Α-alkylation Of Ketones Research Articles

Selective catalytic synthesis of α-alkylated ketones and β-alkylated secondary alcohols via hydrogen-borrowing

A group of three Ir-(iii) complexes supported by a picolinamidato moiety was prepared.

Zinc(II) and Cadmium(II) Salphen Catalyzed Alkylation Reactions to Form α-Alkylated Ketones

The zinc (II) and cadmium (II)-salphen catalyzed α-alkylation of ketones with primary alcohols is reported. Various α-alkylated ketones were obtained in good yields through a borrowing hydrogen strategy by using 1 % of catalysts and a catalytic amount of NaOH (10 mol%) as the base under air atmosphere. All synthesized compounds were characteized by 1H and 13C NMR.

α-Alkylation of Ketones with Alcohols Using a MgO-Codeposited Mn Catalyst Supported on Al2O3

α-Alkylation of Ketones with Alcohols Using a MgO-Codeposited Mn Catalyst Supported on Al2O3

Nickel-Catalyzed Sustainable and Selective Alkylation of Alcohols to α-Alkylated Ketones via Borrowing Hydrogen Approach

AbstractHerein, we report a nickel-catalyzed sustainable, environment­-friendly, and economically affordable borrowing hydrogen approach (BHA) for synthesizing various α-alkylated ketones via dehydro­genative coupling of primary and secondary alcohols. Using a well-­defined, air-stable, inexpensive, and easy-to-prepare four-coordinate macrocyclic Ni(II)-catalyst [Ni(MeTAA)] of a tetra-aza macrocyclic ligand (tetramethyltetraaza[14]annulene (H2MeTAA)), a series of α-alkylated ketones were prepared in good yields. A few control reactions, including deuterium-labelling experiments, were performed to unveil the reaction mechanism.

Heterogeneous Low-Valent Mn Catalysts for α-Alkylation of Ketones with Alcohols through Borrowing Hydrogen Methodology

Heterogeneous Low-Valent Mn Catalysts for α-Alkylation of Ketones with Alcohols through Borrowing Hydrogen Methodology

Ruthenium Complexes Bearing α-Diimine Ligands and Their Catalytic Applications in N-Alkylation of Amines, α-Alkylation of Ketones, and β-Alkylation of Secondary Alcohols.

New Ru(II) complexes encompassing α-diimine ligands were synthesized by reacting ruthenium precursors with α-diimine hydrazones. The new ligands and Ru(II) complexes were analyzed by analytical and various spectroscopic methods. The molecular structures of L1 and complexes 1, 3, and 4 were determined by single-crystal XRD studies. The results reveal a distorted octahedral geometry around the Ru(II) ion for all complexes. Moreover, the new ruthenium complexes show efficient catalytic activity toward the C–N and C–C coupling reaction involving alcohols. Particularly, complex 3 demonstrates effective conversion in N-alkylation of aromatic amines, α-alkylation of ketones, and β-alkylation of alcohols.

Ir-Catalyzed α-Alkylation of Ketones with Alcohols: One-Step Access to Donepezil

AbstractWe demonstrate an iridium-catalyzed alkylation of ketones with alcohols, which enables one-step access to donepezil, cyclic ketones, and linear ketones in high yields. A scale-up experiment shows the excellent practicability of this protocol. Comparative experiments show that a small amount of water is beneficial to the improvement of product yield.

Blue-Light-Induced Iron-Catalyzed α-Alkylation of Ketones.

We report a visible-light-induced iron-catalyzed α-alkylation of ketones. The photocatalytic system is based on the single diaminocyclopentadienone iron tricarbonyl complex. Two catalytic intermediates of this complex are able to harvest light, allowing the synthesis of substituted aromatic and aliphatic ketones at room temperature using the borrowing hydrogen strategy in the presence of various substituted primary alcohols as alkylating reagents. Preliminary mechanistic studies unveil the role of light for both the dehydrogenation and reduction step.

Acridine-Based SNS–Ruthenium Pincer Complex-Catalyzed Borrowing Hydrogen-Mediated C–C Alkylation Reaction: Application to the Guerbet Reaction

AbstractSNS-based ruthenium pincer catalysts were applied in a Guerbet condensation reaction of primary alcohols to give β-alkylated dimeric alcohols in good yields. The ability of these complexes to convert ethanol into butanol was also investigated. The work was then extended toward the C-alkylation of secondary alcohols with primary alcohols to give α-alkylated ketones. Several control experiments showed the involvement of borrowing hydrogen in the protocol.

Direct couplings of secondary alcohols with primary alkenyl alcohols to α-alkylated ketones via a tandem transfer hydrogenation/hydrogen autotransfer process catalyzed by a metal-ligand bifunctional iridium catalyst

A new strategy for the synthesis of α-alkylated ketones from secondary alcohols and primary alkenyl alcohols via a tandem transfer hydrogenation/hydrogen autotransfer process was proposed and successfully accomplished. Mechanistic experiments supported that functional groups in bpy ligand are crucial for the transfer hydrogenation and hydrogen autotransfer process. Furthermore, the utilization of the present catalytic system for the gram-scale synthesis of a biologically active compound was presented.

Nickel-catalyzed alkylation of ketones and nitriles with primary alcohols.

