Recursos de colección

ETD at Indian Institute of Science (3.241 recursos)

Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.

Organic Chemistry (orgchem)

Mostrando recursos 1 - 20 de 82

  1. Organic Transformations in Water : Synthetic and Mechanistic Studies towards Green Methodologies

    Shrinidhi, Annadka
    This thesis entitled “Organic Transformations in Water: Synthetic and Mechanistic Studies towards Green Methodologies” is in two parts. Part-I describes various synthetic studies aimed at developing improved methodologies; Part-II describes certain mechanistic studies directed towards an improved understanding of phase transfer catalysis and the hydrophobic effect. Water is uniquely advantageous as a solvent. It is environmentally benign, non-flammable, liquid over a wide temperature range and possesses a high heat capacity that makes it inherently safe. Water also catalyses chemical transformations between insoluble organic reactants. Water thus serves as a reaction medium, a product partitioner and a reaction catalyst.1 Part-I:- Reactions...

  2. A Study of Supramolecular Gels and Self Assembly of Novel Bile Acid Conjugates

    Ramesh, K
    Chapter 1: Functional and Responsive Supramolecular Gels In this chapter ‘supramolecular gels’ derived from small organic molecules with molecular mass of typically less than 2000 daltons are discussed. Representative examples of various low molecular weight gelators based on their natural availability and also divergent functionalities are mentioned (Scheme 1). Scheme 1 Advances in the recent years have been very rapid in the field of supramolecular chemistry of gels giving rise to ‘Tunable responsive gels’. Control of the gel property in a reversible fashion has been the highlight of responsive gels. A few of the gels which are responsive towards various...

  3. Enantiospecific Total Synthesis of Phomopsolide B, Macrosphelides A & E and Total Synthesis & Determination of Absolute Configuration of Synargentolide B

    Gutala, Phaneendra
    Section I of the thesis deals with the enantiospecific total synthesis of phomopsolide B. Phomopsolide B was isolated from a strain of Phomopsis Oblonga. Enantiospecific total synthesis of phomopsolide B was accomplished in 13 overall yield in 12 linear steps using (S)-lactic acid and L-tartaric acid as chiral pool precursors. Present approach involves the efficient use of -keto phosphonate derived from commercially available (S)-ethyl lactate. Horner-Wadsworth-Emmons reaction and Still-Gennari olefination were employed as key reactions in the synthesis (scheme 1). Scheme 1: Total synthesis of phomopsolide B. [This work has been published: Prasad, K. R.; Gutala, P. Tetrahedron 2012, 68, 7489-7493.] Section II of the thesis...

  4. Design and Application of Bile-Salt/Lanthanide Based Hydrogels

    Bhowmik, Sandip
    Chapter 1: Introduction to the luminescent properties of lanthanides Luminescence properties of trivalent lanthanides have been explored extensively over the past few decades owing to their unique properties. Lanthanides emission is known to be due to intra-configurational f-f transitions. Because the partially filled 4f shell is well shielded from its 26 environment by the closed 5sand 5pshells, the ligands in the first and second coordination sphere perturb the electronic configurations of the trivalent lanthanide ions only to a very limited extent. This leads to interesting properties such as long lifetimes, sharp line-like emissions etc. which in turn make lanthanides very...

  5. Studies On the Ring-Opening Reaftions Of Vinylcyclopropanes, Vinylcyclobutanes And Other Snmall-Ring Systems

    Ganesh, V
    The thesis entitled “Studies on the Ring-opening Reactions of Vinylcyclopropanes, Vinylcyclobutanes, and other Small-ring Systems” is divided into four chapters. Chapter 1: Part A: Bromenium Catalyzed Tandem Ring-opening/Cyclization of Vinylcyclopropanes and Vinylcyclobutanes: A [3+2+1]/[4+2+1] Cascade for the Synthesis of Chiral Amidines. In this part of the Chapter, we discuss our serendipitous results in the reaction of vinylcyclopropanes (VCPs), like Δ2-carene under Sharpless aziridination conditions using chloramine-T and phenyltrimethylammonium tribromide (PTAB) as catalyst in acetonitrile. The reaction follows a [3+2+1] cascade pathway involving acetonitrile (Ritter-type reaction) to give chiral bicyclic amidines in very good yield. The reaction was found to be...

  6. Design, Synthesis and Applications of Novel Thiosugars & Amino Acid Derivatives

    Gunasundari, T
    Glycosidases are carbohydrate processing essential enzymes necessary for the growth and development of all organisms such as intestinal digestion, post-translational processing of glycoproteins and the lysosomal catabolism of glycoconjugates. The function of these glycosidases is limited and studies are still in progress to understand their function at cellular level. In recent years, biological role of carbohydrates has resulted in various carbohydrate-based therapeutics2. These carbohydrates serve as a tool to study the function of glycosidases by inhibiting their active site. The concept of inhibition is yet another approach for the discovery of drugs. Glycosidase inhibitors studied are often sugar analogs and...

