Microwave Assisted Fries and Claisen Rearrangements

A convenient synthesis of various aromatic hydroxyketones via Fries rearrangement is described by condensing a series of aromatic esters with acidic Al2O3-ZnCl2 mixture under microwave conditions. A comparative account of the synthesis of aromatic esters under conventional and microwave conditions is also given. Reactions have been carried out under solvent free conditions with considerable reduction in reaction time and improvement in yield in comparison to classical methods. The adopted procedure provides an energy and time saving protocol

Microwave-assisted organic reactions-A comparative account.

In recent years, the focal point in chemical research is the development of environmentally friendly processes in terms of sustainable chemistry. Of particular importance is a reduction in the amount of solvents and hazardous substances and more efficient use of energy, microwave-assisted synthesis being one of them. In the electromagnetic spectrum, microwave radiation area is located between Infrared and Radio waves having a wave length in the range of 0.3mm to 0.5m corresponding to frequencies between 1 × 1012 - 6 × 108 Hz. In the laboratory, microwave instruments generate the waves corresponding to a wavelength of 12.2 cm and energy of 2.45 GHz, as per the international convention so that any interference with telecommunications and radar equipments is minimized. Microwaves are reflected off metal surfaces but pass through paper, glass, china ware and plastic ware. Hence these materials find extensive use as reaction vessels or utensils since microwaves are absorbed directly by the chemical species or food without affecting the container. Microwaves penetrate several centimeters deep into the material to be heated because of a high penetration power and the dissipation of energy results in a quick and even rise in temperature of the species. Microwave-assisted organic synthesis has blossomed into a useful technique and accelerations have been observed in a wide range of reactions. Microwaves have been successfully applied to combinatorial chemistry whereby synthesis of large numbers of molecules is achieved by varying combinations of molecular building blocks and permutations of modular components. Control of the desired selectivity (chemo, regio, stereo and enantioselectivity) is the most important objective in organic synthesis.The application of microwave irradiation involves the modifications of the reactivity as well as selectivity in relation to conventional heating.Digital copy of Thesis.University of Kashmir

Base Catalysed Hydrolysis Of Certain Furocoumarins

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Microwave Assisted Organic Synthesis (MAOS) - A Comparative Account

The focal point in chemical research now a days is the development of environmentally benign processes. Emphasis is on reduction in the amount of solvents, hazardous substances and more efficient use of energy. Microwave Assisted Organic Synthesis (MAOS) is one of the means to achieve this goal

Synthesis, Crystal Structure and in vitro DNA Binding Studies of Combretastatin A-4 Analogue

Synthesis of a novel Combretastatin A-4 analogue using Schiff’s reaction of benzil and 4-aminoantipyrine has been achieved under solvent free conditions. The structure of compound was examined spectroscopically and confirmed from single crystal diffraction studies. The synthesized Combretastatin A-4 analogue was investigated for its DNA binding ability as the plausible mechanism for its antitumor activity. The binding propensity of the synthesized compound with calf-thymus (CT) DNA was monitored with absorption and emission spectrophotometric titrations. The calculations predict a binding constant of 7.24×104 for the complex of the synthesized compound with CT DNA which is comparable in magnitude to that of DNA binding of bactericidal drug enoxacin and typical intercalation indicator ethidium bromide (EB). Competitive binding studies of the synthesized compound with EB using fluorescence titration reveal that it displaces the DNA-bound EB and binds in intercalative mode which was further supported by circular dichroism (CD) spectroscopy. The probable site and binding energy of the compound with DNA was further theoretically investigated by molecular docking studies. The significant DNA binding ability of the synthesized Combretastatin A4 analogue as revealed from this study could be related to the anticancer activity of the Combretastatin A4

Anti-Metastatic Propensity of Biscoumarin Scaffold Synthesized Under Catalyst Free Aqueous Phase Microwave Irradiation

An environmentally benign, catalyst free, aqueous phase, microwave assisted method for the synthesis of biscoumarin derivatives using 4-hydroxycoumarin and different aldehydes is reported. The comparative investigation of the same synthetic methodology under conventional refluxing, domestic and scientific programmable microwave synthesizer has been attempted for the purpose of comparing the reaction performance in terms of % yield, reaction time, reproducibility and reaction control. In addition to the increased yields and attenuated reaction times for biscoumarin synthesis, the difficulty of reaction control and result reproducibility usually encountered with domestic microwave ovens have been addressed through an optimized synthetic methodology using microwave synthesizer. Screening bioactive compounds for their propensity towards inhibition of cancer metastasis is a must step in advancement of cancer chemotherapy. The synthesized biscoumarin scaffold was investigated for inhibitory metastatic activity against human lung carcinoma cell line, A549 through in vitro wound healing and invasion assays. The biscoumarin scaffold was found to possess an effective anti-proliferative activity. It was also found to be efficient in ablating the migration and invasiveness of these cells under in vitro conditions. This work is licensed under a Creative Commons Attribution 4.0 International License

In vitro bactericidal and fungicidal activities of various extracts of saffron (Crocus sativus L.) stigmas from Jammu & Kashmir, India

Antimicrobial activities of methanolic and petroleum ether extracts of Croccus sativus L. (saffron) stigmas, were tested against various bacterial strains (Proteus vulgaris, Klebsiella pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli) and fungi (Candida albicans, Aspergillus niger and Aspergillus fumigatus) by agar well diffusion method. Minimal inhibitory concentration and minimum bactericidal and fungicidal concentration values of each active extract were also determined. The results showed a strong activity of the petroleum ether and methanolic extracts of saffron stigmas against bacteria and fungi used as test organisms. The results of different antimicrobial assays also indicate that the extracts had significantly higher bactericidal than fungicidal activities (p < 0.05). The results suggest that these extracts can be used in pharmaceutical and food formulations for inhibiting pathogenic bacterial and fungal species

Anti-Metastatic Propensity of Biscoumarin Scaffold Synthesized Under Catalyst Free Aqueous Phase Microwave Irradiation

An environmentally benign, catalyst free, aqueous phase, microwave assisted method for the synthesis of biscoumarin derivatives using 4-hydroxycoumarin and different aldehydes is reported. The comparative investigation of the same synthetic methodology under conventional refluxing, domestic and scientific programmable microwave synthesizer has been attempted for the purpose of comparing the reaction performance in terms of % yield, reaction time, reproducibility and reaction control. In addition to the increased yields and attenuated reaction times for biscoumarin synthesis, the difficulty of reaction control and result reproducibility usually encountered with domestic microwave ovens have been addressed through an optimized synthetic methodology using microwave synthesizer. Screening bioactive compounds for their propensity towards inhibition of cancer metastasis is a must step in advancement of cancer chemotherapy. The synthesized biscoumarin scaffold was investigated for inhibitory metastatic activity against human lung carcinoma cell line, A549 through in vitro wound healing and invasion assays. The biscoumarin scaffold was found to possess an effective anti-proliferative activity. It was also found to be efficient in ablating the migration and invasiveness of these cells under in vitro conditions. This work is licensed under a Creative Commons Attribution 4.0 International License