Mycobacterium tuberculosis glutamine synthetase (MtGS) is a promising target for antituberculosis drug discovery. In a recent high-throughput screening study we identified several classes of MtGS inhibitors targeting the ATP-binding site. We now explore one of these classes, the 2-tert-butyl-4,5-diarylimidazoles, and present the design, synthesis, and X-ray crystallographic studies leading to the identification of MtGS inhibitors with submicromolar IC₅₀ values and promising antituberculosis MIC values.

The unique properties of microwave in situ heating offer unparalleled opportunities for medicinal chemists to speed up lead optimisation processes in early drug discovery. The technology is ideal for small-scale discovery chemistry because it allows full reaction control, short reaction times, high safety and rapid feedback. To illustrate these advantages, we herein describe applications and approaches in the synthesis of small molecules to combat four of the most prevalent infectious diseases; tuberculosis, HIV/AIDS, malaria and hepatitis C, using dedicated microwave instrumentation.

A fast and convenient synthesis of arylamidines starting from readily available potassium aryltrifluoroborates and cyanamides is reported. The coupling was achieved by Pd(II)-catalysis in a one step 20 min microwave protocol using Pd(O₂CCF₃), 6-methyl-2,2′-bipyridyl, TFA, and MeOH, providing the corresponding arylamidines in moderate to excellent yields.

A rapid and versatile one-pot, 2 × 10 min microwave protocol for the preparation of N-1 and C-6 decorated 3,5-dichloro-2(1H)-pyrazinones was developed. Comparable reaction sequences using classical conditions require about 1–2 days of heating. The α-aminonitrile was first generated in a Strecker reaction and thereafter cyclized under microwave heating. The microwave approach developed offers the possibility of efficiently generating and utilizing functionalized 3-amino-5-chloro-2(1H)-pyrazinone-N-1-carboxylic acids as β-strand inducing core structures in a medicinal chemistry context. To illustrate the usefulness of the method, the synthesis of two novel 2(1H)-pyrazinone-containing Hepatitis C virus NS3 protease inhibitors is reported.

Type I signal peptidases are potential targets for the development of new antibacterial agents. Here we report finding potent inhibitors of E. coli type I signal peptidase (LepB), by optimizing a previously reported hit compound, decanoyl-PTANA-CHO, through modifications at the N- and C-termini. Good improvements of inhibitory potency were obtained, with IC50s in the low nanomolar range. The best inhibitors also showed good antimicrobial activity, with MICs in the low μg/mL range for several bacterial species. The selection of resistant mutants provided strong support for LepB as the target of these compounds. The cytotoxicity and hemolytic profiles of these compounds are not optimal but the finding that minor structural changes cause the large effects on these properties suggests that there is potential for optimization in future studies.