N-1-Alkyl-2-oxo-2-aryl amides as novel antagonists of the TRPA1 receptor

A series of potent antagonists of the ion channel transient receptor potential A1 (TRPA1) was developed by modifying lead structure 16 that was discovered by high-throughput screening. Based on lead compound 16, a SAR was established, showing a narrow region at the nitro-aromatic R1 moiety and at the warhead, while the R2 side had a much wider scope including ureas and carbamates. Compound 16 inhibits Ca2+-activated TRPA1 currents reversibly in whole cell patch clamp experiments, indicating that under in vivo conditions, it does not react covalently, despite its potentially electrophilic ketone.