ETD at Indian Institute of Science
(529 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.
Mostrando recursos 1 - 20 de 33
1.
Asymmetric Synthesis Of Troger's Base Analogues And Studies In Molecular Recognition - Bag, Braja Gopal
Troger's base was the first amine to be resolved where the chirality was due to solely very high inversion barrier around nitrogen atom. Though the molecule was known for over a century, work done during the past decade has shown that Troger's base and its analogues could be used as chiral solvating agent, DNA binding ligand and for the construction of biomimetic molecular receptors and clathrare hosts. Asymmetric synthesis of the Trogers base analogues has also been achieved recently. Because of the rigid, 'V'-shaped chiral nature of this molecule, there is growing interest for the use of this unit in...
2.
Cholic acid based new chiral auxiliaries: development and applications - Mathivanan, P.
The thesis entitled Cholic Acid Bused New Chiral Auxiliaries: Development And Applications has been divided into three chapters. Chapter-I describes the synthesis of chiral auxiliaries (1.3) from cholic acid and Diets-Alder reactions on the corresponding a,B- unsaturated ester derivatives. Chapter-I1 deals with the asymmetric dihydroxylation of a,B unsaturated esters of steroidal alcohols (1-3). Chapter-HI describes asymmetric hydride reduction, hydrogenation and allylation of a-keto esters of cholic acid derivatives (1-3).
3.
Organosulfur Reactions In Organic Synthesis With Tetrathiomolybdate - Ramesha, A R
Recent years have seen a dramatic expansion in synthetic and structural molybdenum - sulfur chemistry. The amplest binary Mo-S moiety in MO$ ion. The thromolybdates derived by sulfur substitution from the 0x0 analogue have interesting chemical properties. Although they have been studied extensively by synthetic inorganic chemists and bio-inorganic chemists as models for enzymes like introgenases, their reactivity towards organic substrates remamed unexplored.
4.
Studies on N-Heterocyclic Compounds - Armugam, S
The thesis entitled "Studies on N-Hetero cyclic Compounds: (a) Reaction of 5,6,7,8-Tetrahydroisoquinolines with Vilsmeier Reagent and (b) Amide Induced in situ Alkylation of 5,6-Dihydroisoquinolines" is presented in two parts. Part I involves a study of the Vilsmeier reaction of 4-cyano-1,3-dihydroxy-5,6,7,8 tetrahydroisoquinoline derivatives, while Part II concerns the in situ alkylation of l-alkyl-4-cyano-3-methoxy-5,6- dihydroisoquinolines in presence of KNH2/liq.NH3.
5.
Synthesis and reaction of spironapthalenones - Sattigeri, J A
The thesis entitled 'syntheses and reactions of spironaphthalenones is presented in four chapters.
A general introduction to the chemistry of spironapththalenones covering the recent literature is given in Chapter I.
Chapter II is divided into four sections. In section I, the generality of the reaction of Spironaphthalenones la-e with NH3OH.HCL to give pyrrolotropones 2a-e has been shown.
A mechanism has been suggested for this interesting rearrangement reaction.
6.
Synthetic investigations on terpenoids - Selvakumar, N
The thesis entitled "Synthetic Investigations on Terpenoids" is divided into two sections. Section 1 deals with the total synthesis of sesquiterpenes belonging to the Zizsene group and Section 2 contains the synthetic investigations on the furanoid dlterpenes of labdane group.
7.
Theoretical Studies Of Fullerenes And Fullerene Derivatives - Rathna, A
The detection of Ceo and Cro in 1985 and the subsequent development of a preparative procedure have opened up a new area of research in carbon chemistry. The study of physico-chemical properties of these molecules is currently being pursued with great interest. The goal of the present thesis is to provide simple generalization concerning the structure and bonding which would be of useful interpretive value in understanding the reactivity patterns. The stability of a large number of derivatives have been examined at uniform levels of semiempirical MO theories. The results are shown to be consistent with simple localized bonding model...
8.
Bile Acid Based Molecular Tweezers And Crown Ethers - D'Souza, Lawrence Joseph
Chapter 1. Introduction to Molecular Tweezers
Whitlock and Zimmerman developed a class of molecular hosts, popularly known as molecular tweezers, which sandwich aromatic guests by ii=ii interaction. Chapter 1 summarizes molecular tweezers of various kinds which have recently been synthesized.
