On the Photoisomerization of Pyridine in Vapor Phase

Abstract DFT calculations on the photoisomerization of pyridine, 2,3‐, 2,6, and 3,4‐dimethylpyridine showed that the photoisomerization occurs through the formation of the corresponding Dewar isomers. These compounds can be transformed into the corresponding benzvalene isomers, whose decomposition gives the reaction products. Another way to obtain some observed reaction products is a photoisomerization of the Dewar isomers through an intramolecular thermal or photochemical [2+2]‐cycloaddition reaction.