Synthsis of 4‐Piperidones via Multicomponent Double Mannich Reaction Catalyzed by I2

A multicomponent double Mannich reaction of amines, aldehydes and ketones was efficiently catalyzed by molecular iodine, producing a series of 4‐piperidones in a stereoselective way. A variety of amines, aldehydes and ketones were tolerated in this tandem process, including those with labile functinal groups. Further investigation of the reaction between alkyl‐imines and ketones showed that imines from amines and ketones were formed in situ and isomerized to enamine in the presence of molecular iodine to accelerate the corresponding Mannich addition.     

Synthesis of aldehydes and ketones by the dehydrogenation of alcohols in the presence of a Raney nickel/aluminium isopropoxide/alumina catalyst

The synthesis of aldehydes and ketones by the dehydrogenation of allylic and secondary alcohols using a Raney-Ni-Al(i-OPr)₃-Al₂O₃ catalyst without hydrogen acceptors is presented.     

Cobalt-Catalyzed Aerobic Oxidative Cleavage of Alkyl Aldehydes: Synthesis of Ketones,Esters, Amides,and α-Ketoamides

A widely applicable approach was developed to synthesize ketones, esters, amides via the oxidative C−C bond cleavage of readily available alkyl aldehydes. Green and abundant molecular oxygen (O₂) was used as the oxidant, and base metals (cobalt and copper) were used as the catalysts. This strategy can be extended to the one-pot synthesis of ketones from primary alcohols and α-ketoamides from aldehydes.     

HAlMCM-41介孔分子筛催化1,3-苯并二噁茂烷合成的研究

研究了HAlMCM-41分子筛催化邻苯二酚与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、正己醛、正辛醛、苯甲醛、二苯甲酮等十余种醛(酮)的缩合反应. 考察了反应时间、酚与醛(酮)的配比、HAlMCM-41分子筛用量、硅铝比、催化剂重用次数等因素对邻苯二酚与醛(酮)反应的影响. 结果表明, 当邻苯二酚与醛(酮)物质的量比为1∶1.4, 催化剂用量为3.5 g/mol邻苯二酚, 反应4 h, 分子筛n(SiO₂)/n(Al₂O₃)为15时, 选择性一般在99.4%以上, 转化率也一般在85.6%以上, 因此, HAlMCM-41分子筛对邻苯二酚与醛(酮)的反应有较好的催化性能.     

Aluminium dodecatungstophosphate (AlPW<Subscript>12</Subscript>O<Subscript>40</Subscript>)—An efficient catalyst for three-component <Emphasis Type="Italic">Mannich</Emphasis> reaction in water

One-pot, three-component Mannich reactions of ketones, aldehydes and amines were efficiently catalyzed by AlPW₁₂O₄₀ in water at ambient temperature to give the corresponding β-amino ketones in good to excellent yields. The method has the following merits: Firstly, Catalyst AlPW₁₂O₄₀ is non-corrosive and environmentally benign; Secondly, loading amount of catalyst is very low, less than 1 mol %; Thirdly, water as solvent is green and safe.     

O,O-Diethyl dithiophosphoric acid mediated direct synthesis of thioamides from aldehydes and ketones

A general and convenient method for a one-pot conversion of aldehydes and ketones into thioamides has been developed. The protocol involves oximation of aldehydes and ketones followed by deoxygenative thioamidation of oximes with O,O-diethyl dithiophosphoric acid which acts as an acid as well a source of sulfur. The method is operationally simple, high yielding, and also applicable to the conversion of amides and nitriles into the corresponding thioamides.     

A Green Procedure for the Oxidation of Benzyl Halides to Aromatic Aldehydes or Ketones in Aqueous Media

Green oxidation of benzyl halides to the corresponding aldehydes or ketones was achieved in aqueous media using trimethylamine N-oxide generated in situ from trimethylamine and H₂O₂. The yield of the reaction was excellent and the workup was simple.     

