Access to Mono‐, Di‐ and Tri‐(Het)Arylated Pyrazolo[5,1‐b]oxazoles Using Cyclization, C−H Activation and Suzuki–Miyaura Palladium‐Catalyzed Reactions

Abstract A first access to mono‐, di‐ and tri‐(Het)arylated pyrazolo[5,1‐ b ]oxazoles is reported. The series were generated from a library of 3‐(Het)arylpyrazolo[5,1‐ b ]oxazole platforms selectively functionalized through regioselective arylation procedures. The regioselective functionalization in C ‐2 and C ‐7 positions was investigated. Each Palladium‐catalyzed cross‐coupling condition was optimized and a representative library of the scope and limitations of the reactions was studied.