Ytterbium triflate hydrate catalyzed Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds

Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety of α, β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl3 in aqueous media to afford the corresponding products in good to excellent yields.

Synthesis of α,β-Unsaturated Ketones using Potassium fluoridealumina Catalyst by Microwave Irradiation

Microwave irradiation can accelerate the rate of the synthetic reaction of α,β-unsaturated ketones by using KF-Al2O3 as catalyst. The rate enhancement of the reaction is 360-860 fold.

Methanol as hydrogen source: Chemoselective transfer hydrogenation of α,β-unsaturated ketones with a rhodacycle

Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes highly chemoselective hydrogenation of α,β-unsaturated ketones with methanol as the hydrogen source. A wide variety of chalcones, styryl methyl ketones and vinyl methyl ketones, including sterically demanding ones, were reduced to the saturated ketones in refluxing methanol in a short reaction time, with no need for inter gas protection, and no reduction of the carbonyl moieties was observed. The catalysis described provides a practically easy and operationally safe method for the reduction of olefinic bonds in α,β-unsaturated ketone compounds.

Enantioselective Hydrogenation of α,β-Unsaturated Cyclic Ketones by Double Asymmetric Induction Preparation of (R)-Muscone

By ketal formation with chiral glycols like methyl or ethyl ester of tartaric acid,hydrogenation of ketals from the correspondingα,β-unsaturated 15-membered cyclic ketone produces (R)-muscone in good chemical and optical yield in the presence of chiral catalysts

Chemoselective Catalytic Hydrogenation of α,β-Unsaturated Ketones and α,β-Unsaturated Carboxylic Esters

The effect of catalysts P-2 00-Ni(Nickel boride) and P-2 00-Ni-M(M: Co, Fe, Cu, Sn), prepared by adopting a modified recipe, on the chemoselective hydrogenation of carbon carbon double bonds in α,β- unsaturated ketones, and the activity of catalysts P-1.80-Ni, P-2 00-Ni or P-1.80(2 00) -Ni-M(M: Pd, Co, Cu) in the selective hydrogenation of carbon carbon double bonds in α,β-unsaturated carboxylic esters, were investigated systematically. According to the experimental results, the selectivities of these catalysts toward the hydrogenation of the carbon carbon double bonds of α,β-unsaturated keones or α,β-unsaturated carboxylic esters are 96%—100% or 100%, respectively.

Cyclization Reaction of α-Triazolyl-α, β-unsaturated Ketones with Phenyl hydrazine

The reaction of α-triazolyl-α, β-unsaturated ketones with phenyl hydrazine was studied. The result indicated that cyclization took place and new heterocyclic compounds of substituted 4,5-2H-pyrazoles were obtained, whose structures and conformation were characterized by 1H NMR, IR, MS, elemental analysis and X-ray diffraction.

Ceric Ammonium Nitrate-mediated Oxidative Cycloaddition of 1,3-Dicarbonyls to β-Aryl-α, β-unsaturated Ketones

Regio and stereoselective synthesis of substituted dihydrofurans were accomplished by eeric ammonium nitrate mediated oxidative cycloaddition of 1,3-dicarbonyls to β-aryl-α,β-unsaturated ketones in moderate yields.

Stereoselective cycloaddition of N-acyliminium cations withα,β-unsaturated ketones and esters

The cycloaddition of N-acyliminium cations with some deactivated alkenes such as α,β-unsaturate ketones and esters has been investigated. In most cases, the N-acyliminium cations produced from 3-hydroxy-2-arylisoindol-1-ones in the presence of BFa.OEt2 could be reacted with α,β-unsaturated ketones and esters to afford stereoselectively the cycloaddition products 6-acylisoindolo[2,1- a]quinolin-11-ones in moderate to high yields. C 2009 Wei Zhang. Published by Elsevier B.V, on behalf of Chinese Chemical Society. All rights reserved.

A New Method for the Transformation of Alkenes intoα, β-Unsaturated Ketones via Cycloaddition with Dichloroketene

A new synthetic method is described here to obtain α, β-unsaturated ketones through alkenes through a sequence involving f (1) cycloaddition of alkenes with dichloroketene, (2) dechlorination of adducts, (3)acidpromoted ring-opening isomerization ofcyclobutanones in CF3 CO2H.

