Synthesis and Antioxidant Evaluation of Some New 3‐Substituted Coumarins

Abstract

3-Acetylcoumarin (1) was utilized as a key intermediate for the synthesis of 2-aminothiazole derivative 3 via bromination of 1 to afford acetylbromide 2 followed by treatment with thiourea or via Biginelli reaction of 1. Treatment of 3 with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-methyl-4H-benzo[d][1,3]oxazin-4-one, furo[3,4-b]pyrazine-5,7-dione or 2-methyl-5,6,7,8-tetrahydro-4H-benzothieno[2,3-d][1,3]oxazin-4-one afforded diazine derivatives 4-7. Also, pyridopyrimidine 8 was obtained via a one pot reaction of 6-aminothiouracil, p-chlorobenzaldehyde and 3-acetylcoumarin. Moreover, refluxing of 6-aminothiouracil with one equivalent amount of 2 afforded the thiazolopyrimidine 9, while the pyrrolothiazolopyrimidine 10 was revealed when two equivalent amounts of 2 was used. Furthermore, treatment of enamine 11 with 2-aminobenzothiazole or 6-aminothiouracil afforded the pyrimidine derivatives 12 and 13, respectively. Transamination of enamine 11 with m-anisidine followed by cyclization of the resulting enaminone 14 gave the desired quinoline 15. Also, treatment of 11 with thiophenol in dioxane gave the mercapto derivative 16. Moreover, coupling of 11 with 4,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl-diazonium chloride, followed by complete cyclization of the resulting product afforded the pyridopyrazolothiazine 19 via the intermediate 18. Furthermore, the pyrazolopyrimidine 20 was revealed via a one pot condensation of 11, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and ammonium acetate. The thiadiazine derivatives 21-23 were obtained via treatment of 2 with the corresponding o-aminothiols. Desulphonation of 23 afforded the pyrazolotriazine 24. Finally, reaction of 2 with 2-hydroxybenzaldehyde gave benzofuran derivative 25. Representative compounds of the synthesized products were evaluated as antioxidant agents.

Synthesis and antioxidant evaluation of some new sulphadimidine incorporating thiophene moiety

“…Considering the facts that nearly all of the classes of heterocyclic compounds are biologically active and as a part of our continuous efforts towards the development of more potent antioxidant agents [16][17][18][19][20]. It was thought of interest to combine the above mentioned boilable rings together in a molecular framework to investigate the additive effect of these rings towards antioxidant activity.…”

Proton Sensitive Functional Organic Fluorescent Dyes Based on Coumarin‐imidazo[1,2‐a]pyrimidine; Syntheses, Photophysical Properties, and Investigation of Protonation Ability

“…However, 3‐acetylcoumarin derivatives were synthesized in solventless reaction condition under microwave irradiation (MWI) method as well as conventional methods (CM). In addition, for the synthesis of their brominated derivatives, both literature methods and our improved MWI method were used (Scheme ) , . The coumarin‐imidazo[1,2‐ a ]pyrimidines bearing bromine 19 and 20 were used to increase the length of the conjugation in coumarin‐imidazo[1,2‐ a ]pyrimidine derivatives, and a second family of compounds was obtained.…”

Synthesis and Biological Evaluation of Some Novel Isoxazole Derivatives

“…Therefore, the search for novel and selective anticancer agents has attracted considerable attention because of problems associated with currently available anticancer drugs. Confident by the aforementioned endings and in a continuation of our program aiming to synthesize new heterocyclic compounds with potential chemotherapeutic activities , we report herein the synthesis of some new isoxazole compounds containing basic side chain that would produce effective anticancer activity.…”