- Development and scale-up of an efficient miyaura borylation process using tetrahydroxydiboron
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A revised Miyaura borylation process has been developed using tetrahydroxydiboron that avoids the use of bis(pinacolato) diboron and hence the need to hydrolyze the resulting boronic ester to its corresponding acid. The process was greatly simplified and successfully scaled-up in the pilot plant on a 65 kg scale, reducing plant cycle time and resulting in a 47% overall cost reduction. Furthermore, methodology for the study of the oxygen sensitivity of the process is reported that allowed for optimization of the amount of tetrahydroxydiboron and catalyst used. These studies also demonstrated an oxygen-induced decomposition of tetrahydroxydiboron.
- Gurung, Sing R.,Mitchell, Christopher,Huang, Jie,Jonas, Marco,Strawser, Josiah D.,Daia, Elena,Hardy, Andrew,O'Brien, Erin,Hicks, Frederick,Papageorgiou, Charles D.
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Read Online
- A Straightforward Access to [14C]- and [13C]-Labeled 2-Aminobenzoxazoles and Benzothiazoles via a KCN Polarity Inversion Strategy
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A convenient one-pot synthetic access to 2-aminobenzoxazoles and 2-aminobenzothiazoles has been developed. The protocol uses KCN as starting material and proceeds through an in situ polarity inversion step. This approach provides a new valuable and straightforward entry to carbon-14-radiolabeled pharmaceutically relevant heterocycles and substantially reduces as well the amount of radioactive wastes generated.
- Loreau, Olivier,Camus, Nathalie,Taran, Frédéric,Audisio, Davide
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Read Online
- Theoretical and experimental verification of molecular properties of novel benzamide derivatives using computational platforms and in vitro antibacterial activity
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A series of N-(benzo[d]oxazol-2-ylcarbamothioyl)-2/4-substituted benzamides were synthesized by the reaction of 2-aminobenzoxazole with apposite benzoyl isothiocyanate. The structure of the newly synthesized compounds was confirmed by chemical tests, elemental (C, H, N, and S), and spectral (IR, 1H NMR, 13C NMR, and mass) analysis. All the synthesized compounds were evaluated experimentally for their antibacterial activity against Gram-positive and Gram-negative bacteria. The test results show moderate to potent antibacterial activity compared to the standard drug. The binding interactions of newly synthesized ligand and protein were correlated using a molecular docking study using a binding pocket of GlcN-6-P synthase. [Figure not available: see fulltext.].
- Wanjari, Poonam M.,Mokale, Santosh N.,Bharati, Avinash V.,Ingle, Vishwas N.
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p. 655 - 663
(2021/01/07)
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- Design, synthesis, and evaluation of substituted 2-acylamide-1,3-benzo[d]zole analogues as agents against MDR- and XDR-MTB
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N-(5-Chlorobenzo[d]oxazol-2-yl)-4-methyl-1,2,3-thiadiazole-5-carboxamideox-amide has been identified as a potent inhibitor of Mtb H37Rv, with a minimum inhibitory concentration (MIC) of 0.42 μM. In this study, a series of substituted 2-acylamide-1,3-zole analogues were designed and synthesized, and their anti-Mtb activities were analyzed. In total, 17 compounds were found to be potent anti-Mtb agents, especially against the MDR- and XDR-MTB strains, with MIC values 10 μM. These analogues can inhibit both drug-sensitive and drug-resistant Mtb. Four representative compounds were selected for further profiling, and the results indicate that compound 18 is acceptably safe and has favorable pharmacokinetic (PK) properties. In addition, this compound displays potent activity against Gram-positive bacteria, with MIC values in the range of 1.48–11.86 μM. The data obtained herein suggest that promising anti-Mtb candidates may be developed via structural modification, and that further research is needed to explore other compounds.
