Substantial contributions to Bentham Science Journal Current Organic Synthesis by Indian Authors

COS

Multicomponent 1,3-Dipolar Cycloaddition Reactions in the Construction of Hybrid Spiroheterocycles

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Author(s):NatarajanArumugam, RajuSuresh Kumar, Abdulrahman I. Almansour and SubbuPerumal
Pages 1929-1956 (28)
Abstract:

Spiroheterocyclic ring systems are attractive synthetic targets due to their interesting conformational features and their structural implications on their activity in biological systems. Consequently, a vast deal of research by synthetic organic as well as medicinal chemists pertains to the synthesis of these heterocycles employing diverse synthetic methodologies. Among them, one-pot multicomponent 1,3-cycloaddition reactions have emerged as preferred synthetic protocol in view of their convergence, atom economy, ecofriendliness, flexibility and facile automation. This review article focuses on the assembly of mono-, di- and multispiro heterocyclic hybrids via aforesaid synthetic methodologies with a variety of dipolarophiles.

Palladium Catalyzed C–H Activation and its Application to Multi-bond Forming Reactions

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Author(s): Krishnan Ramachandiran, Thonthula Sreelatha, Neelakandan V. Lakshmi, Thelagathoti H. Babu, Doraiswamy Muralidharan and Paramasiram T. Perumal
Pages 2001-2024 (24)

Abstract:

The focus of the review is on the formation of multiple bonds by palladium catalyzed C-H activation and functionalization. These include alkanylation, alkenylation, arylations, annulations, domino, cascade reaction, coupling and synthesis of spiro compounds. The non-synchronous formation of new carbon-carbon and carbon-heteroatom (N, O) bonds for the construction of various heterocycles is also discussed.

– See more at: http://www.eurekaselect.com/113787/article#sthash.ZC5OrEl6.dpuf


L-Proline Catalysed Domino Reactions for the Synthesis of Heterocycles

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Author(s): Sethuraman Indumathi, Jose C. Menendez and Subbu Perumal
Pages 2038-2064 (27)

Abstract:

L-Proline is a cheap, water-soluble organocatalyst that is able to induce the synthesis of a large number of heterocyclic systems. This work is reviewed, with emphasis on the literature of the 2005-2011 period. The domino reactions have been classified according to the nature of the first step of their proposed mechanisms, as follows: (i) iminium-initiated domino mechanisms; (ii) enamineinitiated domino mechanisms; (iii) reactions proceeding via the intermediacy of dienamines; (iv) reactions in which proline acts as a Lewis base and (v) L-proline/metal catalysed reactions.

– See more at: http://www.eurekaselect.com/113794/article#sthash.BBk9SoXn.dpuf

BSP Journal: Letters in Organic Chemistry [Volume 11, 10 Issues, 2014]

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.

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.

Scholarly Publications by BSP’s Indian Author’s in the Journal, Current Organic Chemistry

Image1. L-Proline Catalysed Domino Reactions for the Synthesis of Heterocycles

Author(s): Sethuraman Indumathi, Jose C. Menendez and Subbu Perumal

Affiliation: Department of Organic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625021, India.

Abstract

L-Proline is a cheap, water-soluble organocatalyst that is able to induce the synthesis of a large number of heterocyclic systems. This work is reviewed, with emphasis on the literature of the 2005-2011 period. The domino reactions have been classified according to the nature of the first step of their proposed mechanisms, as follows: (i) iminium-initiated domino mechanisms; (ii) enamineinitiated domino mechanisms; (iii) reactions proceeding via the intermediacy of dienamines; (iv) reactions in which proline acts as a Lewis base and (v) L-proline/metal catalysed reactions.

 

2. Multicomponent 1,3-Dipolar Cycloaddition Reactions in the Construction of Hybrid Spiroheterocycles

Author(s): Natarajan Arumugam, Raju Suresh Kumar, Abdulrahman I. Almansour and Subbu Perumal

Affiliation: Department of Chemistry, College of Science, King Saud University, PO Box 2455, Riyadh, Saudi Arabia; and Department of Organic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625 021, Tamilnadu, India.

Abstract

Spiroheterocyclic ring systems are attractive synthetic targets due to their interesting conformational features and their structural implications on their activity in biological systems. Consequently, a vast deal of research by synthetic organic as well as medicinal chemists pertains to the synthesis of these heterocycles employing diverse synthetic methodologies. Among them, one-pot multicomponent 1,3-cycloaddition reactions have emerged as preferred synthetic protocol in view of their convergence, atom economy, ecofriendliness, flexibility and facile automation. This review article focuses on the assembly of mono-, di- and multispiro heterocyclic hybrids via aforesaid synthetic methodologies with a variety of dipolarophiles.

 

3. Microwave Assisted Organic Synthesis: Cross Coupling and Multicomponent Reactions

Author(s): Amit Kumar Gupta, Neetu Singh and Krishna Nand Singh

Affiliation: Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi-221005, India.

Abstract

Impact of microwave radiation on organic chemistry has been assessed by workers time to time. This review covers selected recent examples form cross-coupling reactions, multicomponent reactions along with some cycloaddition reactions to reveal the impact of microwave on organic synthesis.

