- A green chemical approach for the N-alkylation of aldoximes to form nitrones in organized aqueous media and their in situ cycloaddition with olefins
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Aldoximes react with α,β-unsaturated carbonyl and sulfonyl compounds in organized aqueous media (nanoreactor system) using dodecylbenzenesulfonic acid (DBSA) as surfactant to generate N-alkylated nitrones, which undergo intermolecular cycloaddition in the same pot with maleimides to give the desired cycloadduct in absence of any organic solvent and catalyst. Divinyl sulfone was successfully used for both N-alkylation and intramolecular cycloaddition, affording only one cycloadduct. This is a new example of green chemistry and provides a new aspect of reactions in water.
- Hota, Sandip K.,Chatterjee, Amrita,Bhattacharya, Pranab K.,Chattopadhyay, Partha
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- 7-Oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-Dioxides: Mechanochemical Synthesis by Tandem Michael Addition–1,3-Dipolar Cycloaddition of Aldoximes and Evaluation of Antibacterial Activities
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A solvent-free, green, and efficient mechanochemical method for the synthesis of a series of bridged bicyclo aza-sulfone derivatives, namely 7-oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-dioxides through tandem Michael addition–1,3-dipolar cycloaddition of aldoximes was developed. Mechanochemical grinding/milling facilitates quick formation of aldoximes from corresponding aldehydes and hydroxylamine, which upon reaction with divinyl sulfone in a mixer mill affords 7-oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-dioxide derivatives in good overall yields. The newly synthesized bicyclo aza-sulfone derivatives 4 were screened for antibacterial activities. Mostly bicyclo aza-sulfones derived from electron-rich aromatic aldehydes inhibit the growth of Mycobacterium smegmatis (mc2155) and those from aliphatic aldehydes the growth of Escherichia coli (DH5α) in moderate to good effect. However, butyraldehyde-derived compound 4r was very effective against both M. smegmatis and E. coli. The key advantages of this mechanochemical method are catalyst- and solvent-free conditions, shorter reaction time, and formation of a new series of 7-oxa-4-thia-1-aza-bicyclo[3.2.1]octane 4,4-dioxide derivatives, which are good antibacterial agents against M. smegmatis and E. coli.
- Bhutia, Zigmee T.,Das, Avijit,Biswas, Malabika,Chatterjee, Amrita,Banerjee, Mainak
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- Site-specific catalytic activities to facilitate solvent-free aerobic oxidation of cyclohexylamine to cyclohexanone oxime over highly efficient Nb-modified SBA-15 catalysts
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The development of highly active and selective heterogeneous catalysts for efficient oxidation of cyclohexylamine to cyclohexanone oxime is a challenge associated with the highly sensitive nitrogen center of cyclohexylamine. In this work, dispersed Nb oxide supported on SBA-15 catalysts are disclosed to efficiently catalyze the selective oxidation of cyclohexylamine with high conversion (>75%) and selectivity (>84%) to cyclohexanone oxime by O2without any addition of solvent (TOF = 469.8 h?1, based on the molar amount of Nb sites). The role of the active-site structure identity in dictating the site-specific catalytic activities is probed with the help of different reaction and control conditions and multiple spectroscopy methods. Complementary to the experimental results, further poisoning tests (with KSCN or dehydroxylation reagents) and DFT computational studies clearly unveil that the surface exposed active centers toward activation of the reactants are quite different: the surface -OH groups can catch the NH2group from cyclohexylamine by forming a hydrogen bond and lead to a more facile cyclohexylamine oxidation to desired products, while the monomeric or oligomeric Nb sites with a highly distorted structure play a key role in the dissociation of O2molecules beneficial for insertion of active oxygen species into cyclohexylamine. These catalysts exhibit not only satisfactory recyclability for cyclohexylamine oxidation but also efficiently catalyze the aerobic oxidation of a wide range of amines under solvent-free conditions.
- Ding, Wei,Mao, Liqiu,Peng, Haoyu,Yin, Dulin,Zhong, Wenzhou
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p. 3409 - 3422
(2020/06/09)
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- Efficient synthesis of 1,2,4-oxadiazine-5-ones via [3+3] cycloaddition of in situ generated aza-oxyallylic cations with nitrile oxides
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1,2,4-Oxadiazin-5-ones were prepared via [3+3] cycloaddition of in situ generated aza-oxyallylic cations with nitrile oxides in good yields and excellent functional group compatibility. This efficient transformation is metal-free and is promoted by an inorganic base Cs2CO3. In addition, this reaction features simple-operation, mild conditions, and high regioselectivity.
