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1.
One‐Pot Multicomponent Synthesis of Novel Substituted Imidazo[1,2‐a]Pyridine Incorporated Thiazolyl Coumarins and their Antimicrobial Activity 下载免费PDF全文
Rajitha Gali Janardhan Banothu Rajitha Bavantula 《Journal of heterocyclic chemistry》2015,52(3):641-646
A series of novel substituted imidazo[1,2‐a]pyridine incorporated thiazolyl coumarin derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p , 4q , 4r , 4s , 4t ) were synthesized in good yields via one‐pot multicomponent condensation of substituted imidazo[1,2‐a]pyridine‐3‐carbaldehyde ( 3a , 3b , 3c , 3d , 3e ), thiosemicarbazide ( 2 ), and substituted 3‐(2‐bromoacetyl)‐2H‐chromen‐2‐ones ( 1a , 1b , 1c , 1d )/2‐(2‐bromoacetyl)‐3H‐benzo[f]chromen‐3‐one ( 1e ) in refluxing ethanol with catalytic amount of acetic acid. All the synthesized compounds ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p , 4q , 4r , 4s , 4t ) have been characterized by IR, NMR, and mass spectral studies as well as elemental analyses and evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains. All the compounds displayed moderate antibacterial activity with minimum inhibitory concentration 150 µg/mL, but none of the compounds have shown any antifungal activity. 相似文献
2.
Fused Heterocycles: Synthesis and Antitubercular Activity of Novel 6‐Substituted‐2‐(4‐methyl‐2‐substituted phenylthiazol‐5‐yl)H‐imidazo[1,2‐a]pyridine 下载免费PDF全文
Yogita K. Abhale Keshav K. Deshmukh Amit V. Sasane Abhijit P. Chavan Pravin C. Mhaske 《Journal of heterocyclic chemistry》2016,53(1):229-233
A series of 6‐substituted‐2‐(4‐methyl‐2‐substituted phenylthiazol‐5‐yl)H‐imidazo[1,2‐a]pyridine derivatives 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l is described. The antitubercular activity of the synthesized compounds was determined against Mycobacterium smegmatis MC2 155 strain. From the activity result, it was found that the phenyl or 4‐fluorophenyl group at 2 position of thiazole nucleus and bromo substituent at 6 position of imidazo[1,2‐a]pyridine showed good antitubercular activity. 相似文献
3.
Virginija Jakubkiene Zana Kacnova Milda M. Burbuliene Povilas Vainilavicius 《Journal of heterocyclic chemistry》2008,45(5):1391-1395
[2‐Alkylthio‐6‐methyl‐4‐oxopyrimidin‐3(4H)‐yl]acetonitriles ( 3‐5 ) treated with sodium methoxide in methanol followed by ammonium chloride were cyclized to 2‐imino‐7‐methyl‐2,3‐dihydroimidazo[1,2‐a]‐pyrimidin‐5(1H)‐ones ( 6‐8 ). Under acid or base‐catalyzed hydrolysis they were converted to 7‐methyl‐imidazo[1,2‐a]pyrimidine‐2,5‐[1H,3H]‐diones ( 9‐11 ), whereas in the reaction with butyl‐ or benzylamine the corresponding 7‐methyl‐2‐(substitutedamino)imidazo[1,2‐a]pyrimidin‐5(3H)‐ones ( 13‐18 ) were produced. The latter were found to exist in two tautomeric forms in CDCl3 solution. 相似文献
4.
Milda M. Burbuliene Rita Dobrovolskaite Povilas Vainilavicius 《Journal of heterocyclic chemistry》2006,43(6):1557-1561
The title ester 1 reacted with hydrazine hydrate to give hydrazide 2 , which underwent intramolecular cyclization to yield 1‐amino‐7‐phenyl‐1H‐imidazo[1,2‐a]pyrimidine‐2,5‐dione ( 3 ) or took place in a substitution reaction with benzylamine to form N‐benzyl‐2‐(2‐benzylamino‐4‐oxo‐6‐phenyl‐4H‐pyrimidin‐3‐yl)‐acetamide ( 4 ). The reaction of ester 1 with benzylamine gave corresponding amide 7 , disubstituted derivative 4 or 1‐benzyl‐7‐phenyl‐1H‐imidazo[1,2‐a]pyrimidine‐2,5‐dione ( 8 ) depending on the reaction conditions. 相似文献
5.
