Regioselective Synthesis of 2,4-Substituted Pyrido[1′,2′:1,5]pyrazolo[3,4- d

International audienceThe synthesis and regioselective functionalization of rare 2,4‐disubstituted‐pyrido[1′,2′:1,5]pyrazolo[3,4‐ d ]pyrimidine derivatives is reported. C‐4 aminations were performed by chlorine nucleophilic substitution S N Ar reactions, and their efficiencies were compared with those for direct one‐pot amide C–O activation with bromotripyrrolidinophosphonium hexafluorophosphate (PyBroP) as a reagent. The latter method was used to perform palladium‐catalyzed C‐4 (het)arylation. Finally, two C‐4 amino and aryl derivatives were prepared on a large scale and engaged in desulfurative Liebeskind–Srogl‐type reactions under microwave irradiation to afford the envisioned compound library. Each step was optimized, and the results are discussed