- Synthesis and spectral properties of fluorescent photochromic diarylethenes with 6,6a-dihydropentalene-2(1H)-one ethene "bridge"
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An alternative synthetic strategy for the preparation of 6,6a-dihydropentalene-2(1H)-one derivatives comprising the stage of the regioselective α-bromination of cyclopentenone system has been proposed. The method along with the bromination process includes the alkylation of ethyl 4-aryl-3-oxobutanoate with bromocyclopentenones and intramolecular carbocyclization reaction of alkylated product. The cyclization reaction has been studied in detail and it was found that the yields of the main and side products depend strongly on alkali concentration, and the method can be also used to design 8,8a-dihydrocyclopenta[a]inden-2(1H)-one unit. The spectral properties of the compounds obtained have been studied, and it was found that pentalenone derivatives as well as starting cyclopentenones, exhibit photochromic properties; in addition, the former, unlike the latter, are also fluorescent.
- Lonshakov, Dmitry V.,Shirinian, Valerii Z.,Zavarzin, Igor V.,Lvov, Andrey G.,Krayushkin, Mikhail M.
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Read Online
- Nickel - promoted favorskii type rearrangement of cyclic α-bromoketones
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Favorskii type rearrangement of cyclic α-bromo ketones 2 is promoted by NiCl2 in refluxing methanol, giving the rearranged carboxylic acid ester 3 in excellent yields. The reaction of 4-bromo-2,3,4,5-tetrahydronaphth [2,1-b]oxepin-5-one (5) and its regioisomer 8 with NiCl2 in McOH resulted in Favorskii rearranged carboxylic acid esters 6 and 9 respectively.
- Tandon, Vishnu K.,Awasthi, Anoop K.,Singh, Kunwar A.,Maurya, Hardesh K.,Gautam, Sanjay K.
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Read Online
- Acridine Orange Hemi(Zinc Chloride) Salt as a Lewis Acid-Photoredox Hybrid Catalyst for the Generation of α-Carbonyl Radicals
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A readily accessible organic-inorganic hybrid catalyst is reported for the reductive fragmentation of α-halocarbonyl compounds. The robust hybrid catalyst is a self-stabilizing combination of ZnCl2 Lewis acid and acridine orange as the photoactive organic dye. Mechanistic specifics of this hybrid catalyst have been studied in detail using both photophysical and electrochemical experiments. A systematic study enabled the discovery of the appropriate Lewis acid for the effective LUMO stabilization of α-halocarbonyl compounds and thereby lowering of reduction potential within the range of a standard organic dye. This strategy resolves the issues like dehalogenative hydrogenation or homo-coupling of alkyl radicals by guiding the photoredox cycle through an oxidative quenching pathway. The cooperativity between the photoactive organic dye and the Lewis acid counterparts empowers functionalization with a wide range of coupling partners through efficient and controlled generation of alkyl radicals and serves as an appropriate alternative to the expensive late transition metal-based photocatalysts. To demonstrate the application potential of this cooperative catalytic system, four different synthetic transformations of α-carbonyl bromides were explored with broad substrate scopes.
- Das, Sanju,Mandal, Tanumoy,De Sarkar, Suman
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supporting information
p. 755 - 765
(2021/12/10)
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- The absolute configuration of 2-bromo-2,3-dihydro-1H-inden-1-ols
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All four possible stereoisomers of cis- and trans-2-bromo-2,3-dihydro-1H-inden-1-ols, which are important intermediates in the synthesis of biologically active compounds, were synthesized and their configurations were studied by enzymatic kinetic resoluti
- Prysiazhnuk, Dmitry V.,Rusanov, Eduard B.,Kolodiazhnyi, Oleg I.
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p. 3023 - 3031
(2021/08/13)
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- A metal-free aerobic oxidative bromination of anilines and aryl ketones with 2-methylpyridinium nitrate as a reusable ionic liquid
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An aerobic oxidative bromination of anilines and aryl ketones catalyzed by recyclable 2-methylpyridinium nitrate ionic liquid is achieved in water using hydrobromic acid as the bromine source and molecular oxygen as the oxidant. The catalytic system shows good efficiency and atom economy.
- Li, Ming-Fang,Wang, Jian,Ke, Yong-Xin,Pan, Song-Cheng,Yin, Hong,Du, Wenting,Li, Jing-Hua
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p. 267 - 270
(2020/01/08)
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- Annulation reaction of cyclic pyridinium ylides with: In situ generated azoalkenes for the construction of spirocyclic skeletons
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Two new types of cyclic pyridinium ylides were designed and further used in reactions with azoalkenes to access structurally diverse spirocyclic compounds. A range of spiropyrazoline oxindoles could be smoothly obtained in up to 99% yield via a [4 + 1] annulation process with oxindole 3-pyridinium ylides as C1 synthons. Similarly, a series of spiropyrazoline indanones could be prepared with indanone 2-pyridinium ylides as C1 synthons. This work represents the first example of cyclic pyridinium ylides as C1 synthons for the efficient construction of spirocyclic compounds.
