Pyridine-N-oxide CAS 694-59-7

Pyridine N-oxide is a stable organic compound that can be used as a starting material to synthesize pyridine derivatives. Using abundant and easily obtainable alkenes as the alkylation reagent, the conversion from pyridine N-oxide to ortho-alkyl-substituted pyridine can be achieved. This approach is very attractive. However, such reports are only a few in number, and they are only applicable to electron-deficient alkenes. For example, perfluoropropane reacts with pyridine N-oxide through 1,3-dipolar cycloaddition and carbon fluoride elimination to obtain tetrafluoroethyl-substituted pyridine. Although pyridine N-oxide contains polar N–O bonds, for the cycloaddition reaction, their 1,3-dipolar activity is relatively low. The reason for this might be that the aromaticity of both substrates is disrupted simultaneously during the reaction. One solution to this problem is to use the free radical species generated from simple alkenes by photo-catalysis as the alkylation component of pyridine N-oxide. Because these cationic free radicals have sufficient electrophilicity, they can couple with pyridine N-oxide to form a radical intermediate, and then undergo intramolecular ortho addition and carbonyl compound elimination to obtain the ortho-substituted pyridine product.