- Wang, Gangqiang,Chen, Rongxing,Zhao, Sen,Yang, Liangfeng,Guo, Haibing,Sun, Shaofa,Wang, Jian,Domena, Justin,Xing, Yalan
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supporting information
p. 2018 - 2020
(2018/04/25)
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- An Efficient One–pot Procedure for the Direct Preparation of 4,5-Dihydroisoxazoles from Amides
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A Mo(CO)6 (molybdenumhexacarbonyl) catalyzed reductive functionalization of amides to afford 5-amino substituted 4,5-dihydroisoxazoles is presented. The reduction of amides generates reactive enamines, which upon the addition of hydroximinoyl chlorides and base undergoes a 1,3-dipolar cycloaddition reaction that gives access to the desired heterocyclic compounds. The transformation of amides is highly chemoselective and tolerates functional groups such as nitro, nitriles, esters, and ketones. Furthermore, a versatile scope of 4,5-dihydroisoxazoles derived from a variety of hydroximinoyl chlorides and amides is demonstrated. (Figure presented.).
- Slagbrand, Tove,Kervefors, Gabriella,Tinnis, Fredrik,Adolfsson, Hans
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supporting information
p. 1990 - 1995
(2017/06/09)
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- Iron-catalyzed synthesis of benzoxazoles by oxidative coupling/cyclization of phenol derivatives with benzoyl aldehyde oximes
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An iron-catalyzed oxidative coupling/cyclization reaction for the synthesis of benzoxazoles at room temperature is reported. This reaction was enabled by an inexpensive iron(iii) catalyst by treating readily available phenol derivatives with benzoyl aldehyde oximes. Mechanistic studies show that benzoyl aldehyde oxime is not only used as a substrate, but also serves as an ancillary ligand to support the iron salt in the promotion of the transformation.
- Gao, Sen,Gao, Liming,Meng, Hong,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 9886 - 9889
(2017/09/11)
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- Water-Assisted Nitrile Oxide Cycloadditions: Synthesis of Isoxazoles and Stereoselective Syntheses of Isoxazolines and 1,2,4-Oxadiazoles
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Conventional methods generate nitrile oxides from oxime halides in organic solvents under basic conditions. However, the present work revealed that water-assisted generation of nitrile oxides proceeds under mild acidic conditions (pH 4-5). Cycloadditions of nitrile oxides with alkynes and alkenes easily occurred in water without using catalysts, thus yielding isoxazoles and isoxazolines, respectively, with excellent stereoselectivity toward five- and six-membered cyclic alkenes. A double stereoselective cycloaddition of two units of a nitrile oxide with cyclohexene was also achieved, thus yielding 1,2,4-oxadiazole derivatives having a unique hybrid isoxazoline-oxadiazole skeleton. Enantiomerically pure isoxazolines were prepared from monoterpenes with a ring strain. In one case, the isoxazoline with a butterfly-like structure was simply prepared, and it might be used as a ligand in asymmetric catalysis.
- Kesornpun, Chatchai,Aree, Thammarat,Mahidol, Chulabhorn,Ruchirawat, Somsak,Kittakoop, Prasat
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supporting information
p. 3997 - 4001
(2016/03/19)
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- M-CPBA mediated metal free, rapid oxidation of aliphatic amines to oximes
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An efficient, rapid oxidation of various aliphatic amines to oximes using m-CPBA as an oxidant in ethyl acetate is described. High conversion (100%) with >90% oxime selectivity is achieved at room temperature under catalyst-free conditions. Mild reaction conditions along with an easy work up procedure offer lower byproduct formation and high selectivity for oximes in good yield and purity.
- Patil, Vilas V.,Gayakwad, Eknath M.,Shankarling, Ganapati S.
