Open Access Repository of Indian Theses

DeSouza-Ticlo, Donna Trella

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49


Synopsis


Diabetes mellitus (DM), long considered a disease (or metabolic disorder) of minor significance to world health, is now taking its place as one of the main threats to human health in the 21st century.  The past two decades have seen an explosive increase in the number of people diagnosed with diabetes worldwide. While T2DM is numerically more prevalent in the general population, T1DM is the most common chronic disease of children. Recent evidences show an increasing prevalence of T2DM in children, teenagers and adolescents.  The socioeconomic and public health impact of this ‘downward shift in disease onset’ on society is much greater through its negative impact on fertility and reproduction and through effects on work force, premature morbidity and mortality.  

	Increased oxidative stress (OS) is a widely accepted participant in the development and progression of diabetes and its complications. Diabetes is usually accompanied by increased products of free radicals and impaired antioxidant defenses. Mechanisms by which increased OS is involved in the diabetic complications are largely unknown. Nevertheless hyperglycemia, auto-oxidation of glycated proteins, increased production of reactive oxygen species (ROS), decreased antioxidant defense, increased lipid peroxidation and associated membrane degeneration are implicated as main causes of cellular apoptosis or necrosis, which are common in diabetes. 

  Reproductive disturbances in diabetic patients are well known and in males, diabetes is reported to cause testicular degeneration and impotence. In experimental diabetic animals, seminiferous tubules have been reported to show increased tubular wall thickness, severe germ-cell depletion, sertoli cell vacuolization, decreased testicular volume, sperm motility and semen volumes.  Further, decreased numbers of Leydig cells and testosterone secretion have also been reported. However, the pathophysiological mechanisms of testicular dysfunctions in diabetic situations are largely unknown. More importantly the possible involvement of OS mechanisms and their contribution towards diabetes associated male reproductive dysfunctions are poorly understood. 

 In the male reproductive system, ROS and free radicals have been ascribed certain regulatory roles as they can modulate some of the structural and morphological changes that the mammalian spermatozoa undergo during their maturation and development. Mammalian testis is anatomically and physiologically more prone for OS.  Although, testicular cells are endowed with various antioxidant defenses their efficiency is restricted due to their limited concentration and varied distribution.  Sperms are even more vulnerable to OS as they are endowed with more of PUFA, superoxide anion generating system in their membranes, less antioxidants and less repair capacity. An elevated production of ROS in testis either of exogenous or endogenous origin can lead to alterations in tissue physiology or cause oxidative damage to DNA, which is of potential risk to the offspring. 

In view of the above, currently, OS has become the focus of interest as a potential cause of male infertility.  There is paucity of data on the involvement of OS mechanisms in testis under diabetic situations has not been comprehensively investigated. Further, under different degree/duration of diabetic state, data on the perturbations of antioxidant levels in testis and the physiological/biochemical implications that may lead to testicular dysfunctions is lacking. Hence there is a need to understand the occurrence and role of oxidative damage in testis during different phases of diabetes (early and progressive), impairments of antioxidant defenses, susceptibility of sperms to OS, and their genotoxic consequences.  Only such an understanding will aid in developing therapeutic strategies to ameliorate the reproductive dysfunctions in diabetic situations.

Hence, it is hypothesized that “the testis under diabetic situations is likely to be subjected to significant oxidative stress and this mechanism may be partly or wholly responsible for the testicular dysfunctions”.  Accordingly, the scope of the present investigation is (1) to understand the involvement of oxidative stress mechanisms under conditions of diabetes associated male reproductive dysfunction and determine its implications on physiology and function of testis (2) to investigate the occurrence of early oxidative damage in testis, its progression and its genotoxic consequences and (3) to examine the propensity of biomolecules to protect testicular tissue from diabetes-induced oxidative damage.



1.	Our principle findings viz., enhanced lipid peroxidation, higher ROS levels, alterations in key non-enzymic antioxidants (vit E and GSH) and activities of enzymic antioxidants  (CAT, SOD, GST, GPx and GR) in testis of adult diabetic rats (rendered diabetic by STZ) clearly demonstrate the occurrence of significant oxidative stress (OS) in the testis during early (week 1) and progressive phase (week 2 onwards). 
2.	The degree of oxidative damage in testis although marginal during the induction phase, was progressive and consistently higher at week 4 and beyond and was associated with varying degree of pathological lesions (evident beyond 3-4 weeks).
3.	Elevation in the protein carbonyl content, marked reduction in the testicular dehydrogenases accompanied with altered lipid metabolism (in terms of increased cholesterol and phospholipids) are indicative of diabetes associated disturbances in testicular physiology.
4.	Sperms sampled at various weeks from the epididymis exhibited varying degree of oxidative impairments indicating their vulnerability to diabetes induced oxidative stress. Although speculative, the excessive and repeated OS in the epididymal milieu is likely to affect the post-testicular maturation process of sperms and their subsequent functional competence.  
5.	Taken together, we interpret our data to mean that excessive oxidative insult in the testis and epididymal milieu in adult rats may participate as well as contribute significantly to the development of various diabetes associated male reproductive dysfunctions and thereby emphasizes the need and scope for further investigations in this area.  
6.	Our data in growing diabetic rats are suggestive of the increased susceptibility of the developing testis to oxidative damage as evidenced by consistently enhanced MDA and ROS levels, elevated mitochondrial ROS production and increased formation of protein carbonyls. 
7.	Depletion of reduced GSH levels and dramatic elevation in testicular GST activity in testis suggested the involvement of GSH pathway in regulation of diabetes associated oxidative stress in developing testis. 
8.	Hyperglycemia in growing testis was associated with significant perturbations in testicular lipid dysmetabolism and is likely to have direct impact on the testicular steriodogenesis, which merits further studies. 
9.	Induction of oxidative damage in developing testis was nearly 2-4 fold higher at early sampling times (week 1 and 2) when compared to the moderate damage in adult testis evident at similar sampling times. The dramatic elevation (4.5 fold) of testicular GST suggests the magnitude of oxidative impact occurring in vivo and merits further investigation. 
10.	 Our studies clearly demonstrate the induction of early (3/ 5 days) oxidative damage in the testis of diabetic mice model which was detectable in terms of selected biochemical markers such as lipid peroxidation, increased generation of ROS levels, perturbations in GSH levels, alterations (reduction) in antioxidant enzymes and enhanced protein carbonyl levels.
11.	The early oxidative damage was not confined only to the testicular milieu, since major oxidative dysfunctions were also discernible in the epididymal sperms during early time points emphasizing the dual targets of diabetes induced OS in the male reproductive system. 
12.	 Interestingly, STZ-induced early oxidative damage in mice was amenable for amelioration by short-term oral treatment with antioxidants viz., AA and TAU. Both antioxidants provided total protection by inhibiting lipid peroxidation and generation of ROS in testicular homogenates/ mitochondria and restoration of antioxidant enzymes to varying degree.  
13.	 During the progressive phase, increased LPO in mice testis was accompanied by decreased serum testosterone levels, reduced sperm numbers and varying degree of pathological alterations which are attributable to a combined consequence of impaired steriodogenesis and spermatogenesis. 
14.	 High levels of ROS in ES correlated with an increased incidence/ magnitude of abnormal sperms and DNA damage, which are indicative of derangements in the regulation of spermiogenesis.  
15.	 Induction of stage–specific DL type mutations during the first three weeks of mating in diabetic male mice suggested that the primary targets are the post-meiotic germ cells (sperms and spermatids).  While it is difficult to delineate the primary genotoxic effects of STZ and OS mediated effects, nevertheless, this data is indicative of the wide range of genotoxic consequences likely to occur under diabetic situations. 