- Quan, Bao-Xue,Yuan, Wei-Cheng,Zhang, Ming-Liang,Zhang, Xiao-Mei,Zhao, Jian-Qiang,Zhou, Ming-Qiang,Zhuo, Jun-Rui
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supporting information
p. 1886 - 1891
(2020/03/23)
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- Method of utilizing micro channel reactor to prepare pentafluorophenoxyl ketones continuously
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The invention discloses a method of utilizing a micro channel reactor to prepare pentafluorophenoxyl ketones continuously. Cheap and easily available styrene and pentafluorophenol are taken as the primary raw materials, two step continuous reactions are carried out in a micro channel reactor to obtain pentafluorophenoxyl ketones, the reaction time is shortened to several minutes from several hours; the product yield is high, the reaction efficiency is obviously enhanced, no any pricy organic catalyst or metal catalyst is needed, the operation is simple, the cost is low, the preparation technology is easy to control, the safety is high, the reaction conditions are mild, and the method can be applied to industrial production.
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Paragraph 0056-0057
(2019/06/30)
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- A Method for the Catalytic Enantioselective Synthesis of Chiral α-Azido and α-Amino Ketones from Racemic α-Bromo Ketones, and Its Generalization to the Formation of Bonds to C, O, and S
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A new and practical method has been developed for the transformation of racemic α-bromo ketones to chiral α-azido and α-amino ketones with high enantioselectivity using phase transfer, ion-pair mediated reactions with a recoverable chiral quaternary salt (10 mol %) as catalyst in fluorobenzene-water. The process has been generalized to a variety of other attachments including of C, O, S, and NHR.
- Da Silva Gomes, Roberto,Corey
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supporting information
p. 20058 - 20061
(2019/12/27)
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- The Electrophilic Fluorination of Enol Esters Using SelectFluor: A Polar Two-Electron Process
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The reaction of enol esters with SelectFluor is facile and leads to the corresponding α-fluoroketones under mild conditions and, as a result, this route is commonly employed for the synthesis of medicinally important compounds such as fluorinated steroids. However, despite the use of this methodology in synthesis, the mechanism of this reaction and the influence of structure on reactivity are unclear. A rigorous mechanistic study of the fluorination of these substrates is presented, informed primarily by detailed and robust kinetic experiments. The results of this study implicate a polar two-electron process via an oxygen-stabilised carbenium species, rather than a single-electron process involving radical intermediates. The structure–reactivity relationships revealed here will assist synthetic chemists in deploying this type of methodology in the syntheses of α-fluoroketones.
- Wood, Susanna H.,Etridge, Stephen,Kennedy, Alan R.,Percy, Jonathan M.,Nelson, David J.
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supporting information
p. 5574 - 5585
(2019/03/21)
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- Synthesis of α,β-dibromo ketones by photolysis of α-bromo ketones with N-bromosuccinimide: Photoinduced β-bromination of α-bromo ketones
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Irradiation of α-bromopropiophenones in the presence of NBS results in the formation of α,β-dibromopropiophenones, which can be viewed as β-bromination of α-bromopropiophenones. The reaction is believed to go through a series of reactions; photoinduced C–Br bond cleavage, elimination of HBr to give α,β-unsaturated ketone intermediates, and addition of Br2, which are formed by the reaction between HBr and NBS. From mechanistic studies of the reaction, we have also found a very convenient method for α-debromination of the α,β-dibromopropiophenones which is by simple irradiation of the dibromo ketones in acetone or 2-propanol without the use of any additives. Our results demonstrate that bromine can be added into or eliminated from the alpha, beta, or both positions to the carbonyl group by photochemical methods, which make synthetic options of bromine containing carbonyl compounds versatile.
- Moon, Da Yoon,An, Sejin,Park, Bong Ser
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- Synthesis of 2-aminothiazoles from styrene derivatives mediated by 1,3-dibromo-5,5-dimethylhydrantoin (DBH)
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An efficient procedure for the synthesis of 2-aminothiazoles via DBH-mediated oxidative cyclization of styrenes and thioureas is reported. Various alkenes were successfully transformed to the corresponding 2-aminothiazoles in yields of 10–81% via a two-step one-pot manner using DBH as both the bromine source and oxidant. The method can be readily carried out in gram-scale and successfully applied to the synthesis of anti-inflammatory drug fanetizole using styrene as starting material.
