Construction of Indazolo[3,2-a]isoquinolines via [3 + 2] Cycloaddition of Benzynes

An [3 + 2] annulation protocol for the construction of N- substituted indazolo[3,2-a]isoquinolines starting from benzynes and C,N-cyclic azomethine imines was developed. A diverse range of highly functionalized products indazolo[3,2-a]isoquinolines featuring an indazole scaffold can be easily approached via one-step reaction under mild conditions and showed good anti-proliferative activity on cancer cells.