- Li, Dongsheng,Liu, Chao,Jiang, Xinhai,Lin, Yuan,Zhang, Jing,Li, Yan,You, Xuefu,Jiang, Wei,Chen, Minghua,Xu, Yanni,Si, Shuyi
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- Chemical synthesis and molecular modeling of novel substituted N-1,3-benzoxazol-2yl benzene sulfonamides as inhibitors of inhA enzyme and Mycobacterium tuberculosis growth
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Abstract: Tuberculosis (TB) is one of the major contagious diseases with high mortality which is caused by Mycobacterium tuberculosis (Mtb) pathogen. Due to the existing antibiotic resistance (MDR-TB) to tuberculosis, the demand for the development of new potential chemotherapy drugs is increasing. Herein, we report synthesis of two novel benzoxazole-based series, namely 2-phenyl benzoxazole sulfonamide and 2-piperidine-benzoxazole sulfonamides. These compounds were evaluated for their antimycobacterial activity against Mycobacterium tuberculosis H37Rv strain, using the microplate alamarBlue assay. Molecular docking studies were carried out to comprehend the binding mode of the compounds. It is evident from molecular docking studies and minimum inhibitory concentration assay (MIC) that 2-phenyl benzoxazole sulfonamide scaffold has a greater potential of antitubercular activity possibly by ENR inhibition (inhA inhibitors). In silico cytotoxicity studies using CLC-Pred tool database suggested that both the series were relatively safe. Graphic abstract: [Figure not available: see fulltext.].
- Chundawat, Narendra Singh,Shanbhag, Gajanan S.,Chauhan, Narendra Pal Singh
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p. 903 - 920
(2020/10/30)
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- Iodine-catalyzed amination of benzothiazoles with KSeCN in water to access primary 2-aminobenzothiazoles
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A facile and sustainable approach for the amination of benzothiazoles with KSeCN using iodine as the catalyst in water has been disclosed under transition-metal free conditions. The reaction proceeded smoothly to afford various primary 2-amino benzothiazoles in up to 96% yield. A series of control experiments were performed, suggesting a ring-opening mechanism was involved via a radical process. This protocol provides efficient synthesis of primary 2-aminobenzothiazoles
- Chen, Xiran,Fu, Lianrong,Hao, Xin-Qi,Shi, Linlin,Song, Mao-Ping,Zhu, Xinju,Zhu, Yu-Shen
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- Benzothiazolyl ureas are low micromolar and uncompetitive inhibitors of 17Β-HSD10 with implications to Alzheimer’s disease treatment
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Human 17β-hydroxysteroid dehydrogenase type 10 is a multifunctional protein involved in many enzymatic and structural processes within mitochondria. This enzyme was suggested to be involved in several neurological diseases, e.g., mental retardation, Parkinson’s disease, or Alzheimer’s disease, in which it was shown to interact with the amyloid-beta peptide. We prepared approximately 60 new compounds based on a benzothiazolyl scaffold and evaluated their inhibitory ability and mechanism of action. The most potent inhibitors contained 3-chloro and 4-hydroxy substitution on the phenyl ring moiety, a small substituent at position 6 on the benzothiazole moiety, and the two moieties were connected via a urea linker (4at, 4bb, and 4bg). These compounds exhibited IC50 values of 1–2 μM and showed an uncompetitive mechanism of action with respect to the substrate, acetoacetyl-CoA. These uncompetitive benzothiazolyl inhibitors of 17β-hydroxysteroid dehydrogenase type 10 are promising compounds for potential drugs for neurodegenerative diseases that warrant further research and development.
- Aitken, Laura,Benek, Ondrej,Chribek, Matej,Dolezal, Rafael,Gunn-Moore, Frank,Hrabinova, Martina,Hroch, Lukas,Jun, Daniel,Kralova, Vendula,Kuca, Kamil,Lycka, Antonin,Musilek, Kamil,Prchal, Lukas,Schmidt, Monika,Vinklarova, Lucie,Zemanova, Lucie
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- Synthesis and Antibacterial Activity of Benzazolyl Azolyl Sulfamoyl Acetamides
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A new class of benzazolyl azolyl sulfamoyl acetamides was prepared from azolyl sulfamoyl acetates and benzazolyl amines in the presence of KOtBu in tetrahydrofuran. Compounds with benzothiazole-thiazole, benzimidazole-thiazole, benzothiazole-imidazole, and benzimidazole-imidazole moieties exhibited excellent antibacterial activity against Bacillus subtilis.
