Hypervalent iodine(III) catalyzed rapid and efficient access to benzimidazoles,benzothiazoles and quinoxalines: Biological evaluation of some new benzimidazole-imidazo[1,2-a]pyridine conjugates

A rapid, simple and highly efficient method for the synthesis of a variety of 2-aryl-benzimidazoles, 2-aryl-benzothiazoles and quinoxalines has been developed using Koser’s reagent [PhI(OH)OTs] as catalyst. The present work highlights the potential of Koser's reagent ([PhI(OH)OTs]) for the synthesis of benzimidazoles, benzothiazoles and quinoxalines, etc. Short reaction time, high yields, importantly low catalyst loading, broad substrate scope and scalability are the salient features of this methodology. Particularly, this method has been employed successfully to synthesize highly structured indole-benzimidazole and quinoxaline-6-carboxamide derivatives as well as biologically important benzimidazole-imidazo[1,2-a]pyridine conjugates in moderate to good yields. These remarkable features make the present methodology a valid contribution to the existing precedents for the synthesis of benzimidazoles, etc. In the MTT assay, benzimidazole-imidazo[1,2-a]pyridine conjugates 3s, 3t and 3v were found to be active on MCF-7 (IC₅₀ values of 5.10 ± 0.10, 8.23 ± 0.02, and 10.75 ± 0.03 µM, respectively) and MDA-MB-231 cell lines (IC₅₀ values of 10.83 ± 0.13, 7.68 ± 0.05, and 7.87 ± 0.24 µM, respectively). Flow-cytometry analysis revealed that the treatment of MCF-7 cells with compound 3s showed moderate effect on the progression of G0/G1 phase of the cell cycle.     

A one-pot three-component reactions for the synthesis of fully substituted spiro indeno[1,2-b]quinoxaline derivatives

An efficient and simple approach of the synthesis of some spiro indeno[1,2-b]quinoxalines via a one-pot three-component reaction of 11H-indeno[1,2-b]quinoxalin-11-one, pyrazolone, and malononitrile in the presence of Na₂CO₃ at 70 °C is reported. This reaction has shown to have high atom economy.     

Unexpected reaction of 2,2-dihydropolyfluoroalkylaldehydes with ammonia and aldehydes or ketones: a novel synthetic method for 4-fluoroalkyl-1,2-dihydropyrimidine

4-Fluoroalkyl-1,2-dihydropyrimidines were synthesized in good yields by the tri-component reaction of 2,2-dihydropolyfluoroalkylaldehydes, ammonia and aldehydes, ketones or enol ethers in the presence of zinc chloride under mild conditions.     

New intra-intermolecular criss-cross cycloaddition of unsymmetrical allenylazines with alkynes leading to three fused five-membered heterocycles

This report describes a new type of intra-intermolecular criss-cross cycloadditions. Thermal reactions of unsymmetrical allenylazines in the presence of alkynes led to three fused five-membered heterocycles in some cases. In the case of unsymmetrical substituted alkynes, a regioselectivity was observed. The molecular structures of all products are discussed. One X-ray crystal structure is also reported.     

Metal-promoted variants of the Passerini reaction leading to functionalized heterocycles

[reaction: see text]. The effect of replacing the Br?nsted acid in classic Passerini reactions with a mild Lewis acid has been studied. Triggered by metal-promoted silylation, condensations of aliphatic or aromatic carbonyl compounds with appropriately substituted isonitriles capable of neighboring group donation afford alpha-hydroxyamides, substituted oxazoles, and other useful heterocycles.     

Direct aldol condensation reaction of ethyl diazoacetate with trifluoromethyl ketones

An efficient and direct aldol-type condensation of ethyl diazoacetate with trifluoromethyl ketones was developed in the presence of dialkyl zinc. A series of trifluoromethylated products were obtained in good to excellent yields (60-95%). A preliminary extension to a catalytic enantioselective aldol reaction of ethyl diazoacetate to trifluoromethyl ketones (up to 72% ee) is also described.     

