The marine sponge alkaloid stevensine (3) has been synthesized from the related C11N5 alkaloid, hymenin (1). The key transformation involves a regioselective protodebromination/ transbromination event of 4′-bromohymenin (2) to install the olefin in 3. Such processes are seldom used for synthetic purposes but appear to be highly applicable to the C11N5 family of marine alkaloids.