Browsing by Author "Raju R. Kale"

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A convenient synthesis of novel glycosyl azetidines under mitsunobu reaction conditions
(2012) Archana Singh; Bhuwan B. Mishra; Raju R. Kale; Divya Kushwaha; Vinod K. Tiwari
A facile, simple, and high-yielding protocol for synthesis of novel glycosyl azetidines was developed from glycosyl-amino alcohols via intramolecular cyclization under Mitsunobu reaction conditions. © 2012 Taylor & Francis Group, LLC.
A facile one-pot MW approach for 3-heteroaryl-2-thioxo-2,3- dihydroquinazolin-4(1H)-one
(Arkat, 2008) Vinod K. Tiwari; Raju R. Kale; Bhuwan B. Mishra; Archana Singh
A microwave-assisted simple, convenient, and high yielding synthetic methodology for diverse thioquinozolinones was developed by the amidine base catalyzed one-pot reaction of anthranilate ester, 1,1′- carbonothioylbis(1H-benzotriazole), and heterocyclic amines containing thiazole, [1,3,4]-oxadiazoles and [1,3,4]-thiadiazole heterocycles. ©ARKAT USA, Inc.
Alkaloids: Future prospective to combat leishmaniasis
(2009) Bhuwan B. Mishra; Raju R. Kale; Rakesh K. Singh; Vinod K. Tiwari
Leishmaniasis, a vector-borne parasitic disease resulting from infection of macrophages by obligate intracellular parasites of genus Leishmania, has been considered a major tropical disease by the World Health Organization. Generic pentavalent antimonials have been the mainstay for therapy in the endemic regions because of its efficacy and cost effectiveness. However, the growing incidence of resistance for the pentavalent antimony complex in endemic and non-endemic regions has seriously hampered their use in these regions. The second line drugs such as amphotericin B, paromomycin and miltefosine are the other alternatives, but they merely fulfill the desired requirements of a safe drug. The recent researches focused on plants have shown a wise way to get a true and potentially rich source of drug candidates against leishmaniasis, where alkaloids have been found more effective. The present review initially highlights the current status of leishmaniasis, synergy of the disease with HIV, therapeutic options available and in later sections summarizes all alkaloids, which have shown significant antileishmanial activities. © 2008 Elsevier B.V. All rights reserved.
Benzotriazole Mediated one-pot Facile Synthesis of N/S-glycosyl Dithiocarbamates
(2009) Archana Singh; Raju R. Kale; Vinod K. Tiwari
A benzotriazole mediated simple, one-pot, facile protocol for diverse N/S/N, S-glycosyl dithiocarbamates with different substitution at thiol chain or at amine chain or at both thiol and amine chains has been developed using bis(benzotriazole-1-yl)methanethione under mild reaction condition.
Benzotriazole-mediated facile synthesis of novel glycosyl tetrazole
(2012) Raju R. Kale; Virendra Prasad; Divya Kushwaha; Vinod K. Tiwari
A facile, simple, and high-yielding synthetic protocol for novel glycosyl tetrazoles has been devised from different carbohydrate-containing amides using benzotriazole methodology under mild reaction condition. © 2012 Copyright Taylor and Francis Group, LLC.