Organocatalyzed Highly Efficient Michael Addition of Malonate Derivatives to α,β-Unsaturated Ketones Using Chiral Schiff Bases

An efficient enantioselective Michael addition of ethyl-2-cyanoacetate and diethyl malonate to α,β-unsaturated ketones catalyzed by a simple chiral Schiff base, and products were obtained in good yields at room temperature.

Copper-Catalyzed C-C(O)C Bond Cleavage of Monoalkylated β-Diketone: Synthesis of α,β-Unsaturated Ketones

A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K3PO4) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .

Facile and Green Synthesis of α,β-Unsaturated Ketone Catalyzed by Air-Stable Organobismuth Complex

Air-stable cationic organobismuth complexes (2-5) possessing both acidic and basic characters were synthesized. The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex and [Bmim]BF4 showed high catalytic activity, diastereoselec-tivity, stability, and reusability in the one-pot synthesis of (E)-α,β-unsaturat-ed ketones through highly selective crossed-condensation of ketones and aldehydes. Through switching the reaction from homogeneous to heterogeneous, the system shows facile separation ability and facile reusability.

Direct oxidation of the C_(sp3)-H bonds of N-heterocyclic compounds to give the corresponding ketones using a reusable heterogeneous MnO_x-N@C catalyst

Novel reusable MnOx‐N@C catalyst has been developed for the direct oxidation of N‐heterocycles under solvent‐free conditions using TBHP as benign oxidant to give the corresponding N‐heterocyclic ketones. The catalytic system exhibited a broad substrate scope and excellent regi‐oselectivity, as well as being amenable to gram‐scale synthesis. This MnOx‐N@C catalyst also showed good reusability and was successfully recycled six times without any significant loss of activity.

CeCl_3·7H_2O as an efficient catalyst for one-pot synthesis of β-amino ketones by three-component Mannich reaction

Cerium trichloride heptahydrate(CeCl_3·7H_2O) was found to be an efficient and recyclable catalyst for the three-component direct Mannich reaction of anilines and benzaldehydes with acetophenone.This protocol has advantages of high yield,no environmental pollution,mild condition,and simple work-up procedure.

Ambient Ionic Liquids Used in the Reduction of Aldehydes and Ketones

The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.

A simple and efficient method for solvent-free iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid by grinding method

Green,mild and efficient iodination of hydroxylated aromatic aldehydes and ketones using iodine and iodic acid in the solidstate by grinding under solvent-free conditions at room temperature.This method provides several advantages such as environmentally friendly,short reaction times,high yields,non-hazardous and simple work-up procedure.

Baeyer-Villiger oxidation of cyclic ketones utilizing potassium peroxydisulfate(K_2S_2O_8) or sodium perborate(NaBO_3) in acidic media

The efficient, green, facile, mild and straightforward conversion procedure for the oxidation of cyclic ketones to lactones at room temperature utilizing potassium peroxydisulfate （K2S2O8） in acidic media is satisfactory to high yields without using traditional chlorinated solvents is reported. This oxidative reagent is cheap and friendly environmental procedure for industrial purposes than use of organic peracids.

Novel Chiral PNNP-Ru Complexes:Synthesis and Application in Asymmetric Transfer Hydrogenation of Ketones

The efficient catalytic systems generated in situ from RuCl2（PPh3）3 and chiral ligands N,N-bis[2-（di-o-tolylphosphino）-benzyl]cyclohexane-1,2-diamine（2） were employed for asymmetric transfer hydrogenation of aromatic ketones, giving the corresponding optically active alcohols with high activities（up to 99% conversion） and excellent enantioselectivities（up to 96% e.e.） under mild conditions. The chiral ruthenium（Ⅱ） complex （R,R）-3 has been prepared and characterized by NMR and X-ray crystallography.

Baeyer-Villiger oxidation of ketones with hydrogen peroxide catalyzed by Sn-aniline complex

Sn-aniline complex was prepared by a simple procedure. Cyclic and acyclic ketones were oxidized into lactones or esters with very high selectivity and yield with 30% hydrogen peroxide in the presence of Sn-aniline complex.