Reversible Photooxygenation of Alkynylanthracenes: Chemical Generation of Singlet Oxygen under Very Mild Conditions

In the dark and very fast: The generation of singlet oxygen (1O2) from endoperoxides, which are readily available by photooxygenation of the corresponding anthracenes, proceeds within minutes in the dark (see scheme), a rate hitherto unknown for other anthracenes or naphthalenes. This provides an efficient chemical source of singlet oxygen under very mild conditions.