16.	Oral supplementation of ferulic acid to diabetic rats over a 4-week period significantly offset diabetes-induced oxidative damage in testis measured in terms of MDA/ ROS levels, activities of AOE (GR/GPX), GSH levels and formation of protein carbonyls. 
17.	 Supplementation of -carotene in diabetic rats also markedly mitigated the diabetes-induced oxidative damage in testis as indicated by various biomarkers of oxidative damage measured.
18.	 Dietary supplementation of FB seed powder to diabetic rats showed no hypoglycemic effect, while it offered significant degree of protection against oxidative stress in both testis and liver, and ameliorated the diabetes associated lipid dysmetabolism in testis. 






English

The Lignin-Degrading Enzyme, Laccase from Marine Fungi : Biochemical and Molecular Approaches

Pandit, Dinesh

 A study of gene functions in Indian cassava mosaic virus 
Abstract of the Ph.D. thesis submitted by  
Basavaprabhu. L. Patil 
Department of Plant Molecular Biology, University of Delhi South Campus,  
New Delhi-110021, India 
   Cassava (Manihot esculenta) is the staple or subsidiary food for about a fifth of the 
world’s population, ranks second to sugarcane in carbohydrate content and is an 
important source of dietary calories. Cassava is infected by numerous geminiviruses 
causing cassava mosaic disease (CMD) that cause devastating losses to poor farmers in 
Africa and India. CMD causes severe mosaic, leaf distortion and stunted growth of 
plants, resulting in considerable reduction of yield. Geminiviruses are a large family of 
plant viruses with circular, single-stranded DNA (ssDNA) genomes packaged within 
geminate particles.  
   The causative agent of CMD in India is believed to be Indian cassava mosaic virus 
(ICMV). As a first step towards assessing the diversity of cassava infecting geminiviruses 
(CIGs) in India, we initiated the studies on molecular variants present in the field by 
using PCR-RFLP and multiplex-PCR analysis. These studies showed the prevalence and 
wide distribution of Sri Lankan cassava mosaic virus (SLCMV) in India and the presence 
of several novel types and recombinants. These observations were further confirmed by 
full length cloning and sequencing of a total of four full length viral genomic 
components. 
   The infectious nature of the cloned genomic components was demonstrated by 
inoculation on the experimental host Nicotiana benthamiana. The ability of the cloned 
DNAs to form viable pseudorecombinants between ICMV & SLCMV and multiple / 
mixed inoculation of ICMV & SLCMV DNAs were also tested to investigate the possible 
synergistic effects.  
   The generation of defective DNA (D-DNA) molecules, possibly associated with 
symptom production was demonstrated in N. benthamiana. Cloning and sequence 
analysis of nine such D-DNAs ranging in size from 549 to 1555 nt revealed that they 
contained the cis-acting regions essential for DNA replication as well as portions of other 
viral genes for DNA-B derivatives. Moreover, evidence of deletion and, for the first time, 
recombination events between DNA-A and DNA-B components to produce D-DNA were 
obtained.  
   The nuclear-replicating geminiviruses require the active participation of the two 
movement-related proteins, NSP (Nuclear Shuttle Protein) and MP (Movement Protein), 
which act cooperatively to transport the viral genomes from its site of replication in the 
nucleus to the cell periphery. In order to gain a better insight into the nucleocytoplasmic 
transport of these viral genomes, the behavior of NSP gene of ICMV was analyzed by 
ectopic expression as GFP fusion in the epidermal cells of N. benthamiana leaves 
introduced by biolistic inoculation followed by the subcellular localization by both 
fluorescence and confocal microscopy. The GFP-NSP fusion protein showed nuclear 
localization and was seen to associate with the cell periphery in some cells as 
discontinuous and discrete bands. This association towards cell periphery might indicate 
its interaction with the cell wall and thus hinting towards the possible presence of PTS 
(plasmodesmal targeting signal). The nuclear localization of NSP was also confirmed in 
other hosts N. tabacum and cassava and a non-host, onion. 
   A number of deletion constructs of NSP fused with GFP were generated and their 
analysis revealed the presence of two bipartite NLSs in its N- terminal end (1-34 aa). 
Further, the N-terminal deletion analysis indicated the presence of a cell wall binding 
domain towards the C-terminal end. This is also supported by the concentration of 
glycosylation and myristoylation domains at the C-terminal end, known for their 
membrane binding.  
 
 


A COMPARATIVE STUDY OF THE PALEOPROTEROZOIC MALANJKHAND AND DONGARGARH GRANITOIDS, CENTRAL INDIA: IMPLICATIONS TO CRUSTAL EVOLUTION AND METALLOGENY

K, KARTHIKEYAN

INTER-RELATIONSHIP BETWEEN BORON AND SULPHUR AS MEASURED BY CROP RESPONSE AND SOIL ANALYSIS

BAGARIA, ASHIMA

CRYSTAL STRUCTURE OF ABRUS PRECATORIUS AGGLUTININ-I (APA-I): INSIGHTS INTO THE REDUCED TOXICITY OF APA-I IN RELATION TO ABRIN. FORMATION OF ORDERED NANOTUBES THROUGH SELF ASSEMBLY IN THE CRYSTAL STRUCTURES OF DIPEPTIDES CONTAINING α, β-DEHYDROPHENYLALANINE

N, KUMARESAN


Abstract/Synopsis The present thesis is an attempt towards the realization of the influence of synthetic conditions in the morphology of nanosized NiFe2O4 and subsequent electronic and magnetic behavior. An attempt also has been made for surface functionalization of these nanosized NiFe2O4 to make them amenable for specific applications. This includes the use of these functionalized particles as catalyst support for the development of a magnetically separable catalyst. Also these materials are synthesized via surfactant-mediated routes to achieve excellent control over morphology and magnetic properties and to make them soluble in specific solvents so that they can be used for specific applications. The Thesis has been divided mainly to 4 chapters.          Chapter 1 begins with an introduction to ferrite nanoparticles with an overview of the synthetic methods, properties and applications. The reasons for the tremendous interests in ferrites, the challenges in the development of suitable synthetic methods for better control of the properties and the scientific concepts have been discussed. Chapter 2 deals with the synthesis of NiFe2O4 nanoparticles by hydrothermal route and the effect of reaction conditions on the conductivity behavior of the material. Here we are discussing in detail about the change in conductivity from n-type to p-type when the pH of the reaction medium has been changed keeping all other conditions identical. We observed n-type conductivity in these synthesized materials when the pH of the reaction medium was maintained at either 7 or 8. When the pH of the reaction medium has been increased to a value greater than or equal to 9, the materials starts exhibiting p-type conductivity behavior. A detailed study on the structural, morphological, electrical, magnetic and elemental analysis has been made and correlated to understand the mechanism of conductivity. 
Chapter 3 has been divided into two parts. In part A we have discussed about the surface functionalization of the hydrothermally synthesized NiFe2O4 nanoparticles with dopamine to ensure its high dispersibility in high polar solvents like water, ethanol etc. This opens up the possibility of using these surface functionalized nanoparticles as a support for noble metal to design a novel magnetically separable catalyst system that can be used for catalysis of a number of scientifically and industrially important organic transformation reactions. Characterization of the prepared catalyst system has been done with XRD, FTIR, TEM, ICP-AES, XPS and VSM. The excellent efficiency and reusability of the catalyst system for a wide range of organic reactions have been discussed in the part II. These include hydrogenation of a range of unsaturated organic compounds, Heck coupling reaction and Suzuki reaction. In Chapter 4 we have made an attempt to synthesize monodisperse and size selective NiFe2O4 nanoparticles with solvent selective dispersity. Such particles are in great demand in the recent field of technology due to the excellent control over the magnetic properties because of their size selectivity. At the end the inferences made from the study and the scope of future work has been included. Finally appendix deals with all other works carried out during the PhD period. 




