Multicomponent Petasis-borono Mannich Preparation of Alkylaminophenols and Antimicrobial Activity Studies

In this work we report the antibacterial activity of alkylaminophenols. A series of such compounds was prepared by a multicomponent Petasis‐borono Mannich reaction starting from salicylaldehyde and its derivatives. The obtained compounds were tested against a large panel of microorganisms, Gram‐positive and Gram‐negative bacteria, and a yeast. Among the several tertiary amine derivatives tested, indoline‐derived aminophenols containing a nitro group at the para‐phenol position showed considerable activity against bacteria tested with minimal inhibitory concentrations as low as 1.36 μm against Staphyloccocus aureus and Mycobacterium smegmatis. Cytotoxicity of the new para‐nitrophenol derivatives was observed only at concentrations much higher than those required for antibacterial activity. Antibiotics by MCR: We disclose a new family of antibacterial agents derived from para‐nitrophenols and indoline, prepared by a multicomponent reaction (MCR). The new alkylaminophenols show minimum inhibitory concentrations lower than 1.4 μm against selected resistant microorganisms. Cytotoxicity assays demonstrated that such compounds are viable candidates as antibacterials, as no cytotoxicity was observed at these concentrations.