Chapter 2. Design and synthesis of "Bile Acid-Based Molecular Tweezers" Bile acids have a rigid backbone, and the array of hydroxyl groups separated by 5-7 A provides opportunities for the attachment of binding surfaces such as two extended chromophoric units.
9.
Radical cyclisation based approaches to 9-pupukeanone and lignan precursors - Danialdoss, S
Application of radical reactions in the organic synthesis for the formation of carbon-carbon bond has dramatically increased over the last fifteen years by virtue of their high degree of chemo-, regio- and stereoselectivity. The present thesis entitled "Radical Cyclisation based Approaches to 9-pupukeanone and Lignan Precursors" describes the application of radical reactions in the synthesis of isotwistane carbon framework present in pupukeananes, and b-arylmethylbutyrolactones, established precursors of various types of lignans. For convenience, the results are presented in two chapters, & ( I ) Radical annulation approach to chiral analogues of 9-pupukeanones; (2) Synthesis of (+-)-enterolactone and lignan precursors; and...
10.
Synthetic Investigations On Terpenoids - Kaliappan, K
The thesis entitled "SYNTHETIC INVESTIGATIONS ON TERPENOIDS" consists of two chapters.
Chapter I deals with the total synthesis of the sesquiterpenes, 2-pupukeanone 1 Norpatchoulenol 2 and patchouli alcohol 3 and is divided into four sections.
11.
Synthesis Of Natural Products Based On Cyclohexadienes - Hariprakasha, H K
The thesis entitled "Synthesis of Natural Products Based on Cyclohexadienes" consists of two chapters.
Chapter 1 is divided into two parts. Part I gives a brief introduction to the structure, synthesis, biosynthesis and biological activities of some naturally occurring phthalides (eg. mycophenolic acid 1, zinniol2, phthalides 3 & 4). A general strategy for the preparation of highly substituted phthalides is also described. Cycloaddition of 1,s-dimethoxycoclohexa-1, 4-diene with dimethylacetylenedicarboxylate(DMAD) followed by an Alder-Rickert reaction gave the diester 5 which upon hydrolysis with KOH and refluxing with acetic anhydride gave the phthalic anhydride 6. Regioselective reductions of the anhydride 6 gave the phthalides...
12.
Synthetic Investigations In Terpenoids And Steroids - Bijoy, P
The thesis entitled "SYNTHETIC INVESTIGATIONS IN TERPENOIDS AND STEROIDS" consists of 3 Chapters
Chapter-I deals with the synthetic studies on the hexacyclic nortriterpene Pfaffic acid 1, and is divided into two sections.
Section-I begins with a brief introduction to Pfaffic acid 1, a naturally occurring hexacyclic nortriterpene, in particular to its isolation, structural elucidation and antitumor activity. The antitumor activities of the Pfafosides A, B, C, D, E and F, the glycosides of pfaffic acid 1, isolated from the same plant is also described. The discussion presents the synthetic strategy developed to construct the AB ring system along with the results of...
13.
Theoretical Studies Of pie-Facial Selectivity In Organic Reactions - Ganguly, Bishwajit
he thesis entitled "Theoretical Studies of pie-Facial Selectivity in Organic Reactions" involve a computational examination of a suitable reactivity problem in organic chemistry. Systematic and efficient -procedures have been developed and tested for rationalizing observed face selectivities in numerous substrates. In a number of cases precise transition state structures have also been computed in a rigorous manner. The molecules examined are by and large sterically unbiased. Considerable emphasis has been placed on obtaining general interpretations, In particular, the relative contributions of various sterio electronic and electrostatic effect have been considered in detail.Predictions of a-face selectivities haw also been made in...
14.
Computational Studies On Some Plausible Structures Of The Hydrides And Oxyhydrides Of [36-D6h] Fullerene - Paul, Ankan
Fullerenes, the highly symmetric molecular carbon clusters, have been in the limelight of scientific research since their discovery by Kroto and coworkers [1]. The focus of experimental and theoretical studies has centered on C60 and, to a lesser extent, on C70. A few larger counterparts have also been characterized [2]. It is generally believed that the cage compounds with adjacent pentagons are unstable (the so-called 'isolated pentagon rule': IPR) [3]. The smallest possible fullerene which satisfies the IPR is C60. Fullerenes smaller than C60 will necessarily have pentagons fused side by side and hence they are predicted to be unstable....
15.