- Rajeswari, Tankam,Rekha, Tamatam,Dinneswara Reddy, Guda,Padmaja, Adivireddy,Padmavathi, Venkatapuram
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p. 2449 - 2459
(2019/08/07)
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- Method for synthesizing benzoxazole through microwave radiation of benzamide compound in water phase
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The invention discloses a method for synthesizing benzoxazole through microwave radiation of a benzamide compound in a water phase. The benzamide compound is added into the water phase under the microwave condition to be subjected to a cyclization reaction for generating the benzoxazole under the alkali condition, and the method for preparing the benzoxazole is environmentally friendly, easy and convenient to operate, safe, low in cost and efficient. Compared with the prior art, the method can be applied to a large number of functional groups, the yield is high, the number of by-products is small, and the method is easy to operate, safe, low in cost and environmentally friendly. (Please see the specifications for the formula).
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Paragraph 0018
(2019/03/08)
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- Diverse Oxidative C(sp2)-N Bond Cleavages of Aromatic Fused Imidazoles for Synthesis of α-Ketoamides and N-(pyridin-2-yl)arylamides
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An efficient and chemoselective C(sp2)-N bond cleavage of aromatic imidazo[1,2-a]pyridine molecules is developed. A broad scope of amide compounds such as α-ketoamides and N-(pyridin-2-yl)arylamides are afforded as the final products in up to quantitative yields. Diverse C-N bond cleavages are controlled by the oxidative species used in this transformation, with various amide products afforded in a chemoselective fashion. A preliminary study indicated that some α-ketoamides exhibit anti-Tobacco Mosaic Virus activity for potential use in plant protection.
- Xu, Fangzhou,Wang, Yanyan,Xun, Xiwei,Huang, Yun,Jin, Zhichao,Song, Baoan,Wu, Jian
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p. 8411 - 8422
(2019/05/17)
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- Cyanoguanidine as a versatile, eco-friendly and inexpensive reagent for the synthesis of 2-aminobenzoxazoles and 2-guanidinobenzoxazoles
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An effective, easy-to-handle, safe and inexpensive protocol is reported for the synthesis of 2-aminobenzoxazoles under Lewis acid activation, utilising cyanoguanidine as the cyanating reagent. An optimized procedure for the synthesis of 2-guanidinobenzoxazole and novel derivatives is also described.
- Grytsai, Oleksandr,Druzhenko, Tetiana,Demange, Luc,Ronco, Cyril,Benhida, Rachid
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p. 1642 - 1645
(2018/03/29)
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- Site-Selective Copper-Catalyzed Amination and Azidation of Arenes and Heteroarenes via Deprotonative Zincation
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Arene amination is achieved by site-selective C-H zincation followed by copper-catalyzed coupling with O-benzoylhydroxylamines under mild conditions. Key to this success is ortho-zincation mediated by lithium amidodiethylzincate base that is effective for a wide range of arenes, including nonactivated arenes bearing simple functionalities such as fluoride, chloride, ester, amide, ether, nitrile, and trifluoromethyl groups as well as heteroarenes including indole, thiophene, pyridine, and isoquinoline. An analogous C-H azidation is also accomplished using azidoiodinane for direct introduction of a useful azide group onto a broad scope of arenes and heteroarenes. These new transformations offer rapid access to valuable and diverse chemical space of aminoarenes. Their broad applications in organic synthesis and drug discovery are demonstrated in the synthesis of novel analogues of natural product (-)-nicotine and antidepressant sertraline by late-stage amination and azidation reactions.
- Hendrick, Charles E.,Bitting, Katie J.,Cho, Seoyoung,Wang, Qiu
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p. 11622 - 11628
(2017/08/30)
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- Synthesis and Antibacterial Activity of Sulfur-linked Bis and Tris Heterocycles
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The bis and tris heterocycles-benzoxazolyl/benzothiazolyl/benzimidazolyl quinazolines linked by sulfur and/or nitrogen were prepared from 2,4-dichloroquinazoline and benzazolyl-2-thiol/benzazolyl-2-amine and studied their antibacterial activity. The nitro-substituted sulfur-linked bisbenzothiazolylquinazoline (12f), bisbenzimidazolylquinazoline (13f), and nitro-substituted sulfur and nitrogen-linked bisbenzothiazolylquinazoline (15f) were found to be potential antibacterial agents against Staphylococcus aureus.