- Ma, Chunhua,Miao, Yuqi,Zhao, Minghao,Wu, Ping,Zhou, Jianglu,Li, Zhi,Xie, Xilei,Zhang, Wei
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p. 3602 - 3607
(2018/05/26)
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- Solvent free, light induced 1,2-bromine shift reaction of α-bromo ketones
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Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by C–Br bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.
- An, Sejin,Moon, Da Yoon,Park, Bong Ser
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p. 6922 - 6928
(2018/10/24)
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- A new and versatile one-pot strategy to synthesize alpha-bromoketones from secondary alcohols using ammonium bromide and oxone
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A new, efficient and green protocol for the one-pot synthesis of α-bromoketones from secondary alcohols using cheap, air stable and non-toxic reagents such as NH4Br and oxone has been developed. This reaction proceeds via two consecutive steps such as oxidation of secondary alcohols and oxidative bromination of in situ generated ketones.
- Rammurthy, Banothu,Swamy, Peraka,Naresh, Mameda,Srujana, Kodumuri,Durgaiah, Chevella,Krishna Sai, Gajula,Narender, Nama
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p. 3710 - 3714
(2017/07/12)
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- METHODS OF PREPARING a,?-UNSATURATED OR a-HALO KETONES AND ALDEHYDES
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Copper(II) bromide mediated oxidation of acylated enol and use of the reaction in the synthesis of α,β-unsaturated or α-bromo ketones or aldehydes are disclosed. The method provides an efficient and practical process for manufacturing dehydrohedione (DHH) and many other versatile α,β-unsaturated or α-bromo ketones or aldehydes in large scales to avoid using precious metal compounds.
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Paragraph 0116; 0117; 0130; 0131; 0132; 0133
(2017/07/14)
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- A 2 - amino yin synthetic method
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The invention relates to a synthetic method for indan-2-amine. According to the synthetic method, the target product indan-2-amine is obtained by the following steps: adopting 2-indanone as a raw material, performing substitution reaction on 2-indanone and a halogenated agent to obtain a compound I, performing reduction reaction on the compound I to obtain a compound II, and finally performing amination reaction. Compared with the prior art, the synthetic method provided by the invention has the advantages that the related reactions are simple, the after-treatment is convenient, the raw material is cheap and easy to obtain, the yield is relatively high, and the reaction conditions are mild, thereby being relatively ideal for indan-2-amine preparation.
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Paragraph 0031; 0032; 0033
(2017/08/25)
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- Green synthesis method of bromoaromatic amine and alpha-bromoaromatic ketone
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The invention discloses a green synthesis method of bromoaromatic amine and alpha-bromoaromatic ketone. The synthesis method comprises: adopting hydrobromic acid as a brominating agent, adopting 2-methylpyridine nitrate as a catalyst, and adopting molecular oxygen as an oxidizing agent, brominating an aromatic compound with a structure shown in formula (1) or aromatic ketone with a structure shown in formula (2) or (3), and preparing corresponding bromoaromatic amine or alpha-bromoaromatic ketone. The synthesis method is wide in substrate application reaction, high in atom utilization rate, capable of avoiding the application of the transitional metal element and volatile organic solvent and has the characteristics of economical efficiency and environmental protection. (Shown in the description).
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Paragraph 0026-0029
(2017/07/21)
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- α,β-Unsaturated ketones via copper(II) bromide mediated oxidation
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A protocol for effecting a rapid Saegusa-type oxidation of enol acetates is reported. This new method relies on the in situ elimination of an α-bromo intermediate to generate α,β-unsaturated ketones using copper(II) bromide. The methodology developed was applied to a range of substrates including a cyclohexanone, which could be directly converted to the corresponding phenol derivative. A catalytic system in which a non-masked ketone was successfully oxidised using substoichiometric CuBr2 was also developed as a proof of principle.
- Sharley, James S.,Collado Pérez, Ana María,Ferri, Estela Espinos,Miranda, Amadeo Fernandez,Baxendale, Ian R.
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supporting information
p. 2947 - 2954
(2016/05/19)
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- 1,3-Dibromo-5,5-dimethylhydantoin (DBH) mediated one-pot syntheses of α-bromo/amino ketones from alkenes in water
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α-Bromo ketones are versatile intermediates of high practical utility. Traditional approaches to these compounds are restricted to a relatively hazardous/complex reagent combination, a long reaction time, the use of non-environmentally friendly solvents, or a limited substrate scope. Herein, we describe the development of a new methodology for the preparation of α-bromo ketones from alkenes using 1,3-dibromo-5,5-dimethylhydantoin (DBH) as a bromine source and an oxidant simultaneously. This easy to carry out two-step one-pot protocol proceeds in water and provides high yield of a great variety of α-bromo ketones. Addition of an amine to the intermediate α-bromo ketone further enables the preparation of α-amino ketones in a one-pot sequence.