  7. Enantiospecific Synthesis Of DI- and Linear Triquinanes

    Janardhan, Ghodke Neetu
    Employing a chiral pool strategy, enantiospecific syntheses of di- and triquinanes have been accomplished. α-Campholenaldehyde 95, readily available from the abundantly available monoterpene α-pinene 94, has been utilised as the chiral starting material. To begin with, enantiospecific synthesis of the diquinane 134 has been developed employing Nazarov cyclisation of the cross-conjugated dienone 132 as the key reaction (Scheme 37).71 Synthesis of the dienone 132 was accomplished by selenium dioxide mediated oxidation of the olefinic methyl group in α-campholenyl methyl ether 130, followed by further elaboration of the resultant aldehyde 131. OMe P2O5 MsOH The Nazarov cyclisation strategy has been further extended,...

  8. Synthesis, Structural and Biophysical Studies of Oligosaccharide Glycolipids and Glycosidic Bond Expanded Cyclic Oligosaccharides

    Maiti, Krishnagopal
    Pathogenesis originating from mycobacterial invasion on host cells is prevalent and is a major challenge in efforts towards overcoming the burden of mycobacterial diseases. Complex architecture of mycobacterium cell wall includes an assortment of glycolipids, phospholipids, glycopeptidolipids (GPLs), peptidoglycans, arabinogalactans, lipoarabinomannans and mycolic acid. Aided by thick cell wall envelope, mycobacteria are known to survive in hostile environment. As most antibiotics target the log phase of the bacteria, bacterial survival is also largely dependent on its stationary phase. Mycobacteria have evolved colonization by means of biofilm formation in the stationary phase, so as to survive under stress and hostile conditions....

  9. Studies on the Stereoselective Geminal and Vicinal Heterodifunctionalization of Alkenes

    Balaji, Pandur Venkatesan
    The thesis entitled “Studies on the Stereoselective Geminal and Vicinal Heterodifunctionalization of Alkenes” consists of three chapters. Chapter 1: Part A: Bromonium Ion Mediated Stereoselective Geminal Aminooxygenation of Vinylarenes In this part (part-A) of Chapter 1, the development and mechanistic studies of the first method for the non-Wacker intermolecular geminal aminooxygenation of vinylarenes (styrenes) has been presented (Scheme 1). Sheme 1 The role of the substituent on controlling the competitive vicinal and geminal addition pathways has been studied. It was found that the unsubstituted amino alcohol takes both the vicinal addition pathways, whereas, the introduction of substituent on the aminoalcohols...

  10. Synthesis of Bivalent and Monovalent Sugar Ligands, their Interfacial and Solution Phase Lectin Bindng Studies

    Murthy, Bandaru Narasimha
    Carbohydrate-protein interactions are responsible for several biological functions. While these interactions maintain high levels of specificities, the binding strength of individual carbohydrate-protein recognitions are weak, with dissociation constants (Kd) ~10-3-10-6 M. In order to increase the binding strengths meaningful to physiological functions, multivalent, clustered patches of carbohydrate ligands are required. Synthetic glycoclusters contribute in a significant manner to understand the fine details of the weak carbohydrate-protein interactions. The extent of clustering of the ligands, spatial, topological orientations and the nature of the scaffolds are prominent issues to address the carbohydrate-protein interactions in general. Chapter 1 of the Thesis presents a...

  11. Synthesis of Cyclic N-Sulfonylamidines through Ritter Type Reaction using Carene and Pinene Derivatives via Carbocation Rearrangement

    Ganesh, V

  12. Regioselective Functionalization of Indoles using Directing Group Strategy : An Efficient Transition Metal Catalysis

    Lanke, Veeranjaneyulu
    The thesis entitled “Regioselective Functionalization of Indoles using Directing Group Strategy: An Efficient Transition Metal Catalysis” is divided into two sections. Section A, which is presented in three chapters, describes the regioselective alkenylation of indoles using directing group strategy. Whereas, Section B, which is divided in to two chapters, narrates the synthesis of 4-amino indoles using directing group strategy and site selective addition of maleimide to indole at C2-position. Section A Chapter 1. C2-Alkenylation of indoles The indole ring system is one of the most abundant heterocycles present in nature. The synthesis and functionalization of indoles is one of the...

