Synthesis of chroman-4-one and indanone derivatives via silver catalyzed radical ring opening/coupling/cyclization cascade

A variety of chroman-4-one and indanone derivatives were conveniently synthesized from readily available cyclopropanols and alkenyl aldehydes via a silver catalyzed radical ring-opening/coupling/cyclization cascade. The reaction proceeded under mild and neutral conditions with broad substrate scope and afforded the desired products in moderate to good yields. A probable mechanism for the cascade reaction was also proposed.     

A novel route to substituted 3-methylidenechroman-2-ones and 3-methylchromen-2-ones

3-Methylidenechroman-2-ones, or their rearrangement products 3-methylchromen-2-ones, were efficiently synthesized by Michael addition of various nucleophiles to 3-diethoxyphosphorylchromen-2-ones followed by Horner-Wadsworth-Emmons reaction of the adducts with formaldehyde. Relative configuration and conformation of the intermediate adducts were studied using NMR spectroscopy and semiempirical PM3 calculations.     

A very simple solvent-free method for the synthesis of 2-arylchromones using KHSO4 as a recyclable catalyst

An efficient and solvent-free procedure for the synthesis of flavones using KHSO₄ as a recyclable catalyst is described. The methodology represents an environmentally friendly process in comprehensive consideration compared with other catalytic systems listed in publications. This method provides a clean, simple, solvent-free reaction and useful alternatives to prepare flavones and chromones. The use of KHSO₄ catalyst provides excellent yields, also leading to an easy separation and recovery of the catalysts, which allows both low environmental impact and low cost. Other green advantages of the method are the low formation of wastes and the replacement of corrosive, soluble mineral acids.     

2-芳基-2,3-二氢4(1H)-喹唑啉酮类化合物的合成

在NaHSO4催化下,以苯甲醛和邻氨基苯甲酰胺为底物,在室温下合成了一系列2-芳基-2,3-二氢-4(1H)-喹唑啉酮类化合物,该反应产率高、操作简单、并且避免使用有毒的金属催化剂.     

The Synthesis of 2-Alkylthio-3-alkyl-5-arylmethylidene4H-imidazol-4-ones

2-alkylthio-3-alkyl-5-arylmethylidene-4H-imidazol-4-ones were synthesized by the S-alkylation and N-alkylation of 2-thioxo-5-arylmethylidene-4-imidazolidinones, which were obtained via a tandem aza-Wittig reaction of vinyliminophosphoranes, carbon disulfide, and excess ammonium hydroxide (28% NH₃ in water).     

Dehydration of 4-hydroxy-4-methyl-3-phenylamino-oxazolidin-2-ones

The dehydration of two 5,5-disubstituted 4-hydroxy-4-methyl-3-phenylaminooxazolidin-2-ones into the corresponding 4-methylene-3-phenylaminooxazolidin-2-ones has been carried out. The structure of the products was confirmed by X-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1512–1517, October, 2004.     

Synthesis of 2-alkenyl-3-hydroxyquinolin-4(1H)-ones as promising antimicrobial and fluorescent agents

2-Alkenyl-3-hydroxyquinolin-4(1H)-ones were prepared by the rearrangement of anthranilic acid esters synthesized by two alternative methods. The prepared derivatives were screened for their antimicrobial activities against representative Gram-positive and Gram-negative bacteria, displaying notable minimum inhibitory concentration values against specific strains. The emission spectra of the target quinolines exhibited two well-separated emission bands, and the maximum excitation wavelengths of the selected compounds were detected at relatively high values.     

2-烷硫基-5-苯基亚甲基-4H-咪唑啉-4-酮的合成与表征

用2-硫代-3-正丁基-5-苯基亚甲基4-咪唑啉二酮的-S-烷基化反应合成了2-烷硫基-3-正丁基-5-苯基亚甲基-4H-咪唑啉-4-酮衍生物。探讨了S-烷基化反应的反应条件和所合成化合物的波谱性质。目标产物均为新的化合物，其结构经元素分析，IR，1H NMR和MS确正。     

Synthesis and reactivity of 3-aralkoxy-4-imino-imidazolidin-2-ones: a novel class of 4-iminohydantoins

Reactions of diethylphosphonoalkyl α-aminonitriles with 1,1′-carbonyl-diimidazole or 1,1′-carbonyl-di-(1,2,4-triazole) and O-substituted hydroxylamines under acidic conditions gave 3-alkoxy-4-imino-imidazolidin-2-ones, whereas in presence of triethylamine 4-alkoxy(aralkoxy)imino-imidazolidin-2-ones were formed.     

Rapid synthesis of 2,3-disubstituted-quinazolin-4-ones enhanced by microwave-assisted decomposition of formamide

An efficient methodology for the preparation of a series of 2,3-disubstituted-quinazolin-4(3H)-ones is described via a three step reaction from anthranilic acid. The obtained results also reveal that microwave-assisted rapid decomposition of formamide under controlled conditions of power, temperature and time is a very convenient source of ammonia for the synthesis of 2-substituted-quinazolin-4(3H)-ones and other rings.     