CHARACTERIZATION OF NOVEL PIGMENTS PRODUCED BY ASPERGILLUS CARBONARIUS AND AN APPROACH TOWARDS INTEGRATED FERMENTATION PROCESS FOR PIGMENTS AND POLYGALACTURONASE PRODUCTION USING THE FUNGUS

Dhale, Mohan A

SYNTHESIS OF α-AMINOACID FUNCTIONALISED NOVEL FLUORO QUINOLONES AS ANTI-BACTERIAL AGENTS, POLYCYCLIC BENZIMIDAZOLES & DEVELOPMENT OF NEW METHODOLOGIES

Introduction:
              Compounds containing fluoroquinolone ring system are known to possess antibacterial activity. The presence of fluorine often leads to increased lipid solubility thereby enhancing rates of absorption and transport of drug in vivo. Non-fluorinated quinolones have been considered as the first generation antibacterials during 1960`s. The introduction of fluorine into quinolone moiety gave rise to second generation quinolones includes Norfloxacin, Ciprofloxacin, Enoxacin etc, which are more potent in vitro, broader antibacterial spectra and have good pharmacological property. However, recent investigations have shown the occurrence of multidrug resistance to bacterial infections. One of the examples is Ciprofloxacin, the worldwide sales of this antibiotic with a turnover of $ 1.26 billion in 1995. This drug is showing resistance problem (Chem. Ind. 17-2-1997, page 131). To overcome this problem, a search for new drugs in the form of tricyclic/polycyclic quinolones, which are considered as third generation quinolones has began. Some of them are identifies as more potent than Ciprofloxacin, however over a period of time resistance problem is at stake. Thus, an extensive research is under progress to get new lead molecules. Preparation of nucleic acid substituted quinolones and other substitutions at different places are considered as fourth generation anti-bacterial compounds retaining the basic skeleton in the structure.
The broad objective of the present research programme is to make a systematic study on the synthesis of α-aminoacid functionalised quinolone anti-bacterial agents as target molecules. And also studies on the formation of hetero ring fused benzimidazoles and strategic new synthetic methodologies for 4(3H) quinazolinones, 4H-pyrans and homoallylic alcohols are well presented. The thesis entitled Synthesis of α-amioacid functionalised novel fluoroquinolones as anti-bacterial agents, polycyclic benzimidazoles & development of new methodologies consists of introduction to quinolone class of compounds, their methods of synthesis and advanced techniques used for organic synthesis are described in Chapter-1. Chapter- 2 deals with the synthesis of novel trifluoromethyl substituted isoindolo benzimidazoles by an elegant method, mechanism of formation of products and structural elucidation by spectra. The chapter-3 covers the efforts to make isoindolo imidazo fused quinolones from the isoindolo benzimidazoles and synthesis of α-amino acid functionalised fluoroquinolones, from quinoline-3-carboxylic ester. The synthesis of α-aminoacid functionalised novel 7-trifluoromethyl substituted quinolones, from quinoline-3-carboxylic ester are described in Chapter-4. Chapter-5 deals with the methodologies developed for quinazolinones, poly functionalised 4H-pyrans and synthesis of homoallylic alcohols. Chapter-VI describes the anti-bacterial activity studies of various fluoro-quinolone compounds synthesized in earlier chapters.
Chapter –1:- A Micro Review on fluoroquinolones & advanced techniques in organic synthesis. 
The Fluoroquinolones are analogues of the earlier developed antibacterial agent Nalidixic acid 1. Since the discovery of Norfloxacin 2 in the early 1980`s, an intense research efforts in this class of anti-bacterials was in progress and many fluorinated quinolones like Ciprofloxacin 3, Ofloxacin 4, Enoxacin 5, Pefloxacin 6, Lomefloxacin 7, Fleroxacin 8, Sparfloxacin 9, Tosufloxacin 10 etc. have been successfully developed with structural modifications for clinical uses as broad spectrum antibacterials.



	The importance of fluorine in drug molecules and the synthetic approach of substituted quinolones, hetero ring fused tricyclic and polycyclic quinolones and nucleic acid substituted quinolones are well described. 
	A brief intoduction, principle and synthetic application of microwave irradiation technique is also described.


Chapter–2:- Synthesis of novel trifluoromethyl substituted Isoindolo      benzimidazoles
          A number of trifluoromethyl substituted heterocyclic compounds such as Mefloquine, Fluoxetine, Flutamide etc., as Pharmaceuticals, several fungicides, herbicides, pesticides as agrochemicals are available as commercial products. In continuation of our research in the preparation of hetero ring fused quinolones, an active intermediate trifluoromethyl substituted isoindolo benzimidazoles are synthesized. The main synthon 3-nitro-5-trifluoromethyl-o-phenylene diamine is prepared from 4-chloro bezotrifluoride. The synthon on nitration, amination and partial reduction furnished the diamine (Scheme-1). 

Reaction of 3-Nitro-5-trifluoromethyl -1,2- Phenylene Diamine 11 with aromatic/aliphatic anhydrides
The synthesis of new trifluoromethyl-substituted 11H-isoindolo[2,1-a] benzimidazol-11-one derivatives are prepared by the condensation of 3-Nitro-5-trifluoromethyl-O-phenylenediamine and aromatic/aliphatic anhydrides in presence of ZnCl2 under solvent-free microwave irradiation conditions. Due to presence of two deactiving functional groups on O-phenylene diamine, the reaction times are longer with lower yields. In order to reduce the reaction times and to facilitate simplified isolation procedure, the reactions are carried out under microwave irradiation conditions. The formation of the  products depends on the intensity of power used for microwave irradiation conditions. The intermediate 2-aryl benzimidazole derivatives 13 obtained at 450 W and isoindolo benzimidazole 14 are formed at 800 W. The structure of the intermediate 13 is characterized by spectral data and is further confirmed by synthesizing an authentic starting from 3,5-dinitro-4-chloro benzotrifluoride as shown in the Scheme-2. 
All compounds are new and characterized based on their spectral data. In order to generalize the synthetic method, the diamine is reacted with tricyclic anhydride to give 2-aryl benzimidazole 15 and further cyclisation furnished pentacyclic derivative 16.
This work has been published in Heterocycles, 2005, 65, 10, 2329-2337.

Chapter – 3: - Synthesis of α-aminoacid functionalised novel 6-fluoroquinolones 
           Trifluoromethyl substituted nitro-isoindolo benzimidazole 14 on reduction with Pd/H2 gave the corresponding amine derivative 18. The latter on treatment with EMME in refluxing diphenyl ether resulted open chain derivative 19. This open chain compound 
 under different set of conditions including heating in presence of either PPA or diphenyl ether did not under go cyclisation except recovery of starting material. This is attributed to the presence of powerful electron withdrawing trifluoromethyl group which deactivated ortho position as a result no cyclisation (Scheme-3).  
 
