. An explanation of the mechanism of asymmetric induction is given.

Synthesis of [1-11C]-2-octynoic acid, [1-11C]-2-decynoic acid and [1-11C]-3-(R,S)-methylocatanoic acid as potential markers for PET studies of fatty acid metabolism

[1-11C]-2-Octynoic acid, [1-11C)-2-decynoic acid and 1-11C]-3-(R,S)-methyloctanoic acid have been synthesized in order to evaluate these compounds as PET (Positron Emission Tomography) tracers for imaging in vivo medium-chain acyl-CoA dehydrogenase and medium-chain fatty acid utilization. The synthesis was performed by the Grignard reaction between alkylmagnesium bromides and [11C]CO2. The radiochemical yields of [1-11C]-2-octynoic acid, [1-11C]-2-decynoic acid, and [1-11C]-3-(R,S)-methyloctanoic acid were 10, 7 and 1% based on the [11C]CO2 used, respectively. Radiochemical purity was >99% in all cases. © 1997 John Wiley & Sons, Ltd.

ChemInform Abstract: A Novel C‐C Single Bond Formation by Use of Ketones, Alkylmagnesium Bromide, and Low‐Valent Vanadium in the Presence of a Catalytic Amount of Molecular Oxygen.

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.

Dialkylation of gem-dibromocyclopropanes with trialkylmanganate and manganese(II) chloride-catalyzed reaction with alkylmagnesium bromide

Treatment of gem-dibromocyclopropanes with trialkylmanganate, derived from manganese(II) chloride and three equivalents of Grignard reagent or alkyllithium, followed by an addition of electrophiles provided dialkylated cyclopropanes in good yields. It was found the reaction with alkylmagnesium halide proceeded in the presence of a catalytic amount of manganese(II) chloride.

A Novel C-C Single Bond Formation by Use of Ketones, Alkylmagnesium Bromide, and Low-Valent Vanadium in the Presence of a Catalytic Amount of Molecular Oxygen.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Novel C−C Single Bond Formation by Use of Ketones, Alkylmagnesium Bromide, and Low-Valent Vanadium in the Presence of a Catalytic Amount of Molecular OxygenYasutaka Kataoka, Hiroaki Akiyama, Isamu Makihira, and Kazuhide TaniView Author Information Department of Chemistry, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka 560, Japan Cite this: J. Org. Chem. 1996, 61, 18, 6094–6095Publication Date (Web):September 6, 1996Publication History Received7 June 1996Published online6 September 1996Published inissue 1 January 1996https://doi.org/10.1021/jo9610725Copyright © 1996 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views313Altmetric-Citations15LEARN 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 (199 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Alcohols,Anions,Bond cleavage,Coupling reactions,Vanadium Get e-Alerts

Excellent Chiral Introduction by Diene Iron-Tricarbonyl Moiety. II: A Formal Synthesis of (+)- and (-)-Frontalin Using a Diastereoselective 1,2-Nucleophilic Addition of Organometallics into a (Z)-Dienone Fe(CO)3 Complex.

A nucleophilic addition of alkyllithiums to the (Z)-dienone iron-tricarbonyl [Fe(CO) 3 ] complex (3) gave the (Z)-dienol complex (4) exclusively, while the reaction of 3 with alkylmagnesium bromide or trialkylaluminum provided the (E)-dienol complex (2) via the isomerization of 3 to the (E)-dienone complex (1). Application of this methodology was demonstrated in a formal synthesis of both (+)- and (-)-frontalin from the same chiral starting material, {(2S,5S)-(2E,4Z)-tricarbonyl[2-5-η-11-chloro-2,4-undecadien-6-one]iron} (8).