2-氨基-4H-咪唑啉-4-酮衍生物的快速平行合成法

咪唑啉酮衍生物是一类具有良好生物活性和药理活性的杂环化合物 [1,2 ] ,尤其是一些 2 -氨基咪唑啉酮表现出良好的杀菌、抗炎及抗癌活性 [3 ,4 ] .从自然界如一些海洋生物中可分离得到含 2 -氨基咪唑啉酮结构的生物碱 [5,6] .最近 ,组合化学方法广泛地应用于有机合成 ,它包括固相合成法和液相合成法[7～ 9] .我们曾应用氮杂 Wittig反应制得 2 -氨基取代咪唑啉酮衍生物 ,部分化合物表现出一定的抑菌活性 [10 ,11] .本文进一步报道应用液相平行反应法快速合成 2 -氨基 - 4H-咪唑啉 - 4-酮衍生物 (4) .该方法应用烯基膦亚胺 1与苯基异氰酸酯的…     

Synthesis of 4-Pyridyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

4-Pyridyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones were obtained by the condensation of ethyl nicotinoyl- or isonicotinoylacetates with o-phenylenediamine. Alkylation of the pyridylbenzodiazepinones with ethyl iodide under phase-transfer catalysis conditions occurred at the amide nitrogen of the heterocycle, whereas in nitromethane it occurred at the nitrogen of the pyridine substituent. Bromination with N-bromosuccinimide occurred at position 3 of the heterocycle. Pyridyldibenzodiazepinones underwent thermal rearrangement to derivatives of vinylbenzimidazole.     

Synthesis and Fungicidal Activities of 2-Alkylthio-5-phenylmethylene-4H-imidazol-4-ones

2-Alkylthio-5-phenylmethylidene-4H-imidazol-4-ones 4 were synthesized by S-alkylation of 2-thioxo-3-aryl-4-imidazolidinones 3 , which were obtained via cyclization of isothiocyanate 2 with aromatic primary amines. 3 and 4 exhibited good fungicidal activity against Physalospora piricola .     

Synthesis of substituted 2-aroyl-3-methylchromen-4-ones from isovanillin via 2-aroyl-3-methylchroman intermediates

The synthesis of substituted 2-aroyl-3-methylchromen-4-one from isovanillin is described. O-Allylphenol (2) prepared from isovanillin (1) was allowed to react with various α-bromoacetophenone (3) to produce 2-(2-allyl-3,4-dimethoxy)phenoxy-1-aroylethanones (4). The resultant 4 were treated with 2 equiv of potassium tert-butoxide to afford the substituted 2-aroyl-3-methylchromans (5) through an isomerization of an allylic double bond and a carbanion-olefin intramolecular 6-endo-trig cyclization reaction. Subsequently, resultant 5 were oxidized with DDQ to yield the title compound 6, in good over-all yields.     

Rapid microwave assisted synthesis of 3-substituted 4-thioxo-oxazolidin-2-ones

The microwave assisted thionation of 3-substituted 4-imino-oxazolidin-2-ones with hydrogen sulfide in dichloromethane-pyridine afforded 3-substituted 4-thioxo-oxazolidin-2-ones.     

Synthesis of 2-Substituted and 2,3-Disubstituted Quinazolin-4-ones Containing a Sterically Hindered Phenol Residue

A series of 2-substituted and 2,3-disubstituted quinazolin-4-ones containing a 3,5-di(tert-butyl)-4-hydroxyphenyl group has been synthesized. They were prepared by the condensation of carboxylic acid imino ester hydrochlorides containing the indicated fragment with ethyl anthranilate and also by the reaction of azomethines, N-acylhydrazones, or the 4-phenylthiosemicarbazone of 3,5-di(tert-butyl)-4-hydroxybenzaldehyde with 2-methyl-4H-2,1-benzoxazin-4-one.     

Synthesis of 4-aroyl-1,2,4-triazolidin-3-ones via ring extension in reactions of 1,2-di-and 1,2,3,3-tetraalkyldiaziridines with aroyl isocyanates

Reactions of 1,2-di-and 1,2,3,3-tetraalkyldiaziridines with aroyl isocyanates involve opening of the diaziridine ring through cleavage of the C—N bond followed by cyclization of the zwitterionic intermediate into 4-aroyl-1,2,4-triazolidin-3-one derivatives. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 534–538, March, 2006.     

Synthesis of unsymmetrically 2,6-disubstituted 2,3-dihydrothiopyran-4-ones

A series of 2,3-dihydrothiopyran-4-one derivatives with unequal substituents in the 2- and 6-position have been prepared by double conjugate addition of sulfide to enynones. These starting materials were accessed in two steps from terminal alkynes and α,β-unsaturated aldehydes.     

Reactions of 3-hydroxy-1,2-dihydroquinazolin-4-ones with acid chlorides

The reactions of 3-hydroxy-1,2-dihydroquinazolin-4-ones with acid chlorides can afford compounds of different types. The structures of the products depend on the type of acid chloride used and on the nature of the substituent at position 2 of the 3-hydroxy-1,2-dihydroquinazolin-4-one. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1346–1349, July, 1999.