No abstract

Multidisciplinary applications of four-coordinate boron(III) complexes make them very attractive and challenging research field in chemistry, biology and material sciences. The dual role played by boron atom in stabilising the chelate ligand and enhancing the π-conjugation makes them very useful as luminescent materials for organic electronics and photonics, and sensing and imaging probes for biomedical purposes. The conventional methods involve the use of diarylborinic acids or anhydrides and triaryl boranes, which are made from organometallic reagents. The strong nucleophilicity of these reagents limits the peripheral modifications onto the boron cores. Here, we report a metal-free one-pot synthesis of four-coordinate organoborons using boronic acids, which represents the first instance of ligand assisted organic group migration between boronic acids. A tetrahedral boron ‘ate’ complex capable of transferring an organic group to the adjacent sp2 boron within a boronic anhydride intermediate is proposed and preliminary mechanistic studies by MALDI-TOF and 11B NMR support this proposal. The products are available from a series of N,O-, N,N- and O,O-bidentate ligands upon a wide array of boronic acids. We anticipate that this reaction will impact the way of producing the four-coordinate organoborons, and propel a new discovery of such materials for optoelectronic and biomedical applications.

The emergence of multi-drug resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis creates the urgency for new anti-tuberculosis drugs to improve the efficiency of current tuberculosis treatment. In the search for a new potential tuberculosis drug, we synthesized an isoindole based chemical library and screened a potential candidate with significant anti-tuberculosis activity. The compound named 2-hydroxy-4-(4-nitro-1,3-dioxoisoindolin-2-yl) benzoic acid (IDD-B40) showed strong activity against all the tested drug-susceptible and drug-resistant strains of M. tuberculosis, with the 50% minimum inhibitory concentrations (MIC50) of 0.39 μg/ml both in culture broth and inside Raw 264.7 cells. Also, IDD-B40, in combination with rifampicin, exhibited a direct synergistic effect against both XDR and H37Rv M. tuberculosis. Besides, IDD-B40 showed a better post-antibiotic effect (PAE) than did some first-line drugs and showed no significant cytotoxicity to any cell line tested, with a selectivity index of ≥ 128. Although IDD-B40 showed a result similar to isoniazid in the preliminary mycolic acid inhibition assay, it did not exhibit any effect against other mycolic acid-producing nontuberculous mycobacterial strains (NTM), and different non-mycobacterial pathogenic strains, so further studies are required to confirm the mode of action of IDD-B40. Considering its results against M. tuberculosis, IDD-B40 is a potential anti-tuberculosis drug candidate. However, further studies are required to evaluate its potential in vivo effect and therapeutic potential.

Aim: Tuberculosis is the leading cause of mortality among infectious diseases worldwide. Finding a new competent anti tubercular therapy is essential. Materials & methods: We screened thousands of compounds and evaluated their efficacy against Mycobacterium tuberculosis. Results: Initially, 2-nitronaphtho[2,3-b]benzofuran-6,11-dione was active against M. tuberculosis. Next, among x15 newly synthesized derivatives, BNF15 showed promising effect against all drug-sensitive and drug-resistant M. tuberculosis (MIC: 0.02–0.78 μg/ml). BNF15 effectively killed intracellular M. tuberculosis and nontuberculous mycobacteria. BNF15 exhibited a prolonged post antibiotic effect superior to isoniazid, streptomycin, and ethambutol and synergistic interaction with rifampicin. In acute oral toxicity test, BNF15 did not show toxic effect at a concentration up to 2000 mg/kg. Conclusion: These results highlight the perspective of BNF15 to treat drug-resistant M. tuberculosis.

Copper-catalyzedr ing-opening reactions of cyclic 1,2-sulfamidates with aw ide range of Grignard reagents have been investigated. Theu se of lithium chloride as an additive is essential to activate C À Ob ond cleavage.T he reactionr epresents highly regio-ands tereoselective,a nd thus allows for efficient synthesis of enantioenriched abranched benzylamine derivatives.F urthermore,w e demonstrated that the productsa re potential to be used as building blocks for the preparation of wide range of nitrogen-containingh eterocycles.