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Thursday, November 10, 2016
Call For Paper
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Bentham Science Publishers would like to invite you to submit your research paper for publishing in the Journal of
Thursday, November 3, 2016
Highlighted Article: A Proof of Concept: 2-Pyrazolines (4,5-Dihydro-1H-pyrazoles) Can Be Used as Organocatalysts via Iminium Activation
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A Proof of Concept: 2-Pyrazolines (4,5-Dihydro-1H-pyrazoles) Can Be Used as Organocatalysts via Iminium Activation
Author(s):
Eduardo Rodrigo, M. Belén Cid, Christian Roussel, Nicolas Vanthuyne, Felipe Reviriego, Ibon Alkorta and José Elguero Pages 414 - 419 ( 6 )
Abstract:
Background: In the field of asymmetric aminocatalysis, chiral catalysts derived from azoles (five-membered heterocycles containing exclusively N atoms) play an important role. Surprisingly, all the catalysts used for enamine and/or iminium ion activation derive from pyrrole or imidazole. We decided to test if other reduced azole derivatives could be used as organocatalysts and particularly in aminocatalysis via iminium ion activation. The azole derivatives that came naturally to mind are the 3,5-disubstituted 2-pyrazolines (also called 4,5-dihydro-1H-pyrazoles).
Methods: We synthesized racemic 3,5-diphenyl-2-pyrazoline, separated both enantiomers by chiral-HPLC on a Lux-Cellulose-4 column (heptane/ethanol 70:30 as mobile phase), determined the absolute configuration of their hydrochloride salts (pyrazolinium) by the combined use of experimental rotatory power and B3LYP/6-311++G(d,p) theoretical calculations and use one the enantiomers, the R, as the catalyst.
Results: We have demonstrated that the enantiopure (R)-3,5-diphenyl-2-pyrazoline is able to catalyze the Michael addition of 1-(4-nitrophenyl)propan-2-one to cinnamaldehyde and crotonaldehyde via iminium activation.
Conclusion: This is the first example of activation of both types of enals, aliphatic and aromatic, via pyrazolinium salts and opens new possibilities to the design of other type of chiral organocatalysts than the traditional pyrrole and imidazole derivatives.
Keywords:
Absolute configuration, DFT calculations, 4, 5-dihydro-1H-pyrazoles, Michael addition, organocatalysis, Pyrazolines.
Affiliation:
Department of Organic Chemistry, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain., Aix-Marseille Université, Centrale Marseille, CNRS, iSm2 UMR 7313, 13397 Marseille, France., Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain.
Graphical Abstract:
For More Information Please Visit Our Website Letter in Organic Chemistry
Thursday, October 27, 2016
Most Accessed Article: A Mild and Green Method for the N-BOC Protection of Amines without Assistant of Catalyst Under Solvent-free Conditions
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A Mild and Green
Method for the N-BOC Protection of Amines without Assistant of Catalyst Under
Solvent-free Conditions
Author(s):
Mohammad Majid Mojtahedi, Nina Niknejad and
Hojat Veisi Pages 121 - 125 ( 5 )
Abstract:
A facile, green and versatile method for the
Boc protection of amines has been developed by a treatment with (Boc)2O without any additive at room temperature. The method is
general for the preparation of N-Boc derivatives of aliphatic (acyclic and
cyclic), aromatic, and heteroaromatic amines; primary and secondary amines. The
advantages of this method are green, simplicity, short reaction times and
excellent yields.
Keywords:
N-BOC protection, green, catalyst-free,
solvent-free
Affiliation:
Department of Chemistry, Payame Noor
University (PNU), 19395-4697 Tehran, Iran.
For More Information Please Visit our Letter in Organic Chemistry
Thursday, October 20, 2016
Thursday, October 13, 2016
Letters in Organic Chemistry, Volume 13 - Number 6
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Contents
Letters in Organic Chemistry, Volume 13 - Number 6
Multicomponent Synthesis of Novel Class of Isatin and 5-isatinyli-denerhodanine Based Diaminofuran Derivatives
, 13(6): 393 - 399Robabeh Baharfar and Somayeh Rassi.
DOI: 10.2174/1570178613666160802145006
One-Pot Synthesis of Biscoumarin and Dihydropyrano[c]chromene Derivatives in the Presence of Organocatalysts under Solvent-Free Conditions
, 13(6): 400- 405Reza Heydari and Fahimeh Shahrekipour.
DOI: 10.2174/1570178613666160728122122
1,4-Diazabicyclo[2.2.2]octanium Diacetate: As a New, Effective and Reusable Catalyst for the Synthesis of 3,4- dihydropyrimidin-2(1H)-ones and –Thiones
,13(6): 406 - 413Leila Zare Fekri and Mahsa Movaghari.
DOI: 10.2174/1570178613666160524160125
A Proof of Concept: 2-Pyrazolines (4,5-Dihydro-1H-pyrazoles) Can Be Used as Organocatalysts via Iminium Activation
, 13(6): 414 - 419Eduardo Rodrigo, M. Belén Cid, Christian Roussel, Nicolas Vanthuyne, Felipe Reviriego, Ibon Alkorta and José Elguero.
