Abstract
<p>About nine 4-substituted 1-naphthacyl bromides and its esters have been synthesized by greener synthetic method using fly-ash catalyzed water mediated reaction. These acyl bromides and esters have been characterized by their physical constants, Mass, IR and NMR spectral data. These carbonyl frequencies(cm-1) of existed rotomers of these compounds have been assigned and correlated with Hammett substituent constants, F, R and Swain-Lupton’s parameters. The insect antifeedant activities of the synthesized acyl bromide and esters have been evaluated using 4<sup>th</sup> instar larvae <em>Achoea Janatha L</em>.</p>
Highlights
Stereoselective, stereospecific and regioselective synthetic methods are important for the synthesis of biologically active carbonyl compounds [1,2,3] through solvent-free green reactions like bromination [4,5,6], esterification[7, 8] and calixarene complexation [9]
Many reagents like Copper(II)bromide [20], N,N-dimethylformamide [21], 1,4-dioxanebromooxoniumbromide [22], tribromoacetophenone [23], N-bromosaccharin [24], tribromoacetyl-tetrabutylammonium bromides [6], human esoinophils [25], peroxo-Mntetrabutylammoniumbromides [7, 8], bromide-bromates [12], acylammonium salts-LDA quenches with bromine [26], benzylic bromides [27], pyridiniumbromide perbromide [28] and pyridinium bromochromate [29] have been utilized for the bromination of organic substrates
Various 1-naphthyl ketones containing electron withdrawing and electron donating groups in position 4 have been subjected to bromination at acyl methyl group with Winkler’s solution in the presence of fly-ash catalyst under water medium (Scheme 1)
Summary
Stereoselective, stereospecific and regioselective synthetic methods are important for the synthesis of biologically active carbonyl compounds [1,2,3] through solvent-free green reactions like bromination [4,5,6], esterification[7, 8] and calixarene complexation [9]. Many natural organic compounds have methylene fragment in their structure and it is the origin for biological activity This methylene fragment is useful for the synthesis of cyclic ketones, acylic ketones, esters, flavones and couma-rone derivatives [16,17,18,19]. The author reports an effective method for bromination selectively at the side chain in a 4-substituted 1-naphthyl ketones with potassium bromide-bromate mixture (Winkler’s reagent) in the presence of fly-ash in water medium.
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