Tertiary Grignard Reagents Research Articles

Ni-Catalyzed Kumada-Corriu Cross-Coupling Reactions of Tertiary Grignard Reagents and Bromostyrenes.

The development of protocols for the construction of congested quaternary centers is highly sought-after. Herein, we report a method for the cross-coupling of C(sp3) tertiary Grignard reagents with C(sp2) styrenyl bromides using readily available nickel precatalysts. We identified conditions that afford the products in practical yield for several combinations of electrophiles and nucleophiles, including sensitive α-magnesiated Grignard reagents. Dependent upon the nature of their substituents, regiodivergency was observed when α-vinyl bromides were employed.

Cyclopropanation with Dibromomethane under Grignard and Barbier Conditions

Tertiary Grignard reagents and dibromomethane efficiently cyclopropanate allylic (and certain homoallylic) magnesium and lithium alcoholates at ambient temperature in ether solvents. Lithium (homo)allyl alcoholates are directly cyclopropanated with magnesium and dibromomethane under Barbier conditions at higher temperatures. The reaction rates depend on the substitution pattern of the (homo)allylic alcoholates and on the counterion with lithium giving best results. Good to excellent syn-selectivities are obtained from α-substituted (homo)allyl alcohols. In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl esters and carbonates or vinyloxiranes. [¹]

ChemInform Abstract: A General and Selective Copper‐Catalyzed Cross‐Coupling of Tertiary Grignard Reagents with Azacyclic Electrophiles.

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A General and Selective Copper‐Catalyzed Cross‐Coupling of Tertiary Grignard Reagents with Azacyclic Electrophiles

A General and Selective Copper‐Catalyzed Cross‐Coupling of Tertiary Grignard Reagents with Azacyclic Electrophiles

A General and Selective Copper‐Catalyzed Cross‐Coupling of Tertiary Grignard Reagents with Azacyclic Electrophiles

Sperrige Heterocyclen: Die hoch selektive katalytische Kreuzkupplung von tertiären Grignard-Reagentien mit Chlorazacyclen ergibt schnell heterocyclische Bausteine für Anwendungen in der pharmazeutischen oder supramolekularen Chemie sowie als Ligandvorstufen für Übergangsmetallkatalysatoren (siehe Schema).

Tandem Cyclopropanation with Dibromomethane under Grignard Conditions

Tertiary Grignard reagents and dibromomethane efficiently cyclopropanate allylic (and certain homoallylic) magnesium and lithium alcoholates at ambient temperature in ether solvents. Lithium (homo)allyl alcoholates are directly cyclopropanated with magnesium and CH2Br2 under Barbier conditions at higher temperatures. The reaction rates depend on the substitution pattern of the (homo)allylic alcoholates and on the counterion with lithium giving best results. Good to excellent syn-selectivities are obtained from alpha-substituted substrates, which are in accord with a staggered Houk model. In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl carboxylates or vinyloxiranes. Using this methodology, numerous fragrance ingredients and their precursors were efficiently converted to the corresponding cyclopropyl carbinols.

Tandem Carbocupration/Oxygenation of Terminal Alkynes

A direct and general synthesis of α-branched aldehydes and their enol derivatives is described. Carbocupration of terminal alkynes and subsequent oxygenation with lithium tert-butyl peroxide generates a metallo-enolate. Trapping with various electrophiles provides α-branched aldehydes or stereo-defined trisubstituted enol esters or silyl ethers. The tandem carbocupration/oxygenation tolerates alkyl and silyl ethers, esters, and tertiary amines. The reaction is effective with organocopper complexes derived from primary, secondary, and tertiary Grignard reagents and from n-butyllithium.

Tandem Carbocupration/Oxygenation of Terminal Alkynes

[chemical reaction: see text]. A direct and general synthesis of alpha-branched aldehydes and their enol derivatives is described. Carbocupration of terminal alkynes and subsequent oxygenation with lithium tert-butyl peroxide generates a metallo-enolate. Trapping with various electrophiles provides alpha-branched aldehydes or stereo-defined trisubstituted enol esters or silyl ethers. The tandem carbocupration/oxygenation tolerates alkyl and silyl ethers, esters, and tertiary amines. The reaction is effective with organocopper complexes derived from primary, secondary, and tertiary Grignard reagents and from n-butyllithium.

Coupling of 6-chloropurines with organocuprates derived from grignard reagents: A convenient route to sec and tert 6-alkylpurines

Purine derivatives bearing a secondary or tertiary alkyl group at the 6-position can be conveniently prepared by CuI mediated reaction of secondary or tertiary Grignard reagents with 9-substituted 6-chloropurines under very mild conditions.

ChemInform Abstract: DIRECT EVIDENCE SUPPORTING A SINGLE ELECTRON TRANSFER PATHWAY IN THE REDUCTION OF KETONES BY PRIMARY, SECONDARY, AND TERTIARY GRIGNARD REAGENTS

Chemischer InformationsdienstVolume 12, Issue 46 Preparative Organic Chemistry ChemInform Abstract: DIRECT EVIDENCE SUPPORTING A SINGLE ELECTRON TRANSFER PATHWAY IN THE REDUCTION OF KETONES BY PRIMARY, SECONDARY, AND TERTIARY GRIGNARD REAGENTS E. C. ASHBY, E. C. ASHBYSearch for more papers by this authorA. B. GOEL, A. B. GOELSearch for more papers by this author E. C. ASHBY, E. C. ASHBYSearch for more papers by this authorA. B. GOEL, A. B. GOELSearch for more papers by this author First published: November 17, 1981 https://doi.org/10.1002/chin.198146156AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue46November 17, 1981 RelatedInformation

Direct evidence supporting a single electron transfer pathway in the reduction of ketones by primary, secondary, and tertiary Grignard reagents

Direct evidence supporting a single electron transfer pathway in the reduction of ketones by primary, secondary, and tertiary Grignard reagents

The Yields of Some Aliphatic Tertiary Grignard Reagents and the Limits of their Usefulness as Synthetic Reagents

The Yields of Some Aliphatic Tertiary Grignard Reagents and the Limits of their Usefulness as Synthetic Reagents