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p. 781 - 786
(2016/02/18)
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- Rhodium(II)-Catalyzed Formal [3 + 2] Cycloaddition of N-Sulfonyl-1,2,3-triazoles with Isoxazoles: Entry to Polysubstituted 3-Aminopyrroles
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A novel rhodium(II)-catalyzed formal [3 + 2] cycloaddition of N-sulfonyl-1,2,3-triazoles with isoxazoles has been achieved that provides an efficient method for the synthesis of polysubstituted 3-aminopyrrole derivatives. An operationally simple one-pot synthesis of the titled compounds from terminal alkynes, tosyl azide, and isoxazoles was also developed. The presented reaction affords an illustrative example of employing 1,2,3-triazoles as the [2C]-component in relevant cycloaddition reactions.
- Lei, Xiaoqiang,Li, Longbo,He, Yu-Peng,Tang, Yefeng
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supporting information
p. 5224 - 5227
(2015/11/18)
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- Highly efficient and stable peracid for rapid and selective oxidation of aliphatic amines to oximes
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A novel, transition-metal free, rapid approach for selective oxidation of aliphatic and benzylic amines to oximes is described. The dodecanebis(peroxoic acid)-DMF combination efficiently oxidizes various aliphatic amines at 50 °C temperature to give 100% conversion in 20 min with high oxime selectivity. The peroxy acid used here shows exceptional stability at room temperature and is non-shock sensitive in nature, which was confirmed by differential scanning colorimetric (DSC) analysis.
- Patil, Vilas V.,Gayakwad, Eknath M.,Shankarling, Ganapati S.
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p. 6677 - 6682
(2015/08/06)
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- Dual nature of polyethylene glycol under microwave irradiation for the clean synthesis of oximes
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Polyethylene glycol (PEG-400 and PEG-600) is an efficient, inexpensive, and recyclable homogeneous medium and catalyst (dual nature) for the clean synthesis of oximes (and aldoximes) under microwave irradiation in the absence of acid and base catalysts. Both aliphatic and aromatic aldehydes/ketones give satisfactory results under microwave irradiation within a short time. Graphical abstract: [Figure not available: see fulltext.]
- Dutta, Papia,Dutta, Arup Kumar,Sarma, Parishmita,Borah, Ruli
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p. 505 - 508
(2014/03/21)
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- Hypervalent iodine catalyzed generation of nitrile oxides from oximes and their cycloaddition with alkenes or alkynes
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Hypervalent iodine catalyzed oxidation of aldoximes using oxone as a terminal oxidant generates nitrile oxides, which react with alkenes and alkynes to give the corresponding isoxazolines and isoxazoles in moderate to good yields. This reaction involves active hypervalent iodine species formed in situ from catalytic iodoarene and oxone in the presence of hexafluoroisopropanol in aqueous methanol solution.
- Yoshimura, Akira,Middleton, Kyle R.,Todora, Anthony D.,Kastern, Brent J.,Koski, Steven R.,Maskaev, Andrey V.,Zhdankin, Viktor V.
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supporting information
p. 4010 - 4013
(2013/09/02)
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- Synthesis and reactivity of trifluoromethyl substituted oxaziridines This paper is dedicated to the memory of Professor Ludovico Ronzini for its precious contribution to the organic chemistry teaching
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This article reports a simple and efficient synthesis of methyl(trifluoromethyl)oxaziridines, a new family of organic oxidizing agents. A detailed study on their oxygen transfer capability with respect to styrene, thioanisole and benzyl alcohol as model substrates for the synthesis of epoxides, sulfoxides and aldehydes is described. Moreover, an oxaziridine auto-oxidation at nitrogen and/or N-benzylic carbon is also reported.
- Perrone, Serena,Rosato, Francesca,Salomone, Antonio,Troisi, Luigino
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p. 3878 - 3884
(2013/06/27)
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- Enhanced reduction of C-N multiple bonds using sodium borohydride and an amorphous nickel catalyst
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Amorphous nickel powder (Ni0) was utilised as a catalyst under mild, aqueous, basic conditions for enhancing the sodium borohydride-mediated reduction of C-N multiple bonds such as oximes, imines, hydrazones and nitriles to produce the corresponding amines in good to excellent yields.
