Reaction Of Aromatic Ketones Research Articles

Microwave-promoted One-pot Synthesis of Imidazo[1,2-a]pyridines in Lemon Juice

Objective: A simple and highly efficient microwave-promoted procedure for the synthesis of imidazo[1,2-a]pyridine derivatives from the reaction of aromatic ketones, N-bromosuccinimide, and 2-aminopyridines in lemon juice was designed. The main advantages of this protocol, such as clean reaction profile, mild reaction condition, high yield, and minimum reaction time, were compared to other previously developed methods. Method: A mixture of aromatic ketones (1a-m) (0.005 m), N-bromosuccinimide (NBS) (0.005 m), and lemon juice (10 ml) was irradiated by microwave at 400-watt power at 85°C, and the formation of α- bromoketones was monitored by Thin Layer Chromatography (TLC). After completion of α-bromination, 2-aminopyridines (0.005 m) was added to the reaction mixture and it was further irradiated at the same reaction condition. After completion of the reaction, the reaction mass was poured in ice-cold water, the solid product obtained was filtered, washed with cold water, and recrystallized from aqueous ethanol. Result: In the present investigation, we have developed an environmentally benign, easy, and highly efficient one-pot procedure for the synthesis of 2-phenylimidazo [1, 2-a] pyridines from the reaction of aromatic ketones, N-bromosuccinimide, and 2-aminopyridines in lemon juice as a natural acid catalyst and solvent under microwave irradiation. This new protocol offers very attractive features such as minimum reaction time, clean reaction profile, mild reaction condition, and green aspects such as avoid poisonous catalyst, hazardous solvents, ease of the work-up procedure, and higher yield. Conclusion: In the present investigation, we have developed an environmentally benign, easy, and highly efficient one-pot procedure for the synthesis of 2-phenylimidazo [1, 2-a] pyridines from the reaction of aromatic ketones, N-bromosuccinimide, and 2-aminopyridines in lemon juice as a natural acid catalyst and solvent under microwave irradiation. This new protocol offers very attractive features such as minimum reaction time, clean reaction profile, mild reaction condition, and green aspects such as no need for a poisonous catalyst and hazardous solvents, ease of work-up procedure, and higher yield.

Highly efficient microwave-assisted one-pot synthesis of 4-aryl-2-aminothiazoles in aqueous medium

The thiazole ring system is one of the most important heterocycles in nature, as it represents an important structural motif of many biological compounds, including vitamin B1 (Thiamin), carboxylase and penicillin. There is, therefore, an urgent need to design rapid, efficient and environmentally benign protocols for the synthesis of thiazoles. Herein, we have developed a one-pot protocol for the synthesis of 4-aryl-2-aminothiazoles from the reaction of aromatic ketones, NBS (N-Bromosuccinimide) and thioureas under microwave irradiation at 80–85 °C in PEG (polyethylene glycol)-400 and water as a green reaction medium. The products were obtained in 84–89% yields in 28–32 min. The method has several advantages such as use of green solvent, easy work-up, excellent yield and avoiding use of lachrymatric α-haloketones.

ChemInform Abstract: Identifying a Highly Active Copper Catalyst for KA2 Reaction of Aromatic Ketones.

AbstractA highly efficient catalytic protocol is developed for the coupling of aromatic ketones with amines and terminal alkynes.

Identifying a Highly Active Copper Catalyst for KA(2) Reaction of Aromatic Ketones.

The well-established A(3) coupling reaction of terminal alkynes, aldehydes, and amines provides the most straightforward approach to propargylic amines. However, the related reaction of ketones, especially aromatic ketones, is still a significant challenge. A highly efficient catalytic protocol has been developed for the coupling of aromatic ketones with amines and terminal alkynes, in which Cu(I) , generated in situ from the reduction of CuBr2 with sodium ascorbate, has been identified as the highly efficient catalyst. Since propargylic amines are versatile synthetic intermediates and important units in pharmaceutical products, such an advance will greatly stimulate research interest involving the previously unavailable propargylic amines.

