Nickel-Catalyzed Ring-Opening Research Articles

Recent Advances in Nickel-Catalyzed Ring Opening Cross-Coupling of Aziridines

Recent Advances in Nickel-Catalyzed Ring Opening Cross-Coupling of Aziridines

Nickel-Catalyzed Thiolation and Selenylation of Cycloketone Oxime Esters with Thiosulfonate or Seleniumsulfonate.

A nickel-catalyzed ring opening and, subsequently, reductive cross-coupling of cycloketone oxime esters with thiosulfonate or seleniumsulfonate are reported, which involves C-C bond cleavage and C(sp3)-S or C(sp3)-Se bond formation. Notably, S-aryl/alkyl sulfonothioates and Se-alkyl seleniumsulfonothioates could be employed in this reaction to afford a variety of 1° and 2° alkyl sulfides, aryl sulfides, and 1° and 2° alkyl selenides in one step. This strategy features easily available substrates and mild reaction conditions.

Nickel-catalyzed ring-opening of α-hydroxycyclobutenones with a remarkable ligand effect.

A Ni-catalyzed ring-opening of α-hydroxycyclobutenones is reported herein. A remarkable ligand effect was observed during transformations following the ring-opening. The employment of PPh3 leads to the formation of 2-furanones 2 through a migration of an alkoxyl group, and 2-furanones 3 were generated through a migration of hydrogen in the presence of Xantphos, affording a divergent approach to 2-furanones bearing multiple functional groups.

ChemInform Abstract: Stereospecific Cross‐Coupling Reactions of Aryl‐Substituted Tetrahydrofurans, Tetrahydropyrans, and Lactones.

The stereospecific ring-opening of O-heterocycles to provide acyclic alcohols and carboxylic acids with controlled formation of a new C–C bond is reported. These reactions provide new methods for synthesis of acyclic polyketide analogs with complex stereochemical arrays. Stereoselective synthesis of the cyclic template is utilized to control relative configuration; subsequent stereospecific nickel-catalyzed ring-opening affords the acyclic product. Aryl-substituted tetrahydrofurans and tetrahydropyrans undergo nickel-catalyzed Kumada-type coupling with a range of Grignard reagents to furnish acyclic alcohols with high diastereoselectivity. Enantioenriched lactones undergo Negishi-type cross-coupling with dimethylzinc to afford enantioenriched carboxylic acids. Application in a two-step enantioselective synthesis of an anti-dyslipidemia agent is demonstrated.

Stereospecific cross-coupling reactions of aryl-substituted tetrahydrofurans, tetrahydropyrans, and lactones.

The stereospecific ring-opening of O-heterocycles to provide acyclic alcohols and carboxylic acids with controlled formation of a new C–C bond is reported. These reactions provide new methods for synthesis of acyclic polyketide analogs with complex stereochemical arrays. Stereoselective synthesis of the cyclic template is utilized to control relative configuration; subsequent stereospecific nickel-catalyzed ring-opening affords the acyclic product. Aryl-substituted tetrahydrofurans and tetrahydropyrans undergo nickel-catalyzed Kumada-type coupling with a range of Grignard reagents to furnish acyclic alcohols with high diastereoselectivity. Enantioenriched lactones undergo Negishi-type cross-coupling with dimethylzinc to afford enantioenriched carboxylic acids. Application in a two-step enantioselective synthesis of an anti-dyslipidemia agent is demonstrated.

Nickel-Catalyzed Ring-Opening Alkylative Coupling of Enone with Methylenecyclopropane in the Presence of Triethylborane

Nickel-catalyzed alkylative coupling of an enone or enal with methylenecyclopropane in the presence of triethylborane was achieved via stereospecific proximal C-C bond cleavage of methylenecyclopropane. With the use of methylenecyclopropane possessing an acyclic alkyl substituent, this reaction was also accompanied by the β-hydrogen elimination.

Nickel-Catalyzed Ring-Opening Hydroacylation of Methylenecyclopropanes: Synthesis of γ,δ-Unsaturated Ketones from Aldehydes

A nickel-catalyzed intermolecular hydroacylation of methylenecyclopropanes (MCPs) has been developed. The reaction proceeds with stereospecific cleavage of the proximal C-C bond of the cyclopropane ring to give gamma,delta-unsaturated ketones with high diastereoselectivities. A nickel catalyst generated in situ from Ni(cod)(2) and P(n-Bu)(3) with a P/Ni ratio of 1:1 is effective for the hydroacylation, in which benzaldehyde derivatives, heteroaryl aldehydes, and aliphatic aldehydes react with MCPs at 60-100 degrees C to afford the corresponding ketones in high yields.

Synthesis of poly(acrylic acid)‐block‐poly(L‐valine) hybrid through combined atom transfer radical polymerization, click chemistry, and nickel‐catalyzed ring opening polymerization methods

AbstractA new hybrid amphiphilic system between a polyacrylic acid (PAA) synthetic segment, and a hydrophobic β‐sheet forming peptide segment, poly(L‐valine) (PLVAL) was synthesized using a combination of Atom Transfer Radical Polymerization, Click Chemistry, and Nickel catalyzed ring opening of L‐valine N‐carboxyanhydride. This is the first reported use of Click Chemistry as an intermediary step for the ω‐amino functionalization of polymers to obtain macroinitiators that are free from deactivating or interfering molecules to be used in subsequent Ni‐catalyzed ring opening reaction. The efficiency of the end‐group functionalization in the macroinitiator is about 90%. Three different PAA‐b‐PLVAL hybrid copolymers with molecular weight range of 8000–15,000 and Mw/Mn <1.3 had been prepared by varying the monomer to macroinitiator ratio. In addition, the highest achievable molecular weight in the copolymerization was found to be limited by the solubility of the growing chains. This combined synthetic approach can potentially be extended for the synthesis of a multitude of other peptide hybrid systems, and hence will be of interest in the preparation of peptide hybrid systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2646–2656, 2007

Nickel-Catalyzed Reactions of Silacyclobutanes with Aldehydes: Ring Opening and Ring Expansion Reaction

[reaction: see text]. The nickel-catalyzed ring opening reaction of silacyclobutanes with aldehydes affords the corresponding alkoxyallylsilanes. In contrast, the ring expansion reaction of benzosilacyclobutene with aldehydes occurs under nickel catalysis to give oxasilacyclohexenes.