Synthesis of 1-aryl-2[3-methylpyrazolin-5?-oxo-1?-yl]-4-[phenyl/p-chlorophenyl]-imidazoles and their antihistamine activity

1-Aryl-2-mercapto-4-(phenyl/n-chlorophenyl) -imidazoles (Ia-j) were condensed with hydrazine to get 1-aryl-2-hydrazino—4-(phenyl/prchlorophenyl)-imidazoles (IIa-j ). Later compounds were subsequently reacted with acetoacetic ester in presence of acetic acid to get the desired 1-aryl-2-(31-methylpyrazolin-5?-oxo-11?-yl)-4-(phenyl/2-chlorophenyl)-imidazoles (IIIa-j). These compounds were screened for anti-histaminic activity. All the compounds (IIIa-j) showed moderate anti-histaminic activity.