DOI: 10.2174/1570178613666160815163117
Epoxide Ring-Opening Reactions of Two Diastereomeric 1,2- Epoxy-3-(N-benzyl-N-methylamino)cycloheptanes
, 13(6): 420 - 427Evgeni A. Larin, Valeri S. Kochubei and Yuri M Atroshchenko.
DOI: 10.2174/1570178613666160803143636
5-Alkylidenethiophen-2(5H)-ones as Biofilm Inhibitors
, 13(6): 428 - 436Tore Benneche, Elahe Jafari Chamgordani, Gunnar Herstad, Bjørg Siw Møller Tannæs and Anne Aamdal Scheie.
DOI: 10.2174/1570178613666160620114658
An Efficient Synthesis of 1,2-Oxazine Derivatives via the Reaction of Acetylenic Esters and 1,2-Diketone Monoxime Derivatives in the Presence of Ph3P
,13(6): 437 - 440Mitra Saghafi and Razieh Mohebat.
DOI: 10.2174/1570178613666160624114703
New Heteroaromatic Derivatives of the Anthelmintic Cyclooctadepsipeptide PF1022A by Click-Chemistry
, 13(6): 441 - 445Sivatharushan Sivanathan, Julian Vollrodt and Jürgen Scherkenbeck.
DOI: 10.2174/1570178613666160502161309
Design and Synthesis of Novel C2-symmetric bis-cinchona Alkaloid Derivatives
, 13(6): 446 - 449MingKun Qin, MingXiang Gao, JiangTao Li, ZhiYong Jiang and Lin Yan.
DOI: 10.2174/1570178613666160815094631
Practical and Efficient Large-Scale Preparation of 4-Methylnicotinic Acid
, 13(6): 450 - 452Zhaoxue Yu, Fei Sha and Peng Wang.
DOI: 10.2174/1570178613666160728154935
Friday, October 7, 2016
BSP Journal: Letters in Organic Chemistry Volume 11, 10 Issues
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L-Proline Catalyzed Synthesis of Novel 5-{[2-(2-phenylpiperazin-1-yl)quinolin] methylene}-2,4-dione Derivatives
Author(s): S.S. Praveen Kumar Darsi, K. Shiva Kumar, B. Rama Devi, A. Naidu and P.K. Dubey
Affiliation: Department of Chemistry, Jawaharlal Nehru Technological University Hyderabad College of Engineering, Kukatpally, Hyderabad (A.P), India-500 085.
Abstract
L-proline is found to be an efficient catalyst for the Knoevenagel condensation of 2-chloroquinoline-3- carboxaldehyde 1a-c with an active methylene compound i.e., 2,4-thazolidinedione 2 in IPA affording novel substituted olefins 3a-c. The latter products reacted with N-substituted-3-phenylpiperazine 4a-c in the presence of KF in DMF to afford the corresponding 5-{[2-(2-phenylpiperazin-1-yl)quinolin]methylene}-2,4-dione derivatives 6a-i. Alternatively, 6ai were also synthesized from another reaction sequence 1 → 5 → 6. The structures of the synthesized compounds have been established on the basis of spectral and analytical data.
Synthesis of 3-substituted Coumarins: An Efficient Green Approach Using L-proline as Catalyst in Triethanolamine Medium
Author(s): Devulapally Srikrishna, Syed Tasqeeruddin and Pramod Kumar Dubey
Affiliation: Department of Chemistry, Jawaharlal Nehru Technological University Hyderabad College of Engineering, Kukatpally, Hyderabad, India – 500085.
Abstract
3-Substituted coumarins were synthesized very efficiently, using Knoevenagel method from salicylaldehydes 1 and active methylene compounds 2 under green conditions. The effect of catalyst and solvent on this condensation was studied. L-proline was found to be the best catalyst and triethanolamine the best reaction medium for this reaction.
Synthesis, Characterization, Antibacterial and Free Radical Scavenging Activities of Some New 1,2,4-triazole Schiff Bases and Mannich Bases
Author(s): Kooi-Mow Sim, Siew-Theng Loo and Kah-Cheng Teo
Affiliation: Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, 31900 Kampar, Perak, Malaysia and Centre for Biodiversity Research, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, 31900 Kampar, Perak, Malaysia.
Abstract
The synthesis of a series of 1,2,4-triazole Schiff bases and Mannich bases incorporating an indole moiety is described. The triazole Schiff bases were synthesized from 4-amino-3-mercapto-5-[(1H-indol-3-yl)methyl]-1,2,4-triazole on treatment with a series of arylaldehyde in presence of (+)-tartaric acid as an acidic catalyst. The triazole Schiff bases are further condensed with piperidine and formaldehyde to yield the corresponding series of Mannich bases. The structures of Schiff bases and Mannich bases were established by IR, NMR and mass spectral data. All the synthesized compounds were screened for their antibacterial and free radical scavenging activities. Schiff base 2d comprising of dichloro substitution exhibited promising antibacterial activity against Bacillus subtilis spizizenni, Bacillus cereus and Staphylococcus aureus at MIC 7.81 μ g/ml. Mannich bases demonstrated weak free radical scavenging activity when compared to their Schiff base counterparts.
