An Effective Synthesis of α-Azido Ketones From Ketones

One-pot transformation of ketones into α-azido ketones has been achieved by successive treatment with HNIB and NaN₃ in acetonitrile.     

Heteropoly Acids as Heterogeneous and Reusable Catalyst for α-Thiocyanation of Ketones

Simple, efficient, and mild method for α-thiocyanation of ketones in presence of heteropolyacid has been developed. This methodology offered α-oxothiocyanates in good to excellent yields at room temperature in a highly selective manner. The catalyst could be efficiently recovered from the reaction and reused.     

m-Iodosylbenzoic Acid: Recyclable Hypervalent Iodine Reagent for α-Tosyloxylation and α-Mesyloxylation of Ketones

m-Iodosylbenzoic acid–mediated reactions of various carbonyl compounds provided α-organosulfonyloxy carbonyl compounds in good yields. The final products could be easily isolated without any chromatographic purification by simple treatment of the crude mixture with an anionic exchange resin.     

Preparation of Functionalized α-Chloromethyl Ketones Using Rieke Zinc

The cross-coupling reaction of highly functionalized organozinc reagents with chloroacetyl chloride mediated by copper allows for the easy preparation of functonalized α-chloromethyl ketones in excellent yields.     

Efficient α-Thiocyanation of Ketones Using Pyridinium Hydrobromide Perbromide

Abstract

The direct α-thiocyanation of ketones with ammonium thiocyanate has been achieved using pyridinium hydrobromide perbromide under mild and neutral conditions to produce α-ketothiocyanates in excellent yields and with high selectivity.     

Aza-Michael Addition of Amines to α,β-Unsaturated Compounds Using Molecular Iodine as Catalyst

Aza-Michael adducts are obtained in very good yields by the conjugate addition of aliphatic amines to α,β-unsaturated compounds using molecular iodine as catalyst in dichloromethane at room temperature. Aromatic amines were found to be reactive under reflux in toluene.     

I2-Mediated Oxidative Amidation of Aryl Methyl Ketones: Synthesis of Primary α-Ketoamides Using Ammonium Carbamodithioate as Amine Surrogate

Here we report the preparation of primary α-ketoamides via a highly efficient molecular iodine-mediated oxidative amidation of aryl methyl ketones with ammonium carbamodithioate. A self-sequenced iodination/nucleophilic substitution/Kornblum oxidation/amidation mechanism was proposed. In this mechanism, α-thiocyanatoacetophenone is the key intermediate.     

Homologation of α,β-Ethylenic Ketones in Substituted β,γ-Ethylenic Ketones Using Phosphoniosilylation

Among the methods described (1–4) to prepare β,γ-unsaturated ketones 2, Warren (4) recommends the Wittig-Horner procedure involving β-acetalated diphenylphosphinoxides reagents |scheme 1 (i)|.     

Regioselective Synthesis of Sugar Esters without Catalyst Using α-Hydroxycarboxylic Acids

A convenient and regioselective synthesis of 6-O-sugar esters, which are useful additives as emulsifiers in food technology and cosmetics, without the use of protecting groups or catalysts is described     

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

Microwaveirradiationhasf0undalotofapplicati0nsinrecentyears'".Thereactiontimecanbeshortenedgreatlyundermicrowaveirradiation,soitisanewandconvenientsyntheticmethod.Inprevi0uspapers"',wereportedtheethoxylationsofnitro-chlorobenzeneandreactionsofcarboxylicacidwithhalidesunderndcrowaveirradiation.a,6-Unsaturatedketonesareusefulcompounds,whosesynthesiswerenoteasybyconventionalways"9.Ontheotherhand,KF-Al2O3isanewkindofbasecatalyststhatcancatalyzemanyreactionsunderndldconditions,t0givehighcatalytic…     

Regiospecific Synthesis of α-Alkylated Ketones

Several solutions have been developed to avoid the troublesome di- and polyalkylation encountered in ketone enolate alkylations¹, including use of the covalent Li enolate, or “additives” to tighten the metal-oxygen bond (M = Si^2,3,4, Sn^5,6, Al⁶, B^7,8,9).     

