New pyridazine–fluorine derivatives: Synthesis, chemistry and biological activity. Part II

•Synthesis and antimicrobial activity of new pyridazine–fluorine (PYF).•The first synthesis of PYF in phase-transfer catalysis under microwave.•Regiochemistry and chorochemistry involved in these reactions are discussed.•Trifluoromethyl group on pyridazine skeleton increase the antimicrobial activity.

A comprehensive study concerning synthesis, structure and biological activity of new pyridazine–fluorine (PYF) derivatives is presented. The first synthesis of PYF derivatives in phase-transfer catalysis (PTC) under microwave (MW) and conventional thermal heating (TH) is reported. Under MW irradiation the consumed energy decreases considerably, the amount of used solvent in liquid phase is at least five-fold less comparative with conventional TH, while PTC did not use solvents. Consequently these reactions could be considered environmentally friendly. Also, the reaction time decrease substantially and, in some cases, the yields are higher. A feasible explanation for MW efficiency is presented. Regiochemistry and chorochemistry involved in these reactions are also discussed; the reactions are regioselective and chorospecific or choroselective, respectively. Ten new pyridazine–fluorine cycloadducts are obtained. The in vitro antibacterial and antifungal activities of the PYF compounds were tested. Introduction of a trifluoromethyl moiety on the pyridazine skeleton is leading to an increasing of the antimicrobial activity. Structure–activity correlationships have been done.

Graphical abstractThe design, synthesis and in vitro antimicrobial activity of new pyridazine–fluorine (PYF) derivatives are presented. The first synthesis of PYF derivatives in phase-transfer catalysis (PTC) under microwave (MW) and conventional thermal heating (TH) is also reported. Introduction of a trifluoromethyl moiety on the pyridazine skeleton is leading to an increasing of the antimicrobial activity.Figure optionsDownload full-size imageDownload as PowerPoint slide