The naturally occurring enediynes are a novel class of antitumor antibiotics. Some members of this family are over 1000 times more potent than adriamicin, one of the most effective antitumor agents in clinical use. However, a major stumbling block to clinical applications of these compounds is their inadequate selectivity, and harnessing the powerful DNA-cleaving activity. In this study, we designed and synthesized a new type of photoactivated enediyne. We modified the core enediyne fragment so as to make the molecule stable in the dark but convertible into an active form upon irradiation. In our approach to the problem we took advantage of in situ generation of a triple bond upon irradiation of cyclopropenones to complete an enediyne π-system.