CHAPTER 1 INTRODUCTION

Transcription

1 List of Tables

2 CHAPTER 1 INTRODUCTION 1.1General Heterocyclic compounds containing nitrogen atom constitute a prominent class of bioactive molecules including both aromatic and aliphatic systems such as pyridine, pyrimidine, pyrrolidine, azetidine and piperidine. Among the saturated heterocycles, piperidine group forms a large number of derivatives which are having many applications in the field of medicinal chemistry, agricultural chemistry, material chemistry and others. In nature itself, piperidine nucleus is present in many alkaloids widely accepted as drugs. Several substituted piperidine derivatives have been synthesized by Mannich condensation of aldehydes, ketone and primary amines/ammonium acetate. Biological effects of these synthesized molecules also evaluated through in vivo as well as in vitro assays. Functionalized piperidines and their derivatives are important pharmacophores which are present in many pharmaceuticals [1]. Substituted piperidines particularly 2 and/or 2,6 disubstituted piperidines are synthetically important [2,3] as they exhibit wide spectrum of biological activities [2e]. Likewise 3,5 disubstituted piperidines are important fundamentally as backbones for alkaloids, [4a] high affinity agonists of human GABA A receptors,[4b] farnesyl protein transferase inhibitors [4c] and continue to be basic moieties in pharmaceutical research and have been target molecules in organic synthesis [5 7]. 4 Piperidone is an important derivative as well as an intermediate in the manufacture of certain chemicals and pharmaceutical drugs [8] such as fentanyl, carfentanyl and ramifentanyl. Further, compounds with 4 piperidone nucleus show desirable biological properties viz. antiviral [9], antitumor [10], central nervous system stimulant [11], analgesic [12], anticancer [13] and antimicrobial activity [14].

3 ! " # $ 1.2 Literature review of 3 alkyl and 3,5 dialkyl 2,6 diarylpiperidin 4 ones A facile, multicomponent Mannich reaction (Scheme 1) of aromatic aldehyde, ketone and ammonium acetate or amine as reported [15] by Noller and Baliah being the simplest procedure among the several reported methods to synthesize various substituted 4 piperidones till date. Easy separation of products, simplicity and yield are some of the notable advantages of this method. 13C NMR spectral studies of several 1 hetera 2,6 diaryl 4 cyclohexanones have been carried out by Ramalingam et al.[16] to account for the conformational priority of the piperidine ring system in comparison with similar thia, oxa and N Me ring systems. A detailed review about the synthesis of 2,6 disubstituted piperidines, oxanes and thianes has been reported by Baliah et al.[17] encompassing various derivatives of 2,6 diarylpiperidin 4 ones. This review includes several methods developed for the synthesis of 4 piperidones and their N alkyl and N aryl derivatives.

4 %! " # $ Bhaskar Reddy and others [18] have made a study on the reactivity of 3 methyl 2,6 diphenyl 4 piperidone. In this study transformation of 4 piperidones into a variety of heterocyclic compounds such as diazepinone, oxazepinone, thiadiazole, γ carboline, isoxazolyl and pyrazolyl tetrahydro pyridines were envisaged. A report [19] about the synthesis, stereochemistry and antimicrobial activity of 2,6 diaryl (3 arylthio)piperidin 4 ones as given in the Scheme 2 reported in the literature. The report narrates the conformational aspects and structure activity relationship of the synthesized derivatives. Manimekalai et al.[20] have made a detailed study about the protonation effect on chemical shifts of some picrate derivatives of 4 piperidones and the study revealed that the syn diaxial interaction between the axial N H bond and axial hydrogen at C5 causes the difference in the chemical shift of the above highly negative. Synthesis and spectral studies of some heteroarylpiperidin 4 ones and their derivatives have been carried out to establish the conformational preference of them in the liquid state by Manimekalai and others [21]. The variation of stereochemical features with various substituents at the 3- and 5- positions on the piperidine ring is explained in detail in the report.