An efficient one‐pot four‐component protocol for the synthesis of imidazo[1,2‐a]pyridines was developed by condensing ethane‐1,2‐diamine ( 2 ), 1,1‐bis(methylthio)‐2‐nitroethene ( 1 ), aldehydes 3 , and activated methylene compounds in EtOH under reflux conditions (Tables 1–3). The features of this procedure are operational simplicity, good yields of products, in situ preparation of heterocyclic ketene aminals (HKA), and catalyst‐free conditions. 相似文献
6.
Reaction of 3,5‐diaminothiophene‐2‐carbonitrile derivatives 3a‐c with ethoxycarbonylmethyl isothiocyanate and/or N‐[bis(methylthio)methylene]glycine ethyl ester led to formation of 7‐substituted‐8‐amino‐5‐thioxo‐6H‐imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one derivatives 6a‐c and 7‐substituted‐8‐amino‐5‐(methylthio)imidazo[1,2:1′,6′]pyrimido[5,4‐b]thiophene‐2(3H)‐one 7a‐c , respectively. Also, the synthetic potential of the β‐enaminonitrile moiety in 3a‐c has been explored; it proved to be a promising candiate for the synthesis of 1,6‐disubstituted‐2,4‐diamino‐7,8‐dihydro‐8‐oxopyrrolo[1,2‐a]thieno[2,3‐e]pyrimidine derivatives 10a‐f and pyrido[2′,3′:6,5]pyrimido[3,4‐a]benzimidazole derivatives 12a,b . 相似文献
7.
Yoshihisa Okamoto Yoshimi Yamaguchi Mitsuaki Maeda Yoshihisa Kurasawa 《Journal of heterocyclic chemistry》2008,45(3):717-721
Fused tetracycles, 6‐alkyl‐3‐alkoxy‐2‐cyano‐4,5,6a,11‐tetraazabenzo[a]fluorene derivatives ( 5a , b , c , d , e , f ), are synthesized from 2‐alkoxy‐5‐(benzimidazol‐2‐ylidene)‐3‐cyano‐6‐imino‐5,6‐dihydro‐pyridines ( 4b , c ), and when refluxed in ethyl orthoacetate or ethyl orthopropionate, the elecrophilic aromatic substitution occurs at the ortho position of the cyanopyridine ring in the fused tetracycles ( 5b , c , e , f ) to afford 6‐alkyl‐3‐alkoxy‐2‐cyano‐1‐ethyl‐4,5,6a,11‐tetraazabenzo[a]fluorenes( 6b , c , e , f ). 相似文献
8.
Copper‐promoted annulation reactions of terminal alkynes with 2‐aminopyridines have been developed for the synthesis of 2‐halogenated imidazo[1,2‐a]pyridines using copper halide as the halogen source. A variety of substrates survived under the reaction conditions and gave the desired products in good yields. This reaction features advantages such as easily available starting materials, broad substrate scope, and mild reaction conditions. 相似文献
9.
To find novel bleaching herbicide lead compounds, a series of novel 2‐alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines was designed and synthesized by the multistep reactions. N,S‐acetal 1 reacted with 2 to obtain multisubstituted pyridines 3 in the presence of zinc nitrate as the catalyst. The target compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l were formed by the oxidation of 3 , followed by the substitution with 3‐(trifluoromethyl)phenol in the presence of potassium carbonate. Their structures were confirmed by IR, 1H NMR, EI‐MS, and elemental analyses. The preliminary bioassays indicated that some of them displayed moderate herbicidal activity against dicotyledonous weed Brassica campestris L at the concentration of 100 mg/L. 相似文献
10.
