Synthesis and Bioactivity Evaluation of Novel 2-Salicyloylbenzofurans as Antibacterial Agents

Abstract

In order to discover new antibacterial agents, series of 2-salicyloylbenzofuran derivatives were designed, synthesized and evaluated for their antibacterial activities against three Gram-(+) strains (methicillin-sensitive Staphylococcus aureus (MSSA) ATCC 29213, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, and Streptococcus faecalis (S. faecalis) ATCC 29212) and one Gram-(−) strain (Escherichia coli (E. coli) ATCC 25922). The 2-salicyloylbenzofuran heterocycles were generated by Rap–Stoermer condensation of salicylaldehydes with phenacyl bromides and then converted to diverse O-ether derivatives by Williamson synthesis. The targeted products were screened for in vitro qualitative (zone of inhibition) and quantitative (MIC) antibacterial activities by agar well diffusion assay and agar dilution method. Amongst the compounds, those bearing carboxylic acid functional group were found to exhibit reasonable activity against Gram-(+) bacterial strains including S. faecalis, MSSA and MRSA with the most potent antibacterial agent 8h (MICs = 0.06–0.12 mM). Besides, the 2-salicyloylbenzofurans partly displayed inhibitory activity against MRSA with the best MICs = 0.14 mM (8f) and 0.12 mM (8h). Finally, the antibacterial results preliminarily suggested that the substituent bearing carboxylic acid group at salicyloyl-C2 and the bromine atoms on the benzofuran moiety seem to be the functionality necessary for antibacterial activities.

New antiproliferative 3-substituted oxindoles inhibiting EGFR/VEGFR-2 and tubulin polymerization

“… 2-bromo-1-(4-bromophenyl) ethan-1-one (2b) White powder; 0.2 g, 72.20% yield; m.p:111 °C; (Reported 108–110 °C) [ 80 ]. 2-bromo-1-(4-methoxyphenyl) ethan-1-one (2c) Yellow crystals; 0.23 g, 76.66% yield; mp: 68–71 °C; (Reported 69–72 °C) [ 81 ]. …”

Salicylaldehydes Derived from 5-Chloromethyl-2-hydroxybenzaldehyde – Synthesis and Reactions

“…1 Alkene-or alkyne-tethered salicylaldehyde derivatives (such as Oallylsalicylaldehyde or O -propargylsalicylaldehyde) can generate diverse compound libraries with rich stereochemical and scaffold diversity that include benzopyranes, chromenoquinolines, various other chromene-fused heterocycles, benzoxazepines and macrocycles. 2,3 Upon cyclocondensation with α-haloketones under the conditions of the Rap-Stoermer reaction, salicylaldehydes produce 2-acylbenzofurans, 4,5 while this particular reaction was shown to be amenable to an ultrasound-assisted approach that improves the yields of the target benzofurans. 6 Also, several synthetic variants for the preparation of 1,2benzisoxazoles from oximes of ortho-hydroxybenzaldehydes using para-toluenesulfonyl chloride in the presence of an amine in acetonitrile, 7 trifluoromethanesulfonic anhydride in dichloromethane, 8 or a triphenylphosphine-2,3-dichloro-5,6-dicyano-1,4-benzoquinone system 9 have been reported.…”

Synthesis, Characterization and Antifungal Activity of Novel Thiazolo-Pyrimidine Fused Heterocycles

“…(1) Among them thiazole and pyrimidine derivatives possess diverse pharmacological activities (2,3). Fused Thiazolopyrimidine, heterocyclic derivatives are also display various biological activities like, anticancer (4,5),antimicrobial (6,7), antibacterial effects (8),antiviral (9,10), anti parkinsonian, analgesic (10), anti-inflammatory and analgesic activities (11,12), and exhibit potent antitumor (13,14).…”