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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;bromomethylcoumarins;cyanogen bromide;acetonyl acetone;antimicrobial activity
Issue Date: Jan-2006
Publisher: CSIR
IPC Code: Int.Cl.7 C 07 D
Abstract: 4-Bromomethylcoumarins 1 on reaction with thiourea gives 4-mercaptomethyl coumarins 2, which on further reaction with ethyl chloroacetate afford the corresponding sulphide esters 3a-c. The sulphone esters 3d-f which are obtained upon oxidation of compounds 3a-c, undergo cyclisation with salals through Knoevenagel reaction to furnish biscoumarins 4 in good yield. Also esters 3a-f on reaction with hydrazine hydrate (99.9%) give the corresponding carbohydrazides 5. Compounds 5 when reacted separately with cyanogen bromide and acetonyl acetone yield aminooxadiazolyl 6 and N-(2,5-dimethyl)pyrrolylcoumarins 7, respectively. The compounds have been characterized by elemental analysis, IR, 1H NMR, mass and 2D-HOMO COSY data. All the newly synthesized compounds have been screened for antimicrobial activity against gram-ve bacterium Escherishia coli, gram+ve bacterium Bacillus staphylococci and fungi penicillium and Aspergillus.
Page(s): 258-266
ISSN: 0975-0983(Online); 0376-4699(Print)
Appears in Collections:IJC-B Vol.45B(01) [January 2006]

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