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Title: Chemoselective Knoevenagel reaction as a novel route for the synthesis of biscoumarinyl methylsulphones and 4+1, 1+4 approach synthesis of aminooxadiazolyl and N-(2,5-dimethyl)pyrrolylcoumarins
Authors: Alawandi, Ganesh N
Kulkarni, Manohar V
Keywords: Knoevenagel reaction
cyanogen bromide
acetonyl acetone
antimicrobial activity
Issue Date: Jan-2006
Publisher: CSIR
Series/Report no.: <b>Int</b>.<b>Cl</b>.<b><sup>7</sup> C 07 D</b>
Abstract: 4-Bromomethylcoumarins <b style="">1</b> on reaction with thiourea gives 4-mercaptomethyl coumarins <b style="">2</b>, which on further reaction with ethyl chloroacetate afford the corresponding sulphide esters <b style="">3a-c</b>. The sulphone esters <b style="">3d-f</b> which are obtained upon oxidation of compounds <b style="">3a-c</b>, undergo cyclisation with salals through Knoevenagel reaction to furnish biscoumarins <b style="">4</b> in good yield. Also esters <b>3a-f</b> on reaction with hydrazine hydrate (99.9%) give the corresponding carbohydrazides <b style="">5</b>. Compounds <b>5</b> when reacted separately with cyanogen bromide and acetonyl acetone yield aminooxadiazolyl <b>6</b> and N-(2,5-dimethyl)pyrrolylcoumarins <b style="">7</b>, respectively. The compounds have been characterized by elemental analysis, IR, <sup>1</sup>H NMR, mass and 2D-HOMO COSY data. All the newly synthesized compounds have been screened for antimicrobial activity against gram-ve bacterium <i style="">Escherishia coli</i>, gram+ve bacterium <i style="">Bacillus staphylococci</i> and fungi <i style="">penicillium</i> and <i style="">Aspergillus</i>.
Description: 258-266
ISSN: 0975-0983(Online); 0376-4699(Print)
Appears in Collections:IJC-B Vol.45B(01) [January 2006]

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