Abstract Light-induced cyclizations of suitably functionalized polyalkene terpenoids, such as geranyl, all-trans-farnesyl, and all-trans-geranylgeranyl derivatives, via formation of radical cations are proven to be a powerful method for the single-step synthesis of mono-and mostly all-trans-fused polycyclic compounds from readily available precursors. Whereas some of these highly stereo-and chemoselective transformations required the use of micel ar ...