Synthesis Of Carbasugars And Other Related Structural Motifs - Talukdar, Pinaki
Recent years have witnessed a great deal of interest in the design and synthesis of small molecules, which can mimic complex carbohydrates of vital importance in various life processes. Carbasugars constitute one such class of molecules among several others, in which ring oxygen of sugar is replaced by a methylene unit. Several approaches have been reported in the literature for the synthesis of carbasugars emanating both from carbohydrate and non-carbohydrate sources. While the carbohydrate-based approaches require extensive prote'ction-deprotection maneuver, the non-carbohydrate-based approaches generally have problems of diastereoselection and introduction of chirality.
In the context of synthesis of carbasugars, we envisaged that...
16.
Design And Synthesis Of Novel Interacalator Based Chemical Nuclease - Ghosh, Sumana
Deoxyribonucleic acid and ribonucleic acid under physiological condition are polyanions composed of heterocyclic bases linked through sugar phosphate backbone. Due to Watson-Crick base pairing, DNA exists in double-helical form between two antiparallel strands of nucleic acid. Different conformations of DNA is possible among which the B-DNA form is considered to be the most common, and it is a right-handed double-helix with base pairs stacked at the center. There are two well-defined grooves termed as major and minor grooves, each has characteristic width and depth. Most of the DNA binding proteins generally approach DNA through the major groove, while small molecules...
17.
One-Pot Synthesis Of Chiral Disulfides & Diselenides From ?-Amino Acids Mediated By Ammonium Tetrathiomolybdate In Water - Navin, V
We have described herein a convenient one-pot synthesis of lisulfides/diselenides from a-amino acids mediated by ammonium etrathiomolybdate in water. (Figure 1)
(Figure)
Figure 1 Transformation of ?-amino acids into the corresponding tiiocyanates/selenocyanates/disulfides/diselenides
Halo-de-amination of a-amino acids using HBr/NaNCte followed by treatment with ammonium tetrathiomolybdate (NH4)2]VloS4 jLb provided a general route for the the one-pot synthesis of chiral a,a' bis (dithio) carboxylic acids (Figure 1, 2b). The yields were moderate, limited mainly the moderate conversion of a-amino acids into the corresponding chiral a-bromides.
It was possible to synthesize the 2-thiocyanto carboxylic acids from the corresponding a-amino acids by a similar strategy. Thus diazotization...
18.
Towards The Total Synthesis Of Terpenoid Natural Products - Umarye, Jayant Durgaram
The construction of diverse molecular architecture conceived and created by Nature, continues to be the most exiting and challenging task to the practitioners of organic synthesis. As a result of refinement in isolation and purification techniques, recent advances in the spectroscopic methods particularly two-dimensional NMR spectroscopy and routine use of single crystal X-ray crystallography, the isolation and structural elucidation of the complex natural products has become a routine exercise. Even those natural products which are present in minute quantity, are being unraveled from the newer and exotic sources such as marine flora and fauna, microbial organisms and insect world. This...
19.
Molecular Modulation Of Material Properties: Studies On Nanoparticles, Nanoassemblies, And Low Molecular-Mass Gelator - Srivastava, Aasheesh
The present thesis titled Molecular Modulation of Material Properties: Stud-
ies on Nanoparticles, Nanoassemblies and Low Molecular Mass Gelator deals with the preparation, characterization, and investigations into the properties of gold nanoparticles coated with novel thiols. The coverage of nanoparticle surfaces with these thiols renders them with special characteristics that will be of interest in biological and sensor applications. Also, a novel low molecular mass tetrameric
sugar-based hydrogelator was synthesized and its gelation properties were studied in detail.
Chapter 1 gives a general introduction and an overview about Nanomaterials, with
emphasis towards nanoparticles of gold, which form the basis of this work. It...
20.
Synthesis Of Sesquiterpenes Containing Two Vicinal Quaternary Carbon Atoms - Rao, M Srinivasa
Among nature's creation, terpenoids are more versatile and exciting natural products. In a remarkable display of synthetic ingenuity and creativity, nature has endowed terpenes, more so sesquiterpenes, with a bewildering array of carbocyclic frameworks with unusual assemblage of rings and functionality. This phenomenal structural diversity of this class of natural products makes them ideal targets for developing and testing new synthetic strategies for efficient articulation of carbocyclic frameworks. The present thesis entitled "Synthesis of sesquiterpenes containing two vicinal quaternary carbon atoms" describes the synthesis of a number of herbertane sesquiterpenoids, antimicrobial sesquiterpenes enokipodins A and Bf and spirocyclic sesquiterpenes acorone...
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