- Liu, Shouxin,Yang, Yihua,Zhen, Xiaoli,Li, Junzhang,He, Huimin,Feng, Juan,Whiting, Andrew
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experimental part
p. 663 - 670
(2012/01/15)
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- Highly regioselective nitrile oxide dipolar cycloadditions with ortho-nitrophenyl alkynes
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The dipolar cycloadditions of ortho-nitrophenyl alkynes with aryl nitrile oxides has been demonstrated. A range of substituents are tolerated on the alkyne. These reactions proceed with excellent levels of regioselectivity. Subsequent functionalization of the isoxazole scaffold has been demonstrated.
- McIntosh, Melissa L.,Naffziger, Michael R.,Ashburn, Bradley O.,Carter, Rich G.,Zakharov, Lev N.
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supporting information
p. 9204 - 9213,10
(2012/12/12)
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- An efficient catalytic method for the Beckmann rearrangement of ketoximes to amides and aldoximes to nitriles mediated by propylphosphonic anhydride (T3P)
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An efficient method for the Beckmann rearrangement of ketoximes to amides mediated by a catalytic amount (15 mol %) of propylphosphonic anhydride (T3P) is described. Aldoximes underwent second order Beckmann rearrangement to provide the corresponding nitriles in excellent yields on reacting with T3P (15 mol %) at room temperature. The main advantages of this environmentally friendly protocol include procedural simplicity, and particularly ease of isolation of the products.
- Augustine, John Kallikat,Kumar, Rajesha,Bombrun, Agnes,Mandal, Ashis Baran
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experimental part
p. 1074 - 1077
(2011/03/22)
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- Discovery, synthesis, and biological evaluation of a novel group of selective inhibitors of filoviral entry
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Herein, we report the development of an antifiloviral screening system, based on a pseudotyping strategy, and its application in the discovery of a novel group of small molecules that selectively inhibit the Ebola and Marburg glycoprotein (GP)-mediated infection of human cells. Using Ebola Zaire GP-pseudotyped HIV particles bearing a luciferase reporter gene and 293T cells, a library of 237 small molecules was screened for inhibition of GP-mediated viral entry. From this assay, lead compound 8a was identified as a selective inhibitor of filoviral entry with an IC50 of 30 μM. To analyze functional group requirements for efficacy, a structure-activity relationship analysis of this 3,5-disubstituted isoxazole was then conducted with 56 isoxazole and triazole derivatives prepared using "click" chemistry. This study revealed that while the isoxazole ring can be replaced by a triazole system, the 5-(diethylamino)acetamido substituent found in 8a is required for inhibition of viral-cell entry. Variation of the 3-aryl substituent provided a number of more potent antiviral agents with IC50 values ranging to 2.5 μM. Lead compound 8a and three of its derivatives were also found to block the Marburg glycoprotein (GP)-mediated infection of human cells.
- Yermolina, Maria V.,Wang, Jizhen,Caffrey, Michael,Rong, Lijun L.,Wardrop, Duncan J.
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experimental part
p. 765 - 781
(2011/04/15)
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- Mechanistic studies into metal-catalyzed aldoxime to amide rearrangements
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The metal-catalyzed rearrangement of aldoximes into primary amides is a completely atom economical synthetic method for the preparation of one of the most important functional groups in chemistry. There have been several reports of various metals successfully catalyzing this reaction, however, there are conflicting views as to the mechanism involved. Herein we report new experimental evidence to support the mechanism and whether this is universal to all catalysts reported or metal specific. We also describe our further studies into the mechanism of the nickel-catalyzed acylation of amines with aldoximes. Copyright
- Allen, C. Liana,Lawrence, Ruth,Emmett, Liam,Williams, Jonathan M. J.
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supporting information; experimental part
p. 3262 - 3268
(2012/01/19)
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- Transformation of amines to oximes using heterogeneous nanocrystalline titanium(IV) oxide as a green catalyst
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The oxidation of amines into corresponding oximes has been described using heterogeneous nanocrystalline titanium(IV) oxide as catalyst and H 2O2 as oxidizing agent in quantitative yields. Both aromatics and aliphatic amines undergo oxidation. Besides this, nanocrystalline TiO2 was recovered and used for further reactions. Hence our present protocol is economical and clean and uses green reagent, solvent, and catalyst. Taylor & Francis Group, LLC.
