Photoxydation sensibilisée du benzhydrylidéne-cyclobutane : Addition d'oxygéne singulet à un système conjugué éthylénique-aromatique

The bis-peroxide 5 was obtained by sensitized photo-oxidation of benzhydrylidene-cyclobutane 1. The structure was established on the basis of a series of reactions, including selective acidolysis (to the hydroperoxides 11) and reductions of the bis-peroxide 5 (to the diols 6, 8 and tetrol 9) and some of its derivatives (to the diols 7, 21 and derivatives, epoxide 12, alcohol 13, triol 14, tetrols 15, 22), and partial oxidative degradations (to the bis-hemiacetal 17, hemiacetal-lactone 18, ketol 19, and lactones 27, 28, 29). The configurations and conformations of all the derivatives were established by NMR spectroscopy including the use of a europium shift reagent.