Photooxidative decarboxylation of proline, a novel oxidative stress to natural amines

Article abstract of DOI:10.3987/COM-97-S(N)93

Proline was decarboxylated quantitatively to Δ¹-pyrroline on photoirradiation in the presence of rose bengal, while its methyl ester yielded an equimolar mixture of Δ¹- and Δ⁵-pyrroline-2-carboxylic acid methyl esters. The decarboxylation of proline took place under either an aerobic (O₂ bubbling) or an anaerobic (N₂ bubbling) conditions, and under the latter condition, extent of the reaction depended on the amount of rose bengal employed. These results imply mechanistically that the reaction is the Type I photooxidation, indicating a new type of oxidative stress to natural secondary amines.