- Mallikarjuna Reddy,Lavanya,Lakshmi Teja,Padmaja,Padmavathi
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p. 2755 - 2766
(2017/09/26)
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- Substituted benzo - 1, 3 - [...] compound, its preparation and use
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The invention relates to a substituted benzo-1, 3-miscellaneous azole compound shown in the general formula I, and further relates to a preparation method of the compound and application to the preparation of antituberculosis drugs. The compound provided by the invention has effect not only on mycobacterium tuberculosis sensitive strains, but also on resistant strains which have drug resistance to isoniazid, rifampicin, and other traditional frontline antituberculosis drugs, and is a novel antimycobacterium tuberculosis compound.
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Paragraph 0018; 0119
(2017/04/21)
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- A new NBS/oxone promoted one pot cascade synthesis of 2-aminobenzimidazoles/2-aminobenzoxazoles: A facile approach
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A new strategy for the synthesis of 2-aminobenzimidazoles via a reaction of α-halogenated cyclohexanone with guanidine is reported. It provides a facile N-bromosuccinimide (NBS) mediated transition metal free, sustainable path for the synthesis of 2-substituted azoles. NBS along with the oxone promotes in situ halogenation of cyclohexanone, which in turn, when allowed to react with guanidine, afforded 2-aminobenzimidazoles (2-ABI). This eco-friendly protocol provides a competent laboratory synthesis method associated with significant advantages such as greater selectivity, cost-efficiency, mild reaction conditions, absence of chromatographic purification, clean reaction profile, and a simple work-up procedure to furnish high yields. The structures of all the synthesized compounds were confirmed on the basis of IR, 1H and 13C NMR, mass spectrometry, and elemental analyses data. In addition, we have also extended the scope of this strategy for obtaining 2-amino substituted benzoxazoles.
- Daswani, Ujla,Dubey, Nitin,Sharma, Pratibha,Kumar, Ashok
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supporting information
p. 8093 - 8099
(2016/09/12)
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- Synthesis and antimicrobial activity of amino linked heterocycles
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Amino-linked benzoxazolyl/benzothiazolyl/benzimidazolyl quinazolines were prepared and their antimicrobial activity studied. The nitro-substituted benzothiazolyl quinazoline (8f) may be a potential antibacterial agent against Staphylococcus aureus and nitro-substituted benzimidazolyl quinazoline (9f) may be a potential antifungal agent against Aspergillus niger.
- Mallikarjuna Reddy, Lingaladinne,Dinneswara Reddy, Guda,Padmaja, Adivireddy,Padmavathi, Venkatapuram
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- A facile synthesis of 2-aminobenzoxazoles and 2-aminobenzimidazoles using N -cyano- N -phenyl- P -toluenesulfonamide (NCTS) as an efficient electrophilic cyanating agent
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A facile synthesis of 2-aminobenzoxazole and 2-aminobenzimidazole derivatives employing a nonhazardous electrophilic cyanating agent: N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) with various substituted 2-aminophenols and benzene-1,2-diamine derivatives in the presence of lithium hexamethyldisilazide (LiHMDS) is described. This novel protocol boasts operational simplicity, shorter reaction time, and simple workup.
- Kasthuri, Mahesh,Babu, H. Sharath,Kumar, K. Shiva,Sudhakar, Ch.,Kumar, P. V. Nagendra
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p. 897 - 900
(2015/04/27)
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- Α 7 as intranuclear hydroxynicotinic acetylcholine receptor quinuclidines compd.
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PROBLEM TO BE SOLVED: To provide ligands for the nicotinic α-7 receptor used for the treatment of various disorders of the central nervous system, especially affective and neurodegenerative disorders.SOLUTION: The disclosure provides compounds of the specified formula I, including their salts, and compositions and methods using the compounds.