Alternate Method for the Synthesis of Six-Membered Carbocycles with Five Stereocenters: 1,2,3,4,6-Pentasubstituted-4-hydroxy-cyclohexanes

A series of novel 1,2,3,4,6-pentasubstituted-4-hydroxy-cyclohexanes (3a–u) were synthesized from the reaction of aromatic ketones with aromatic aldehydes under mild reaction conditions in good yields. The stereochemistry of the synthesized compounds was established using 1D and 2D-NMR spectra.

ChemInform Abstract: Coordinating Chiral Ionic Liquids: Design, Synthesis, and Application in Asymmetric Transfer Hydrogenation under Aqueous Conditions.

Hydrophilic coordinating chiral ionic liquids with an amino alcohol substructure were developed and efficiently applied to the asymmetric reduction of ketones. Their careful design and adaptability to the desired reaction conditions allow for these chiral ionic liquids to be used as the sole source of chirality in a ruthenium-catalyzed transfer hydrogenation reaction of aromatic ketones. When used in this reaction system, these chiral ionic liquids afforded excellent yields and high enantioselectivities.

Hydrogenation of Aldehydes and Ketones to Corresponding Alcohols with Methylamine Borane in Neat Water

Chemoselective hydrogenation of various aldehydes and ketones with methylamine borane (MeAB) in neat water was investigated. MeAB is suitable for green organic reactions, for MeAB is a nontoxic, environmentally benign, and easily handled reagent. Aldehydes were selectively and rapidly hydrogenated in excellent yields (86–97%) for 30 min, but hydrogenation of aromatic ketones needed over 20 h at room temperature because of their poor water solubility and steric hindrance. Thus we investigated polyethylene glycol (PEG400) and acidic cation-exchange D072 resin as catalysts to accelerate the hydrogenation reaction of aromatic ketones and achieved excellent yields within several hours. PEG 400 and D072 resin are both suitable for green organic reactions. The D072 resin was reused up to four times without any significance loss in activity.

ChemInform Abstract: Ruthenium Chloride as an Efficient Catalytic Precursor for Hydroarylation Reactions via C—H Bond Activation.

AbstractThe reaction of aromatic ketones with triethoxyvinylsilane tolerates a wide range of functional groups and heteroaromatic substituents.

On the reactions of trifluorovinylsilanes with aromatic ketones – Expected and some unexpected results

The reactions of aromatic ketones with trialkyl(trifluorovinyl)silanes in the presence of fluoride ions were studied. The conditions for the selective addition of trialkyl(trifluorovinyl)silanes to the carbonyl function of aromatic ketones in the presence of cesium fluoride and absence of any solvents to form the trifluorovinyl containing “silylated” alcohols have been worked out. The analogous reactions in common organic solvents are not terminated on the stage of “silylated” alcohols formation; consecutive reactions lead to fluorinated olefins and acids under the influence of fluoride ions.

A RuH2(CO)(PPh3)3‐Catalyzed Regioselective Arylation of Aromatic Ketones with Arylboronates via Carbon—Hydrogen Bond Cleavage.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A RuH2(CO)(PPh3)3-Catalyzed Regioselective Arylation of Aromatic Ketones with Arylboronates via Carbon−Hydrogen Bond Cleavage

When the reaction of aromatic ketones with arylboronates (arylboronic acid esters) using RuH(2)(CO)(PPh(3))(3) (3) as a catalyst was conducted in toluene, the corresponding arylation product was obtained in moderate yields. In this case, a nearly equivalent amount of a benzyl alcohol derived from a reduction of an aromatic ketone was also formed. The use of aliphatic ketones, such as pinacolone and acetone, as an additive or a solvent dramatically suppressed the reduction of the aromatic ketones and, as a result, ortho-arylation products were obtained in high yield based on the aromatic ketones. In these reactions, the aliphatic ketone functioned as a scavenger of ortho-hydrogens of the aromatic ketones and the B(OR)(2) moiety of the arylboron compound (HB species). A variety of aromatic ketones, such as acetophenones, acetonaphthones, tetralones, and benzosuberone, could also be used in this coupling reaction. Several arylboronates containing electron-donating (NMe(2), OMe, and Me) and -withdrawing (CF(3) and F) groups were also applicable to this coupling reaction. Intermolecular competitive reaction using pivalophenone-d(0)() and -d(5) and intramolecular competitive reaction using pivalophenone-d(1) were carried out using 3 as a catalyst. The k(H)/k(D) value for the intermolecular competitive reaction was substantially different, compared with intramolecular competitive reaction. This strongly suggests the production of an intermediate where the ketone carbonyl is coordinated to the ruthenium involved in this catalytic reaction. (1)H and (11)B NMR studies using 2'-methylacetophenone, phenylboronate (2), and pinacolone (6) indicate that 6 functions effectively as a scavenger of the HB species.