 Unsuccessful attempts to synthesise isoindolo imidazole ring fused quinolones led to the preparation of α-aminoacid functionalised fluoroquinolones of much higher potent molecules than hetero fused quinolones. 
α-Amino acid functionalised fluoroquinolones:
The synthetic methodology involves condensation of 3-chloro-4-fluoro aniline 20 with EMME and its thermal cyclisation gave compound 21. The 6-fluoro-quinoline ester 21 is an interesting and important synthon is further utilized in synthesis of a new series of α-aminoacid functionalised fluoro-quinolones.
Thus the 6-fluoro-quinoline ester 21 was treated with various α-aminoacids (L-aminoacids) in 1:2 proportions under basic conditions resulted the compound 22. Based on spectral data they are characterised as α-aminoacid functionalised quinolones (3-substituted). Compound 22 is alkylated by ethyl iodide with an aim to get N-ethylated compound and in that process acid group is also esterified as 23. Further hydrolysis of the ester compound 23 with LiOH gave the corresponding acid 24. The chlorine group is replaced with piperazine ring to afford the target compound 25 (Scheme-4).

The target molecule α-amioacid functionalised 6-fluoro-quinolones 25 and their intermediates 22, 23, 24 (total 24 new compounds) are evaluated for their antibacterial activity.
Chapter – 4: - Synthesis of α-aminoacid functionalised novel 7-trifluoromethyl substituted quinolones. 
Fluorine containing α-aminoacid functionalised quinolones showed promising activity against Gram +ve and Gram –ve species comparable with Ciprofloxacin. The presence of trifluoromethyl group in the molecule is hopefully enhance the activity. Thus we have designed the synthetic strategy to prepare CF3 substituted α-amioacid functionalised quinolones to see their bioactivity.
Condensation of 3-trifluoromethyl aniline 26 with EMME and thermal cyclisation gave compound 27. The 7-trifluoromethyl quinoline ester 27 is reacted with α-aminoacids (L-aminoacids & D-aminoacids) in 1:2 proportions under basic conditions to afford the compound 28. Based on spectral data they are characterised as α-aminoacid functionalised 7-trifluoromethyl quinolones (3-substituted). Alkylation of compound 28 with ethyl iodide to get the N-ethylated compounds and acid group is also protected as ester compounds 29. The hydrolysis of the ester functionality of compound 29 with LiOH gave the corresponding acid compound 30 (Scheme-5).

The target molecule α-amioacid functionalised 7-trifluoromethyl substituted quinolones 30 and their intermediates 28, 29 (total 24 compounds) are evaluated for their antibacterial activity.   
Chapter-V: - New synthetic methodologies
The invention of new methodologies for known molecules, which are active, synthons useful for further transformations into bioactive molecules, is an ongoing process. In this direction three ring systems are selected and developed an elegant method of preparation and the details are described.
1. Quinazolinones
Quinazolin-4-(3H)-one derivatives possess a broad spectrum of biological and pharmaceutical activities. Several bioactive natural products contain quinazolinone moiety. The products like, Febrifugine and Isofebrifugine, which are naturally occurring 2- substituted 4-(3H)-quinazolinones, are highly potential antimalerial compounds. 
An one-pot synthesis of 2,3-disubstituted 4 (3H)- Quinazolinones 31 is prepared by  efficient coupling of three components, isatoic anhydride/anthranilic acid, orthoesters and amines in the presence of Nafion- H (perfluorinated resin-sulfonic acid) as a heterogeneous catalyst. The reaction occurred within a few minutes under solvent-free microwave irradiation conditions to afford the products in good yields (Scheme-6). This catalyst has been recovered and recycled without loss of activity. 

This piece of work is published in Synlett, 2006, 15, 2507-2509.
2. Poly functionalised pyrans
The chemistry of polyfunctionalised 4H-pyrans is an on-going area of interest because of their wide range of applications. These 4H-pyrans are Isosters of 1, 4-dihydro pyridine with potential pharmacological interest and active synthons that have been extensively used in heterocyclic synthesis. The 4H-pyrans are synthesized mainly by three-component coupling reaction of aromatic aldehydes, malononitrile and ß-ketones/ ß -diketones catalyzed by bases like triethylamine, piperidine etc. Alkali metal fluorides are also used in solid-liquid reactions more specifically for halogen exchange reactions and the reactivity increases from sodium fluoride to cesium fluoride.  Alkaline metal fluorides or metal salts are also used in amination process and Michael addition reactions.  In continuation of our interest in the development of new procedures by using suitable catalysts from simple available starting materials, we developed first time a novel methodology for the synthesis of polyfunctionalized   4H-pyrans in shortest reaction time using Rubidium fluoride as a catalyst.			
The methodology involves an aldehyde, active methylene compound and a third component 1,3-diethyl acetone dicarboxylate/ethylacetoacetate/1,3-diketones/ diethyl malonate in presence of catalytic amount of Rubidium fluoride under thermal conditions to give the desired pyrans.  The rubidium fluoride acts as a base and promotes reaction by abstracting a proton from active methylenes sequentially in two folds as a result the Knoevenagel condensation with aromatic/aliphatic aldehydes and malononitrile to form an alkene intermediate which in situ reacts with 1,3-diethyl acetone dicarboxylate/ethylacetoacetate/1,3-diketones/diethyl malonate by Michael addition to give polyfunctionalized 4H-pyrans 32 in good yields (Scheme-7).  

These results are published in Synthetic Communications, 2004, 23, 4431- 4437. 
3. Homoallylic alcohols
In recent years the synthesis of homoallylic alcohols has become an intense research area. Homoallylic alcohols are useful tools for the construction of complex molecules and can be easily converted into many important building blocks for natural products synthesis. Lewis acid catalyzed C-C bond forming reactions have gained much importance in organic synthesis because of their mild reaction conditions and high selectivity. Recently, we found that GdCl3.6H2O has become an attractive candidate as a powerful Lewis acid in C-C bond forming transformations, which would extend the scope and generality of these allylation reactions. 
Carbonyl compounds efficiently undergo nucleophilic addition reactions with allylstannanes in the presence of GdCl3.6H2O in acetonitrile under extremely mild reaction conditions to give the corresponding homoallylic alcohols in excellent yields and with high chemoselectivity.





These results are published in Tetrahedron Lett., 2006, 47, 4315-4318.

Chapter – VI: - Anti-bacterial activity of Fluoro-quinolones
Chapter- VI describes the studies of anti-bacterial activity of the α-aminoacid functionalised Fluoro-quinolones. These compounds are tested for their antibacterial activity against Gram +ve (Bacillus Subtilis, Staphylococcus Epidermidis and Staphylococcus Aureus) and Gram -ve (Escherichia Coli, Klebsiella aerogene and Pseudomonas Aeruginosa) species. The tests adopted for screening and results exhibited by the compounds are described. The preliminary results showed that some of the compounds have promising activity.







Physiology of Monascus purpureus in relation to metabolite production and application as functional food

HIMA, BINDU M.

MICROBIAL AND BIOCHEMICAL STUDIES ON GENTAMICIN PRODUCTION BY FERMENTATION USING FREE AND IMMOBILIZED CELLS OF MICROMONOSPORA SP.

