text: All 3 types of photooxygenation have been applied in the context of organic synthesis. In particular, type II photooxygenations have proven to be the most widely used (due to the low amount of energy required to generate singlet oxygen) and have been described as "one of the most powerful methods for the photochemical oxyfunctionalization of organic compounds." These reactions can proceed in all common solvents and with a broad range of sensitizers.
  Many of the applications of type II photooxygenations in organic synthesis come from
  Waldemar Adam's investigations into the ene-reaction of singlet oxygen with acyclic alkenes. Through the cis effect and the presence of appropriate steering groups the reaction can even provide high regioselectively and diastereoselectivity - two valuable stereochemical controls.