scholarly journals Supramolecular catalyst functions in catalytic amount: cucurbit[8]uril accelerates the photodimerization of Brooker’s merocyanine

2017 ◽  
Vol 8 (12) ◽  
pp. 8357-8361 ◽  
Author(s):  
Yuetong Kang ◽  
Xiaoyan Tang ◽  
Hongde Yu ◽  
Zhengguo Cai ◽  
Zehuan Huang ◽  
...  

As low as 1% content of a supramolecular catalyst, cucurbit[8]uril, is sufficient to accomplish the photodimerization of Brooker’s merocyanine within 10 minutes.

2019 ◽  
Author(s):  
Samir Messaoudi ◽  
Nedjwa Bennai ◽  
Amelie Chabrier ◽  
Maha Fatthalla ◽  
Expédite Yen-Pon ◽  
...  

We have discovered a new mode of reactivity of 1-thiosugars in the presence of Cu(II) or Co(II) for a stereoselective <i>O</i>-glycosylation reaction. The process involves the use of a catalytic amount of Cu(acac)2 or Co(acac)2 and Ag2CO3 as an oxidant in α,α,α-trifluorotoluene (TFT). Moreover, this protocol turned out to have a broad scope, allowing to prepare a wide range of com-plex substituted <i>O</i>-glycoside esters in good to excellent yields with an exclusive β-selectivity. The late-stage modification of phar-maceuticals by this method was also demonstrated.


2019 ◽  
Author(s):  
Łukasz Ciszewski ◽  
Jakub Durka ◽  
Dorota Gryko

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.


Author(s):  
Hadis Khodadad ◽  
Farhad Hatamjafari ◽  
Khalil Pourshamsian ◽  
Babak Sadeghi

Aim and Objective: Microwave-assisted condensation of acetophenone 1 and aromatic aldehydes 2 gave chalcone analogs 3, which were cyclized to pyrazole derivatives 6a-f via the reaction with hydrazine hydrate and oxalic acid in the presence of the catalytic amount of acetic acid in ethanol. Materials and Methods: The structural features of the synthesized compounds were characterized by melting point, FT-IR, 1H, 13C NMR and elemental analysis. Results: The antibacterial activities of the synthesized pyrazoles was evaluated against three gram-positive bacteria such as Enterococcus durans, Staphylococcus aureus, Bacillus subtilis and two gram-negative bacteria such as Escherichia coli and Salmonella typhimurium. Conclusion: All the synthesized pyrazoles showed relatively high antibacterial activity against S. aureus strain and none of them demonstrated antibacterial activity against E. coli.


2019 ◽  
Vol 16 (9) ◽  
pp. 740-749
Author(s):  
Sushil R. Mathapati ◽  
Arvind H. Jadhav ◽  
Mantosh B. Swami ◽  
Jairaj K. Dawle

Zinc sulfamate (Zn(NH2SO3)2 is a derivative of sulfamic acid (H3NSO3) which possesses “Lewis acidity” and finds well suited in a number of catalytic applications. The present paper describes an efficient, eco-friendly, and clean synthesis of 2-substituted benzimidazole derivatives by reacting diverse o-phenylenediamine with various substituted aromatic aldehydes using a catalytic amount of zinc sulfamate in ethanol at ambient temperature. As a result, 10 mol.% of Zinc sulfamate catalyst showed 92% of respective product yield with 100% conversion using short reaction period in ethanol. Meanwhile, effect of reaction parameters, such as amount of catalyst, different solvents, and reaction temperature on reaction product, was also studied. In addition, in the optimized reaction condition various substituted biological important benzimidazoles derivatives were prepared by using optimized reaction condition in good to efficient yield. In addition, possible reaction mechanism in the presence of zinc sulfamate for the preparation of benzimidazole derivative was sketched and discussed. The present green approach showed significances with faster reaction rate with inexpensive catalyst, which showed excellent and clean yield of benzimidazole in mild reaction condition with easy work-up procedure.


Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4424
Author(s):  
Uzma Arshad ◽  
Sibtain Ahmed ◽  
Nusrat Shafiq ◽  
Zaheer Ahmad ◽  
Aqsa Hassan ◽  
...  

Objective: In this study, small molecules possessing tetrahydropyrimidine derivatives have been synthesized having halogenated benzyl derivatives and carboxylate linkage. As previously reported, FDA approved halogenated pyrimidine derivatives prompted us to synthesize novel compounds in order to evaluate their biological potential. Methodology: Eight pyrimidine derivatives have been synthesized from ethyl acetoacetate, secondary amine, aromatic benzaldehyde by adding catalytic amount of CuCl2·2H2O via solvent less Grindstone multicomponent reagent method. Molecular structure reactivity and virtual screening were performed to check their biological efficacy as an anti-oxidant, anti-cancer and anti-diabetic agent. These studies were supported by in vitro analysis and QSAR studies. Results: After combined experimental and virtual screening 5c, 5g and 5e could serve as lead compounds, having low IC50 and high binding affinity.


Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 503
Author(s):  
Morten Gundersen ◽  
Guro Austli ◽  
Sigrid Løvland ◽  
Mari Hansen ◽  
Mari Rødseth ◽  
...  

Sustainable methods for producing enantiopure drugs have been developed. Chlorohydrins as building blocks for several β-blockers have been synthesized in high enantiomeric purity by chemo-enzymatic methods. The yield of the chlorohydrins increased by the use of catalytic amount of base. The reason for this was found to be the reduced formation of the dimeric by-products compared to the use of higher concentration of the base. An overall reduction of reagents and reaction time was also obtained compared to our previously reported data of similar compounds. The enantiomers of the chlorohydrin building blocks were obtained by kinetic resolution of the racemate in transesterification reactions catalyzed by Candida antarctica Lipase B (CALB). Optical rotations confirmed the absolute configuration of the enantiopure drugs. The β-blocker (S)-practolol ((S)-N-(4-(2-hydroxy-3-(isopropylamino)propoxy)phenyl)acetamide) was synthesized with 96% enantiomeric excess (ee) from the chlorohydrin (R)-N-(4-(3-chloro-2 hydroxypropoxy)phenyl)acetamide, which was produced in 97% ee and with 27% yield. Racemic building block 1-((1H-indol-4-yl)oxy)-3-chloropropan-2-ol for the β-blocker pindolol was produced in 53% yield and (R)-1-((1H-indol-4-yl)oxy)-3-chloropropan-2-ol was produced in 92% ee. The chlorohydrin 7-(3-chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one, a building block for a derivative of carteolol was produced in 77% yield. (R)-7-(3-Chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one was obtained in 96% ee. The S-enantiomer of this carteolol derivative was produced in 97% ee in 87% yield. Racemic building block 5-(3-chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one, building block for the drug carteolol, was also produced in 53% yield, with 96% ee of the R-chlorohydrin (R)-5-(3-chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one. (S)-Carteolol was produced in 96% ee with low yield, which easily can be improved.


2019 ◽  
Vol 10 (11) ◽  
pp. 3242-3248 ◽  
Author(s):  
Atsushi Obata ◽  
Akane Sasagawa ◽  
Ken Yamazaki ◽  
Yusuke Ano ◽  
Naoto Chatani

The reaction of N-heteroaromatic compounds, such as 2-aryl-pyrrole, benzimidazole, imidazole, indole, and pyrazole derivatives, with alkynes in the presence of a catalytic amount of a nickel complex results in C–H/N–H oxidative annulation.


2019 ◽  
Vol 6 (11) ◽  
pp. 3097-3103
Author(s):  
Lingxue Tang ◽  
Kok-Giap Haw ◽  
Ping He ◽  
Qianrong Fang ◽  
Shilun Qiu ◽  
...  
Keyword(s):  

The crystallisation of SSZ-24 is accelerated by using a catalytic amount of SSZ-13 (CHA) seeds.


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