Tricyclic 3,4-dihydropyrimidine-2-thione derivatives as potent TRPA1 antagonists.

The transient receptor potential A1 (TRPA1) channel has been implicated in a number of inflammatory and nociceptive processes, and antagonists of the TRPA1 receptor could offer a potential treatment for conditions such as inflammatory or neuropathic pain, airway disorders, and itch. In a high throughput screen aimed at the identification of TRPA1 antagonists, 4-phenyl-2-thioxo-1,2,3,4-tetrahydro-indeno[1,2-d]pyrimidin-5-one (1) was identified as a potent TRPA1 receptor antagonist. A series of analogous tricyclic 3,4-dihydropyrimidine-2-thiones has been prepared via the multi-component Biginelli reaction and subsequent derivatization.

Analogues of morphanthridine and the tear gas dibenz[b,f][1,4]oxazepine (CR) as extremely potent activators of the human transient receptor potential ankyrin 1 (TRPA1) channel.

The TRPA1 channel can be considered as a key biological sensor to irritant chemicals. In this paper, the discovery of 11H-dibenz[b,e]azepines (morphanthridines) and dibenz[b,f][1,4]oxazepines is described as extremely potent agonists of the TRPA1 receptor. This has led to the discovery that most of the known tear gases are potent TRPA1 activators.