Metal‐free and One‐pot for the Synthesis of Indolo[2,1‐a]isoquinoline Aldehyde via a Free Radical Cascade Pathway followed by Direct Hydrolyzation

As one of the most versatile intermediate group in synthetic chemistry, the introduction of an aldehyde group into a specific moiety is important for the transformation of molecular structures. Herein, we provided a metal‐free, regioselective and one‐pot formylation of the indolo[2,1‐a]isoquinoline moiety. This strategy features an oxidative coupling process using commercially available 1,3‐dioxolane as a formylated reagent followed by direct hydrolyzation without a separation process. This reaction can be carried out under common reaction conditions and displays broad functional group tolerance.