Tunable Cysteine-Targeting Electrophilic Heteroaromatic Warheads Induce Ferroptosis

Once considered potential liabilities, the modern era witnesses a renaissance of interest in covalent inhibitors in drug discovery. The available toolbox of electrophilic warheads is limited by constraints on tuning reactivity and selectivity. Following our work on a class of ferroptotic agents termed CETZOLEs, we discovered new tunable heterocyclic electrophiles which are capable of inducing ferroptosis. The biological evaluation demonstrated that thiazoles with an alkyne electrophile at the 2-position selectively induce ferroptosis with high potency. Density functional theory calculations and NMR kinetic studies demonstrated the ability of our heterocycles to undergo thiol addition, an apparent prerequisite for cytotoxicity. Chemoproteomic analysis indicated several potential targets, the most prominent among them being GPX4 protein. These results were further validated by western blot analysis and the cellular thermal shift assay. Incorporation of these heterocycles into appropriate pharmacophores generated highly cytotoxic agents such as the analogue BCP-T.A, with low nM IC50 values in ferroptosis-sensitive cell lines.

Electrophilic Thiocyanato Reagent Assisted Oxa-Michael/Thiocyanation of α,β-Unsaturated Ketones

A route for thiocyanation-functionalization of the electron-deficient C═C double bond was developed. Regioselective thiocyanation-etherification of α,β-unsaturated ketones was achieved. The desired products were obtained in moderate to high yields under mild conditions. It was suggested that the nucleophile was activated by the electrophilic thiocyanato reagent, and difunctionalization was achieved through a 1,4-addition/thiocyanation pathway.

Boron Lewis Acid-Catalyzed Hydrophosphinylation of N-Heteroaryl-Substituted Alkenes with Secondary Phosphine Oxides

We report the boron-catalyzed hydrophosphinylation of N-heteroaryl-substituted alkenes with secondary phosphine oxides that furnishes various phosphorus-containing N-heterocycles. This process proceeds under mild conditions and enables the introduction of a phosphorus atom into multisubstituted alkenylazaarenes. The available mechanistic data can be explained by a reaction pathway wherein the C-P bond is created by the reaction between the activated alkene (by coordination to a boron catalyst) and the phosphorus(III) nucleophile (in tautomeric equilibrium with phosphine oxide).