  13. Investigating the Intercarbonyl X...C' (X=O/S/N) Interactions in Short Peptides and Peptidomimetics. Evidence of charge->II* Interactions. Synthesis and Characterization of Thioimidate Isostere Containing Peptidomimetics

    Tumminakatti, Shama
    This thesis entitled “Investigating the Intercarbonyl X···C′ (X = O/S/N) Interactions in Short Peptides and Peptidomimetics. Evidence of Charge→π* Interactions. Synthesis and Characterization of Thioimidate Isostere Containing Peptidomimetics” is divided into two chapters. First chapter is further subdivided into four sections where investigation of the nature of intercarbonyl X···C′ (X = O/S/N) interactions in short peptides and peptidomimetics has been described. The second chapter also has been subdivided into three parts where the syntheses and characterization of thioimidate (1,3-thiazine) and imidate (1,3-oxazine) isostere containing peptidomimetics have been discussed. Chapter 1: Section A: Revisiting the earlier models for the intercarbonyl O···C′...

  14. Iodine and Copper Catalyzed Oxidative Cross Coupling Reactions : Design and Development of Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions

    Dhineshkumar, J
    Design and Development of Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions” is divided into two sections. Section-A, contains two chapters, describes the catalytic ability of iodine for cross coupling reactions. Section-B, divided into three chapters, presents the azidation of organic scaffolds under oxidative conditions. Section A Chapter 1 presents a C-H functionalization of tetrahydroisoquinolines using iodine as a catalyst under aerobic conditions.1 This methodology employs Cross Dehydrogenative Coupling (CDC) strategy as a key step, which is highly atom economical as it doesn’t require pre-functionalized starting materials.2 Owing to the importance of tetrahydroisoquinoline moiety which is present in the umpteen natural products, considerable...

  15. Enantiospecific Total Synthesis of Indole Alkaloids Eburnamonine, Aspidospermidine, Quebrachamine, Henrycinols A and B and Synthesis of Azepino [4,5 -b] Indolones

    Nidhiry, John Eugene
    The thesis entitled “Enantiospecific total synthesis of indole alkaloids eburnamonine, aspidospermidine, quebrachamine, henrycinols A and B and synthesis of azepino[4,5-b]indolones” is divided into three chapters. In the first chapter, a unified strategy for the enantiospecific total synthesis of monoterpene indole alkaloids (+)-eburnamonine (1), (–)-aspidospermidine (2) and (–)-quebrachamine (3) is described. The chiral pool synthesis commenced with (S)-ethyl lactate 4, which was elaborated to the allylic alcohol 5. Johnson-Claisen orthoester rearrangement of the allylic alcohol 5 furnished the key chiral building block 6 possessing a quaternary stereogenic center. Pictet-Spengler cyclization of tryptamine with the corresponding aldehydes obtained by appropriate functionalization of...

  16. Enantiospecific Total Synthesis of Indole Alkaloids Eburnamonine, Aspidospermidine, Quebrachamine, Henrycinols A and B and Synthesis of Azepino [4,5 -b] Indolones

    Nidhiry, John Eugene
    The thesis entitled “Enantiospecific total synthesis of indole alkaloids eburnamonine, aspidospermidine, quebrachamine, henrycinols A and B and synthesis of azepino[4,5-b]indolones” is divided into three chapters. In the first chapter, a unified strategy for the enantiospecific total synthesis of monoterpene indole alkaloids (+)-eburnamonine (1), (–)-aspidospermidine (2) and (–)-quebrachamine (3) is described. The chiral pool synthesis commenced with (S)-ethyl lactate 4, which was elaborated to the allylic alcohol 5. Johnson-Claisen orthoester rearrangement of the allylic alcohol 5 furnished the key chiral building block 6 possessing a quaternary stereogenic center. Pictet-Spengler cyclization of tryptamine with the corresponding aldehydes obtained by appropriate functionalization of...

  17. Crystal Structures as Mechanistic Probes : Anomeric Effects, Antiaromaticity, Molecular Inclusion and Other Studies

    Mukherjee, Somnath

  18. Design, Synthesis and Applications of Novel Two-Component Gels and Soft-Nanocomposites

    Bhattacharjee, Subham

  19. Design, Synthesis and Applications of Novel Two-Component Gels and Soft-Nanocomposites

    Bhattacharjee, Subham

  20. Novel Redox Responsive Cationic Lipids, Lipopolymers, Glycolipids And Phospholipid-Cationic Lipid Mixtures : Syntheses, Aggregation And Gene Transfection Properties

    Guru Raja, V
    The thesis entitled “Novel Redox Responsive Cationic Lipids, Lipopolymers, Glycolipids and Phospholipid-Cationic Lipid Mixtures: Syntheses, Aggregation and Gene Transfection Properties” elucidates the design, synthesis, aggregation and gene transfection properties of novel cholesterol based cationic lipids with ferrocene as the redox moiety, polyethylenimine based ferrocenylated lipopolymers and cholesterol based non-ionic glycolipids. The thesis also discusses the cationic phospholipid-cationic lipid mixtures as superior gene transfection agents. The work has been divided into six chapters. Chapter 1. Introduction Part A. Various Cholesterol based Systems for Applications as Biomaterials Liposomes composed of cationic lipids have become popular gene delivery vehicles. A great deal of research...

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