Efficient One‐Pot Synthesis of β‐Acetamido Carbonyl Compounds Using Fe3O4 Nanoparticles

A new, one‐pot condensation of aldehydes, enolizable ketones and esters, AcCl, and MeCN, in the presence of Fe₃O₄ nanoparticles (nano‐Fe₃O₄) as an efficient catalyst, for the preparation of β‐acetamido carbonyl compounds at room temperature is described.     

α-Phenylselenenylation of aldehydes and ketones with diphenyl diselenide mediated by KF/Al2O3

The utility of KF/Al₂O₃ for the synthesis of α-phenylseleno aldehydes and ketones from the corresponding aldehydes or ketones and diphenyl diselenide has been investigated. Simple stirring of a mixture of aldehyde or ketone and diphenyl diselenide in the presence of KF/Al₂O₃ at room temperature selectively produces the corresponding α-phenylseleno aldehyde or ketone in good to excellent yields.     

Reaction of Cα,O-dilithiooximes with functionalized carbonyl compounds. Part 2 . Reaction with α-chloroketones and α,β-unsaturated aldehydes and ketones

The reaction of Cα,O-Dilithiooximes 2 and α-chloroketones afforded 5-(hydroxymethyl)-Δ²-soxazolines 4 . α,β-Unsaturated aldehydes and ketones reacted with 2 to give the corresponding acyclic 1,2-addition products 5 . The latter were cyclized with phosphorus pentoxide to 5-vinyl-Δ²-isoxazolines 6 .     

Synthesis of sterically hindered ketones from aldehydes via O-silyl oximes

A mild and efficient method to synthesize sterically hindered ketones from aldehydes via O-silyl oximes was developed. Treatment of O-triphenylsilylated oximes with alkyl iodides in the presence of triethyl borane afforded the corresponding ketones.     

Radical C−H Acylation of Nitrogen Heterocycles Induced by an Aerobic Oxidation of Aldehydes

An aerobic radical approach for the synthesis of unsymmetrical heteroaryl ketones is described herein. The reaction involves cross‐dehydrogenative coupling between aldehydes and heteroaromatic bases with molecular oxygen (O₂). The key aspect of the method is the generation of reactive acyl radical via homolytic activation of aldehyde C?H bond using O₂ as the sole oxidant. The reaction has a good substrate scope with respect to aldehydes and functionalized nitrogen heterocycles. Based on our mechanistic studies, a radical chain pathway is suggested for the reaction. A synthetic application of the method is demonstrated in the formal synthesis of natural alkaloid (±) angustureine.     

Enolizable Carbonyls and N,O‐Acetals: A Rational Approach for Room‐Temperature Lewis Superacid‐Catalyzed Direct α‐Amidoalkylation of Ketones and Aldehydes

An efficient catalytic room‐temperature direct α‐amidoalkylation of carbonyl donors, that is, ketones and aldehydes with unbiased N,O‐acetals, is described. Sn(NTf₂)₄ is an optimal catalyst to promote this challenging transformation at low loading and the reaction shows promising scope. A comprehensive and rational evaluation of this reaction has led to the establishment of an empirical scale of nucleophilic reactivity for a broad set of ketones that should be helpful in the synthetic design and development of carbonyl α‐functionalization methods.     

New Recoverable Organoselenium Catalyst for Hydroperoxide Oxidation of Organic Substrates

New benzisoselenazol-3(2H)-one covalently bounded to a silica support was synthesized and characterized. It was used as an effective, selective, and easy-to-regenerate catalyst for t-BuOOH and H₂O₂ oxidation of alkyl arenes to alkyl aryl ketones, aromatic aldehydes to arene carboxylic acids, and sulfoxides and/or sulfones.     

AN EFFICIENT PRO CEDURE FOR THE PREPARATION OF MONO,AND DI-BIS-INDOLYL METHANES CATALYZED BY MOLIBDATOPHOSPHORIC ACID

H ₃ PMo ₁₂ O ₄₀ · xH ₂ O was found to be an effective catalyst for the preparation of bis-indolyl derivatives from indole and aromatic, aliphatic, heterocyclic aldehydes or ketones in ethanol at room temperature.     

