Organic Chemistry Insights

The reaction of 4,5-diphenylimidazol-2-thione 1 with chloroacetic acid in presence of acetic acid and sodium acetate afforded 5,6-diphenylimidazo [2,1-b]thiazole-3-one 3. Compound 3, when treated with acetic anhydride in presence of sodium acetate, dimethyl formamide dimethylacetal (DMFDMA), thiophene-2-carbaldehyde and 2-thenylidene activated nitriles gave 5,6-diphenylimidazo[2,1-b] thiazole derivatives 4, 6, 8 and 7,8-diphenyl imidazo[2,1-b] thiazolo [2,3-b] pyran derivatives 9e,f, 10. Claisen condensation of compound 4 with diethyl oxalate gives 7,8-diphenylimidazo [2,1-b] thiazolo [2,3-b]-4-pyron derivatives 5a,b. While, 6,7-diphenylimidazo[2,1-b] thiazolo[2,3-c] oxazole or (N-phenylpyrazole) 7c,d were obtained directly upon reaction of 6 with hydroxylamine hydrochloride and phenyl hydrazine. Compound 1 reacted with α-chloroacetylacetone and α-chloroethylacetoacetate to give 2-acetyl or (2- ethoxycarbonyl) 3-methyl-5,6-diphenylimidazo[2,1-b] thiazole 12h,i. Treatment of 12h with thiophene-2-carbaldehyde led to the formation of 3-methyl-5, 6-diphenyl-2(2-thenylidene-2-propenoyl) imidazo[2,1-b]thiazole 13h. Compound 13h react with each of 2-chlorophenyl hydrazine and benzamidine hydrochloride to give 14h and 15h. Cyclocondensation of 12h with hydroxylamine hydrochloride and hydrazine hydrate gave 16j and 16k. The newly synthesized compounds were tested for antibacterial and antifungal activity. Most of the tested compounds showed activity toward fungi while many of these did not have activity toward bacteria.