- Xu, Senhan,Wu, Ping,Zhang, Wei
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p. 11389 - 11395
(2016/12/18)
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- Copper nitrate-catalyzed α -bromination of aryl ketones with hydrobromic acid
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An efficient method for α-bromination of aryl ketones, using the combination of molecular oxygen and aqueous hydrobromic acid as a brominating agent in the presence of the copper nitrate, has been developed. This catalytic system, which uses cheap and readily available reactants, shows good atom economy with water as the only by-product.
- Wang, Jianqiang,Wang, Xiaolei,Niu, Zong-Qiang,Wang, Jian,Zhang, Man,Li, Jing-Hua
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p. 165 - 168
(2016/02/23)
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- Kinetic Resolution Driven Diastereo- and Enantioselective Synthesis of cis-β-Heteroaryl Amino Cycloalkanols by Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation
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The utility of tethered Ru-TsDPEN catalyst has been demonstrated for the asymmetric transfer hydrogenation of rac-α-heteroaryl amino cycloalkanones to construct biologically important cis-β-heteroaryl amino cycloalkanols with two contiguous chiral centers
- Vyas, Vijyesh K.,Bhanage, Bhalchandra M.
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supporting information
p. 6436 - 6439
(2016/12/23)
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- Metal-free protocol for the synthesis of α-bromo ketones from olefins using TsNBr2
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TsNBr2 reacts readily with olefins to produce α-bromo ketones at room temperature. The synthesis was carried out by treating an olefin with TsNBr2 in acetone-water mixture in 30:1 ratio. Excellent yield of corresponding α-bromo ketone could be achieved within a short time.
- Rajbongshi, Kamal Krishna,Hazarika, Debojit,Phukan, Prodeep
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supporting information
p. 356 - 358
(2015/04/27)
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- Highly enantioselective hydrogenation of o-alkoxy tetrasubstituted enamides catalyzed by a Rh/(R, S)-josiphos catalyst
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Rh/(R,S)-JosiPhos complex-catalyzed asymmetric hydrogenation of o-alkoxy tetrasubstituted enamides has been achieved, and it furnished a set of β-amino alcohol analogues in high yields and excellent enantiomeric excesses (>99% conversion, up to 99% ee).This method provides valuable chiral building blocks in chiral pharmaceuticals and useful motifs for catalysts.
- Meng, Jingjing,Gao, Min,Lv, Hui,Zhang, Xumu
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supporting information
p. 1842 - 1845
(2015/04/27)
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- NEW ARYLALKENYLPROPARGYLAMINE DERIVATIVES EXHIBITING NEUROPROTECTIVE ACTION FOR THE TREATMENT OF NEURODEGENERATIVE DISEASES
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The invention relates to novel arylalkenylpropargylamine derivatives of general formula (I) or enantiomers or diastereomers thereof or salts, optionally pharmaceutically acceptable salts, or solvates of any of these. The compounds can be used in treating or preventing a disease or condition in a mammal related to monoamine oxidase dysfunction, especially in neurodegenerative diseases, e.g. Parkinson's disease, Alzheimer's disease or Huntington's disease.
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Page/Page column 57; 58
(2015/06/25)
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- IBX works efficiently under solvent free conditions in ball milling
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IBX (2-iodoxybenzoic acid), discovered in 1893, is an oxidant in synthetic chemistry whose extensive use is impeded by its explosiveness at high temperature and poor solubility in common organic solvents except DMSO. Since the discovery of Dess-Martin Periodinane in 1983, several modified IBX systems have been reported. However, under ball milling conditions, IBX works efficiently with various organic functionalities at ambient temperature under solvent free conditions. Also, the waste IBA (2-iodosobenzoic acid) produced from the reactions was in situ oxidized to IBX in the following step using oxone and thus reused for multiple cycles by conserving its efficiency (only ~6% loss after 15 cycles). This work describes an overview of a highly economical synthetic methodology which overcomes the problems of using IBX, efficiently in gram scale and in a non-explosive way. This journal is the Partner Organisations 2014.
- Achar, Tapas Kumar,Maiti, Saikat,Mal, Prasenjit
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p. 12834 - 12839
(2014/04/03)
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- Synthesis of phenacyl bromides via K2S2O 8-mediated tandem hydroxybromination and oxidation of styrenes in water
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Non-transition metal-catalyzed synthesis of phenacyl bromides was achieved through K2S2O8-mediated tandem hydroxybromination and oxidation of styrenes. The advantages of this reaction are its excellent functional group compatibility, mild reaction conditions (60 °C) and use of pure water as reaction medium. Based upon experimental observations, a plausible reaction mechanism is proposed.
