One-Step Synthesis of 1-Chloro-3-arylacetone Derivatives from Arylacetic Acids

Design, synthesis and modelling of photoreactive chemical probes for investigating target engagement of plasmepsin IX and X in Plasmodium falciparum

The emergence of Plasmodium parasite resistance to current front-line antimalarial treatments poses a serious threat to global malaria control and highlights the necessity for the development of therapeutics with novel targets and mechanisms of action. Plasmepsins IX and X (PMIX/PMX) have been recognised as highly promising targets in Plasmodium due to their contribution to parasite's pathogenicity. Recent research has demonstrated that dual PMIX/PMX inhibition results in the impairment of multiple parasite's life cycle stages, which is an important feature in drug resistance prevention. Herein we report novel hydroxyethylamine photoaffinity labelling (PAL) probes, designed for PMIX/PMX target engagement and proteomics experiments in Plasmodium parasites. The prepared probes have both a photoreactive group (diazirine or benzophenone) for covalent attachment to target proteins, and a terminal alkyne handle allowing their use in bioorthogonal ligation. One of the synthesised benzophenone probes was shown to be highly promising as demonstrated by its outstanding antimalarial potency (IC50 = 15 nM versus D10 P. falciparum) and its inhibitory effect against PfPMX in an enzymatic assay. Molecular docking and molecular dynamics studies show that the inclusion of the benzophenone and alkyne handle does not alter the binding mode compared to the parent compound. The photoaffinity probe can be used in future chemical proteomics studies to allow hydroxyethylamine drug scaffold target identification and validation in Plasmodium. We expect our findings to act as a tool for future investigations on PMIX/PMX inhibition in antimalarial drug discovery.

"On water" palladium catalyzed diastereoselective boronic acid addition to structurally diverse cyclopropane nitriles

An efficient palladium catalyzed diastereoselective addition of arylboronic acids to complex spirocyclopropyl dinitriles is developed in the presence of a catalytic amount of 4-dodecylbenzenesulphonic acid (DBSA) as a Brønsted acid surfactant in aqueous media. The protocol is also found to be highly effective when different types of nitrile compounds and organo-boron compounds are used. The overall reaction has been found to be very cost efficient since it requires low catalyst loading, mild thermal energy and short reaction time. Wide substrate scope, operational simplicity, good to excellent product yield, and use of green solvents make the reaction a practical route to transform nitrile into a keto functionality in biorelevant heterocyclic scaffolds. The scale-up synthesis of the target scaffolds can also be achieved with ease which also signifies the practicability of this protocol.