PEG-400促进的硝酸铋氧化二芳基乙醇酮合成二芳基乙二酮

PEG-400作为绿色反应溶剂能有效地促进硝酸铋氧化二芳基乙醇酮为二芳基乙二酮。产物结构用IR和1H NMR光谱进行了表征。该方法具有反应时间短,产率较高,操作简便,环境友好等优点。     

NHC-coordinated palladacycle catalyzed 1,2-addition of arylboronates to unactivated ketones

Abstract

Palladium catalyzed intermolecular 1,2-addition of arylboronate to unactivated ketone was investigated. NHC-coordinated palladacycle 4c exhibited catalytic activity for the reactions and provided the corresponding tertiary alcohols and γ,γ-disubstituted γ-lactones in good to excellent yields.     

A novel three-component reaction for the synthesis of 1,2-dihydroisoquinolines via the reaction of isoquinoline and isocyanides with strong CH-acids in water

A straightforward and efficient method for the synthesis of 1,2-dihydroisoquinolines via the one-pot, three-component reaction of an isocyanide, isoquinoline and a strong CH-acid in water without using any catalyst at 70 °C is reported. The method offers several advantages including high yields of products and an easy work-up procedure.     

Polymers containing fluorinated ketone groups. II. NMR studies of the reaction of methylbenzyl trifluoromethyl ketones with alcohols in carbon tetrachloride

Prior to the study of poly(o- and p-vinylbenzyl trifluoromethyl ketone) (PVTFK) polymers and their reaction with alcohols, the reactions of some simple model compounds with alcohols were investigated. The reaction of fluorinated ketones toward alcohols was determined by proton nuclear magnetic resonance (NMR) spectroscopy. Two fluorinated ketones–p-methylbenzyl trifluoromethyl ketone (p-MTFK) and o-methylbenzyl trifluoromethyl ketone (o-MTFK)–were prepared. Studies of the reaction of p-MTFK and o-MTFK to various alcohols based on NMR produced equilibrium constants (1M in CCl₄) at 31°C that ranged from 0.1 to 6.0. The equilibrium constants for p-MTFK with alcohols were larger than those for o-MTFK. In addition, the equilibrium constants for primary alcohols were larger than those for secondary and tertiary alcohols. Steric effects in this reaction could explain the lowered equilibrium constants for o-MTFK and the secondary and tertiary alcohols.     

Reaction of α-halogen substituted β-ethoxyvinyl trifluoromethyl ketones with 2-aminopyridine: new route to trifluoroacetyl-containing heterocycles

The reaction of α-halosubstituted β-ethoxyvinyl trifluoromethyl ketones with 2-aminopyridine gives 3-trifluoroacetyl imidazo[1,2-a]pyridine and 3-halo-1,1,1-trifluoro-4-(2-pyridinylamino)-3-buten-2-ones. The product ratio depends on the nature of the α-halogen atom and the solvent.     

Features of the reaction of unsymmetrical 2-mercapto-imidazoles with aromatic and aliphatic ketones

The cyclization of unsymmetrical 2-mercaptoimidazoles with aliphatic and aromatic ketones has been studied. Using ¹H NMR and X-ray analysis it has been shown that 4-R¹-1H-2-mercaptoimidazoles undergo selective oxidative cyclization to the corresponding 3-R³-2-R²-6-R¹-imidazo[2,1-b][1,3]thiazoles while 6-R⁴-1H-2-mercaptobenzo[d]imidazoles give a mixture of 6-R⁴-3-R²-2-R³-benzo[4,5]imidazo[2,1-b][1,3]thiazole and 7-R⁴-3-R²-2-R₃-benzo[4,5]imidazo[2,1-b][1,3]thiazole in the ratio 1: 1. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–122, January, 2007.     