- Jiang, Qing,Sheng, Wenbing,Guo, Cancheng
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p. 2175 - 2179
(2013/09/24)
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- Synthesis and biological evaluation of dihydroindeno and indeno [1,2-e] [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines as antimicrobial agents
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Two series of compounds namely, dihydroindeno and indeno [1,2-e] [1,2,4]triazolo [3,4-b] [1,3,4]thiadizines (9a-l & 11a-l) were synthesized by cyclocondensation between α-bromoindanones (7a-b) or/and α,α-dibromoindanones (8a-b) and various 3-alkyl/aryl-4-
- Prakash, Om,Aneja, Deepak K.,Hussain, Khalid,Lohan, Poonam,Ranjan, Pooja,Arora, Sanjiv,Sharma, Chetan,Aneja, Kamal R.
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experimental part
p. 5065 - 5073
(2011/11/29)
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- Synthesis of quinoxaline analogues
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Substituted tricyclic or tetracyclic quinoxalines, tricyclic pyridoquinoxalines and bis-quinoxalines were synthesized in high yields starting from cyclic ketones by the -bromination of cyclic ketones with N-bromosuccinimide (NBS) followed by condensation of the resulting -bromo ketones with 1,2-diaminobenzene, 3,4-diaminopyridine, or 3,3-diaminobenzidine. Georg Thieme Verlag Stuttgart New York.
- Chang, Meng-Yang,Lee, Tein-Wei,Hsu, Ru-Ting,Yen, Tzu-Lin
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experimental part
p. 3143 - 3151
(2011/10/30)
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- Cyclic trans-β-amino alcohols: Preparation and enzymatic kinetic resolution
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Enantioenriched cyclic β-amino alcohols, trans-2-aminocyclohexanols (ee, >99%), trans-2-aminocyclopentanols (ee, >99%), trans-1-amino-2- indanols (ee, >99%) and trans-2-amino-1-indanols (ee, ~98%) were prepared in high yields via an Arthrobacter sp. Lipase/PLAP catalyzed kinetic resolution of racemic phthalimido acetates. The addition of toluene as a co-solvent dramatically improved the hydrolysis and enantioselectivity, whereas for indanols, substrate immobilization on Celite improved the efficacy of the kinetic resolution.
- Rouf, Abdul,Gupta, Pankaj,Aga, Mushtaq A.,Kumar, Brijesh,Parshad, Rajinder,Taneja, Subhash C.
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scheme or table
p. 2134 - 2143
(2012/05/04)
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- Facile one-pot synthesis of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent
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A new method for the preparation of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent has been developed. Several α-bromoketones were successfully prepared from a variety of olefins by this method. This procedure is an alternative to conventional molecular bromine.
- Patil, Rajendra D.,Joshi, Girdhar,Adimurthy, Subbarayappa,Ranu, Brindaban C.
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experimental part
p. 2529 - 2532
(2009/09/06)
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- Synthesis of phosphonate derivatives of 2,3-dihydroindene
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Simple and convenient procedures for the synthesis of derivatives of 2,3-dihydroinden-2-ylphosphonic acid are developed. The reaction strategies utilize both functionalization of the already existing 2,3-dihydroindene skeleton and an annulation reaction starting from readily available o-disubstituted benzene derivatives.
- Prokopowicz, Monika,M?ynarz, Piotr,Kafarski, Pawe?
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experimental part
p. 7314 - 7317
(2010/02/28)
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- An expedient protocol for conversion of olefins to α-bromo/iodoketones using IBX and NBS/NIS
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A variety of olefins have been shown to undergo conversion to the corresponding α-bromo/iodoketones when reacted with NBS/NIS and IBX in DMSO at room temperature. While the reaction is found to occur rapidly with e-rich arylolefins leading to the corresponding haloketones in 65-95% yields in 0.3-3.0 h, those containing e-withdrawing groups are found to yield diketones concomitantly, such that the latter are the exclusive products over extended duration of the reactions.
- Moorthy, Jarugu Narasimha,Senapati, Kalyan,Singhal, Nidhi
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experimental part
p. 2493 - 2496
(2009/08/17)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- Thioglycoluril as a novel organocatalyst: Rapid and efficient α-monobromination of 1,3-dicarbonyl compounds
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Thioglycoluril as a novel hydrogen-bonding organocatalyst, combined with NBS, in MeOH provided rapid and efficient α-monobromination of 1,3-dicarbonyl compounds in excellent yields at room temperature. A bifunctional catalytic mechanism was proposed from
- Cao, Liping,Ding, Jiaoyang,Yin, Guodong,Gao, Meng,Li, Yitao,Wu, Anxin
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scheme or table
p. 1445 - 1448
(2009/10/10)
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- Synthesis and bioactivity of substituted indan-1-ylideneaminoguanidine derivatives
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In our efforts to discover more potent and lasting NHE1 inhibitors, we designed and synthesized a series of substituted indan-1-ylidene aminoguanidine derivatives (5). NHE1 inhibitory activity of twenty-one compounds 5 was evaluated in a rat platelet swelling assay. It is found that most of the tested compounds possess NHE1 inhibitory effects. 2-(5-methoxybenzimidazol-2-ylthio)-5-chloro-2,3-dihydroinden-1-ylidene aminoguanidine hydrobromide (5m) proved to be sixty-nine times more potent than cariporide. Furthermore, when tested in vivo, compound 5m also displayed superior cardioprotective effects against SD rat myocardial ischemic-reperfusion injury over those of cariporide.