Over the years, various strategies have been reported for the synthesis of imidazo[1,2‐a]pyridines due to their importance in different fields. In this account, we represent the methods developed by our group for the synthesis and functionalization of imidazo[1,2‐a]pyridines. Different synthetic strategies have been developed using easily accessible reactants for this purpose. We envisage that these newly developed protocols will be very useful for the synthesis of functionalized molecules bearing imidazo[1,2‐a]pyridine scaffolds. These strategies will also be attractive for the construction of other pharmaceutically important heterocycles.
11.
Regioselective,Solvent‐ and Metal‐Free Chalcogenation of Imidazo[1,2‐a]pyridines by Employing I2/DMSO as the Catalytic Oxidation System 下载免费PDF全文
Dr. Jamal Rafique Dr. Sumbal Saba Dr. Alisson R. Rosário Prof. Dr. Antonio L. Braga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11854-11862
Highly efficient molecular‐iodine‐catalyzed chalcogenations (S and Se) of imidazo[1,2‐a]pyridines were achieved by using diorganoyl dichalcogenides under solvent‐free conditions. This approach afforded the desired products that had been chalcogenated regioselectively at the C3 position in up to 96 % yield by using DMSO as an oxidant, in the absence of a metal catalyst, and under an inert atmosphere. This mild, green approach allowed the preparation of different types of chalcogenated imidazo[1,2‐a]pyridines with structural diversity. Furthermore, the current protocol was also extended to other N‐heterocyclic cores. 相似文献
12.
Synthesis of Novel Imidazo[1,2‐a]pyridin‐2‐amines from Arylamines and Nitriles via Sequential Addition and I2/KI‐Mediated Oxidative Cyclization 下载免费PDF全文
Xianhai Tian Lina Song Manman Wang Zhigang Lv Dr. Jie Wu Dr. Wenquan Yu Prof. Dr. Junbiao Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7617-7622
A novel and practical strategy for the construction of imidazo[1,2‐a]pyridin‐2‐amine frameworks has been developed. The present sequential approach involves addition of arylamines to nitriles and I2/KI‐mediated oxidative C?N bond formation without purification of the intermediate amidines. This operationally simple synthetic process provides a facile access to a variety of new 2‐amino substituted imidazo[1,2‐a]pyridines and related heterocyclic compounds in an efficient and scalable fashion. 相似文献
13.
The imidazo[1,2‐a]pyridines are an important target in organic synthetic chemistry and have attracted critical attention of chemists mainly due to the discovery of the interesting properties exhibited by a great number of imidazo[1,2‐a]pyridine derivatives. Although lots of synthetic methods of imidazo[1,2‐a]pyridines have been developed in the past years, the chemistry community faces continuing challenges to use green reagents, maximize atom economy and enrich the functional group diversity of product. Undoubtedly, with its low cost and lack of environmentally hazardous byproducts, cascade reactions and C?H functionalizations are ideal strategies for this field. In this record we highlight some of our progress toward the goal to synthesis of imidazo[1,2‐a]pyridine derivatives through carbene transformations or C?H functionalizations. 相似文献
14.
Iodobenzene‐catalyzed synthesis of imidazo[1,2‐a]pyridines from aryl ketones with mCPBA as a cooxidant in ionic liquid is described. The method is simple, rapid and practical, generating Imidazo[1,2‐a]pyridines from the aryl ketone without isolation of α‐tosyloxyketones in good to excellent yields. 相似文献
15.
Cécile Enguehard‐Gueiffier Cécile Croix Maud Hervet Jean‐Yves Kazock Alain Gueiffier Mohamed Abarbri 《Helvetica chimica acta》2007,90(12):2349-2367
A systematic study on the Stille and Sonogashira cross‐coupling of iodinated imidazo[1,2‐a]pyridines was performed, permitting the preparation of various vinyl‐, ethynyl‐, and allenyl‐substituted derivatives. These methods are particularly valuable, given their experimental simplicity and high degree of flexibility with regard to functional groups that can be introduced in positions 3, 6, or 8 of the imidazo[1,2‐a]pyridine core. Effects concerning different substitution positions and the nature of the 2‐substituent under various reaction conditions are reported in detail for the above types of unsaturated groups introduced. 相似文献
16.
