Selenium-incorporated polymeric carbon nitride for visible-light photocatalytic regio-specific epoxidation of β-ionone

Abstract

Selenium-incorporated polymeric carbon nitride (PCN)-catalyzed epoxidation reaction of β-ionone was developed for producing (E)-4-(2,2,6-trimethyl-7-oxabicyclo[4.1.0]heptan-1-yl)but-3-en-2-one, which was a popular spice in perfume production as well as the key intermediate for the total synthesis of the highly demanded phytohormone abscisic acid. The reaction employed water as cheap, safe and green precursor of H2O2 oxidant and utilized visible light as the driving force. It was found that introducing Se into the material from Se powder significantly enhanced the catalytic activity of PCN owing to the predominantly increased specific surface area of the catalyst (37.7 m²/g of PCN-Se vs. 16.6 m²/g of simple PCN) and the oxygen carrier catalyst features of incorporated Se. The highly electropositive Se sites facilitated their electrophilic additions with the thermodynamically unfavourable endocyclic C=C of β-ionone, affording a regio-specific access to useful epoxide product. This is the first report of the unique PCN-Se relay catalysis procedure.