Carbohydrate chemistry and room temperature ionic liquids (RTILs): Recent trends, opportunities, challenges and future perspectives
(2010) Virendra Prasad; Raju R. Kale; Vipin Kumar; Vinod K. Tiwari
Since past few decades, Room Temperature Ionic Liquids (RTILs) have extensively been used in organic synthesis as solvents, catalysts and catalyst/solvents in chemical as well as enzymatic reactions, whereas their interest in various different branches of science is expanding exponentially. RTILs show an enhanced performance in a number of syntheses involving carbohydrates when compared to the conventional organic solvents owing to their very interesting and attractive features, viz. simple handling, high yield, less reaction time, benign environmental character, ease of synthesis and excellent recyclability. Carbohydrates are not known only for their vital commercial applications as foods, drugs and chemical feed stocks etc., but sugar based molecules are also identified to play pivotal roles in various pathologically and physiologically important biological processes including cellular recognition, adhesion, migration, invasion, communication, bacterial/viral infection, tumor metastasis etc. The clear understanding of role of sugars in these important biological events has led to the increased demand for significant amounts of carbohydrate based molecules for complete chemical, biological, medicinal, and pharmacological investigations. Therefore, tremendous efforts have been made to develop novel and facile procedures for the synthesis of sugar based molecules of great biological interest and their modification. With an increasing focus on the glycomics, the RTILs solvent may offer promising solutions in carbohydrate chemistry. However, there is lack of recent and concise reports dealing with the RTILs in the field of carbohydrate chemistry particularly, in relevance to dissolution and functionalization, and their further modifications including glycosylation. This review highlights the application of RTILs that have been extensively used in carbohydrate chemistry. © 2010 Bentham Science Publishers Ltd.
Cu(acac) 2 as novel and efficient catalyst for azide-alkyne cycloaddition reaction: Facile synthesis of regioselective 1,4-triazolyl glycoconjugates
(2012) Divya Kushwaha; Pathya Pandey; Raju R. Kale; Vinod K. Tiwari
Cu(acac) 2, a low-cost and readily available, Cu(II) system has been optimized as an efficient catalyst for carbohydrate based azide-alkyne cycloaddition reaction. A wide variety of 1,4-disubstituted triazolyl-glycoconjugates have been prepared straightforwardly, at ambient temperature using 0.1 equiv of Cu(acac) 2 catalyst in good yields.
Diacetoxyiodobenzene mediated one-pot synthesis of diverse carboxamides from aldehydes
(2012) Virendra Prasad; Raju R. Kale; Bhuwan B. Mishra; Dhananjay Kumar; Vinod K. Tiwari
A novel, one-pot, and highly facile protocol has been devised for an easy access of a series of novel glycosyl carboxamides from aldehydes using diacetoxyiodobenzene in the presence of ionic liquid at ambient temperature. © 2012 American Chemical Society.
Facile route for N1-aryl benzotriazoles from diazoamino arynes via CuI-mediated intramolecular N-arylation
(2010) Raju R. Kale; Virendra Prasad; H.A. Hussain; Vinod K. Tiwari
A facile and high-yielding protocol for diverse benzotriazoles through intramolecular N-arylation of different o-chloro-1,2,3-benzotriazenes using CuI/Cs2CO3 has been developed. © 2010 Elsevier Ltd. All rights reserved.
Facile route for novel quinazolinone-fused azauracils through cyclodesulfurization of thioquinazolinones
(2011) Raju R. Kale; Virendra Prasad; Vinod K. Tiwari
An efficient, novel, short, and high-yielding one-pot protocol for the synthesis of diverse quinazolinone-fused azauracil heterocycles through cyclodesulfurization and intramolecular cyclization of thioquinazolinone using silver cyanate is described. © Georg Thieme Verlag Stuttgart.
Facile synthesis of novel glycosyl carboxamide with sugar in furanose and pyranose form using benzotriazole methodology
(2010) Raju R. Kale; Virendra Prasad; Vinod K. Tiwari
There is an increased demand for significant amounts of carbohydrate based molecules for complete biological, medicinal, and pharmacological investigations where tremendous efforts have been made to develop novel and facile procedure for the synthesis of glycoconjugates and diverse carboxamides. Limitations with the common approaches for amide bond formation, including use of hazardous chemicals, long reaction times, low reaction yields, frequently require strong basic catalysts, strictly anhydrous conditions, harsh reaction conditions, expensive and limited availability of coupling materials, and moreover the less stability of activated acids warrant the search of a simple, short, and high yielding amide bond synthetic methodology. Herein, a facile and high yielding synthesis of novel glycosyl carboxamide with both furanose and pyranose sugar using benzotriazole methodology has been developed under mild conditions. © 2010 Bentham Science Publishers Ltd.
