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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
|Series/Report no.:||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.|
|Appears in Collections:||IJC-B Vol.45B(01) [January 2006]|
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