Bicyclic cyclopentafuranols were formed by photoinitiated radical cyclization of allyl-and propinyloxymethyl substituted cyclopentanones with high regioselectivity. The irradiations were carried out at a wavelength of 300nm in aprotic solvents such as benzene and acetonitrile. We could also show that reductive photoinduced electron transfer (PET) of the propynyloxymethyl substituted cyclopentanone does not lead to any cyclization. The ...