JOBBY, M K

Abstract


	
This thesis entitled “Synthesis of New Glycosubstances, attempted synthesis of Isoavenaciolide and New Reagents for the conversion of alcohols into p-methoxybenzyl ethers” is divided into three chapters.
Chapter 1: Synthesis of New Glycosubstances
This chapter is divided into two sections.
Section A describes the synthesis of carbon-carbon linked disaccharides using furan as masked sugar synthon and new furyl sugars as intermediates for ‘new glycosubstances’.
Section B deals with the description on the synthesis of acetylenic new glycosubstances, which are useful intermediates for the synthesis of New Chemical Entities of therapeutic value.
Section A: This section is further divided into two parts.
Part I: Synthesis of C(4)-C(5) linked (L)- and (D)-disaccharides from ‘diacetone glucose’
The role of carbohydrates in nature goes under the broad heading of “Glycobiology”1, an eye-opening subject encompassing many areas of interest particularly to the synthetic organic chemist and more recently receiving attention from a therapeutic drug development aspect2.

The C-glycosides3, where a methylene group replaces the interglycosidic oxygen atom, are non-metabolisable analogues of natural disaccharides and represent an interesting class of compounds for therapeutic studies. Synthetic C-glycosyl compounds are starting chiral synthons, suitable for the synthesis of complex molecules, as they contain a large number of chiral centres and functional groups. In a broader context, this subclass also includes examples in which the monosaccharide units are connected either directly or by way of more extended as well as substituted carbon spacers.

In the present study, addition of 2-furyl lithium to the enantiopure aldehyde template 4 obtained from DAG and further transformations was identified in offering a direct access to the disaccharides 1, 2 and 3, where the new sugar unit has been constructed from the furan moiety, while chirality was induced from the parent sugar template.
Accordingly, addition of 2-furyl lithium to the known aldehyde 4 (Scheme 1) afforded the derivatives 5a and 5b as a diastereomeric mixture separable by column chromatography. However, this mixture was successively converted into the major diastereomer 5a by a two step synthetic sequence viz a) oxidation of the diastereomeric mixture under Swern oxidation conditions and b) subsequent reduction of the ketone 6 with NaBH4.
Scheme 1
Reagents: a) 2-furyl lithium, THF, -780C; b) (COCl)2, DMSO, Et3N, CH2Cl2, -780C; c) NaBH4, MeOH, 00C.	

Oxidative unmasking of furan4 with Br2-pyridine in aqueous acetone gave the lactols 7 (Scheme 2), which on reaction with Ag2O-MeI, was subsequently converted into an inseparable mixture of -O-methyl pyranosides 8.
Scheme 2

Reagents: a) Br2, pyridine, aqueous acetone; b) Ag2O, MeI; c) NaBH4, MeOH, 00C; d) Ac2O, pyridine; e) OsO4, t-BuOH: THF.	

Stereoselective reduction of 8 using NaBH4 in MeOH afforded after chromatographic purification, the two -glycosides 9 (minor) and 10 (major) in 3:5 ratio while the -anomers 11 were not separable. The major isomer 10 was subjected to acetylation (Ac2O, pyridine) to give the acetate 12, which on selective5 cis dihydroxylation of the double bond using OsO4-NMO in t-BuOH-THF gave the diol 13. Finally, acetylation of the diol 13 (Ac2O, pyridine) gave the tri-acetate 1.
Similar functional group transformations performed on the minor isomer 5b resulted in obtaining 2, the antipode of 1 and 3. Accordingly, oxidative ring opening of 5b gave the lactols 7a (Scheme 3), which were subsequently converted into the methyl glycosides 8a. Reduction of the enones 8a with NaBH4 and chromatographic separation gave the allylic alcohols 9a (major) and 10a (minor) in 2:1 ratio. Acetylation of 9a and chromatographic purification afforded 11a (major) and 11b (minor). These were subsequently submitted to catalytic osmylation to afford the diols 12a and 12b, which on acetylation furnished the respective tri–acetates 2 and 3.
Scheme 3

Reagents: a) Br2, pyridine, aqueous acetone; b) Ag2O, MeI; c) NaBH4, MeOH, 00C; d) Ac2O, pyridine; e) OsO4, t-BuOH: THF.	


Part II: Synthesis of furyl sugars – intermediates for ‘new glycosubstances’
 In the preceding section, D-glucose was efficiently converted into furyl sugars (Scheme 1).
Scheme 1

Reagents: a) 2-furyl lithium, THF, -780C; b) (COCl)2, DMSO, Et3N, CH2Cl2, -780C.	

Similarly, galactose diacetonide 4 was subjected to oxidation to give 5, which on reaction with 2-furyl lithium gave 6 (Scheme 2) as an inseparable mixture of isomers. Further oxidation of 6 under Swern conditions gave the keto derivative 7.
Scheme 2

		Reagents: a) (COCl)2, DMSO, Et3N, CH2Cl2, -780C; b) 2-furyl lithium, THF, -780C.

In a further study, aldehyde 5 (Scheme 3) was converted into acetylene 9 through 8. Reaction of 9 with 2-furaldehyde gave the furyl sugar 10.
Scheme 3

Reagents: a) PPh3, CBr4, CH2Cl2, 00C; b) n-butyl lithium, THF, -780C; c) n-butyl lithium, 2-furaldehyde, THF, -780C.

Likewise, the known olefin 11 (Scheme 4) was subjected to 1, 3-dipolar cycloaddition reaction with the oxime derived from furaldehyde to give the adduct 12, which on reduction using LAH afforded the furyl derivative 13.

Scheme 4
	Reagents: a) PPh3, I2, Imidazole, Toluene, 1100C; b) furaldoxime, NCS, Et3N, CH2Cl3, RT; c) LAH, ether, 00C.

In a similar study, the known alcohol 14 (Scheme 5) on oxidation with DMSO-(COCl)2 gave the aldehyde 15, which on reaction with 2-furyl lithium afforded 16a and 16b. Further oxidation of the isomeric mixture furnished the keto derivative 17.
Scheme 5
Reagents: a) TMSOI, t-BuOK, DMSO; b) (COCl)2, DMSO, Et3N, CH2Cl2, -780C; c) 2-furyl lithium, THF, -780C; d) NaBH4, MeOH.

		The thus prepared furyl sugars are very useful intermediates for the synthesis of C-disaccharides, glycosyl hydroxy, keto and amino acids, aza-C-disaccharides and others. 












SECTION B: Synthesis of (2R, 5R)-5-Ethynyl-2-(p-fluorophenoxymethyl)-3, 4-O-isopropylidinetetrahydrofuran from mannose diacetonide:
Chiral tetrahydrofuran based compounds such as A and several 2, 5-disubstituted tetrahydrofurans with biological activity were found in nature6. The research for the development of new drugs based on such chiral tetrahydrofurans resulted in several analogues having anti-inflammatory activity. Such a research resulted in a therapeutically interesting tetrahydrofuran A and its stereoisomers as potent 5-LO inhibitors7. In furthering the research on the development of new chiral furans with potent activity, synthesis of 1 was reported starting from ‘mannose diacetonide’.

