Synthesis of (±)-Mersicarpine and Related Kopsia Alkaloids Frameworks via a Cyanomethyl Radical Addition/Cyclization Cascade Process

In this work, we report a concise, protecting-group-free, seven-step total synthesis of (±)-mersicarpine in 15% overall yield, from commercial γ-caprolactone, representing the shortest racemic route reported to date. In addition, formal synthetic approaches to rhazinilam and leuconoxine alkaloids were achieved. The strategy relies on a cyanomethyl radical cascade cyclization of N-alkene-linked indole and pyrrole substrates under either DLP-mediated or photoredox conditions, providing rapid access to key polycyclic frameworks.