تحضير ودراسة الفعالية الحيوية لبعض مشتقات 2-امينوبنزوثيازول الجديدة

Synthesis and Study the Biological Activity of Some New Derivatives of 2-Aminobenzothiazole

abstract

This work includes the synthesis of new benzothiazole derivatives containing thiazolidinone, quinazolinone, and chalcone moieties. First, the amino group in 2-aminobenzothiazole was converted to the corresponding diazonium salt through the reaction with nitrous acid (H2SO4 / NaNO2), which is directly introduced in the coupling reaction (electrophilic substitution) with an alkaline solution of 2-hydroxybenzaldehyde as a coupling reagent to give the azo-benzothiazole derivative (A) containing the aldehyde group. The resulting aldehyde has then been introduced in condensation reactions with some anilines in absolute ethanol using the microwave irradiation method to obtain some benzothiazolic imines (S1-S12). The synthesized imines (S1-S12) have been reacted with α-mercaptoacetic acid in N,N-dimethylformamide using the microwave irradiation method to obtain some new thiazolidin-4-one derivatives (T1-T12). In addition, the prepared imines (S1-S12) have been treated with α-anthranilic acid in N,N-dimethylformamide using the microwave irradiation method to obtain some new quinazolinone derivatives (Q1-Q12). Chalcones (C1-C5) were synthesized by condensing the resulting aldehyde (A) with some acetophenone derivatives in a dilute ethanolic sodium hydroxide solution at room temperature according to Claisen-Schmidt condensation, which are considered important intermediates that can be introduced in several reactions to obtain interesting heterocyclic compounds. New heterocyclic derivatives including 2-amino-1,3-oxazines (Ca1-Ca5), 2-amino-1,3-thiazines (Cb1-Cb5), 2-methyl-1,3-thiazines (Cb6-Cb10), and 2-aminopyrimidines (Cd1-Cd5) were synthesized by treating chalcones with urea, thiourea, thioacetamide, and guanidine hydrochloride, respectively, in the presence of ethanolic sodium hydroxide. The chemical structures of the target compounds have been deduced from FT-IR, 1H NMR, 13C NMR, and mass spectral measurements. All the newly synthesized compounds have been screened for their antioxidant and antibacterial activity. The DPPH was used to determine the antioxidant activity of the new compounds. Compounds like T1, T9, T10, T11, T12, Q8, Q9, Q11, Q12, Cb5, Cd3, Cd4, and Cd5 have DPPH radical scavenging properties that are especially potent and equivalent to ascorbic acid. In an antibacterial study, it was found that the synthesized compounds like T2, T3, T12, C2, C5, Ca1, Ca2, Ca4, Cb1, Cb2, Cb6, Cb8, and Cb9 were more effective than Gentamycin as a control drug against Staphylococcus aureus; on the other hand, T3 and T11, were more effective than the reference drug against Escherichia coli.