1, is a tetrahydrofuran derivative related to A, with a dihydroxy group. The synthesis of acetylene 2 would serve as a key intermediate for the synthesis of NCEs and radio labelled compounds for the metabolic studies. As seen from the Scheme 1, it was envisaged that 2 could be made from ‘mannose diacetonide’ 3 by the transformations as indicated. 
Scheme 1
Accordingly, the known alcohol 4 (Scheme 2) was subjected to tosylation using p-TsCl and Et3N in CH2Cl2 to give 5, which on etherification with p-fluorophenol using NaH in dry DMF gave 6 in 53% yield. Deprotection of isopropylidene functionality in 6 with catalytic Conc. HCl in MeOH at room temperature afforded the diol 7, which on oxidative cleavage with NaIO4 in the presence of aqueous NaHCO3 in CH2Cl2 gave the corresponding aldehyde 8 (79%). Finally, aldehyde 8 on treatment with CBr4 and Ph3P 


in CH2Cl2 at room temperature afforded dibromo compound 9, which on further reaction with n-BuLi gave 2 in 77% yield.
Scheme 2

Reagents: a) TMSOI, t-BuOK, DMSO, 0ºC to RT, 1 h; b) p-TsCl, Et3N, CH2Cl2, RT, 4 h; c) 4-F-C6H4OH, NaH, DMF, 80ºC, 5 h; d) Conc. HCl, MeOH, RT, 2 h; e) NaIO4, saturated aqueous NaHCO3, CH2Cl2, RT, 6 h; f) CBr4, Ph3P, CH2Cl2, 0ºC to RT, 30 min; g) n-BuLi, THF, -78ºC to RT, 2 h.

Thus, in the present study, the acetylene 2 was prepared by the introduction of hydroxymethylene substituent at C-1 of mannose diacetonide while C-5 was converted to acetylene moiety.
In a further study, the change of the sequence, i.e., introduction of -CH2OAr group at C-5 position and acetylenic substituent at C-1 position results in a different isomer of 2. Accordingly, 3 (Scheme 3) was treated with diphenyldisulphide and TBP in dichloromethane to afford the thioglycoside 10. 10 was hydrolysed with catalytic Conc. HCl in MeOH for 2 h, to afford the diol 11, which on oxidative cleavage with NaIO4 in aqueous dichloromethane afforded the aldehyde 12.
Scheme 3

Reagents: a) PhSSPh, Bu3P, CH2Cl2; b) H+, MeOH; c) NaIO4, aqueous CH3CN; d) NaBH4, MeOH; e) p-TsCl, Et3N, CH2Cl2; f) 4-F-PhOH, NaH, DMF, 80ºC; g) Ammonium molybdate, H2O2, EtOH.

Reduction of 12 with NaBH4 in MeOH gave the hydroxy compound 13. Tosylation of the hydroxyl group in 13 using TsCl and Et3N in CH2Cl2 afforded 14, which on reaction with 4-F-C6H4OH using NaH in DMF gave 15. The next step was to oxidise thiophenyl substituent to sulfone funtionality, which can be substituted with the required R-group through zinc mediated coupling. Oxidation of thiophenyl substituent in 15 was achieved with ammonium molybdate and H2O2 in ethanol affording the sulfone 16. However, efforts to substitute sulfone moiety in 16 with zinc mediated alkynyl bromide coupling met with failure in offering 17.

CHAPTER 2: New reagents for the conversion of alcohols into p-methoxybenzyl ethers

		This chapter is dealt with the description of development of new methodologies for the conversion of alcohols into p-methoxybenzyl ethers using the lanthanide triflates such as Yb(OTf)3 and Y(OTf)3 as Lewis acid catalysts and with newly developed reagents.
		
This chapter is further divided into two sections.

SECTION A: p-Methoxybenzyl acetate (PMBA)- A new reagent for the conversion of alcohols into p-methoxybenzyl ethers through Yb(OTf)3 catalysis
		The p-methoxybenzyl group is frequently used for the protection of alcohols, which is introduced by NaH and p-methoxybenzyl bromide in the conventional method where base sensitive groups are not compatable. Herein, simpler method for the preparation of PMB-ethers is described employing milder conditions wherein acid and base sensitive groups do survive the reaction conditions.
		A new reagent, p-methoxybenzyl acetate (PMBA) was prepared and developed as a new and facile reagent for PMB protection. p-Methoxybenzyl alcohol was treated with Ac2O in pyridine to give PMBA. Alcohol was subjected to reaction with PMBA and 5 mol% Yb(OTf)3 in dichloromethane at room temperature to give the PMB-ethers, where both acid and base sensitive groups survive under the reaction conditions.


The generality of the reaction was established by studying the protection of a wide variety of alcohols such as aliphatic, terpenoidal and sugar derivatives.

SECTION B: Y(OTf)3 mediated conversion of alcohols into p-methoxybenzyl ethers with PMBA and PMB-silyl ethers
		Two new reagents, t-butyldimethylsilyl p-methoxybenzyl ether (PMB-OTBS) and t-butyldiphenylsilyl p-methoxybenzyl ether (PMB-OTPS) were prepared and used for the preparation of PMB-ethers. p-Methoxybenzyl alcohol was treated with TBS-Cl and imidazole in CH2Cl2 to give PMB-OTBS, while treating PMB-OH with TPS-Cl under same conditions furnished PMB-OTPS.
		PMB protection of a variety of alcohols was performed using the rare earth triflate Y(OTf)3 in catalytic quantity employing the newly developed reagents PMBA, PMB-OTBS and PMB-OTPS, in an extension to the protocol developed in our group8, wherein PMB-OH was employed as a reagent for the formation of PMB-ethers. Comparative studies for better choice of the reagents and catalysts are recorded.



The generality of the reaction was established by studying the protection of a wide variety of alcohols such as aliphatic, terpenoidal and sugar derivatives.



CHAPTER 3: Radical mediated approaches for the attempted synthesis of isoavenaciolide

		This chapter describes the synthetic efforts towards the synthesis of isoavenaciolide and is further divided into two sections.

SECTION A: Attempted synthesis of isoavenaciolide starting from ‘Diacetone glucose’ (DAG)
		Isoavenaciolide9 1, avenaciolide10 2 and ethisolide9 3 (Figure 1) are secondary metabolites isolated fro Asperigillus and Pencillium fermentation broths, which inhibit fungal growth. Carbohydrates are appropriate starting materials and intermediates for the synthesis of enantiomerically pure compounds (chiron approach)11.

Figure 1. Metabolites isolated from Asperigillus and Pencillium fermentation broths
The apparent structural similarity of 1 to DAG and the presence of exo methylene group in the unique bis-butyrolactone skeleton prompted us to evolve a strategy using radical route for its synthesis. The utility of radical12 reactions on carbohydrate13 derived ‘chiral templates’, a fascinating protocol, particularly for the creation of cis-fused bicyclic systems has been well documented in our group earlier, where the syntheses14-16 of avenaciolide, discosiolide, 4-epi-ethisolide, sporothriolide and (-)-canadensolide has been successfully achieved. From the antithetic analysis of 1 (Scheme 1), it was envisaged that the bicyclic system 4 would conveniently furnish 1, and 4 in turn could be easily made by radical cyclisation of xanthate 5 that is obtained from DAG.
Scheme 1

		Accordingly, the aldehyde 9 prepared from the triol 8 was converted to 10 (Scheme 2) through Wittig olefination and hydrogenation. Oxidation of 10 gave 7, which on reaction with Ac2O/pyridine gave the enol acetate 11. Catalytic hydrogenation of 11 afforded the derivative 6. Deacetylation of 6 followed by treatment of 12 with PMB-Br furnished 13. Methanolysis of 13 afforded 14, which on reaction with propargyl bromide gave 15. Treatment of 15 with DDQ and subsequent reaction of 16 with CS2-MeI-NaH gave 5. However, attempts to cyclise the xanthate 5 into the fused bicyclic system 4 met with failure.
Scheme 2

Reagents: a) NaIO4, aqueous CH2Cl2; b) C6H13P+Ph3Br-, n-BuLi, THF; c) H2, 5% Pd/C, EtOAc; d) PDC, NaOAc, Ac2O, CH2Cl2, 40ºC; e) Ac2O, pyridine; f) Na, MeOH; g) NaH, PMB-Br, THF; h) H+resin, MeOH, 40ºC; i) NaH, 1-bromopropyne, THF; j) DDQ, aqueous CH2Cl2; k) NaH, CS2, MeI, THF.

