ZnO in ionic liquid under microwave irradiation: A novel medium for synthesis of phloroglucide derivatives as antimicrobial agents

Abstract

Owing to the wide applications and significance of phloroglucide analogues in organic synthesis, pharmacology and industry, there is considerable interest in the synthesis of these compounds. Nevertheless, there are few methods for preparation of these compounds. Here we reported a simple, clean, and highly efficient procedure for the green synthesis of tricyclic polyhydroxyl aromatic compounds. Microwave-assisted alkylation reaction between 4-substituted-2,
6-bis(chloromethyl)phenols and various phenol derivatives, in the presence of zinc oxide (ZnO) in 1-butyl-3-methylimidazolium hexaflourophosphate ([Bmim]PF₆), affords the title compounds in short duration with high yields. We have synthesized 18 derivatives of the title compounds 3a-3r by this procedure. Chemical structures of all synthesized compounds have been confirmed by spectrophotometric methods such as IR, NMR and mass spectroscopy. Some of the synthesized compounds have been screened for their antimicrobial activities. Antifungal and antibacterial activities have been evaluated against different species of microorganisms including gram positive and gram negative bacteria as well as fungi. Broth microdilution method as recommended by Clinical and Laboratory Standard Institute has been used for this purpose. The results show compounds 3i, 3k and 3m have the best antibacterial and antifungal activity against most of the examined species. Compounds 3b, 3f, 3o, 3p and 3q also show good activity against some species.