5 &! " # $ Antimicrobial evaluation along with the synthesis and stereochemical studies of 3 benzyl 2,6 diarylpiperidin 4 ones and their derivatives has been reported in the literature [22]. In this study, conformational analysis of the synthesized compounds has been carried out and compared with the theoretically derived structures. Detailed evaluation of compounds against selected bacterial and fungal strains has also been carried out. The environmentally benign one pot synthesis of 1 methyl 2,6 diarylpiperidin 4 ones (Scheme 3) using montmorrilonite K 10 as a catalyst has been developed by Nithya and co workers [23]. Antimicrobial evaluation of some selected synthesized compounds has also been done by the same research group. Stereospecific synthesis of 4 piperidone through double Mannich reaction and tandem cyclization using I2 as a catalyst has been reported [24]. The starting materials used are unactivated ketones and Schiff bases (Scheme 4). Jia et al. [25] reported the cross double Mannich reaction (Scheme 5) catalyzed by I2. Stereospecificity and efficiency are some of the advantages of this protocol.

6 '! " # $ 1.3 Literature review of 3 alkyl and 3,5 dialkyl 2,6diarylpiperidin 4 one oximes and their derivatives Biological significance of oximes and their derivatives Oximes and oxime ethers have important pharmaceutical and synthetic applications such as medicines and pesticides [26]. These functional groups are incorporated in many medicinally important molecules used as antibiotics (e.g. gemifloxacin mesylate), drugs used in the treatment of organophosphate poisoning (e.g. pralidoxime chloride, obidoxime chloride etc) caused by insecticides such as malathion and diazinon. Similarly, Fluvoxamine, an antidepressant drug belonging to the group of selective serotonin reuptake inhibitors (SSRIs) also contains oxime ether functionality in its structure. Both O alkyl and O aryl oximes have been demonstrated to be stable at

7 (! " # $ physiological ph with O alkyl oxime present in a number of approved drugs [27]. Besides their use in the medicinal field, oxime ether derivatives are also widely used in agriculture as insecticides [28], fungicides [29], herbicides [30] and in the senescence of cut carnation flowers [31] Synthetic methods of 4 piperidone oximes and oxime ethers NMR spectral studies ( 1 H and 13 C) of some piperidin 4 one oximes have been carried out by Pandiarajan et al [32]. Conformational aspects of the piperidinyl system have been discussed in the report. Similarly, certain N hydroxy oximes of piperidin 4 ones synthesized from dibenzalacetone and structural elucidation of the same through 1D and 2D NMR spectra has also been carried out by Aguilera and co workers [33]. A report about the spectral studies of some sterically hindered oximes of 2,6 diarylpiperidin 4 ones has also been available in the literature [34]. Synthesis and biological activities of some oxime derivatives of 2,6 diarylpiperidin 4 ones with and without substituents at N atom

8 )! " # $ were studied by Balasubramanian et al. [35] and Ramesh Kumar et al. [36]. Oximes of 1 acyl 2,6 diarypiperidin 4 ones with i Pr substituent at the C3 carbon have been synthesized and their spectral along with the computational studies have been reported by some researchers [37,38]. Ramalingan et al. [39] have reported the synthesis of O benzyl oxime ethers of 1 methyl 2,6 diarylpiperidin 4 ones for the first time by following the Scheme 6. Study about the stereochemistry as well as antimicrobial evaluation of the synthesized oxime ethers is also elaborated in the report. Similarly, O benzyl oxime ethers of N unsubstituted piperidin 4 one analogues have been synthesized through Scheme 7 and their NMR spectral studies were carried out by Parthiban et al. [40].

9 *! " # $ Synthesis of polyfunctionalized piperidone oxime ethers and their cytotoxicity on HeLa cells has been studied by Parthiban et al. [41]. The synthetic protocol followed is shown in Scheme 8. Some oximes and benzyl oxime ethers of N allyl piperidin 4 ones have been synthesized (Scheme 9) by Narayanan et al.[42] The spectral, single crystal X ray diffraction and biological evaluation of the same have also been done by the same research group to explore the biological properties. A recent report [43] about the synthesis and cytotoxicity studies of N benzyl piperidin 4 one oximes available in the literature is showing the growing research on the oxime functionality

10 +! " # $

11 , -! " # $ 1.4 Literature review of 3 alkyl and 3,5 dialkyl 2,6 diarylpiperidin 4 one hydrazones and their derivatives Industrial and Biological significance of hydrazones Hydrazones are having remarkable physiological and biological activities and also found application as insecticides, anticoagulants, antitumor agents, antioxidants and plant growth regulators.[44 49] Metal complexes formed from hydrazone ligands are having application in non liner optics, sensors, medicine etc.[50] Several anti inflammatory, antinociceptive, and antiplatelet active drugs contain hydrazone and acylhydrazone moieties as core pharmacophore units in their structure [51] Biological significance of cyano group The biocompatibility of the nitrile functionality supports the prevalence of the nitrile containing pharmaceuticals and their continued clinical trials [52]. They are characterized by their short, polarized triple bond [53]. Only a minimum steric demand (a cylindrical diameter of 3.6 Å) [54] is required for it when compared to a methyl group (for which the steric requirement is eight times higher). Further, nitriles play an important role as hydrogen bond acceptors [53,55]. Certain recent drugs such as vildagliptin, anastrazole and saxagliptin are having a cyano group in their structure indicating its importance.

