Thieno[3,2-b]thiophene-2-carboxylic acid derivatives as GPR35 agonists

The optimization of a series of thieno3,2-b]thiophene-2-carboxylic acid derivatives for agonist activity against the GPR35 is reported. Compounds were optimized to achieve β-arrestin-biased agonism for developing probe molecules that may be useful for elucidating the biology and physiology of GPR35. Compound 13 was identified to the most potent GPR35 agonist, and compounds 30 and 36 exhibited the highest efficacy to cause β-arrestin translocation.