Kinetic study of nucleophilic reactivity of heterocyclic amines with 4,6-dinitrobenzofuroxan in acetonitrile

Design, synthesis, and in vitro biological evaluation of meta-sulfonamidobenzamide-based antibacterial LpxH inhibitors

New antibacterial compounds are urgently needed, especially for infections caused by the top-priority Gram-negative bacteria that are increasingly difficult to treat. Lipid A is a key component of the Gram-negative outer membrane and the LpxH enzyme plays an important role in its biosynthesis, making it a promising antibacterial target. Inspired by previously reported ortho-N-methyl-sulfonamidobenzamide-based LpxH inhibitors, novel benzamide substitutions were explored in this work to assess their in vitro activity. Our findings reveal that maintaining wild-type antibacterial activity necessitates removal of the N-methyl group when shifting the ortho-N-methyl-sulfonamide to the meta-position. This discovery led to the synthesis of meta-sulfonamidobenzamide analogs with potent antibacterial activity and enzyme inhibition. Moreover, we demonstrate that modifying the benzamide scaffold can alter blocking of the cardiac voltage-gated potassium ion channel hERG. Furthermore, two LpxH-bound X-ray structures show how the enzyme-ligand interactions of the meta-sulfonamidobenzamide analogs differ from those of the previously reported ortho analogs. Overall, our study has identified meta-sulfonamidobenzamide derivatives as promising LpxH inhibitors with the potential for optimization in future antibacterial hit-to-lead programs.

Comparative modeling of improved synthesis of energetic dinitrobenzofuroxan (DNBF) derivatives

Quantum chemical theoretical computation was performed on gaseous molecular reaction systems to simulate parallel synthesis of energetic primary explosive precursor 4,6-dinitrobenzofuroxan (4,6-DNBF) and its isomeric derivatives. Related polarized continuum model (PCM) and Materials Studio (MS/forcite) energies were collected via kinetic rate and thermodynamic equilibrium analyses, enabling comparison of and suggestions as to suitable reaction conditions (reaction temperature, reagent concentration, mixed acid ratio) together with feasible pathways to obtain a high production yield of the research target. In summary, at a low reaction temperature of 278 K, 1.0 M 4-nitrobenzofuroxan (or 5,6-nitrobenzofuroxan) could be nitrated using concentrated nitric acid/sulfuric acid at a 1 to 2 volume ratio to efficiently and rapidly produce 4,6-dinitro-benzofuroxan (or 5,6-dinitrobenzofuroxan), in agreement with the experimental results reported in the literature. Graphical abstract.