Photooxygenation Catalysis with a Polyol-Decorated Disc-Shaped Porphyrin Sensitizer: Shell-Recognition Effects



Polar meso-tetraarylporphyrins 24 were synthesized from tetrakis-4-hydroxyphenylporphyrin 1 as the central building block by consecutive base-induced reactions with glycidol. The decorating units form a polar hydrogen-bonded shell around the sensitizer core which is proposed as the binding site for polar substrates in photocatalyzed oxygenation reactions. As substrate, the polarity-sensor mesitylol (5) was applied and the reaction constrained in a polystyrene matrix. Increasing shell dimensions lead to increased diastereoselectivities for the allylic hydroperoxides 6 and thus clearly demonstrate the concept of shell-induced substrate stereoselectivity in singlet oxygen reactions.