- A Practical Procedure for Regioselective Bromination of Anilines
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A highly practical procedure for the preparation of bromoanilines by using copper-catalyzed oxidative bromination has been developed. Treatment of free anilines with readily available NaBr and Na 2S 2O 8in the presence of a catalytic amount of CuSO 4·5H 2O enabled regioselective bromination.
- Takahashi, Yusuke,Seki, Masahiko
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p. 1828 - 1832
(2021/04/15)
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- Making endo-cyclizations favorable again: A conceptually new synthetic approach to benzotriazoles via azide group directed lithiation/cyclization of 2-azidoaryl bromides
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Although benzotriazoles are important and ubiquitous, currently there is only one conceptual approach to their synthesis: bridging the two ortho-amino groups with an electrophilic nitrogen atom. Herein, we disclose a new practical alternative-the endo-cyclization of 2-azidoaryl lithiums obtained in situ from 2-azido-aryl bromides. The scope of the reaction is illustrated using twenty-four examples with a variety of alkyl, alkoxy, perfluoroalkyl, and halogen substituents. We found that the directing effect of the azide group allows selective metal-halogen exchange in aryl azides containing several bromine atoms. Furthermore, (2-bromophenyl)diazomethane undergoes similar cyclization to give an indazole. Thus, cyclizations of aryl lithiums containing an ortho-X = Y = Z group emerge as a new general approach for the synthesis of aromatic heterocycles. DFT computations suggested that the observed endo-selectivity applies to the anionic cyclizations of other functionalities that undergo "1,1-additions" (i.e., azides, diazo compounds, and isonitriles). In contrast, cyclizations with the heteroatomic functionalities that follow the "1,2-addition" pattern (cyanates, thiocyanates, isocyanates, isothiocyanates, and nitriles) prefer the exo-cyclization path. Hence, such reactions expand the current understanding of stereoelectronic factors in anionic cyclizations.
- Ageshina, Alexandra A.,Chesnokov, Gleb A.,Topchiy, Maxim A.,Alabugin, Igor V.,Nechaev, Mikhail S.,Asachenko, Andrey F.
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supporting information
p. 4523 - 4534
(2019/05/17)
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- Method of catalytically synthesizing polybromo-aniline in water phase
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The invention discloses a method of catalytically synthesizing polybromo-aniline in a water phase. The method comprises following steps: adding a catalytic amount of a free radical initiator, aniline derivatives, cheap and low-toxic bromine salts, and water into a reactor; carrying out reactions in a photocatalytic reaction instrument under power of 5W at a room temperature; after a while, extracting the reaction product by ethyl acetate, and carrying out recrystallization to obtain polybromo-aniline; wherein the free radical initiator is eosin, sodium persulfate, or potassium persulfate. The power of the incandescent lamp of the photocatalytic reaction instrument is 5W. The free radical initiator and bromine salts are cheap and easily available. The method is an ideal synthesis method of polybromo-aniline. Cheap and low-toxic bromine salts are used to replace liquid bromine. The cheap and easily available free radical initiator is used to replace unstable and explosive hydrogen peroxide. After 4 to 10 hours of reactions under the power of 5W, polybromo-aniline can be synthesized, the yield and the reaction selectivity are high, the byproducts are few, and the post treatment is simple.
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Paragraph 0012; 0034
(2019/10/04)
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- Facile synthesis and biological evaluation of novel fluorine-containing N-nitro-N′-substituted phenylurea
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Twenty-two novel N-nitro-N′-substituted phenyl-N-(2,6-dibromo-4- fluorophenyl)urea derivatives were designed and synthesized via a simple and convenient BTC 'one-pot' procedure using DMAP as the catalyst. The structures of all newly synthesized compounds were confirmed by IR, 1H NMR, and elemental analysis, and a part has been identified by 13C NMR. The preliminary bioassay indicates that the target compounds possesses moderate herbicidal activity against Sorghum sudanense. However, some of the title compounds presented high plant growth regulating activity against rape.
- Wang, Yunchun,Bai, Zhongyuan,Wei, Zengjun,Xu, Shengzhen,Li, Xuegang,Li, Jianhong,Cao, Xiufang,Chen, Changshui
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p. 1029 - 1039
(2012/04/17)
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- Pyrrolidine-3-carboxylic acids as endothelin antagonists. 4. Side chain conformational restriction leads to ET(B) selectivity
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When the dialkylacetamide side chain of the ETA-selective antagonist ABT-627 is replaced with a 2,6-dialkylacetanilide, the resultant analogues show a complete reversal of receptor selectivity, preferring ETB over ETA. By optimizing the aniline substitution pattern, as well as the alkoxy group on the 2-aryl substituent, it is possible to prepare antagonists with subnanomolar affinity for ETB and with selectivities in excess of 4000-fold. A number of these compounds also show promising pharmacokinetic profiles; a useful balance of properties is found in A-192621 (38). Pharmacology studies with A-192621 serve to reveal the role of the ETB receptor in modulating blood pressure; the observed hypertensive response to persistent ETB blockade is consistent with previous postulates and indicates that ETB-selective antagonists may not be suitable as agents for long-term systemic therapy.
- Von Geldern, Thomas W.,Tasker, Andrew S.,Sorensen, Bryan K.,Winn, Martin,Szczepankiewicz, Bruce G.,Dixon, Douglas B.,Chiou, William J.,Wang, Liming,Wessale, Jerry L.,Adler, Andy,Marsh, Kennan C.,Nguyen, Bach,Opgenorth, Terry J.
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p. 3668 - 3678
(2007/10/03)
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