Pyrrolidinyl phenylurea derivatives as novel CCR3 antagonists

Optimization starting with our lead compound 1 (IC50 = 4.9 nM) led to the identification of pyrrolidinyl phenylurea derivatives. Further modification toward improvement of the bioavailability provided (R)-1-(1-((6-fluoronaphthalen-2-yl)methyl)pyrrolidin-3-yl)-3-(2-(2-hydroxyethoxy)phenyl)urea 32 (IC50 = 1.7 nM), a potent and orally active CCR3 antagonist.