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Paragraph 0575; 0576
(2018/10/03)
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- Electrochemical intramolecular c-h amination: Synthesis of benzoxazoles and benzothiazoles
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A new method for metal-free intramolecular C-H amination has been developed. Electrochemical oxidation of 2-pyrimidyloxybenzenes and 2-pyrimidylthiobenzenes, which can be easily prepared from phenols and thiophenols, respectively, followed by the treatment of the resulting pyrimidinium ions with piperidine gives 2-aminobenzoxazoles and 2-aminobenzothiazoles, respectively.
- Morofuji, Tatsuya,Shimizu, Akihiro,Yoshida, Jun-Ichi
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p. 3211 - 3214
(2015/03/05)
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- Practical synthesis of N -substituted cyanamides via tiemann rearrangement of amidoximes
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A facile and general synthesis of various N-substituted cyanamides was accomplished by the Tiemann rearrangement of amidoximes with benzenesulfonyl chlorides (TsCl or o-NsCl) and DIPEA.
- Lin, Chia-Chi,Hsieh, Tsung-Han,Liao, Pen-Yuan,Liao, Zhen-Yuan,Chang, Chih-Wei,Shih, Yu-Chiao,Yeh, Wen-Hsiung,Chien, Tun-Cheng
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p. 892 - 895
(2014/03/21)
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- Ru/C: A simple heterogeneous catalyst for the amination of azoles under ligand free conditions
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A ligand free Ru/C-catalyzed amination of 2-halo azoles with a broad scope of aminating reagents has been developed. A variety of 2-aminoazole derivatives were synthesized in moderate to good yields by utilizing this protocol. The methodology is operationally simple and not sensitive to air and moisture. It provides potentially useful products by using an inexpensive and recyclable catalytic system under ligand free conditions without significant loss of its catalytic activity up to four cycles. This journal is
- Harsha Vardhan Reddy,Anil Kumar,Prakash Reddy,Uday Kumar,Nageswar
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p. 45579 - 45584
(2014/12/11)
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- Poly (ethylene glycol)-bound sulphonic acid as a novel catalyst for synthesis of benzoxazoles
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ABSTRACT Ahighly efficient, simple and rapid method for the preparation of various 2-aminobenzoxazoles and other benzoxazole derivatives using a catalytic amount of poly (ethylene glycol)-bound sulphonic acid (PEG-SO3H) is described. PEG-SO3H is found to be economical and reusable catalyst with low catalytic loading. The percentage yield was found to be satisfactory, experimental set-up and purification of final products is facile and easy. GRAPHICAL ABSTRACT.
- Chikhale, Rupesh V.,Pant, Amit M.,Menghani, Sunil S.,Wadibhasme, Pankaj G.,Khedekar, Pramod B.
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p. 254 - 262
(2013/12/04)
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- A metal-free oxidative amination of benzoxazoles with primary amines and ammonia
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An efficient synthesis of 2-aminobenzoxazoles is described by a direct oxidative amination of unfunctionalized benzoxazoles with primary amines. The reaction could be performed in the absence of transition metals by using catalytic amounts of a quaternary ammonium iodide and tert-butylhydroperoxide as a cheap and easy-to-handle co-oxidant. In addition to primary amines, aqueous solutions of NH3 were used to introduce a primary amine group into the heterocyclic core. Georg Thieme Verlag Stuttgart. New York.
- Kloeckner, Ulrich,Weckenmann, Nicole M.,Nachtsheim, Boris J.
