Transition metal free α-C-alkylation of ketones using secondary alcohols

Dambatta, Mubarak B.; Santos, J. Marcos Leite; Bolt, Robert R. A.; Morrill, Louis C.

doi:10.1016/j.tet.2020.131571

Cited by 22 publications

(14 citation statements)

References 37 publications

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“…Scheme shows the reaction conditions for the borrowing hydrogen procedure and the subsequent retro-Friedel–Crafts reaction, with representative examples . In recent years, this approach with secondary alcohols has been extended to cobalt, iron, manganese, and transition-metal-free catalysis …”

Section: C–c Bond-forming Processesmentioning

confidence: 99%

“…128 In recent years, this approach with secondary alcohols has been extended to cobalt, 131 iron, 132 manganese, 133 and transition-metal-free catalysis. 134 Scheme 10. Selected Approaches for the Catalytic Synthesis of Dihydrochalcone via Borrowing Hydrogen The Ph* group was also used in an iridium-catalyzed (5 + 1) annulation strategy to synthesize cyclohexanes using 1,5-diols as alkylating agents by the same authors.…”

Section: ■ Introductionmentioning

confidence: 99%

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Borrowing Hydrogen for Organic Synthesis

et al. 2021

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Borrowing hydrogen is a process that is used to diversify the synthetic utility of commodity alcohols. A catalyst first oxidizes an alcohol by removing hydrogen to form a reactive carbonyl compound. This intermediate can undergo a diverse range of subsequent transformations before the catalyst returns the “borrowed” hydrogen to liberate the product and regenerate the catalyst. In this way, alcohols may be used as alkylating agents whereby the sole byproduct of this one-pot reaction is water. In recent decades, significant advances have been made in this area, demonstrating many effective methods to access valuable products. This outlook highlights the diversity of metal and biocatalysts that are available for this approach, as well as the various transformations that can be performed, focusing on a selection of the most significant and recent advances. By succinctly describing and conveying the versatility of borrowing hydrogen chemistry, we anticipate its uptake will increase across a wider scientific audience, expanding opportunities for further development.

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Section: C–c Bond-forming Processesmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Borrowing Hydrogen for Organic Synthesis

et al. 2021

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“…The residue was purified by column chromatography using hexane/ethyl acetate (100:1) as an eluent to afford pure products. The desired products were fully characterized by 1 H, and 13 C NMR spectroscopies.…”

Section: C) General Procedures For α-Alkylation Of Bis-ketone By Seco...mentioning

confidence: 99%

“…Recently, a metal-free version of this α-alkylation has also been documented. [13] We became currently very much interested in discovering efficient nickel catalysts, because nickel is very cheap, it is abundant in the earth's crust and most of the nickel salts are non-toxic and environmentally friendly. [14] Surprisingly, no nickel catalyst is known that can monoalkylate a ketone by a secondary alcohol to furnish β-branched carbonyl product.…”

Section: Introductionmentioning

confidence: 99%

“…To date, there are only three base metal examples of Co, [10] Mn [11] and Fe [12] which can α‐alkylate ketones using secondary alcohols to generate β,β‐disubstituted product (Scheme 1a). Recently, a metal‐free version of this α‐alkylation has also been documented [13] . We became currently very much interested in discovering efficient nickel catalysts, because nickel is very cheap, it is abundant in the earth's crust and most of the nickel salts are non‐toxic and environmentally friendly [14] .…”

Section: Introductionmentioning

confidence: 99%

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Nickel‐Catalysis Enabling α‐Alkylation of Ketones by Secondary Alcohols

et al. 2022

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The α-alkylation of ketones utilizing a secondary alcohol has been accomplished by an isolable, bench-stable, inexpensive nickel catalyst affording high yields of β,β-disubstituted products. This report contributes a nickel catalyst in the pool of a few scarce examples of base metal discovered for this purpose. The substrate scope can span a wide range including aliphatic, alicyclic, and cyclic secondary alcohols. Functionalization of a cholesterol molecule is also possible following this methodology. The catalyst can interconvert between azo and hydrazo form in a reversible fashion to enable this chemical transformation.

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Synthesis of a CCC‐NHC pincer Re complex: An air stable catalyst for coupling ketones with primary alcohols via borrowing hydrogen

Pham

Donnadieu

Hollis

2022

Applied Organom Chemis

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To date, no CCC‐NHC pincer complexes of Re have been reported in the literature. The first CCC‐NHC pincer complex of Re is reported. It was fully characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy, elemental analysis, and X‐ray crystallographic methods to determine the molecular structure. It was synthesized via transmetallation from an isolated Zr precursor and was found to be air stable. The catalytic activity of the CCC‐NHC Re(I) pincer complex was demonstrated for the borrowing hydrogen coupling reaction between benzylic ketones and primary alcohols to generate a new C–C bond in an environmentally friendly catalysis requiring no activating groups for the alcohol functionality. This borrowing hydrogen coupling reaction produced a stoichiometric amount of water as the only by‐product and did not require the conversion of the primary alcohol to a leaving group. A broad range of substrates was examined, and isolated yields from 53% to 92% were obtained. A catalytic cycle for the CCC‐NHC Re(I) pincer complex catalyzed borrowing hydrogen coupling reaction is proposed.

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Transition metal free α-C-alkylation of ketones using secondary alcohols

Cited by 22 publications

References 37 publications

Borrowing Hydrogen for Organic Synthesis

Borrowing Hydrogen for Organic Synthesis

Nickel‐Catalysis Enabling α‐Alkylation of Ketones by Secondary Alcohols

Synthesis of a CCC‐NHC pincer Re complex: An air stable catalyst for coupling ketones with primary alcohols via borrowing hydrogen

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