Isothiazole and isoxazole fused pyrimidones as PDE7 inhibitors: SAR and pharmacokinetic evaluation

The synthesis and structure-activity relationship studies of isothiazole and isoxazole fused pyrimidones as PDE7 inhibitors are discussed. The pharmacokinetic profile of 10 and 21 with adequate CNS penetration, required for in vivo Parkinson's disease models, are disclosed.