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supporting information; experimental part
p. 97 - 100
(2012/02/03)
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- An efficient solid-phase parallel synthesis of 2-amino and 2-amidobenzo[d]oxazole derivatives via cyclization reactions of 2-hydroxyphenylthiourea resin
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An efficient solid-phase methodology has been developed for the synthesis of 2-amino and 2-amidobenzo[d]- oxazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo- [d]oxazole resins 4 by cyclization reaction of 2-hydroxyphenylthiourea resin 3. The resin-bound 2-hydroxyphenylthiourea 3 is produced by the addition of 2-aminophenol to the isothiocyanate-terminated resin 2 and serve as a key intermediate for the linker resin. This core skeleton 2-aminobenzo[d]oxazole resin 4 undergoes functionalization reaction with various electrophiles, such as alkylhalides and acid chlorides to generate 2- amino and 2-amidobenzo[d]oxazole resins 5 and 6 respectively. Finally, 2-amino and 2-amidobenzo[d]oxazole derivatives 7 and 8 are then generated in good yields and purities by cleavage of the respective resins 5 and 6 under trifluoroacetic acid (TFA) in dichloromethane (CH2Cl2).
- Jung, Se-Lin,Kim, Seul-Gi,Lee, Gee-Hyung,Gong, Young-Dae
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p. 4109 - 4116
(2013/08/23)
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- Synthesis, anticancer and antioxidant activities of some novel N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3-ylidene) hydrazinecarboxamide derivatives
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A series of N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3- ylidene) hydrazinecarboxamide derivatives were synthesized by treating N-(benzoxazol-2-yl)hydrazinecarboxamide with different isatin derivatives. The newly synthesized compounds were characterized on the basis of spectral analyses. All the synthesized derivatives (Va-l) were screened for anticancer and antioxidant activities. The results showed the anticancer activity of test compounds against HeLa, IMR-32 and MCF-7 cancer cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. All the synthetic compounds produced a dose-dependant inhibition of growth of the cells. The IC50 values of some compounds were comparable with standard anticancer agent, cisplatin. All the title compounds effectively scavenged the free radical, α,α-diphenyl-β-picryl hydrazyl. The test compounds having substitution with different halides (electron withdrawing groups) at C5 position showed more potent anticancer and antioxidant activities than those at C7 position. These results indicate that C5-substituted derivatives may be useful for developing antioxidant agents that play a protective role in many pathological conditions such as cancer, diabetes and so on.
- Gudipati, Rajyalakshmi,Reddy Anreddy, Rama Narsimha,Manda, Saranagapani
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experimental part
p. 813 - 818
(2012/03/26)
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- Formation of nitrogen-containing heterocycles using di(imidazole-1-yl)methanimine
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A mild and efficient synthesis of five- and six-membered nitrogen containing heterocyclic compounds, in which di(imidazole-1-yl)methanimine serves as a one-carbon source, is reported.
- Wu, Yong-Qian,Limburg, David C.,Wilkinson, Douglas E.,Hamilton, Gregory S.
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p. 191 - 193
(2007/10/03)
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- Quantitative gas-solid reactions with ClCN and BrCN: Synthesis of cyanamides, cyanates, thiocyanates, and their derivatives
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Gas-solid reaction techniques allow quantitative cyanations with ClCN and BrCN. Three primary and four secondary cyanamides, a cyanimide, four cyanates, and four thiocyanates were all prepared as solids in 100% yield from solid anilines, benzimidazoles, imides, phenolates, and thiolates, respectively. Intramolecular solid-state reactions of cyanated o-aminophenol and of cyanated hydrazides gave heterocyclic compounds. When comparable reactions were performed in solution the reported product yields were considerably less than 100% in all cases. The reasons for the success of the environmentally benign solid-state syntheses are discussed in terms of phase rebuilding, phase transformation, and crystal disintegration. Atomic force microscopy (AFM) of selected systems indicates the occurrence of long-range molecular movements which are governed by the crystal packing. This is evident from the obvious correlations between the molecular movements and the known crystal packing data. A new type of geometric surface feature, a rectangular and a rhombic depression which resembles a swimming-pool basin, was found in the cyanation of o-aminophenol and benzohydrazide.
- Kaupp, Gerd,Schmeyers, Jens,Boy, Juergen
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p. 2467 - 2474
(2007/10/03)
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- Ozonation of thioamide containing heterocycles. A new general and selective procedure for the synthesis of C-2 substituted heteroazole derivatives
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2-Mercaptoheteroazoles readily react with ozone in the presence of nucleophiles and under mild experimental conditions to form several C-2 substituted heterazoles.
