Nano-TiO₂/SiO₂ catalyzed synthesis, theoretical calculations and bioactivity studies of new α-aminophosphonates

A simple and highly efficient method has been employed for the synthesis of a novel series of diverse biologically active α-aminophosphonates (4a-m) by reacting 7-nitro-2,3-dihydrobenzo[b][1,4]dioxine-6-carbaldehyde (1) with various aromatic/hetero aromatic amines (2a-m) and dimethyl phosphite (3) by the Kabachnik-Fields reaction in the presence of an efficient heterogeneous Nano-TiO₂/SiO₂ (5 mol%) catalyst, which represents an effective Lewis acid and reusable catalyst under reflux conditions. A systematic structure activity relationships (SAR) analysis was performed on all the title compounds to define a relationship between their chemical structures and their antimicrobial activities. In addition, theoretical calculations such as density functional theory (DFT) and minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were also evaluated.