Ultrasonic and Microwave Assisted Synthesis of Nitrogen-Containing Derivatives of Juglone as Potential Antibacterial Agents
Author(s): Lluvia Itzel Lopez-Lopez, Jesus Javier Vaquera Garcia, Aide Saenz-Galindo and Sonia Yesenia Silva-Belmares
Affiliation: Department of Organic Chemistry, School of Chemistry, Universidad Autonoma de Coahuila, Saltillo, 25280, Coahuila, Mexico.
Abstract
Ultrasound and microwave assisted expedient synthesis of potential antibacterial compounds, 2-(anilino)-5- hydroxy-1,4-naphthoquinone derivatives 3a-c and 5-hydroxybenzo[f]indole-4,9-dione derivatives 8a-c and 10- hydroxybenzo[b]carbazole-6,11-dione derivatives 9a-c have been developed. For the preparation of 3a-c derivatives the methods Room Temperature Synthesis (RTS), Conventional Heating Synthesis (CHS) and Ultrasound Assisted Synthesis (UAS) were performed. In addition, the Conventional Synthesis (CS) and Microwave Assisted Synthesis (MAS) were used for 8a-c and 9a-c derivatives. UAS and MAS showed the best results and are considered green alternatives of synthesis. In general, the yields obtained were good to excellent (58 to 93%). In addition, antibacterial activity against five bacterial strains was tested, showing bacteriostatic activity at lower concentrations and greater bactericidal against Gram negative strains. The compounds carrying chlorine atoms at 2 and 4 positions on the phenyl ring were the most active. The results obtained indicate that the 1,4-naphthoquinone derivatives presented here have promising use as antibacterial agents. A reaction mechanism is also proposed.
For details, please visit: http://benthamscience.com/journal/abstracts.php?journalID=loc&articleID=121704
Laccase Inhibiting Activity of Some Coumarin Derivatives
Author(s): Marina Ti sma, Maja Molnar, Marija Skarica, Milan Cacic and Bruno Zelic
Affiliation: J.J. Strossmayer University of Osijek, Faculty of Food Technology Osijek, F. Kuha ca 20, HR-31000 Osijek, Croatia.
Abstract
Seven coumarin derivatives were screened for their inhibitory effect on laccase utilizing ABTS and L-DOPA as substrates. 2-[(4-Methyl-2-oxo-2H-1-benzopyran-7-yl)oxy]acetic acid (E)-2-[(dihydroxyphenyl)methylene]hydrazides were proven to be stronger inhibitors than corresponding thiosemicarbazides when ABTS [2,2′-azinobis(3- ethylbenzothiazoline-6-sulfonic acid)] was used as a substrate. In kinetic experiments mixed type inhibition was determined for 2-[(4-methyl-2-oxo-2H-1-benzopyran-7-yl)oxy]acetic acid (E)-2-[(2,5-dihydroxyphenyl)methylene]hydrazide and (E)-2-[(3,4-dihydroxyphenyl)methylene]hydrazide. In reaction of L-DOPA (L-3,4-dihydroxyphenylalanine) oxidation catalyzed by laccase none of the tested compounds has shown inhibitory effect.
Efficient Chemical Synthesis of a Scutellarein Derivative Containing Morpholine Ring
Author(s): Qian-Ping Shi, Zhi-Hao Shi, Nian-Guang Li, Yu-Ping Tang, Hao- Tang, Wei Zhang, Min-Zhe Shen, Ze-Xi Dong, Peng-Xuan Zhang, Jian-Ping Yang and Jin-Ao Duan
Affiliation: Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing University of Chinese Medicine, Nanjing 210023, P.R. China.
Abstract
Scutellarin (1) [5,6-dihydroxy-2-(4-hydroxyphenyl)-4-oxo-4H-1-benzopyran-7-yl β -D-glucopyranosiduronic acid] is very effective in the clinical treatment of cerebral infarction and coronary heart disease in China. Pharmacokinetic studies showed that scutellarin (1) is readily metabolized to scutellarein (2) [5,6,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1- benzopyran-4-one] in the intestine by β -glucuronide enzyme prior to absorption. In order to improve the biological activity of scutellarin (1), our group has previously synthesized many scutellarin derivatives based on their in vivo metabolic mechanism. The results showed that morpholine ring substituted at C-7 or C-8 position induced better antioxidant activity, water solubility and anticoagulant activity compared to scutellarin (1). In this paper, an efficient synthetic method for the construction of 5,6,7-trihydroxy-2-[4-[2-(4-morpholinyl)ethoxy]phenyl]-4H-1-benzopyran-4-one (5) is reported. This synthetic route will facilitate the synthesis of scutellarein derivatives containing an amine side chain at the C- 4′ position.
For details, please visit: http://benthamscience.com/journal/abstracts.php?journalID=loc&articleID=121705
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