Irradiation of terminal aromatic gamma,delta-epoxy ketones with a 450 W UV lamp led to Norrish type II cyclization/semi-pinacol rearrangement cascade reaction which formed the benzocyclobutanones containing a full-carbon quaternary center, whereas irradiation of substituted aromatic gamma,delta-epoxy ketones led to the indanones through a photochemical epoxy rearrangement and 1,5-biradicals cyclization