12 .. / : ; < = 3 > : Role of azoles in synthesis and medicinal fields Azoles are forming a crucial part in the history of heterocyclic chemistry and also been used as synthons in synthetic organic chemistry. The growing interest in the research of azole chemistry is pertaining to the versatility of azole groups in chemotherapeutical activity. Reports are available about the benzotriazole derivative which are potent in biological activity [56,57] The role of benzotriazole derivatives as a precursor in organic syntheses [58],antiprotozoal [59], antimicrobial [60], anticonvulsant, anti inflammatory [61] and anti tumor [62] agents has been proven by several researchers. The synthesis of some N aroyl hydrazones (I) and NMR spectral studies which revealed the amido imidol tautomerism has been reported by Manimeklai et al. [63]. They also carried out the synthesis and spectral studies of some hydrazones of heteroarylpiperidin 4 ones (II) [64]. A single crystal X ray diffraction study of isonictinoyl hydrazone of 3,3 dimethyl 2,6 diphenylpiperidin 4 one (III)has been undertaken by Sankar and others [65].

13 .? / : ; < = 3 > : 9 NMR spectral study of some 2,6 diarylpiperidin 4 one (3 hydroxy 2 naphthoyl)hydrazones with special reference to γ syn effect has been done by Sylvestre and Pandiarajan [66]. The investigated compounds have been synthesized via the Scheme 10 given below. Xavier and co workers [67] have made the synthesis (Scheme 11), NMR spectral studies and antimicrobial evaluation of some 2 (benzothiazol 2 yl) 1 (alkyl 2,6 diarylpiperidin 4 ylidene)hydrazine derivatives. Application of 2D NMR spectral techniques and SAR investigation are some of the highlights in that study.

14 / : ; < = 3 > : 9 Recently, the synthesis, antioxidant, antitumor and antimicrobial activity evaluation of thiadiazole based acid hydrazones of piperidin 4 ones has been reported by Kodisundaram et al.[68] Structure activity correlations exhibited by different derivatives are discussed. Synthetic procedure involved is depicted in Scheme Literature review of alkyl thiocyanates and N acyl derivatives of 3 alkyl 2,6 diarylpiperidin 4 ones Thiocyanate group is present in various anticancer natural products formed by deglycosylation of glucosinolates derived from cruciferous vegetables [69]. Further, this functional group could be used as a masked mercapto group and as a precursor for sulphur

15 . A / : ; < = 3 > : 9 containing heterocycles. Their role as pesticides [70,71] in agriculture is also significant industrially. Other important applications of alkyl thiocyanates are biocidal [72], antiasthmatic [73], vulcanization accelerators [74] etc. The synthetic applications of organic thiocyanates are exemplified by their use in the synthesis of sulphur containing compounds such as sulphur heterocycles [75], sulfides [76], cyano thiolated compounds [77], and nitriles (through desulphuration) [78]. Despite the above facts, it is pertinent to note that thiocyanate moiety is present in some biologically active natural products [79]. A study on the reactivity of 3 methyl 2,6 diphenylpiperidin 4 one has been carried out by Bhaskar Reddy et al.[80]. Bicyclic, spiro as well as N acetyl derivatives of the piperidine were synthesized and characterized through spectral studies and presented in that work. Krishna Pillay and co workers [81] have discussed the conformational analysis of some heterocyclic systems based on N aroyl derivatives of piperidin 4 ones (IV). A comparison of the results of spectral analysis with X ray crystallographic data has also been a part of that study.

