Condensation of rhodanine withβ-dicarbonyl compounds

Reaction of acetylacetone with rhodanine in ethanol solution, in the presence of ammonia and ammonium chloride gives two condensation products, containing one or two rhodanine groups. Under the same conditions benzoylacetone condenses with one molecule of rhodanine. Methylation of these compounds with methyl iodide takes place at an exocyclic sulfur atom, to give mono- and dimethylmercapto derivatives. The condensation products from the above carbonyl compounds and rhodanine have an active methylene group which can react with nitroso compounds and diazonium salts.     

Preparation of indolylmethanes catalyzed by metal hydrogen sulfates

Solid acids were developed and applied to the condensation reactions of indole with carbonyl compounds at ambient temperature. Tetra-(indolyl)methanes were obtained by the condensation reaction of indole with dialdehyde compounds.     

Knoevenagel condensation catalysed by aluminium oxide.

The Knoevenagel condensation of carbonyl compounds with active methylene compounds was readily carried out with aluminium oxide as catalyst.     

Studies on azolidones and their derivatives

The action of a concentrated aqueous solution of ammonia on 4-thioxothiazolid-2-one has given an isomer of pseudothiohydantoin, 4-iminothiazolid-2-one (I). 5-Substituted derivatives of I have been obtained by the condensation of 1 with carbonyl and nitroso compounds and 4-substituted derivatives by condensation with amino compounds.     

Magnesium perchlorate as an efficient catalyst for the synthesis of imines and phenylhydrazones

Magnesium perchlorate has been found to be an efficient catalyst for the synthesis of imines and phenylhydrazones by the reaction of carbonyl compounds with amines and phenylhydrazine in high yields at room temperatures and in short times. The condensation of less electrophilic carbonyl compounds with poorly nucleophilic amines affords the imines in excellent yields.     

A stereoselective, multiple-component approach to α-β-substituted-β-amino carbonyl derivatives

A new stereoselective multiple-component condensation is presented. This three-component condensation combines an aldehyde, aniline, and chlorotitanium enolates, to afford α-β-substituted-β-amino carbonyl compounds as its core structure.     

Phosphazene base-catalyzed condensation of trimethylsilylacetate with carbonyl compounds

The t-Bu-P4 base was found to be an excellent catalyst for the condensation of trimethylsilylacetate or trimethylacetonitrile with carbonyl compounds to form functionalized alkenes and beta-enaminoesters were also synthesized by the condensation with formanilides.     

2-(1,3-亚丙二硫)亚甲基-3-羰基丁酸作为硫醇替代试剂在缩硫醛/酮化反应中的应用

探讨了以2-(1,3-亚丙二硫)亚甲基-3-羰基丁酸作为硫醇替代试剂,乙醇作溶剂的缩硫醛/酮化反应.实验结果表明,该硫醇替代试剂能与各类醛、酮化合物快速、顺利地进行缩硫醛/酮化反应,以较高的产率生成相应的1,3-二噻烷类化合物.同时,该缩硫醛/酮化反应对不同的醛、酮化合物具有较高的化学选择性.     

A CLEAN CONVERSION OF CARBONYL COMPOUNDS TO OXIMES USING SILICA GEL SUPPORTED HYDROXYLAMINE HYDROCHLORIDE

The efficient condensation of carbonyl compounds with hydroxylamine hydrochloride under solvent free conditions is described.     

水介质中无催化剂下醛酮与活泼亚甲基化合物的缩合反应

报道了水相中无催化剂下各种羰基化合物与活泼亚甲基化合物的Knoevenagel缩合反应. 芳香醛与活泼亚甲基化合物如丙二腈、氰基乙酸乙酯、氰基乙酰胺的缩合在室温下即能顺利进行, 获得了很高的收率; 而对于杂环芳醛、α,β-不饱和的醛以及脂肪醛与活泼亚甲基化合物的缩合, 需在50～65 ℃下进行, 也取得了很高的收率; 对于脂肪酮、芳香酮以及二元醛与丙二腈的缩合在75～85 ℃下也能顺利地进行, 获得中等以上的收率. 反应简单、高效而且对环境友好.     