Nickel(II)-salen or nickel(II)-salphen catalyzed α-alkylation of ketones and nitriles with primary alcohols is reported. Various α-alkylated ketones and nitriles were obtained in high yields through a borrowing hydrogen strategy by using 1-3 mol% of nickel catalyst and a catalytic amount of NaOH (5-10 mol%) under aerobic conditions.

A heterogeneous cobalt catalyst for C–C bond formation by a borrowing hydrogen strategy

Co–MgO/TiO2 exhibited high activity for α-alkylation of ketones with alcohols through a borrowing hydrogen strategy without the addition of bases which were utilized in reported heterogeneous catalytic systems.

Scope and Mechanism of the Redox-Active 1,2-Benzoquinone Enabled Ruthenium-Catalyzed Deaminative α-Alkylation of Ketones with Amines

Scope and Mechanism of the Redox-Active 1,2-Benzoquinone Enabled Ruthenium-Catalyzed Deaminative α-Alkylation of Ketones with Amines

From selective transfer hydrogenation to selective hydrogen auto-transfer process: An efficient method for the synthesis of alkenyl ketones via iridium-catalyzed α-alkylation of ketones with alkenyl alcohols

A strategy for the synthesis of alkenyl ketones via the α-alkylation of ketones with alkenyl ketones has proposed and accomplished. In the presence of a metal–ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(H2O)], a series of desirable products were obtained in high yields. Mechanistic investigation revealed that functional groups in the ligand are crucial for the activity of catalyst and selective transfer hydrogenation is the determining step of the formation of alkenyl ketones as products. Notably, the present research exhibited also the unique potential of metal–ligand bifunctional catalysts for the activation of unsaturated alcohols as electrophiles for hydrogen auto-transfer process.

α-Alkylation of Ketones with Alkenes Enabled by Photoinduced Activation of Silyl Enol Ethers in the Presence of a Small Amount of Water.

Under blue-light irradiation conditions with a photocatalyst [1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene], silyl enol ethers reacted with alkenes in the presence of a small amount of water to afford the α-alkylation products in good to high yields. A thiol cocatalyst was found to expand the substrate scope of the reaction.

Synthesis of α-Alkylated Ketones via Selective Epoxide Opening/Alkylation Reactions with Primary Alcohols.

A new method for converting terminal epoxides and primary alcohols into α-alkylated ketones under borrowing hydrogen conditions is reported. The procedure involves a one-pot epoxide ring opening and alkylation via primary alcohols in the presence of an N-heterocyclic carbene iridium(I) catalyst, under aerobic conditions, with water as the side product.

A Proton-Responsive Pyridyl(benzamide)-Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols.

A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1 H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1 H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2 )Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.

(Cyclopentadienone)iron Complexes: Synthesis, Mechanism and Applications in Organic Synthesis.

(Cyclopentadienone)iron tricarbonyl complexes are catalytically active, inexpensive, easily accessible and air-stable that are extensively studied as an active pre-catalyst in homogeneous catalysis. Its versatile catalytic activity arises exclusively due to the presence of a non-innocent ligand, which can trigger its unique redox properties effectively. These complexes have been employed widely in (transfer)hydrogenation (e. g., reduction of polar multiple bonds, Oppenauer-type oxidation of alcohols), C-C and C-N bond formation (e. g., reductive aminations, α-alkylation of ketones) and other synthetic transformations. In this review, we discuss the remarkable advancement of its various synthetic applications along with synthesis and mechanistic studies, until February 2021.

Selective Catalytic Synthesis of α-Alkylated Ketones and β-Disubstituted Ketones via Acceptorless Dehydrogenative Cross-Coupling of Alcohols.

Herein, a phosphine-free pincer ruthenium(III) catalyzed β-alkylation of secondary alcohols with primary alcohols to α-alkylated ketones and two different secondary alcohols to β-branched ketones are reported. Notably, this transformation is environmentally benign and atom efficient with H2O and H2 gas as the only byproducts. The protocol is extended to gram-scale reaction and for functionalization of complex vitamin E and cholesterol derivatives.

Unveiling the catalytic nature of palladium-N-heterocyclic carbene catalysts in the α-alkylation of ketones with primary alcohols.

We report herein the synthesis of four new Pd-PEPPSI complexes with backbone-modified N-heterocyclic carbene (NHC) ligands and their application as catalysts in the α-alkylation of ketones with primary alcohols using a borrowing hydrogen process and tandem Suzuki-Miyaura coupling/α-alkylation reactions. Among the synthesized Pd-PEPPSI complexes, complex 2c having 4-methoxyphenyl groups at the 4,5-positions and 4-methoxybenzyl substituents on the N-atoms of imidazole exhibited the highest catalytic activity in the α-alkylation of ketones with primary alcohols (18 examples) with yields reaching up to 95%. Additionally, complex 2c was demonstrated to be an effective catalyst for the tandem Suzuki-Miyaura-coupling/α-alkylation of ketones to give biaryl ketones with high yields. The heterogeneous nature of the present catalytic system was verified by mercury poisoning and hot filtration experiments. Moreover, the formation of NHC-stabilized Pd(0) nanoparticles during the α-alkylation reactions was identified by advanced analytical techniques.