SECTION B: Attempted synthesis of isoavenaciolide from ‘xylose monoacetonide’
		From the retrosynthetic analysis of 1 (Scheme 1), it was envisaged that a general strategy could be arrived at where the alkyl chain could be incorporated at a later stage on C-1 position i.e., after acquiring the required bicyclic system as in 3, while the C-5 carbon could be converted into lactone moiety. The bicyclic system 3 could be easily 

envisaged by radical cyclisation of xanthate 4, as is evidenced by the lack of steric hindrance offered by the existing functional groups. Xanthate 4 could be obtained in usual functional group manipulations of the xylose monoacetonide 5.
Scheme 1

Accordingly, 5 was monoprotected with trityl group to give 6 (Scheme 2), which on reaction with NaH and 1-bromopropyne in THF gave 7, a crucial unit required for the target molecule. Methanolysis of 7 with catalytic Conc. H2SO4 in MeOH gave the diol 8, which was then selectively alkylated with TBS-Cl and imidazole in dichloromethane to give 9. Further transformation of 9 into xanthate 4 using NaH, CS2 and MeI in THF and radical cyclisation of 4 using n-Bu3SnH and AIBN in benzene at reflux for 24 h afforded 3. Having obtained the bicyclic system 3, next it was aimed at incorporating the alkyl chain by performing Grignard reaction. To achieve this, 3 was treated with aqueous TFA (5:1) to afford the required system 10, which on reaction with C8H17MgBr in THF afforded 2. The triol 2 on oxidative cleavage with NaIO4 in aqueous CH3CN resulted the lactol 11, which on oxidation with CrO3 and pyridine in dichloromethane at 40ºC afforded the mono lactone 12. However, attempts were unsuccessful in further oxidation of 12 to give 1.
Scheme 2

Reagents: a) TrCl, Et3N, CH2Cl2; b) NaH, 1-bromopropyne, THF; c) Conc. H2SO4, MeOH, 50ºC, 2 h; d) TBS-Cl, imidazole, CH2Cl2; e) NaH, CS2, MeI, THF; f) n-Bu3SnH4, C6H6, 80ºC; g) aqueous TfOH; h) C8H17MgBr, THF; i) NaIO4, aqueous CH3CN; j) CrO3, pyridine, CH2Cl2, 40ºC.

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Structure, Stability and calcium-binding properties of βγ-crystallins and their microbial homologues

Gopika, N

Abstract


ABSTRACT
Introduction:
	Oxygen and nitrogen containing heterocycles are getting immense importance in the area of pharmaceuticals and agrochemicals. Pesticides belong to agrochemical area, which includes insecticides, fungicides, rodenticides, herbicides and fumigants. Among pesticides, insecticides are widely used chemicals by Indian farmers to control various diseases caused by different insects. Indiscriminate usage of pesticides in the fields is causing resistance development by insects resulting lower yields of the crops. Ultimately the farmer is at receiving end with enormous financial loss. To overcome this problem an intense research is currently in progress to develop pyrethroids, nicotinoids where the usage of chemical is at gross level; however, the insect based diseases are well controlled. This is the emerging area with a lot of potential and there is a need to synthesize a new class of pyrethroids, nicotinoids and subjected to bio-evaluation in order to find a promising candidate. 
	The broad objective of the present investigation is concerned with making a systematic and extensive study on the synthesis of Nicotinoids, pyrethroids, pyrano/furo fused quinolines and azabicyclo[2,2,2]octane derivatives and their bio-evaluation. The programme of work is accomplished and formated into a thesis entitled "DESIGN, SYNTHESIS OF NOVEL ISOXAZOLE DERIVATIVES, QUINOLINES & AZA BICYCLO [2,2,2] OCTANE HETEROCYCLES AND THEIR BIOLOGICAL ACTIVITY "
	Chapter-I, covers literature update on insecticides; includes the organo phosphorous compounds, chlorinated pyrethroids, nicotinoids, pyrazoles, pyrroles, pyridazines, isoxazoles and synthetic pyrethroids. Chapter-II deals with the synthesis of isoxazole nicotinoids. The synthesis of cyclopropane containing pyrethroids and non-cyclopropane pyrethroids is well documented in chapter-III. Chapter-IV, deals with the imino Diels-Alder reaction involving the preparation of pyrano and furo quinolines. Chapter-V, describes the synthesis of aza bicyclo [2,2,2] octane derivatives. Chapter-VI, deals with the studies on bioactivity of the compounds prepared in the present investigation. 
	The research work covered under each chapter has been briefly outlined below.

CHAPTER-I
	Insecticides belong to pesticides and their application is mainly to target pests/insects harmful to various crops and mankind. They include organochlorines, organophosphates, carbamates, pyrethroids, nicotinoids and various heterocycles like pyrazoles, pyrroles, quinazolines etc,. A detailed literature coverage of earlier and existing insecticides is described in this chapter. Some of the commercially well known products are outlined below.   

                   
                      DDT                                   Monocrotophos                      carbaryl   

       
               Cypermethrin                                 Imidacloprid                        Diflubenzuron

CHAPTER II

Synthesis of isoxazole Neo-nicotinoids:
The present chapter demonstrates the synthesis of isoxazole containing new heterocyclic compounds and tests their insecticidal activity. 
The salient feature of our strategy involves initial conversion of acetophenones into methyl 5-phenyl substituted isoxazole-3-carboxylate using dimethyloxalate, hydroxylaminehydrogensulphate in methanol. The isoxazole ester is further transformed into alcohol and then converted to chloride. The chloro fragment is coupled with the other moiety 2-nitroimineimidazole to obtain novel insecticidal heterocyclic compounds. The structure of the compounds are well characterized by the spectroscopic methods like IR, 1HNMR, 13C NMR, Mass, elemental analysis and also by X-ray analysis. The details of the strategy adopted to synthesise novel heterocyclic compounds are given in Scheme 1. 
In order to generalize and show the versatility of the reaction, different substituted acetophenones are prepared and tested for the reactions and they underwent smooth transformation to give final products in quantitative yields. 



a = H, b = 4-Cl, c = 4-Br, d = 4-F, e = 4-CH3, f = 4-OCH3, g = 4-Isobutyl,
h = 3-OCH3, i = 3-Cl, j = 2-OCH3, k = 2-Cl
Scheme 1

CHAPTER III

The synthesis of cyclopropane containing isoxazoles and non-cyclopropane isoxazoles retaining the active functional groups like dimethyls at C2 and stereochemistry at C3 positions is well documented in chapter-III. The completed work is conveniently divided into two sections.

