Abstract Oxidative photoinduced electron transfer (PET) reactions have been performed with various cyclic cyclopropyl (vinyl) silyl ethers bearing an olefinic or acetylenic side chain. The reactions result in bi-to tetracyclic ring systems via a fragmentation–radical/radical cationic addition reaction pathway with well defined ring juncture. The mode of cyclisation (endo/exo) can be partially controlled by addition of nucleophiles due to the suppression ...