Treatment of 6-aminothiouracil (1) with 2,3-dichloroquinoxaline (2) in ethanol/TEA
afforded 6-amino-2-(3-chloroquinoxalin-2-ylthio)pyrimidin-4(3H)-one (3), which was
refluxed in DMF to give 2-aminopyrimido[2',1':2,3]thiazolo[4,5-b]quinoxaline-4-one
(4). Compound 4 was utilized as a key intermediate for the synthesis of a new pyrimido[2',1':2,3]thiazolo[4,5-b]quinoxaline
derivatives 5-14via the reaction with 2-chlorobenzaldehyde, 2-chlorocyclohex-1-enecarbaldehyde,
2-chlorobenzoic acid, 2,4-dichlorobenzoic acid, 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde,
2-chloro-4,6-dimethylnicotinonitrile, alpha,beta-unsaturated ketones and isonicotinaldehyde,
respectively. The chemical structures of the newly synthesized compounds were characterized
by IR, NMR and mass spectral analysis. These compounds were also screened for their
analgesic and anti-inflammatory activities. Some of these compounds (3, 4, 9, 10 and
12-14) exhibited promising activities.
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