16 . B / : ; < = 3 > : 9 Crystallographic studies of N phenyl acetyl and N diphenyl acetyl derivatives of piperidin 4 one (V and VI) have been reported [82]. The conformations and non covalent interactions were studied through the X ray diffraction analysis. A report by Aridoss et al. [83] about the synthesis (Scheme 13) and antimicrobial studies of N chloroacetyl 2,6 diarylpiperidin 4 ones is available in the literature in which piperidin 4 ones with varying substituents at C3/C5 carbons and phenyl rings have been synthesized from corresponding piperidien 4 ones and chloroacetyl chloride. Marked antibacterial and antifungal potencies are explored through antimicrobial screening. The same research group [84] has synthesized some N morpholinoacetyl 2,6 diarylpiperidin 4 ones by applying Scheme 14, studied their stereochemistry and evaluated the antimicrobial activity against selected microorganisms. Significant activity against C. Albicans, A. Flavus and Rhizopus sp. exhibited by synthesized compounds has been observed.

17 . C / : ; < = 3 > : 9 Vimalraj and others [85] have reported the synthesis and structural studies of N benzoyl derivative of piperidin 4 one oxime. In that report a comparative study between spectral and crystallographic analysis have been carried out and possible conformational preferences of the molecule was inferred. Some heteroaryl piperidin 4 one oximes with C3 isopropyl substituent have been synthesized and spectral along with computational studies carried out by Manimekalai et al.[86] Presence of two possible rotamers (VII A and VII B) observed from NMR spectra was also supported by computational studies undertaken by the researchers.

18 . D / : ; < = 3 > : 9

19 . E / : ; < = 3 > : 9 Structural conformation of N acryloyl derivative of 3 methyl 2,6 di(p tolyl)piperidin 4 one has been reported in the literature [87]. Twist boat conformational preference of the molecule in the solid state was revealed by this study Design and synthesis of piperazine unit inbuilt derivatives of piperidin 4 ones and their antitubercular and antimicrobial assay have been carried out (Scheme 15) by Rani et al. [88]. Various derivatives synthesized by them have been characterized through spectral and single crystal X ray diffraction analysis 1.6 Literature review of coumarin and fused piperidine derivatives Coumarins and their derivatives are being attractive to the research community because of their promising biological, synthetic and industrial applications. Their uses as insecticides [89], optical brighteners [90], laser dyes [91], inhibitors of platelet aggregation [92], anticancer [93], antibacterial [94] and antifungal [95] attracted the research community to concentrate on them. Geiparvarin, a naturally occurring compound having coumarin part in its structure has been reported to be active against a variety of cell lines including sarcoma 180, Lewis lung carcinoma, P 388 lymphocytic leukemia and Walker 256 carcinosarcoma [96]. Warfarin and bis hydroxycoumarins have been therapeutically used as oral anticoagulants [97], β adrenergic blocking agents [98] and vasorelaxants [99].

20 . F / : ; < = 3 > : 9 Structures having piperidine and pyran rings fused together have been synthesized (Scheme 16) from chalcones derived from 1 methyl piperidin 4 one and shown to be antimycobacterial by Ranjith Kumar and others [100,101a].

21 ? G / : ; < = 3 > : NMR spectroscopy 1 H and 13 C NMR spectroscopy are the widely used tools in the structural elucidation of organic compounds. The 1 H and 13 C chemical shifts are affected by the electron density around the nuclei concerned and tell about the environment of the protons and the carbons H NMR spectroscopy and its significance Diamagnetic anisotropy arises due to the presence of ring currents, caused in most cases by π electrons and affects the chemical shifts. This can either shield or deshield a proton. C bonds are small compared to that of the circulating π electrons. Due to this effect, the equatorial protons in cyclohexane and similar six membered rings are deshielded by about 0.5 ppm than the corresponding axial protons. The stereochemistry of a compound can be assigned from the 1H NMR chemical shifts, since steric, polar and conformational effects alter the proton chemical shifts. The influence of the substituents on the chemical shift of the ring protons can be used for configurational assignments. Coupling constants are of immense use in configurational and conformational studies since vicinal coupling constants between two protons depend on their relative positions. In saturated systems, the vicinal coupling constant depends on the dihedral angle between the coupled protons. It has been found by Karplus [101b] that using valence bond calculations, the vicinal coupling constant between two protons will have a maximum value for any system when the torsional angle between them is 180. Karplus also pointed out that the vicinal coupling constants decrease with increase in the electronegativities of the substituents in the C C segment.