-(1-phenylhydrazino)-alkanone phenylhydrazones: The reaction with carbonyl compounds

The unsymmetrically disubstituted hydrazines 1 were condensed with carbonyl compounds. Some of the expected condensation products were isolated, but some were formed as unstable intermediates which underwent 1,4-elimination: The phenylhydrazone of the carbonyl compound used was obtained, together with the corresponding phenylazo-alkene 11 or alternatively, the 1,4-addition product of a different protic nucleophile to 11.     

n—Butyl Pyridinium Nitrate as a Reusable Ionic Liquid Medium for Knoevenagel Condensation

The Knoevenagel condensation of carbonyl substrates with active methylenecompounds proceeds smoothly with ammonium acetate as catalyst in n-butyl pyridinium nitrate to afford the desired products of good purity in moderate yields.     

A convenient one-pot synthesis of thiazol-2-imines: application in the construction of pifithrin analogues

For the first time a reaction intermediate has been isolated giving further insight into the mechanism of thiazol-2-imine formation. The first step of the reaction requires a basic medium, while the second step is an acid mediated E1 elimination reaction. An efficient one-pot synthesis of substituted thiazol-2-imines have been achieved by the condensation of carbonyl compounds with thioureas and 1,3-disubstituted thioureas using 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT). Unsymmetrical 1,3-disubstituted thioureas give regioselective products with symmetrical ketones, which are mainly governed by the pK_as of NH protons of thiourea, whereas symmetrical 1,3-disubstituted thioureas give regioselective products with symmetrical carbonyl compounds owing to the regioselective bromination of ketones. The methodology is extended to access novel neurodegenerative drug candidate pifithrin-α analogues in good yields in shorter reaction time. This method is simple, versatile and is applicable for different 1,3-disubstituted thioureas as well as a range of carbonyl compounds.     

Knoevenagel Condensation Catalysed by Alumina

在Ａｌ２Ｏ３催化下活泼亚甲基化合物和羰基化合物进行克脑文格尔缩合反应，在温和的反应条件下得到较高收率的产物。将超声波辐射应用于该缩合反应使反应速度明显提高。     

Substituted 2-aryliminonaphtho[1,8-bc]thiophene

The first dyes based on naphtho[1,8-bc]thiophen-3-(2H)-one were synthesized. The carbonyl group of these compounds has lower reactivity than the carbonyl group of naphthostyryl in condensation with arylamines.     

N,N′-Alkylidenpeptide: Peptidsynthese-Nebenprodukte bei Einwirkung von Carbonylverbindungen

Byproducts of peptide synthesis, formed in the course of accidental attack by Pd-activated oxygen on ethanol and triethylamine in reaction media, have been identified as products of condensation between peptides and acetaldehyde, and demonstrated to represent N,N′-alkylidenepeptides, i.e. derivatives of 4-imidazolidinones. The same products are obtained by direct action of acetaldehyde on the respective peptides, and analogs resulted in some cases when acetaldehyde was replaced by formaldehyde or acetone. The condensation is reversible, imidazolidinone stability depending on structural features of both the involved peptide and carbonyl compound. There are evidently implications of these findings with respect to the chemistry and biochemistry of peptides and proteins.     

A regio- and stereo-controlled synthesis of α,β-unsaturated carbonyl compounds

α,β-Unsaturated carbonyl compounds and butenolides are readily prepared by the rhodium(I) catalyzed isomerization of 1,3-diene monoepoxides and α-alkylidene-γ-butyrolactones, respectively. The former transformation is formally regarded as the equivalent of a regiospecific aldol condensation of an unsymmetrical ketone.     

A highly negatively charged γ-Keggin germanodecatungstate efficient for Knoevenagel condensation

A tetra-n-butylammonium (TBA) salt of a γ-Keggin -6-charged germanodecatungstate, [γ-H(2)GeW(10)O(36)](6-) (I), could act as an efficient homogeneous catalyst for Knoevenagel condensation of active methylene compounds with carbonyl compounds.     

New highly nucleophilic and practically accessible chlorocarbenoids for carbonyl olefination

[reaction: see text] Direct oxidative addition of CHCl3 to the Mg-TiCl4 bimetallic species resulted in the generation of a highly nucleophilic and practically convenient chloromethylenetitanium complex, which efficiently effected condensation even with enolizable or inert carbonyl compounds, such as sterically congested ketones, to provide vinyl chloride compounds.     

Organic Synthesis in Ionic Liquids： Condensation of 3-Methyl-1- phenyl-5-pyrazolone with Carbonyl Compounds Catalyzed by Ethylenediammonium Diacetate （EDDA）

The derivatives of pyrazolone are important class of antipyretic and analgesic compounds1. 1-Phenyl-3-methyl-4-arylmethylene-5-pyrazolones are very useful inter- mediates in the synthesis of substituted pyrazolones, generally, which were prepared by the c…