http://nopr.niscair.res.in/handle/123456789/6003 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/6406 Title: A convenient method for the oxidation of Hantzsch 1,4-dihydropyridines with N-bromo succinimide <br/> <br/>Authors: Nagarajan, R; Anthonyraj, J C A; Muralidharan, D; Saikumar, C; Perumal, P T <br/> <br/>Abstract: A convenient and mild method for the conversion of Hantzsch 1,4-dihydropyridines to pyridines using N-bromo succinimide at room temperature in excellent yields has been described. <br/> <br/>Page(s): 826-828 Sun, 26 Feb 2006 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/6405 Title: Microwave assisted rapid and efficient synthesis of aryl methyl ketones and β-keto esters using Meldrum’s acid <br/> <br/>Authors: More, D H; Mahulikar, P P <br/> <br/>Abstract: Microwave mediated rapid and efficient synthesis of aryl methyl ketones and β-keto esters from acyl Meldrum’s acid by hydrolysis and alcoholysis, respectively, has been reported. <br/> <br/>Page(s): 823-825 Sun, 26 Feb 2006 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/6404 Title: A convenient synthesis of xyridin A metabolite from <i>Xyris</i><i style=""> indica</i> L. <br/> <br/>Authors: Ahmed, Hafiz Badar-ud-Din; Rama, Nasim Hasan; Malana, Muhammad Aslam; Qadeer, Ghulam <br/> <br/>Abstract: A convenient synthesis of xyridin A<b style=""> </b>(isocoumarin) isolated from <i style="">Xyris indica</i> L. has been carried out. 4,5-Dimethoxyhomophthalic acid is condensed with butanoyl chloride to yield 3-<i>n</i>-propyl-6,7-dimethoxyisocoumarin which on demethylation with aluminium chloride followed by reaction with dibromomethane and Adogen 464 as a catalyst affords xyridin A. <br/> <br/>Page(s): 820-822 Sun, 26 Feb 2006 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/6403 Title: Aza-crown ether tethered with benzothiazole: Synthesis and optical spectral studies <br/> <br/>Authors: Mashraqui, Sabir H; Dhaval, Vashi; Subramanian, S; Khan, Tabrez B <br/> <br/>Abstract: Synthesis of a new fluoroionophore <b style="">2 </b>encompassing aza-phenyl-crown and benzothiazole is described. The UV-Vis spectra of <b style="">2</b> are not altered with change in solvent polarity indicating the absence of solvatochromism. However, the fluorescence spectra are progressively red shifted in more polar solvents on account of increasing charge transfer character of the excited state. In the presence of trifluoroacetic acid (TFAA), protonation of benzothiazole nitrogen results in the red shift of the absorption spectra. Contrary to expectation, the emission spectra suffers blue shift in the presence of TFAA. Presumably, the emission for the case <b style="">2</b>+H⁺occurs from higher vibrational energy levels which accounts for the blue shift. Unfortunately, selected alkali or alkaline earth metals ions examined for metal sensing applications have failed to induce significant perturbations either in the absorption or emission spectra. This may be attributed to poor electronic communication between the crown-bound metal ions and the benzothiazole fluorophore due to steric encumbrance between the <i style="">ortho-</i>substituted benzothiazole chromophore and the phenyl aza-crown moiety. <br/> <br/>Page(s): 815-819 Sun, 26 Feb 2006 22:58:59 GMT