The synthesis and ΔF508-CFTR corrector activity of a 148-member methylbithiazole-based library are reported. Synthetic routes were devised and optimized to generate methylbithiazole analogs in four steps. Corrector potency and efficacy were assayed using epithelial cells expressing human ΔF508-CFTR. These structure–activity data establish that the bithiazole substructure plays a critical function; eight novel methylbithiazole correctors ...