On the reaction of 3-nitro-1,2-phenylenediamine with ethyl acetoacetate. Condensed dihydrodiazepinones

Condensation of 3-nitro-1,2-phenylenediamine with ethyl acetoacetate in boiling xylene gave two isomeric 2,3-dihydro-4-methyl-9-nitro- and 2,5-dihydro-4-methyl-6-nitro-1H-1,5-benzodiazepin-2-ones, the 9-nitro derivative thermal rearrangement product N-isopropenyl-4-nitrobenzimidazolone and a non cyclic acetoacetamide derivative. At room temperature these reactants afforded 2,3-dihydro-2-ethoxycarbonyl-methyl-2-methyl-4-nitrobenzimidazole.     

Formation of 1,2-dioxolanes using Mn(III)-based reaction of various arylacetylenes with 2,4-pentanedione and related reaction

The manganese(III)-based aerobic oxidation of arylacetylenes with 2,4-pentanedione at ambient temperature unexpectedly gave the 1,2-dioxolane derivatives in moderate yields together with a small amount of the oxiranes. The 1,2-dioxolanes underwent silica gel-assisted contraction to quantitatively give the oxiranes. The reaction pathway for the formation of the 1,2-dioxolanes and the by-product was discussed.     

Unusual condensation of 4,5-dimethyl-1,2-phenylenediamine with phthalaldehyde in the presence of NiII complexes giving rise to 4,5-dimethyldiisoindolo[2,1-a:1,2-c]quinoxaline-1,8-dione

The reaction of 4,5-dimethyl-1,2-phenylenediamine (1) with phthalaldehyde (2) in the presence of Ni^II complexes afforded 4,5-dimethyldiisoindolo[2,1-a:1,2-c]quinoxaline-1,8-dione (3), whose structure was established by X-ray diffraction analysis.     

Synthesis of new difluoroalkyl propargylic ketones and their use for the preparation of fluorinated heterocycles

Synthetic methodology studies are reported towards the preparation of new propargylic ketones with CF₂R side chains. These molecules are used for the synthesis of various types of five- or six-membered heterocycles with difluoroalkyl side chains.     

A remarkably simple α-oximation of ketones to 1,2-dione monooximes using the chlorotrimethylsilane-isoamyl nitrite combination

Ketones undergo α-oximation by NOCl formed in situ from Me₃SiCl and isoamyl nitrite, either in solution or under solvent-free conditions, to produce 1,2-dione monooximes in excellent yields. The oximation is regiospecific in appropriate cases.     

1,2-Dibromoethane and KI mediated α-acyloxylation of ketones with carboxylic acids

The 1,2-dibromoethane-and Kl-mediatedα-acyloxylation of ketones is reported in moderate to good yield without the use of transition metals and strong oxidants.Various acids are well tolerated with wide functional group compatibility.An 1,2-dibromoethane-and Kl-catalysed reaction mechanism is proposed based on the results of control experiments.     

不同载体负载Cu催化剂上甘油氢解制1,2-丙二醇催化性能的研究

采用等体积浸渍法合成了一系列不同载体负载的Cu基催化剂,并研究了其在甘油氢解反应中的催化性能。借助X射线衍射(XRD)、程序升温还原(H₂-TPR)和氨气程序升温脱附(NH₃-TPD)等手段对催化剂进行了表征,同时考察了反应温度、反应压力、反应时间和催化剂重复使用次数对其催化性能的影响。结果表明,载体对催化剂反应性能影响较大,且甘油氢解反应需要适当的酸性;当在催化剂8Cu/γ-Al₂O₃用量为反应原料质量的2.5%、反应温度513 K、反应压力6 MPa、反应时间6 h、反应原料为质量分数为10%的甘油水溶液的条件下,其催化效果最优,甘油转化率最高为88.4%,1,2-丙二醇的选择性可达到86.2%,且催化剂显示了良好的稳定性。     

SO3-Mediated reaction of phenylselenenylamide with 1,2-alkadienylphosphonates

SO₃-Mediated reaction ofN,N-diethylphenyiselenenylamide with 1,2-alkadienyl phosphonates under conditions of generation of weak electrophilic species results in the formation of cyclization products involving phosphoryl oxygen.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya No. 3, pp. 779–780, March, 1996