- Zhang, Rui,Dong, Jin,Xu, Yun-gen,Hua, Wei-yi,Wen, Na,You, Qi-dong
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experimental part
p. 3771 - 3776
(2009/12/04)
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- Halogenation of ketones with N-halosuccinimides under solvent-free reaction conditions
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Several aryl substituted ketones, cyclic ketones, 1,3-diketones and a β-ketoamide were halogenated with N-halosuccinimides under solvent-free reaction conditions (SFRC) at various temperatures (20-80 °C), whereas less enolized ketones required the presence of an acid catalyst (p-toluenesulfonic acid, PTSA). Bromination of substituted acetophenones obeys first order kinetics v=kBr[ketone] and the following correlation with the keto-enol equilibrium constant: log kBr=0.3pKE+C1, less enolized substrates being more reactive; the moderate positive charge developed in the rate determining step was confirmed by the Hammett correlation (ρ=-0.5). On the other hand, in cyclic ketones an opposite relation was observed: log kBr=-0.6pKE+C2, indicating higher reactivity of substrates with higher enolization constant (KE). The important role of the nature of the solvent (MeCN, MeOH) in preorganization of the ketone-NBS-PTSA mixture prior to SFRC bromination was found.
- Pravst, Igor,Zupan, Marko,Stavber, Stojan
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p. 5191 - 5199
(2008/09/21)
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- Simple and regioselective bromination of 5,6-disubstituted-indan-1-ones with Br2 under acidic and basic conditions
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Bromination of 5,6-dimethoxyindan-1-one with Br2 in acetic acid at room temperature produced exclusively the corresponding 2,4-dibromo compound in 95% yield. Reaction of 5,6-dimethoxyindan-1-one with Br2 in the presence of KOH, K2CO3 or Cs2CO3 at ~0°C gave the monobrominated product 4-bromo-5,6-dimethoxyindan-3-one in 79%, 81% and 67% yield, respectively. 5,6-Dihydroxyindan-1-one was dibrominated on the aromatic ring affording 4,7-dibromo-5,6-dihydroxyindan-1-one both in acetic acid at room temperature and in the presence of KOH at ~0° C. 5,6-Difluoroindan-1-one and 1-indanone were α-monobrominated in acetic acid and α,aα-dibrominated under KOH conditions at room temperature.
- Choi, Taeyoung,Ma, Eunsook
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- Functionalisation of indene
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Dibromo- and tribromoindane were synthesised by bromination of indene. Treatment of dibromo- and tribromoindane with various silver salts (silver acetate, perchlorate, sulfate and nitrate) in different solvents opened up an entry to the synthesis of various di- and tri-substituted indane derivatives.
- Tutar, Ahmet,Cakmak, Osman,Balci, Metin
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p. 507 - 511
(2007/10/03)
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- A green approach for efficient α-halogenation of β-dicarbonyl compounds and cyclic ketones using N-halosuccinimides in ionic liquids
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Room temperature ionic liquids (ILs) are used as a green recyclable reaction media for the α-monohalogenation of 1,3-diketones, β-keto-esters and cyclic ketones with N-halosuccinimides in excellent yields in the absence of a catalyst. The recovered ionic liquid was reused five to six times with consistent activity.
- Meshram,Reddy,Vishnu,Sadashiv,Yadav
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p. 991 - 995
(2007/10/03)
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- Synthesis and evaluation of heteroaryl-substituted dihydronaphthalenes and indenes: Potent and selective inhibitors of aldosterone synthase (CYP11B2) for the treatment of congestive heart failure and myocardial fibrosis
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In this study, the synthesis and biological evaluation of heteroaryl-substituted dihydronaphthalenes and indenes (1-16) is described. The compounds were tested for activity by use of human CYP11B2 expressed in fission yeast and V79 MZh cells and for selectivity by use of human CYP11B1, CYP17, and CYP19. The most active inhibitor was the 6-methoxydihydronaphthalene 4 (IC 50 = 2 nM), showing a Ki value of 1.3 nM and a competitive type of inhibition. The 5-methoxyindene 3 was found to be the most selective CYP11B2 inhibitor (IC50 = 4 nM; CYP11B1 IC50 = 5684 nM), which also showed only marginal inhibition of human CYP3A4 and CYP2D6. Docking and molecular dynamics studies using our homology-modeled CYP11B2 structure were performed to understand some structure-activity relationships. Caco-2 cell experiments revealed highly cell-permeable compounds, and metabolic studies with 4 using rat liver microsomes showed sufficient stability.