- Kidwai, Mazaahir,Bhardwaj, Saurav
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experimental part
p. 2655 - 2662
(2011/08/05)
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- ISOXAZOLE-PYRIDINE DERIVATIVES AS GABA MODULATORS
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The present invention is concerned with novel isoxazole derivatives of formula (I) wherein X, R1, R2, R3 and R4 are as described herein, as well as pharmaceutically acceptable salts and esters thereof. The active compounds of the present invention have affinity and selectivity for GABA A α5 receptor. Further the present invention is concerned with the manufacture of the active compounds of formula (I), pharmaceutical compositions containing them and their use as medicaments.
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Page/Page column 25
(2010/11/18)
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- Synthesis of 5-isoxazol-5-yl-2′-deoxyuridines exhibiting antiviral activity against HSV and several RNA viruses
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This paper describes a simple method for synthesizing a small library of 5-isoxazol-5-yl-2′-deoxyuridines from 5-iodo-2′-deoxyuridine. Nitrile oxides were generated in situ from oximes using a commercial bleaching agent; their cycloaddition with 5-ethynyl-2′-deoxyuridine yielded isoxazoles possessing activity against herpes simplex viruses 1 and 2, Encephalomyocarditis virus, Coxsackie B3, and vesicular stomatitis virus; these isoxazoles were, however, inactive against corona virus, influenza virus, and HIV.
- Lee, Yoon-Suk,Park, Sun Min,Kim, Byeang Hyean
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scheme or table
p. 1126 - 1128
(2009/08/07)
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- Biologically active hydroxymoyl chlorides as antifungal agents
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Several oximes and oxime ethers have been developed as antimicrobial agents. A series of chlorooximes (hydroximoyl chlorides) have been synthesized and tested for antifungal activity under in-vitro conditions against Candida albicans, Candida parapsilosis, Candida glabrata, Candida krusei, Aspergillus fumigatus, Aspergilhis flaviis and Aspergillus niger. The derived antifungal activity has been compared with the corresponding oximes. The results show that most of the chlorooximes exhibit potent antifungal activity with anti-isomers showing better activity. It is observed that most of the chlorooximes show interesting antifungal activity (MICs ≤ 32 μg/mL) compared to oximes. Compound 3q (2,3-dimethoxy phenyl hydroxymoyl chloride) is the most active compound. This compound is active against all the Candida species (MIC 0.5 μg/mL) as well as filamentous fungi with MIC range of 2-4 μg/mL. This series of compounds are fungicidal in nature as evident from the MFC results.
- Ismail, Tabasum,Shafi, Syed,Singh, Parvinder Pal,Qazi, Naveed Ahmed,Sawant, Sanghapal D.,Ali, Intzar,Khan, Inshad Ali,Kumar,Qazi, Ghulam Nabi,Alam, M. Sarwar
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p. 740 - 747
(2008/12/20)
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- Ramoplanin derivatives possessing antibacterial activity
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Novel ramoplanin derivatives are disclosed. These ramoplanin derivatives exhibit antibacterial activity. As the compounds of the subject invention exhibit potent activities against gram positive bacteria, they are useful antimicrobial agents. Methods of synthesis and of use of the compounds are also disclosed.
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Page/Page column 39; 50
(2010/11/23)
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- ZnO/CH3COCl: A new and highly efficient catalyst for dehydration of aldoximes into nitriles under solvent-free condition
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A rapid and efficient synthesis of nitriles via dehydration from the corresponding aldoximes has been carried out in the presence of ZnO/CH 3COCl as catalyst under solvent free conditions in 83-95% yields. The zinc oxide (ZnO) powder can be re-used upto three times after simple washing with CH2Cl2.
- Sarvari, Mona Hosseini
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p. 787 - 790
(2007/10/03)
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- Oxidation of Aliphatic and Aromatic Amines with Hydrogen Peroxide Catralyzed by Peroxoheteropoly Oxometalates
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Peroxotungstophosphate (PCWP) was found to be an efficient catalyst for the oxidation of amines with 35percent H2O2 under the biphasic or homogeneous condition.Thus, primary and secondary amines were oxidized to oximes and nitrones, respectively, in good yields.Aromatic amines afforded to the corresponding nitroso compounds and/or nitrobenzenes.
- Sakaue, Shigeki,Sakata, Yasuyuki,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 289 - 292
(2007/10/02)
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