Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/12667
Title: Synthesis of ethoxyphthalimido derivatized thiazolodihydropyridines assembled with pyrazole and isoxazole systems from common intermediate chalcone and evaluation of their antibacterial activity
Authors: Pemawat, Gangotri
Talesara, Ganpat L
Keywords: Malononitrile
Thioglycolic acid
Triethylamine
Piperidine
Isatin
Issue Date: Sep-2011
Publisher: NISCAIR-CSIR, India
Abstract: Condensation of aromatic aldehydes, malononitrile and thioglycolic acid gives 5-amino-3-oxo-7-substitutedphenyl-2-substitutedarylidene-2,3-dihydro-7<i style="">H</i>-[1,3]thiazolo[3,2-<i style="">a</i>] pyridine-6,8-dicarbonitrile <b style="">1a-e</b>. This acts as key intermediate for two series of final compounds <b style="">4a-e</b> and <b style="">7a-e</b>. In the first route compounds <b style="">1a-e</b> are refluxed with hydroxylamine hydrochloride to yield tricyclic compound 8-amino-3,6-bis(substitutedphenyl)-1,3,3<i style="">a</i>,9<i style="">a</i>-tetrahydro-6<i style="">H</i>-isoxazolo[3',4':4,5]­[1,3]thiazolo[3,2-<i style="">a</i>]pyridin-5,7-dicarbonitrile <b style="">2a-e</b>. These when condensed with isatin give the corresponding Schiff bases <b style="">3a-e</b>. Condensation of <b style="">3a-e</b> with bromoethoxyphthalimide give the final products 8-[(1<i style="">N</i>-ethoxyphthalimido-2-oxo-1,2-dihydro-3<i style="">H</i>-indol-3-ylidene)amino]-3,6-bis(substitutedphenyl)-1,3,3<i style="">a</i>,9<i style="">a</i>-tetrahydro-6<i style="">H</i>-isoxazolo[3',4':4,5] [1,3]thiazolo­[3,2-<i style="">a</i>]­pyridine-5,7-dicarbonitrile <b style="">4a-e</b>. In the second pathway NH<sub>2</sub> group of compounds <b style="">1a-e</b> is protected by bezoylation to furnish <b style="">5a-e</b>. These <img src='/image/spc_char/alpha.gif' border=0> ,<img src='/image/spc_char/beta.gif' border=0>-unsaturated compounds (ring chalcones) when treated with hydrazine hydrate undergo cyclization to form <i style="">N</i>-(5,7-dicyano-3,6-diphenyl-2<i style="">H</i>,6<i style="">H</i>-pyrazolo[3',4':4,5][1,3]thiazolo[3,2-<i style="">a</i>] pyridine-8-yl)benz- amide <b style="">6a-e</b>. Active hydrogen of their pyrazole ring is replaced by ethoxyphthalimido moiety to afford the final compounds <i style="">N</i>-(5,7-dicyano-3,6-bis (substitutedphenyl)-2<i style="">N</i>-ethoxyphthalimido-2<i style="">H</i>,6<i style="">H</i>-pyrazolo[3',4':4,5][1,3]thiazolo[3,2-<i style="">a</i>] pyridine-8-yl)benzamide<b style=""> 7a-e</b>. The structures of synthesized compounds have been assigned on the basis of elemental analysis and spectral data.
Description: 1173-1180
URI: http://hdl.handle.net/123456789/12667
ISSN: 0975-0983(Online); 0376-4699(Print)
Appears in Collections:IJC-B Vol.50B(09) [September 2011]

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