A Novel Efficient Synthesis of α‐Keto Triflates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Novel Efficient Synthesis of α-Keto Triflates

The direct and efficient synthesis of α-keto triflates by the reaction of aromatic ketones with thallium(III) triflate is decribed.

ChemInform Abstract: Solvent-Free Three-Component Condensation Reaction of Aromatic Ketones with Aliphatic Amines and Formaldehyde.

A solvent-free procedure for the synthesis of several 1-aryl-2-(dialkylaminomethyl)-prop-2-en-1-ones 3 (a–e) and 4 (a–e) is reported. Reaction of arylmethyl ketones with formaldehyde and dialkylami...

Solvent-Free Three-Component Condensation reaction of Aromatic Ketones with Aliphatic Amines and Formaldehyde

A solvent-free procedure for the synthesis of several 1-aryl-2-(dialkylaminomethyl)-prop-2-en-1-ones 3 (a–e) and 4 (a–e) is reported. Reaction of arylmethyl ketones with formaldehyde and dialkylamines, such as diethyl- or dibutylamines at room temperature in silica gel produce 3 and 4 with moderate yields.

ChemInform Abstract: Ureas in the Organic Synthesis. Part 5. Reactions of Aromatic Ketones and 1,2‐Diketones with Ureas in Formic Acid.

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ChemInform Abstract: Mechanism of the Grignard Reaction

Mechanism of the Grignard reactions of aromatic ketones in THF was studied by spectroscopic and kinetic methods. The stable radical intermediates generated in the initial electron transfer from Grignard reagent to ketones are in a state of aggregated dimer of corresponding ion–radical pairs; in which two ketone anion radicals are bridged by a dimer di–cation of Grignard reagent. Subsequent alkyl radical transfer from dimeric Grignard reagent cation moiety to ketone anion radical aggregated each other are promoted by a participation of another neutral Grignard reagent. Proposed mechanism by present authors is able to explain well addition products/reduction products ratios in the Grignard reactions.

Reduction of aromatic ketones by some rare earth metals in ether: Reversibility of the reduction steps

The reaction of aromatic ketones with rare earth metals in 1,2-dimethoxyethane produces, by hydrolysis, the corresponding alcohols, pinacols and hydrocarbons depending on the metal, the ketone and the molar ratio of the reactants. The formation of the various reduced products is reversible.

The mechanism of the primary process in the photoreduction of aromatic carbonyl compounds

Experimental data concerning the temperature dependence of the rate constants and the deuterium kinetic isotope effects on the photochemical hydrogen-abstraction reaction of aromatic ketones and quinones show that nuclear tunnelling is not important in the primary process, which is best described as a thermally activated reaction of the electronically excited molecule. The kinetics of the primary photochemical process are controlled by the activation barrier, which is made up of at least three contributions related to the bond strength of the hydrogen atom donor, to the bond strength of the excited carbonyl molecule and to an electrostatic interaction of the partners.

A novel synthesis of α,β-unsaturated nitriles from aromatic ketones via cyanophosphates

Reaction of aromatic ketones with diethyl phosphorocyanidate in the presence of lithium cyanide gave cyanophosphates, which were converted into α,β-unsaturated nitriles by treatment with boron trifluoride etherate in high yields.