- Voets, Marieke,Antes, Iris,Scherer, Christiane,Müller-Vieira, Ursula,Biemel, Klaus,Marchais-Oberwinkler, Sandrine,Hartmann, Rolf W.
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p. 2222 - 2231
(2007/10/03)
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- Directed regioselectivity of bromination of ketones with NBS: solvent-free conditions versus water
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The reaction conditions employed directed the site of functionalisation of ketones with NBS: under solvent-free conditions α-bromination was the exclusive process, while in water, ring functionalisation occurred in the case of methoxy substituted aromatic ketones.
- Pravst, Igor,Zupan, Marko,Stavber, Stojan
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p. 4707 - 4710
(2007/10/03)
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- A new amino-masking group capable of pH-triggered amino-drug release
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The prodrug approach is potentially useful for mitigating pharmaceutical problems - such as poor membrane permeability or stability - which commonly occur with amino drugs. On the other hand there persists a dearth of useful systems for masking amines tha
- Gilmer, John F.,Simplicio, Ana Luisa,Clancy, John M.
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p. 315 - 323
(2007/10/03)
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- Efficient microwave induced direct α-halogenation of carbonyl compounds
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A novel and direct method for the synthesis of α-halocarbonyl compounds using sequential treatment of carbonyl compounds with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation conditions is described.
- Lee, Jong Chan,Park, Jin Young,Yoon, So Young,Bae, Yong Hun,Lee, Seung Jun
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p. 191 - 193
(2007/10/03)
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- Studies on bromination of active methylene by a mixture of hydrobromic acid and hydrogen peroxide (or TBHP)
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Studies on bromination of active methylene with a mixture of hydrogen peroxide or tert-butylhydroperoxide (TBHP) and hydrobromic acid are discussed. Substituted acetophenones, benzocyclic ketones provide α-bromo-keto compounds in high yields under this re
- Tillu, Vasudha H.,Shinde, Popat D.,Bedekar, Ashutosh V.,Wakharkar, Radhika D.
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p. 1399 - 1403
(2007/10/03)
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- Radical chain reactions of α-azido ketones with tributyltin hydride: Reduction vs nitrogen insertion and 1,2-hydrogen shift in the intermediate N-stannylaminyl radicals
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The radical chain reactions of a variety of acyclic and cyclic α-azido ketones with tributyltin hydride have been investigated. The derived N-(tributylstannyl)aminyl radicals normally undergo H-abstraction reaction yielding corresponding amines, and thence symmetrical pyrazines by subsequent self-condensation, in competition with 1,2-H-migration from the α-carbon to nitrogen leading to α-imino ketone decomposition products with loss of the chain-carrying tributyltin radical. The noteworthy occurrence of a quite uncommon radical 1,2-hydrogen-atom shift is considered to be largely due to consequent formation of a highly stable, captodative carbon-centred radical. In contrast with our previous N-stannylaminyl radicals produced from α-azido-β-keto esters, the present aminyl congeners give poor amounts (or even none) of nitrogen-inserted amides/lactams, which are envisaged to arise from intramolecular three-membered cyclisation onto the ketone moiety followed by β-scission of the resultant alkoxyl radical. It is inferred that adequate stabilisation of the eventual ring-opened carbon radical be a major factor for the successful outcome of the regiospecific nitrogen insertion process. Evidence is also presented that chemoselective attack of tris(trimethylsilyl)silyl radical to the ketone oxygen of an α-azido ketone gives rise to deazidation as a likely consequence of β-elimination of azidyl radical by the ensuing α-silyloxyalkyl radical. X-Ray crystal structure analyses of the bromo ketone 5a, the azido ketone 5b, the caprolactam 22, and the pyrazine 26 have been performed.