- Saladino, Raffaele,Crestini, Claudia,Occhionero, Francesca,Nicoletti, Rosario
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p. 3241 - 3251
(2007/10/03)
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- OXIDATION OF 2-MERCAPTOBENZOHETERAZOLES BY DIMETHYLDIOXIRANE. A NEW METHOD FOR A SYNTHESIS OF C-2 SUBSTITUTED BENZIMIDAZOLE, BENZOXAZOLE, AND BENZOTHIAZOLE DERIVATIVES
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New and efficient reactions in which 2-mercaptobenzoheterazoles are selectively converted by dimethyldioxirane, under mild experimental conditions, to several C-2 substituted benzoimidazole, benzoxazole, and benzothiazole derivatives are reported.
- Frachey, Giuseppe,Crestini, Claudia,Bernini, Roberta,Saladino, Raffaele,Mincione, Enrico
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p. 2621 - 2630
(2007/10/02)
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- One Pot Synthesis of 4-Arylbenzoxazolo-s-triazine-2-thiones
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The reaction of 2-aminobenzoxazoles (1a-b) with aroyl isothiocyanates in acetone gave 4-arylbenzoxazolo-s-triazine-2-thiones (3a-g), aroylthioureas (5a-e) and 2-benzoxazolones (6a-b).A reasonable pathway for the formation of 3, 5 and 6 from 1 has been suggested.
- Sambaiah, T.,Reddy, K. Kondal
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p. 693 - 701
(2007/10/02)
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- Ring Contraction of 1,2,4-Benzoxadiazines to Benzoxazoles
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1,2,4-Benzoxadiazines (1) undergo a ring contraction to benzoxazoles (2) on heating.Other products of the reaction have been identified as nitrogen and ammonia.A mechanism is suggested for this reaction which involves (i) electrocyclic ring opening to an o-benzoquinone imine, (ii) recyclisation to a diaziridine, and (iii) extrusion of a nitrene fragment.Evidence is presented which is consistent with this proposal: thus, the benzoxazole (7) is produced on heating 3,5-di-t-butyl-o-benzoquinone with benzamidine and 4-nitrobenzoylnitrene is intercepted as the ylide (11) from the thermolysis of the substituted benzoxadiazine (10).
- Gilchrist, Thomas L.,Harris, C. John,King, Frank D.,Peek, Michael E.,Rees, Charles W.
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p. 2169 - 2174
(2007/10/02)
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- REACTION OF 2-AMINOBENZOXAZOLES WITH COMPOUNDS WITH ACTIVATED MULTIPLE BONDS
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The reaction of 2-aminobenzoxazoles with activated alkenes of the acrylic acid type and its derivatives and methyl vinyl ketone proceeds in the presence of basic catalysts to give products of mono- and diaddition at the exocyclic nitrogen atom.The reaction of 5(6)-substituted 2-aminobenzoxazoles with esters of propyl and acetylenedicarboxylic acids in the absence of catalysts leads to the production of condensed 2-oxopyrimidines.The effect of substituents and the reaction conditions on the course of the process was investigated.
- Kalcheva, V. B.,Peshakova, L. S.,Simov, D. A.
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p. 1210 - 1213
(2007/10/02)
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- Iminoisoindolinone metal complex
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Iminoisoindolinone metal complexes of formula STR1 wherein A represents a 5- or 6-membered heterocyclic radical which contains at least one further heteroatom and can be fused or doubled with benzene nuclei, M represents a divalent metal atom excluding the alkaline earth metals, X represents a hydrogen atom, Y represents a halogen atom, Z represents a nitro group, an alkoxycarbonyl group of 2 to 6 carbon atoms or a group of formula RY2 --, wherein R represents a hydrogen atom, an alkyl group of 1 to 6 carbon atoms which is substituted by an aryl radical or is unsubstituted, a cycloalkyl group of 5 to 6 carbon atoms, or represents an aryl group, and Y2 represents an oxygen or a sulphur atom, m and n are 0 to 4, p is 0 to 2, and the sum of m+n+p must be 4, which are useful for pigmenting high molecular organic material.
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