Pyridone photoelectrocyclizations to pyridophenanthrenes

This article describes the synthesis of pyridophenanthrenes from the stereoselective electrocyclization and [1,5]-hydride shift sequences of biphenyl pyridones. The regioselectivity of the reaction of meta-substituted biphenyl substrates depended on the electronic environment of the substituents. That is, substrates having electron-withdrawing substituents underwent a regioselective sequence while electron-donating substituents gave mixtures of products.

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