- Benati, Luisa,Leardini, Rino,Minozzi, Matteo,Nanni, Daniele,Spagnolo, Piero,Strazzari, Samantha,Zanardi, Giuseppe,Calestani, Gianluca
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p. 3485 - 3492
(2007/10/03)
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- Improvement in the selectivity and metabolic stability of the serotonin 5-HT1A ligand, S 15535: A series of cis- and trans-2-(arylcycloalkylamine) 1-indanols
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S 15535 (1) displays a distinctive profile of agonist and antagonist (weak partial agonist) activity at pre- and postsynaptic 5-HT1A receptors, respectively. It has proven to be active in several models predictive of anxiolytic, antidepressant,
- Peglion,Goument,Despaux,Charlot,Giraud,Nisole,Newman-Tancredi,Dekeyne,Bertrand,Genissel,Millan
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p. 165 - 176
(2007/10/03)
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- A comparative study on the inhibition of human and bacterial kynureninase by novel bicyclic kynurenine analogues
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A series of novel bicyclic analogues of kynurenine were synthesised as inhibitors of kynureninase. The trytophan-induced bacterial enzyme from Pseudomonas fluorescens were compared to the constitutive recombinant human enzyme expressed in a baculovirus/insect cell system, with regard to their inhibition by these compounds. All the compounds studied were found to be simple competitive, reversible inhibitors of kynureninase. It was found that altering the size of the second ring of the inhibitor affected the observed Ki values for both enzymes. The addition of an oxygen atom into the second ring had little effect on binding to the bacterial enzyme but gave a more potent inhibitor of human kynureninase. Of the compounds tested, a naphthyl analogue of desaminokynurenine was found to be the most potent inhibitor for both enzymes with Ki values of 5 and 22 μM for bacterial and human enzyme respectively. This report also describes an alternative system for the expression of recombinant human kynureninase which is more convenient for expression in mammalian cells and produces a relatively greater quantity of enzyme. Copyright
- Fitzgerald, Deirdre H.,Muirhead, Karen M.,Botting, Nigel P.
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p. 983 - 989
(2007/10/03)
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- An efficient preparative route to fused imidazo[1,2-a]pyrazin-4-one derivatives
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New fused imidazo[1,2-a]pyrazin-4-one derivatives (1a-f) are easily obtained from ring closure reactions of ethyl imidazole-2-carboxylate derivatives (4a, c, d) or imidazole-2-carboxamide derivatives (5b, e).
- Damour, Dominique,Aloup, Jean-Claude,Barreau, Michel,Genevois-Borella, Arielle,Jimonet, Patrick,Leconte, Jean-Pierre,Ribeill, Yves,Vuilhorgne, Marc,Mignani, Serge
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p. 259 - 267
(2007/10/03)
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- 5-HT3 receptor agonist, novel thiazole derivative and intermediate thereof
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A 5-HT3 receptor against containing a thiazole derivative as the effective ingredient is provided and is represented by the Formula (I): STR1 wherein the A ring is substituted or unsubstituted and represents a benzene or a heterocyclic ring with one or two heteroatoms; one of L1 or L2 represents a single bond and the other is non-existent or represents an alkylene or alkenylene group; R represents: STR2
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- 3-(Trifluoromethyl)indenyl Cation: Ion Pair Return in the Formation of an Antiaromatic and Electron-Deficient Doubly Destabilized Carbocation
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The solvolysis of 3-(trifluoromethyl)-3-indenyl tosylate (15) occurs with extensive isomerization to 1-(trifluoromethyl)-3-indenyl tosylate (16), which reacts in a slower process to give the substitution product 17. Kinetic analysis of a model involving an intermediate allyl cation/tosylate ion pair 18 gave a partitioning ratio in CD3CO2D at 99.6°C for 18 of 7.7 for return with allylic rearrangement compared with solvent capture. Studies of 15 with specific 18O labeling show no scrambling in recovered 15 and partial scrambling in rearrangement to 16. The m value measuring the dependence of the reactivity of 15 on the solvent-ionizing parameter YOTs is 0.78, which is significantly less than that of 1.23 for the analogous 9-(trifluoromethyl)-9-fluorenyl tosylate 7. Normal salt effects in CF3CO2H predominate for 15, and the special salt effect involves no more than 14% capture of solvent-separated ion pairs by 0.551 M KO2CCF3. The substrate 15 has a net diminution in reactivity of more than 109 relative to the secondary indanyl tosylate 22, with factors of 106 and 103 attributable to antiaromaticity and to the electron-withdrawing CF3 group, respectively. The solvolysis of 15 is proposed to occur by formation of an ion pair with significant nucleophilic solvation at the relatively unhindered allylic carbon, but internal return occurs in preference to solvent or salt capture. Solvolysis of the rearranged tosylate 16 occurs with a strong rate retardation by the γ-CF3 group, a large extent of internal return, and with a normal salt effect.
- Allen, Annette D.,Fujio, Mizue,Mohammed, Nageib,Tidwell, Thomas T.,Tsuji, Yutaka
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p. 246 - 252
(2007/10/03)
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- Novel cyclopenta-1,3-dithioles
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Reactions of 2-chloro-cyclopentanone (4) with alkali dithiocarbamates followed by treatment with perchloric acid yields the cyclic 1,3-dithiole-2-dialkyliminium perchlorates 6. By sulfhydrolysis of 6 the 1,3-dithiole-2-thione 8 is obtained, by desulfuriza
- Hartke,Timpe
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p. 117 - 121
(2007/10/02)
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