Silica gel Supported Boric tri-Sulfuric Anhydride (SiO2-BTSA): An Efficient Catalytic System for the Synthesis of Phloroglucide Analogs as Antimicrobial Agents

Abstract

Background: Polyhydroxy aromatic compounds are one of the most important classes of phenolic compounds with different biological activities. Some important and biologically active phenol-based compounds have also been isolated from nature. Methods: An efficient procedure for the synthesis of polyhydroxy aromatic compounds (phloroglucide analogs) is described. In this procedure, a reaction took place between different 4-substituted phenols and 2,6-bis(hydroxymethyl) phenols. The reactions proceed in the presence of catalytic amount of silica gel supported boric tri-sulfuric anhydride (SiO2-BTSA) in excellent yields. Results: 16 compounds were synthesized (I1-I16). Chemical structures of all the compounds were confirmed by spectroscopic methods. We optimized the chemical reactions in the presence of different acidic catalysts, different solvents and also different temperatures. A catalytic amount of SiO2-BTSA in dichloroethane (DCE) was the best condition. Some of the synthesized compounds were screened for their antimicrobial activities. Antifungal and antibacterial activities of the synthesized compounds were evaluated by broth microdilution method as recommended by CLSI. Some of the tested compounds showed good in vitro biological properties. Conclusion: Our active compounds could introduce as good candidates for further studies as antimicrobial agents.