Abstract

Madhavi Devarakonda, Vijaya Kumar Polem*, Sai Leela Ramayanam and l. K. Ravindranath

ABSTRACT

The reaction of pyrazole derivative (3) with mono chloro ethyl formate in presence or triethyl amine as base resulted ethyl-4-(((3,4-dimethoxyphenyl)imino)methyl-5-oxo-3-(trifluoro methyl)-4,5-dihydro-1H-pyrazole-1-carboxylate (4) which on further with mercapto acetic acid and catalytic amount of znic chloride in 1,4- dioxane affords the ethyl-4-(3-(3,4-dimethoxyphenyl)-4-oxothiazolidin-2-yl)-5-oxo-3-(trifluoromethyl)-4,5-dihydro-1H-pyrazole-1-carboxylate (5). The synthon (5) reacts with hydrazine hydrate followed by acetophenone forms 4-(3-(3,4-dimethoxyphenyl)-4-oxothiazolidin-2-yl)-5-oxo-N'-(1-phenylethylidene)-3-(trifluoromethyl)-4,5-dihydro-1H-pyrazole-1-carbo hydrazide (8). Acetylation of hydazone derivative (8) followed by internal rearrangement gives analogue(9) which on hydrolysis affords 2-(1-(4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)-5-oxo-3-(trifluoromethyl)-4,5-dihydro-1H-pyrazol-4-yl)-3-(3,4-dihydroxy phenyl)thiazolidin-4-one (10)A new series of 2-(1-(4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)-5-oxo-3(trifluoro methyl)-4,5-dihydro-1H-pyrazol-4-yl)-3-(2-oxido-2-(4-substituted phenoxy) benzo[d] [1,3,2]dioxaphosphol-5-yl)thiazolidin-4-one (12a-f) were synthesized from 2-(1-(4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)-5-oxo-3-(trifluoromethyl)-4,5-dihydro-1H-pyrazol-4-yl)-3-(3,4-dihydroxy phenyl)thiazolidin-4-one (10) by condensing with 4-substituted phenyl phosphoro dichloridates (11a-f). The structures of these analogues (12a-f) have been established by 1H NMR, IR, Mass spectral data and elemental analysis.