Section A: Synthesis of new series of cyclopropane pyrethroids:

The present work is initiated with the condensation of optically pure cyclopropane containing acid fragment with the heterocycle moiety containing alcohol similar to cypermethrine and cyhalothrin. The synthon (methyl 5-phenyl substituted isoxazole-3-carboxylate) which was prepared and covered in chapter II is utilized further and converted to aldehyde (2) using sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al) at -70˚C in toluene. The other moiety, optically pure acid part is converted into acid chloride using thionyl chloride in hexane. The acid chloride (3/4) and aldehyde was coupled via insitu generation of cyanohydrin by using NaCN and DABCO as PTC in dichloroethane and target molecule is obtained. The coupling product is obtained in diastereomeric pairs, which could not be separated by column chromatography. The details of reaction is depicted in scheme 2.
In order to study the versatility of the above series of reactions, we have synthesized various aldehydes by changing the constituent R groups and prepared a series of new molecules. They are tested for larvicidal activity. 


3. R' = R'' = Cl (cypermethric acid)
4.  R' = Cl, R'' = CF3 (cyhalothric acid)
R = H, 4-CH3, 4-F, 4-OCH3, 4-Cl, 2-OCH3, 2-Cl, 3-OCH3, 3-Cl

Scheme 2
Section B: Synthesis of non-cyclopropane pyrethroids:

In continuation of our studies on structure modifications in the alcohol moiety of pyrethroids 5 [(R,S)Cyano(5-aryl-3-isoxazole)methyl(1R)-cis-3-(2,2-dichlorovinyl) -2,2-dimethyl cyclopropanecarboxylate] and 6 [(R,S)Cyano(5-aryl-3-isoxazole) methyl(1R)-cis-3-(2-chloro-3,3,3-trifluro-1-propenyl)-2,2-dimethylcyclopropane-1-car boxylate] as discussed in the section A of chapter-III, we have adopted alternate strategies to achieve the final target molecule of noncyclopropane isoxazoles. The S-acid [(2S)-2-(4-chlorophenyl)-3-methylbutanoicacid] is converted into acid chloride (7) and treated with aldehyde and obtained desired product (8) in good yield (scheme 3). All the compounds prepared in this section are screened for their activity.


R = H, 4-CH3, 4-F, 4-OCH3, 4-Cl, 2-OCH3, 2-Cl, 3-OCH3, 3-Cl
Scheme 3

CHAPTER IV

Zirconium tetrachloride mediated imino Diels-Alder Reactions: Synthesis of pyrano and furo [3,2-c] quinolines. 
Natural products containing pyrano and furoquinoline moieties are widely distributed in nature and found to be associated with a wide range of biological activities such as psychotropic, antiallergic, anti-inflammatory, estrogenic activities. Hence, efforts are directed towards the synthesis of these compounds by imino Diels-Alder reaction catalyzed by a Lewis acid from N-benzylideneanilines and nucleophilic olefins. We have used ZrCl4 as a green catalyst for imino Diels-Alder reaction and reported here for the first time.
Here we describe the synthesis and characterization of mono and di-substituted pyrano and furoquinolines 3, 4, 6, 7, 8, 9, 10, 11 and 12, 13 for the first time by the application of the imino Diels-Alder reaction using ZrCl4 as a new catalyst. This procedure is simple, efficient and has general application for the synthesis of pyrano and furo [3,2-c] quinolines starting from respective N-benzylideneanilines as dienes and 3,4-dihydro-2H-pyran (DHP) or 2,3-dihydrofuran (DHF) as dienophiles to yield pyrano or furo quinolines respectively. Reaction of N-benzylideneanilines (1a-k) with DHP or DHF in the presence of ZrCl4 (10 mol%) in DCM at ambient temperature resulted in the formation of endo (3a-k) and exo (4a-k) pyrano and furoquinolines in 72-97% yield 


Scheme 4

The structures of the final products are characterized by IR, ׀H NMR, 13C NMR, Mass spectroscopic data, elemental analysis and X-ray crystallography studies. 
Interestingly, the di-substituted 3-chloro-4-fluoro-N-benzylideneaniline (5) and DHP (2a) under the present reaction conditions yielded four isomers 6, 8, 10, and 12 in the ratio 50: 15: 18: 17 respectively in an overall yield of 69% (Scheme 5) containing a large excess of the endo isomer. It is for the first time that all four isomers are isolated in pure state from the reaction mixture by column chromatography and characterized unequivocally by ׀H NMR spectra and reported. As observed in the case of DHP, DHF (2b) also acted as a good dienophile in reaction with 3-chloro-4-fluoro-N-bezylideneaniline (5) to obtain the expected mixture of four isomers in the ratio of 60: 12: 17: 11 in 93% yield. All the four compounds (7, 9, 11, 13) are new and the structures assigned are in consonance with the ׀HNMR spectra. 


Scheme 5

It is noteworthy to mention that exo and endo isomers (6, 7, 8, 9, 10, 11, 12, 13) of compounds are reported for the first time and the structures unambiguously assigned using IR, ׀HNMR, 13CNMR, Mass spectroscopic data, elemental analysis and X-ray crystallography. 
In order to generalize and show the versatility of the reaction, different substituted imines are prepared and condensed with DHP and DHF to obtain diastereomerically pure final products in quantitative yields.



CHAPTER V

Zirconiumtetrachloride mediated imino Diels-Alder Reactions: Synthesis of aza bicyclo [2, 2, 2] octane derivatives. (imine acting as dienophile):

The imino Diels-Alder reaction has emerged as a powerful tool for the synthesis of nitrogen containing heterocycles. 
In the present chapter the use of cyclic α, β-unsaturated ketone (cyclohexene-2-one) as diene in imino Diels-Alder reaction catalyzed by zirconium tetrachloride furnished cycloaddition products. N-benzylideneanilines, prepared according to the reported procedure, reacted with cyclohexene-2-one in the presence of zirconium tetrachloride  (10 mol%) in dichloromethane at ambient temperature, resulted in the formation of new compounds 3a, 4a, 5a in the ratio 45: 2: 18 respectively in an overall yield of 65% (scheme 6). The compounds 3a, 4a, 5a are unequivocally characterized by 1D and 2D NMR spectroscopic techniques, including HSQC and HMBC analysis.

Scheme 6

Unlike 1a-e, when imine 1f-g derived from benzyl amine, is used as substrate (scheme 7) in presence of ZrCl4  (10 mol %), the reaction proceeded smoothly at ambient temperature to furnish exclusively a single product 4f-g in 30-35% yield Table 1 (entry f-g). These products are new and characterized by spectroscopic data (IR, 1HNMR, 13CNMR, MS). 


Scheme 7


A probable reaction mechanism is depicted in scheme 8 


Scheme 8


In order to generalize and show the versatility of the reaction, different substituted imines are prepared and tested for the above mentioned reactions and they underwent smooth transformation to give final products in quantitative yields.  The reaction of imine with cyclopentenone in presence of ZrCl4 found that there is no product formation. 


CHAPTER VI
The compounds prepared in chapter II, III, IV and V are subjected to activity screening and some of the compounds showed promising activity against fourth instar larvae of Culex quinquefasciatus and tetrahydroquinolines have been tested for anti bacterial activity using Bacillus subtilis, Psudomonas aeruginosa, Aspergillus niger, Alternaria radicinia as test species

Conclusion:
The research programme covered in this thesis is demonstrated to synthesize well targeted molecules adopting various strategies and each compound is screened for activity in order to find its potency to identify a lead molecule, which is prone to become a drug.


















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