22 ?. / : ; < = 3 > : C NMR spectroscopy and its significance The 13 C chemical shifts of six membered ring compounds are also influenced by many factors such as the inductive effect of the substituents, hybridization state of the observed nucleus, van der Waals and steric effects between closely spaced nuclei, electric fields originating from molecular dipoles or point charges, hyper conjugation, mesomeric interactions in π electron systems, diamagnetic shielding due to heavy substituents and neighbouring anisotropic effects. Further, the electrostatic effects owing to the presence of a heteroatom in the cyclohexane moiety and steric perturbation effects are of intrinsic importance in this context. The effect of a heteroatom present in a six membered cyclic system has been studied any The deshielding effect of heteroatom on the benzylic carbon of 1 hetera 2,6 diaryl 4 cyclohexanones has been found in the order as O>N Me>NH>S. The heteroatom causes an upfield resonance of the carbonyl group attributed as a field effect. 13 C NMR spectra is of importance in deciding the configuration of carbonyl derivatives such as oximes, hydrazones, thiosemicarbazones and semicarbazones that the distinction between E and Z isomers could be done from the knowledge of the 13 C chemical shift values of the carbon atoms present either sides of the imino group D NMR spectral techniques H 1 H COSY (Homonuclear Correlation Spectroscopy) This technique is also known as HOMOCOSY and reveals the correlation between the coupled protons as cross peaks in the spectrum. In this type of spectra off diagonal peaks are considered significant and they are exhibited by protons that are having measurable coupling. The diagonal peaks present in the spectrum are due to the chemical shift equivalent protons are they are deemed to be unimportant in deriving information.

23 ?? / : ; < = 3 > : H 13 C COSY (Heteronuclear Single Quantum Coherence HSQC) This two dimensional NMR technique correlates 13 C nuclei with directly attached protons. Only one bond coupling between a carbon and its attached proton is detected eliminating two and three bond coupling in this experiment. It is of importance in structural elucidation of organic compounds DEPT (Distortion less Enhancement by Polarization Transfer) It is a two dimensional NMR spectral technique [101b] in which three different variants are available such DEPT 45, DEPT 90 and DEPT 135 of which DEPT 135 is the widely used one. In this type of spectrum the carbon having odd number of protons (CH and CH3) exhibit positive peaks and carbons with even number protons (CH2) are observed in the negative part of the spectrum while quaternary carbons don t show their peaks. This technique finds its use in the case of large molecules with many types of carbon atoms HMBC (Heteronuclear Multiple Bond Coherence) This is also a two dimensional technique which detects the long range coupling between carbons and protons avoiding one bond coupling. It is useful in the case of assigning carbon signals of compounds having more quaternary carbon atoms NOESY (Nuclear Overhauser Exchange Spectroscopy) The Nuclear Overhauser Enhancement (NOE) can be used to demonstrate that two protons or group of protons are in close proximity within the molecule and is therefore of considerable value in the study of molecular geometry. In this type of spectrum, cross peaks reveal the spatial proximity of the protons. The usual range of protons detected in this spectrum is 2 5 Å.

24 / : ; < = 3 > : Single crystal X ray diffraction technique X ray crystallography is the chief method for characterizing the atomic structure of solid materials. It is a method of determining the arrangement of atoms within a crystal and it involves X rays to get a diffraction pattern generated by the scattering of the same by electrons present in the crystal lattices. A three dimensional picture of the density of the electrons within the crystal can be produced from the angles, bond distances and dihedral angles. During the process of X ray diffraction, the intensities of various diffracted beams are collected by passing the X ray beam through the crystal and this process is called (intensity) data collection. Then this data is converted into a more corrected and usable form by preliminary manipulation which is known as data reduction. After the data reduction step, a process known as refinement by which electron densities map that is closer to the real structure is obtained. Structure refinement is the process of improving the parameters for all atoms in an approximate (trial) structure, until the best fit of calculated structure factor amplitudes to those observed is obtained. The atomic positions in the molecular structure are determined by noting the electron density maxima in the unit cell and it is dependent on volume of the unit cell and structure factor. The structure factor is the resultant of all waves scattered in the direction of the reflections by all the atoms in the unit cell. The close agreement between observed structure factors and calculated structure factors represents the true structure. It is represented by a residual index called R factor, which describes the correctness of the model structure. R=0 indicates a perfect structure and any value of R<0.5 indicates a close correspondence between the trial and real structure.