Pyrazolo[1,5‐a]pyrimidine and imidazo[1,2‐b]pyrazole derivatives were synthesized via intermolecular aza‐Wittig reaction of 5‐(triphenylphosphoranylideneamino)‐3‐phenylpyrazole 3 derived from 5‐amino‐3‐phenylpyrazole with some selected α‐chloroketones. 相似文献
17.
《Journal of heterocyclic chemistry》2017,54(6):3440-3446
2‐(1H ‐benzo[d ]imidazol‐2‐yl)anilines reacted with haloketones including 5‐chloropentan‐2‐one and 6‐chlorohexan‐2‐one catalyzed by iodine, giving benzo[4,5]imidazo[1,2‐c ]pyrrolo[1,2‐a ]quinazoline and 6H ‐benzo[4,5]imidazo[1,2‐c ]pyrido[1,2‐a ]quinazoline derivatives, respectively. This domino‐type reaction formed two new heterocycles and three new covalent bonds in one‐pot procedure and provided a green method for the synthesis of fused pentacyclic heterocycles bearing both quinazoline and benzimidazole moieties in ionic liquids. 相似文献
18.
Swarna A. Gamage Julie A. Spicer Kit Y. Tsang Patrick D. O'Connor Jack U. Flanagan Woo‐Jeong Lee James M. J. Dickson Peter R. Shepherd William A. Denny Gordon W. Rewcastle 《化学:亚洲杂志》2019,14(8):1249-1261
Using a scaffold‐hopping approach, imidazo[1,2‐a]pyridine analogues of the ZSTK474 (benzimidazole) class of phosphatidylinositol 3‐kinase (PI3K) inhibitors have been synthesized for biological evaluation. Compounds were prepared using a heteroaryl Heck reaction procedure, involving the palladium‐catalysed coupling of 2‐(difluoromethyl)imidazo[1,2‐a]pyridines with chloro, iodo or trifluoromethanesulfonyloxy (trifloxy) substituted 1,3,5‐triazines or pyrimidines, with the iodo intermediates being preferred in terms of higher yields and milder reaction conditions. The new compounds maintain the PI3K isoform selectivity of their benzimidazole analogues, but in general show less potency. 相似文献
19.
Shunichi Aikawa Chiharu Sekiguchi Yuko Yamazaki Mika Hattori Tatsuya Isaka Yasuhiko Yoshida Shogo Ihara 《Journal of heterocyclic chemistry》2014,51(2):343-348
The reaction of N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n with diphenyl carbonate 2a or ethyl phenyl carbonate 2b synthesized 2‐arylquinazolin‐4(3H)‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n in simple and safe process with good yields (71–90%). It was suggested that different electron‐donating substituent in N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n afforded similar effect to the yields of 2‐arylquinazolin‐4(3H)‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n . In these reactions, N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n built up intermediate compounds by nucleophilic addition to carbonates 2 to give annulation products 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , following to cyclization involving the elimination of ethanol/phenol. 相似文献
20.
Maud Hervet Isabelle Thry Alain Gueiffier Ccile Enguehard‐Gueiffier 《Helvetica chimica acta》2003,86(10):3461-3469
The scope of the Suzuki‐cross‐coupling reaction of 6‐haloimidazo[1,2‐a]pyridines is dependent on the availability of the (hetero)arylboronic acids. Thus, with the aim to develop expanded applications of (hetero)arylations of imidazo[1,2‐a]pyridines, we investigated the Negishi‐ and Stille‐cross‐coupling reactions at the 6‐position. Remarkably, attempts to apply the Negishi‐cross‐coupling conditions to the organozinc derivative prepared from 6‐haloimidazo[1,2‐a]pyridine via a lithium? zinc exchange led to the 5‐phenyl compound 3 in 54% yield instead of the desired 6‐phenyl isomer (Scheme 1). In contrast, various commercially available halogenated five‐ or six‐membered‐ring heterocycles were efficiently coupled to the 6‐(trialkylstannyl)imidazo[1,2‐a]pyridine under Stille conditions (Table 2). 相似文献