Graphene Oxide as Recyclable Catalyst for One-Pot Synthesis of α-Aminophosphonates

We report the synthesis of α-aminophosphonates from aromatic aldehydes, aromatic and aliphatic amines, and trimethylphosphite (Kabachnik–Fields reaction) using a “carbocatalyst,” graphene oxide, at room temperature with excellent yield and recyclability. Enhanced catalytic activity of graphene oxide as compared to other catalysts studied is possibly due to the presence of carboxylic acid and hydroxyl groups.     

Diels-Alder Reactions of N-Functionalized Acryloyl α-Pyrrolidone Derivatives Using FeCl3·6H2O as an Efficient Catalyst under Solvent-free Conditions

Diels-Alder reactions of N-functionalized acryloyl α-pyrrolidone derivatives were investigated, which were catalyzed by FeCl3·6H2O as an efficient catalyst under solvent-free conditions at room temperature. The corresponding cycloadducts with functionalized-pyrrolidone were prepared in high yield with high stereoselectivity by a green chemistry procedure. N-Functionalized acryloyl pyrrolidone derivatives, a kind of pyrrolidone-functionalized chelating α,β-unsaturated ketone usable as a dienophile in Diels-Alder reaction, were synthesized by N-acylation procedure in ionic liquid as a novel synthetic method.     

Dicyano-Functionalized MCM-41-Supported Palladium Complex as An Efficient Catalyst for Allylation of Aldehydes and Ketones

Dicyano-functionalized MCM-41-supported palladium complex was prepared from dicyano-functionalized MCM-41 and palladium chloride. This complex exhibited high catalytic activity in the allylation of aldehydes and ketones with allylic chlorides in the presence of SnCl2. This polymeric palladium complex can be recovered and reused without noticeable loss of activity.     

Conversion of Alkynes into α,α-Dichloro Ketones and α,α-Dichlorodimethyl Ketals Using Trichloroisocyanuric Acid

Abstract

Trichloroisocyanuric acid reacts with alkynes in the presence of water in acetone or acetonitrile to form α,α-dichloro ketones and in methanol to form α,α-dichlorodimethyl ketals.     

Synthesis of α-Diketones from α,β-Dihydroxy Ketones

Treatment of α,β-dihydroxy ketones with carbonyldiimidazole resulted in the formation of α-diketones based on the elimination of the cyclic carbonates formed in situ.     

Ultrasound-Assisted Epoxidation of Olefins and α,β-Unsaturated Ketones over Hydrotalcites Using Hydrogen Peroxide

Abstract

An efficient ultrasound-assisted epoxidation of olefins and α,β-unsaturated ketones over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile is described. This general and selective protocol is relatively fast and is applicable to a wide variety of substrates.     

Cyclometalated Ruthenium Pincer Complexes as Catalysts for the α-Alkylation of Ketones with Alcohols

Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H⁻ as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts.     

A Modified and Green Procedure for the Synthesis of β-Amido Ketones Using a BrΦnsted-Acidic Ionic Liquid as Novel and Reusable Catalyst

A green and improved method for the synthesis of β‐amido ketones through one‐pot multi‐component reaction of an enolizable ketone, aryl aldehyde, acetonitrile or benzonitrile in the presence of trimethylsilyl chloride using 3‐methyl‐1‐(4‐sulfonic acid)butylimidazolium hydrogen sulfate [(CH₂)₄SO₃HMIM][HSO₄], a Br?nsted‐acidic ionic liquid, as an effective and recyclable catalyst is described. The present methodology offers several advantages such as simple procedure with an easy work‐up, relatively short reaction time, and good to excellent yields.     

Catalytic Enantioselective Direct Aldol Addition of Aryl Ketones to α-Fluorinated Ketones

The catalytic enantioselective synthesis of α-fluorinated chiral tertiary alcohols from (hetero)aryl methyl ketones is described. The use of a bifunctional iminophosphorane (BIMP) superbase was found to facilitate direct aldol addition by providing the strong Brønsted basicity required for rapid aryl enolate formation. The new synthetic protocol is easy to perform and tolerates a broad range of functionalities and heterocycles with high enantioselectivity (up to >99:1 e.r.). Multi-gram scalability has been demonstrated along with catalyst recovery and recycling. ¹H NMR studies identified a 1400-fold rate enhancement under BIMP catalysis, compared to the prior state-of-the-art catalytic system. The utility of the aldol products has been highlighted with the synthesis of various enantioenriched building blocks and heterocycles, including 1,3-aminoalcohol, 1,3-diol, oxetane, and isoxazoline derivatives.