Syntheses of aromatic substituted hydrazino-thiazole derivatives to clarify structural characterization and antioxidant activity between 3-arylsydnonyl and aryl substituted hydrazino-thiazoles.
This work clarifies the structural characterization and antioxidant activity between aromatic and 3-arylsydnonyl substituted hydrazino-thiazoles by further synthesizing a series of aromatic ring-substituted hydrazino-thiazole derivatives 8a-h and 9a-h. Hydrazino-thiazole derivatives 8a-h and 9a-h were obtained by reacting aromatic or heterocyclic aromatic aldehyde thiosemicarbazones 7a-h with cyclization reagents ethyl 2-chloroacetoacetate (2a) and 2-bromoacetophenone (2b), respectively. The ORTEP drawings of compounds 8g, 8h and 9f provide strong evidence of the structure of aromatic thiazole derivatives 8a-h and 9a-h. Undoubtedly, the structure of compounds 3e-h and 4e-h synthesized by the reaction of 3-aryl-4-formylsydnone thiosemicarbazones 1e-h with cyclization reagents 2a and 2b in the previous work should have the thiazole moiety, and not the thiazoline moiety. Both the new thiazole derivatives 8a-h and 9a-h and the 3-arylsydnonyl-substituted derivatives 3e-h and 4e-h were investigated to determine their antioxidant activity by two tests that have been highly documented-the direct scavenging effect on a stable free 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and the inhibition of the 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical. Results of this study demonstrate that not only the thiazole ring and the aryl ring has the contribution to the antioxidant activities, the sydnone ring of 3-arylsydnonyl moiety also has its considerable contribution.
Shih
Mei-Hsiu
MH
Department of Chemical and Materials Engineering, Southern Taiwan University, Tainan, Taiwan, R.O.C. meihsius@mail.stut.edu.tw
Su
Yu-Sheng
YS
Wu
Cheng-Ling
CL
D000447:Aldehydes / Q000138:chemical synthesis; D000975:Antioxidants / Q000138:chemical synthesis* / Q000737:chemistry; D052160:Benzothiazoles / Q000737:chemistry; D001713:Biphenyl Compounds; D018360:Crystallography, X-Ray; D003500:Cyclization; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000737:chemistry; D006834:Hydrazines / Q000138:chemical synthesis / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007202:Indicators and Reagents; D007700:Kinetics; D010851:Picrates / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D013844:Thiazoles / Q000138:chemical synthesis / Q000737:chemistry; D024502:alpha-Tocopherol / Q000737:chemistry
D000447:Aldehydes; D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D006834:Hydrazines; D007202:Indicators and Reagents; D010851:Picrates; D013451:Sulfonic Acids; D013844:Thiazoles; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D024502:alpha-Tocopherol