In situ generated CF3CHN2 with 3-ylideneoxindoles to access CF3-containing pyrazolo[1,5-c]quinazolines derivatives†

Toward a selective and facile method for the synthesis of CF₃-containing pyrazolo[1,5-c]quinazolines, we developed a [3 + 2] cycloaddition/1,3-H shift/rearrangement/dehydrogenation cascade involving in situ generated CF₃CHN₂ and 3-ylideneoxindoles with DBU as a base. The reaction is distinguished by its mild conditions, metal-free process, operational simplicity, and broad functional group tolerance, thus presenting a convenient protocol for the construction of pyrazolo[1,5-c]quinazolines that are of interest in medicinal chemistry.