25 ? A / : ; < = 3 > : 9 Now a days structure solution and structure refinement is carried out using SHELX 97 program package developed by Prof. George Sheldrick of University of Gottingen, Germany. It is a set of programs for crystal structure determination from single crystal diffraction data. 1.9 Antimicrobial assay methods Antimicrobial susceptibility tests measures the ability of an antimicrobial agent to inhibit the bacterial and fungal growth in vitro. In general, methods used are classified into two namely: Disc diffusion method Serial dilution method Disc diffusion method or Kirby Bauer method is recommended as a general purpose method or a qualitative method in which inhibitory power of the antimicrobial agent is arbitrarily assigned based on their zone of inhibition (ZI) values observed while serial dilution method is used to determine minimum inhibitory concentration (MIC) of the antimicrobial agent. A preliminary investigation of a group of biologically active molecules could be proceeded through disc diffusion method and from the results obtained a further step to find the suitability of the antimicrobial agent towards particular microorganism be tested via serial dilution method. Therefore we can arrive at a conclusion about the biological efficacy of the compounds in a qualitative and quantitative basis Theoretical studies of molecular systems Theoretical chemistry seeks to provide explanations to physical and chemical observations. It includes fundamental laws of physics such as Coulomb's law, the Virial theorem, Planck's law, Pauli's

26 Z Z Z H I J K L M N O P Q R S T N P U V W X N Y U T exclusion principle and many others to explain and predict observed phenomena. A theoretical model or method is a way to model a system using a specific set of approximations. The approximations are then combined with a calculation algorithm and applied to atomic orbitals, defined by the basis set. A basis set is a set of wave functions that describes the shape of atomic orbitals which are later combined linearly by LCAO method to form molecular orbitals. The level of approximation is directly related to the basis set used. In general, the theoretical methods [101c] can be divided into four main types: Semi empirical Ab initio Density Functional and Molecular Mechanics The selection of a theoretical method depends on the size of the system and on the level of approximation. Ab initio methods of computation are based only on theoretical principles and not on the experimental data. These include Hartree Fock model (HF) Moller Plesset (MPn) and Configuration Interaction (CI). HF model uses the approximation that Coulombic electron electron repulsion can be averaged, instead of considering explicit repulsion interactions. Further, this method can be splitted into two namely: UHF (unrestricted) and RHF (restricted). CI calculations are most often used for excited states.

27 H [ J K L M N O P Q R S T N P U V W X N Y U T Semi empirical methods use certain number of experimental data through the calculation and usually applied for very big systems, since they can handle large amounts of calculation. Some examples of semi empirical methods are ZINDO (used for computing UV transitions) and AM1 (Austin Model 1, used to model organic molecules) Density Functional Theory (DFT) methods differ from HF methods in such a way that it uses electron density instead of a wave function to compute the energy of the system. Some examples of these methods are B3LYP (Beckman Lee Young Par hybrid functional) correlation method, PW91 (gradient corrected) and VWN (local density approximated). Molecular Mechanics (MM) approximate atoms as spheres and bonds as springs and uses an algebraic equation for the energy calculation, not a wave function or electron density. UFF (Universal Force Field) and MMFF (Merck Molecular Force Field) are examples of MM methods Scope of the present investigation From the available literature reports about the significance of piperidine derivatives, oximes, hydrazones, azoles, alkyl thiocyanates and coumarin derivatives, we have planned and carried out the synthesis of a library of compounds having active functional groups as pharmacophores. It is also known from the literature that the stereochemistry of the biologically active molecules plays a pivotal role in deciding the biological activities. Among the characterization techniques, NMR spectroscopy is an effective tool to study about the conformation and relative stereochemistry of cyclic system with relatively rigid structures. Similarly single crystal X ray diffraction analysis is considered as an ultimate technique or structural investigation. Therefore in the present work, synthesis, NMR spectral

28 H \ J K L M N O P Q R S T N P U V W X N Y U T characterization along with IR and mass spectral studies are undertaken for some piperidine derivatives with varied functionalities. Structural studies with the aid of 1 D and 2 D NMR spectroscopy are the main task of the present work. Antimicrobial assay, single crystal X ray analysis and theoretical studies (based on HF Theory) are also done for some selected compounds. Stereochemical investigation is limited to find relative stereochemistry and determination of absolute stereochemistry is beyond the scope of the present work.