Direct reductive amination and selective 1,2-reduction of α,β-unsaturated aldehydes and ketones by NaBH4 using H3PW12O40 as catalyst

A simple and convenient procedure for direct reductive amination of aldehydes and ketones with sodium borohydride is described. The reaction has been carried out in methanol in the presence of a catalytic amount of H₃PW₁₂O₄₀ (0.5 mol %). α,β-Unsaturated aldehydes and ketones can be easily converted into the corresponding allyl alcohols by reaction with H₃PW₁₂O₄₀ (0.5 mol %)/NaBH₄.     

Alkenediazonium Salts: A New Chapter of Classical Organic Chemistry

Whereas the protonation of α-diazo-β-diketones and α-diazo-β-oxo esters with hydrogen chloride and antimony pentachloride yields the corresponding hydroxyalkenediazonium hexachloroantimonates, the “acid-sensitive” α-diazomonocarbonyl compounds can be transformed into resonance-stabilized alkenediazonium salts by an analogous O-alkylation with triethyloxonium hexachloroantimonate. A general route for synthesizing these compounds consists in the transformation of the p-toluenesulfonylhydrazones of α-halogenated aldehydes and ketones with Lewis acids. Alkenediazonium ions which are not resonance stabilized can be isolated at room temperature only if their decomposition at higher temperatures leads, via evolution of nitrogen, to vinyl cations in particularly high energy levels. Facile substitution reactions at the CC double bond with anisole and methanol demonstrate the strongly electrophilic nature of alkenediazonium salts. When electron-donating substituments are attached to C2 of an ethylenediazonium ion, the bond order of the NN triple bond can be reduced to a level comparable with that in diazoacetic ester.     

Facile preparation of aromatic ketones from aromatic bromides and arenes with aldehydes

Aromatic ketones were efficiently prepared in good yields by the reactions of aryl bromides with n-BuLi, followed by the reactions with aromatic aldehydes or aliphatic aldehydes and the subsequent treatment with molecular iodine and K₂CO₃, in a one-pot method. The same treatment of arenes, instead of aromatic bromides, also provided the corresponding aromatic ketones in good yields. Using these methods, various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatics and electron-deficient aromatics could be prepared efficiently by a simple, transition-metal-free, and therefore environmentally benign experimental procedure.     

Solvent-switchable Acetalization by Yb（OTf）3-Catalyzed Procedures

O,O＇Diethyl acetals were prepared in high yields under mild conditions via the reaction of triethyl orthoformate with aldehydes and ketones in absolute ethanol in the presence of as low as 0.1 tool% of Yb（OTf）3. Using the same catalyst in THF-H2O, these O,O＇-diethyl acetals could be converted to the corresponding carbonyl compounds efficiently. This new protection-deprotection protocol presents the advantages of ease of execution, high efficiency and good chemoselectivity.     

Production of oxychemicals from precipitated hardwood lignin

Lignin is a major byproduct in the biomass-to-ethanol process. The lignin produced from acid treatment of biomass has characteristics suitable for further conversion to organic chemicals. It is free of contaminants and has a relatively low molecular weight. In this study, catalytic oxidative conversion of the acid-soluble lignin precipitated from acid hydrolysates of hardwood was investigated. The process is based on aqueous alkaline oxidation of lignin with dissolved O₂ in the presence of Fe³⁺ and Cu²⁺ catalysts at moderate reaction temperatures (160–180°C). Aromatic aldehydes, ketones, and organic acids are found to be the primary products identifiable on extraction with ether. The combined weight yield of the total ether extractable products is about 20–25% of the initial lignin. The yield of the aldehydes (vanillin + syringaldehyde) is in the vicinity of 15% with an additional 3 to 4% of aromatic ketones. The yields of aldehydes plus ketones observed in this work far exceeded those obtainable from the conventional alkaline air oxidation of spent sulfite liquors. This article also provides comprehensive batch reaction data on conversion and product distribution.