 

4. Applications of Ultrasound in Organic Synthesis – A Green Approach

Author(s): Saurabh Puri, Balbir Kaur, Anupama Parmar and Harish Kumar

Affiliation: Department of Chemistry, Sant Longowal Institute of Engineering & Technology, Longowal-148106 (Pb.), India.

Abstract

Ultrasound irradiation differs from conventional energy sources (such as heat, light, or ionizing radiation) in time, pressure, and energy per molecule. The use of ultrasound waves in organic synthesis has attracted an increasing interest over the last years. Use of ultrasound waves as alternative source of energy is of great interest in the area of green and pharmaceutical chemistry. This review will focus on the uses of ultrasound waves in heterocyclic chemistry, condensation reactions, substitution reactions, oxidation, reduction, addition reactions, photochemical reactions, protection/deprotection reactions, coupling reaction photochemical reactions, polymerization reactions etc

 

5. Renewable Energy via Photocatalysis

Author(s): Ravikrishnan Vinu and Giridhar Madras

Affiliation: Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India

Abstract

The generation of renewable energy through photocatalysis is an attractive option to utilize the abundantly available solar radiation for a sustainable future. Photocatalysis refers to charge-carrier, i.e. electron and hole, mediated reactions occurring on a semiconductor surface in presence of ultraviolet or visible light radiation. Photocatalysis is a well established advanced oxidation technique for the decontamination of toxic organic pollutants to CO2 and H2O. However, the generation of energy in the form of hydrogen, hydrocarbon fuels and electricity via photocatalysis is an upcoming field with great many technical challenges towards practical implementation. This review will describe the fundamental reaction mechanism of (i) photocatalytic water splitting, (ii) photocatalytic H2 generation in presence of different sacrificial agents, (iii) H2 and electricity generation in a photofuel cell, (iv) photocatalytic reduction of CO2 to hydrocarbons and useful chemicals, and (v) photocatalytic water-gas shift reaction. A historic and recent perspective of the above conversion techniques, especially with regard to the development of TiO2-based and non-TiO2 materials is provided. The activity of different materials for the above reactions based on quantifiers like reaction rate, quantum yield and incident-photon-to-current efficiency is compared, and key design considerations of the “best” photocatalyst or photoelectrode is outlined. An overall assessment of the research area indicates that the presently achieved quantum efficiencies for the above reactions are rather moderate in the visible region, and the goal is to develop a catalyst that absorbs visible radiation, provides good charge-carrier separation, and exhibits high stability for long periods of usage.

 

6. Non-Metathetic Behaviour of Olefin Metathesis Catalysts

Author(s): Sambasivarao Kotha, Shilpi Misra, Gaddamedi Sreevani and Bandarugattu V. Babu

Affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.

Abstract

We describe various non-matathetic reactions catalyzed by metathesis catalysts. These examples include: isomerization of olefins, dehydrogenative oxidation, dihydroxylation, allylic alcohol to methyl ketone conversion, dimerization, vinylation of acetylenes, hydrosilylation, Kharasch addition, cyclopropanation, cycloisomerization, hydrogenation, deprotection of N- or O-allyl groups, [2+2+2] cyclotrimerization, [3+2] and [4+2] cycloaddition reactions. These advances indicate that metathesis catalysts have potential to generate new strategies other than the metathesis based methodologies.

 

7. Pyrrole: Chemical Synthesis, Microwave Assisted Synthesis, Reactions and Applications: A Review

Author(s): Shrinivas D. Joshi, Uttam A. More, Venkatrao H. Kulkarni and Tejraj M. Aminabhavi

Affiliation: Department of Pharmaceutical Chemistry, S. E. T’s College of Pharmacy, S. R. Nagar, Dharwad 580 002, Karnataka, India.

Abstract

Pyrrole is one of the main five membered heterocyclic systems reported for its various chemotherapeutic activities. Subsequently, pyrroles have been highlighted as the important biologically active scaffolds. This review focuses on the synthesis, reactions and pharmacological activity associated with pyrroles, and its derivatives. Microwave-assisted reactions are also covered to understand green chemistry aspects of pyrrole and its derivatives. Various pharmacological applications are discussed critically to assess the importance of the compounds.

 

8. Aromaticity in Polyacenes and Their Structural Analogues

Author(s): Ranjita Das, Arindam Chakraborty, Sudip Pan and Pratim K. Chattaraj

Affiliation: Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology Kharagpur, 721302, India.

Abstract

The successful synthesis of different polyacenes including theoretical assessment on the stability of larger acenes are discussed. The existence of favorable aromaticity criterion in polyacenes is understood in terms of different aromaticity indicators like nucleus independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), bond resonance energy (BRE). Clar’s Π- sextet rule is also very much effective in explaining their aromaticity. By virtue of low HOMO-LUMO gap, the probable application of polyacenes in the field of organic electronics is also highlighted. The polyacene analogues of inorganic ring compounds, viz., BN-acenes, CN-acenes, BO-acenes, BS-acenes, AlN-acenes and of alkali ring compounds, viz., Na-acenes and K-acenes also have polyacene-like aromaticity although in few cases the origin of aromaticity and qualitative nature of aromaticity differ significantly.

 
For details on the journal, please visit: Current Organic Chemistry
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