Hypervalent iodine reagents in carbohydrate modification
(2009) Virendra Prasad; Raju R. Kale; Bhuwan B. Mishra; Vinod K. Tiwari
There is an increasing demand for the significant amount of carbohydrate based molecules for complete biological, medicinal, and pharmacological investigations and to have a clear understanding of their role in many important biological events, where tremendous efforts have been made to develop novel and facile procedures for the synthesis of diverse glycoconjugates. Since past few decades polyvalent iodine compounds have been extensively used in organic synthesis due to their very useful oxidizing properties accompanying benign environmental character and commercial availability. However, there is lack of concise and recent reports dealing with the role of hypervalent iodine in the field of carbohydrate chemistry particularly, in relevance to functional group transformation and the regiospecific, stereo-, and/or chemoselective aspects. This review highlights the application of these reagents that have been explored in carbohydrate chemistry up to the fair extent.
Recent developments in benzotriazole methodology for construction of pharmacologically important heterocyclic skeletons
(2010) Raju R. Kale; Virendra Prasad; Prabhu P. Mohapatra; Vinod K. Tiwari
Benzotriazole methodology, nowadays recognized as a versatile, useful, and most successful synthesis protocol, has grown from an obscure level to very high popularity, since benzotriazole can easily be introduced into a molecule by a variety of reactions, activates it toward numerous transformations, is sufficiently stable during the course of reactions, and finally can easily be removed at the end of the reaction sequence. In this review, we briefly describe the way benzotriazole methodology has grown to its present height, the opportunities and its potentiality in the synthesis of diverse pharmacologically important heterocyclic skeletons. © 2010 Springer-Verlag.
Room-Temperature Ionic Liquids in Glycoscience: Opportunities and Challenges
(Bentham Science Publishers, 2021) Sanchayita Rajkhowa; Raju R. Kale; Jyotirmoy Sarma; Abhijeet Kumar; Prabhu P. Mohapatra; Vinod K. Tiwari
Carbohydrates are fascinating molecular scaffolds known for their diverse applications in chemistry, biology, medicine, technology, and materials science. In addition, owing to the notable features of Room-Temperature Ionic Liquids (RTILs) such as high-yield, short reaction time, simple handling, excellent recyclability, and environmentally benign nature, they have been extensively utilized as green solvents, catalysts, or both in a wide range of organic transformation methodologies for easy access of a diverse range of biologically relevant molecules. This review highlights the importance of RTILs that offer promising solutions in glycoscience, particularly in relevance to the dissolution, functionalization, glycosylation, and modification of carbohydrates as well as their challenges, impact, and future perspectives. © 2021 Bentham Science Publishers.
Synthesis and functionalization of coumarin-pyrazole scaffold: Recent development, challenges, and opportunities
(Bentham Science Publishers, 2021) Nitin K. Jadhav; Balkrishna R. Kale; Mohammad S. Alam; Vishwas B. Gaikwad; Virendra Prasad; Raju R. Kale
Heterocycles are the main structural motif of DNA and RNA and play a crucial role in various chemical reactions of metabolisms. Therefore, heterocyclic compounds show good physiological and pharmacological properties. Coumarin and pyrazole scaffolds are present in many commercial drug molecules and natural products. This review overviews the progress made in the synthesis and functionalization of the cou-marin-pyrazole hybrid heterocycle. It also includes discussion on the possible reactive sites of heterocycles, functionalization, and mechanistic pathways to incorporate pyrazole pharmacophore unit in synthesis. Several synthesis and biological studies reveal that the combination of the coumarin-pyrazole moiety is a prominent structural motif to find lead compounds in drug discovery. © 2021 Bentham Science Publishers.