ChemInform Abstract: Carbomethoxyethylation of Aryl and Alkyl Bromides Catalyzed by Nickel Complexes.

Лебедев, С. А.; Lopatina, V. S.; Berestova, S. S.; Петров, Е. С.; Beletskaya, I. P.

doi:10.1002/chin.198650194

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“…stoichiometric alkylmetal reagents) and were limited to crosscouplings involving styrene. 15,16,[28][29][30] Using palladium catalysis, we were able to overcome these limitations and develop an alkyl-Mizoroki-Heck-type cross-coupling using nonstyrenyl substrates. We began our studies with the catalytic cross-coupling of iodocyclohexane with acrylonitrile (Scheme 4).…”

Section: Cross-couplings Of Unactivated Alkyl Iodidesmentioning

confidence: 99%

Transition-Metal (Pd, Ni, Mn)-Catalyzed C–C Bond Constructions Involving Unactivated Alkyl Halides and Fundamental Synthetic Building Blocks

Kwiatkowski

Alexanian

2019

Acc. Chem. Res.

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The catalytic construction of C-C bonds between organo-halide or -pseudohalide electrophiles and fundamental building blocks such as alkenes, arenes, or CO are widely utilized metal-catalyzed processes. The use of simple, widely available unactivated alkyl halides in these catalytic transformations has significantly lagged behind the use of aryl or vinyl electrophiles. This difference is primarily due to the relative difficulty in activating alkyl halides with transition metals under mild conditions. This account details our group's work towards developing a general catalytic manifold for the construction of C-C bonds using unactivated alkyl halides and a range of simple chemical feedstocks. Critical to the strategy was the implementation of new modes of hybrid organometallic-radical reactivity in catalysis. Generation of carbon-centered radicals from alkyl halides using transition metals offers a solution to challenges associated with the application of alkyl electrophiles in classical two-electron reaction modes.A major focus of this work was the development of general, palladium-catalyzed carbocyclizations and intermolecular cross-couplings of unactivated alkyl halides (alkyl-Mizoroki-Heck-type reactions). Initial studies centered on the use of alkyl iodides in these processes, but subsequent studies determined that the use of an electron-rich, ferrocenyl bisphosphine (dtbpf) enables the palladium-catalyzed carbocyclizations of unactivated alkyl bromides. Mechanistic studies of these reactions revealed interesting details regarding a difference in mechanism between reactions of alkyl iodides and alkyl bromides in carbocyclizations. These studies were consistent with alkyl bromides reacting via an auto-tandem catalytic process involving atom-transfer radical cyclization (ATRC) followed by catalytic dehydrohalogenation. Reactions of alkyl iodides, on the other hand, involved metal-initiated radical chain pathways.Recent studies have expanded the scope of alkyl-Mizoroki-Heck-type reactions to the use of a first-row metal. Inexpensive nickel precatalysts, in combination with the bisphosphine ligand Xantphos, efficiently activate alkyl bromides for both intra-and intermolecular C-C bond-forming reactions. The reaction scope is similar to the palladium-catalyzed system, but in addition, alkene regioisomeric ratios are dramatically improved over those in reactions with palladium, solving one of the drawbacks of our previous work. Initial mechanistic studies were consistent with a hybrid organometallic-radical mechanism for the nickel-catalyzed reactions.

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Section: Cross-couplings Of Unactivated Alkyl Iodidesmentioning

confidence: 99%

Transition-Metal (Pd, Ni, Mn)-Catalyzed C–C Bond Constructions Involving Unactivated Alkyl Halides and Fundamental Synthetic Building Blocks

Kwiatkowski

Alexanian

2019

Acc. Chem. Res.

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ChemInform Abstract: Carbomethoxyethylation of Aryl and Alkyl Bromides Catalyzed by Nickel Complexes.

Abstract: The reactions between the aryl or secondary alkyl bromides (I) and methyl acrylate (II) in the presence of H2O, Py and Ph3P · NiCl2 /Zn afford the methyl propanoates (III) in fair to good yields.

Cited by 1 publication

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Transition-Metal (Pd, Ni, Mn)-Catalyzed C–C Bond Constructions Involving Unactivated Alkyl Halides and Fundamental Synthetic Building Blocks

Transition-Metal (Pd, Ni, Mn)-Catalyzed C–C Bond Constructions Involving Unactivated Alkyl Halides and Fundamental Synthetic Building Blocks

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