Synthesis, Antibacterial, and Antioxidant Evaluation of Novel Series of Condensed Thiazoloquinazoline with Pyrido, Pyrano, and Benzol Moieties as Five- and Six-Membered Heterocycle Derivatives

Abstract

A novel synthesis of thiazolo[2,3-b]quinazolines 4(a–e), pyrido[2′,3′:4,5]thiazolo[2,3-b]quinazolines {5(a–e), 6(a–e), and 7(a–e)}, pyrano[2′,3′:4,5]thiazolo[2,3-b]quinazolines 8(a–e), and benzo[4,5]thiazolo[2,3-b]quinazoloine9(a–e) derivatives starting from 2-(Bis-methylsulfanyl-methylene)-5,5-dimethyl-cyclohexane-1,3-dione 2 as efficient α,α dioxoketen dithioacetal is reported and the synthetic approaches of these types of compounds will provide an innovative molecular framework to the designing of new active heterocyclic compounds. In our study, we also present optimization of the synthetic method along with a biological evaluation of these newly synthesized compounds as antioxidants and antibacterial agents against the bacterial strains, like S. aureus, E. coli, and P. aeruginosa. Among all the evaluated compounds, it was found that some showed significant antioxidant activity at 10 μg/mL while the others exhibited better antibacterial activity at 100 μg/mL. The results of this study showed that compound 6(c) possessed remarkable antibacterial activity, whereas compound 9(c) exhibited the highest efficacy as an antioxidant. The structures of the new synthetic compounds were elucidated by elemental analysis, IR, 1H-NMR, and 13C-NMR.

Synthesis and Biological Evaluation of Octahydroquinazolinones as Phospholipase A2, and Protease Inhibitors: Experimental and Theoretical Exploration

“…Heterocyclic structures having a nitrogen bicyclic nucleus such as quinzolines and octahydroquinazolines are the pioneers for the development of a large number of drugs, and several researchers around the world have also focused on other studies [ 7 ]. Recently, octahydroquinazoline scaffolds have been reported with a variety of medicinal properties, including anticancer [ 8 ], anti-inflammatory [ 9 ], and antimicrobial [ 10 ]. The acid-catalyzed cyclocondensation of aldehydes, ethylacetoacetate, and urea to produce octahydroquinazoline is a well-known Bigineli type of reaction [ 11 ].…”

Synthesis of the Antioxidant Compounds from the Eugenol to the Lubricating Oils

“…Antioxidant compounds also have functional importance in biological activities and in the pharmaceutical industries as radical scavengers [13,14] . In this study, antioxidant compounds were synthesized from the reaction of thiols with alkene compound such as, eugenol and then added them to industrial lubricating oils, and the oxidative stability of oils was observed.…”