Photocyclization of 2-cinnamylphenols via excited state proton transfer (ESPT) involving the lowest-lying styrenic singlet

Article abstract of DOI:10.1016/S0040-4020(97)00942-3

The attachment of substituents to the styrenic ring of trans-2-cinnamylphenol produces a decrease in the singlet energy of the styrenic moiety. As a consequence, the resulting chromophore becomes responsible for the photophysical and photochemical properties of this type of bichromophoric compounds. Both fluorescence emission and photocyclization occur predominantly from the lowest-lying styrenic singlet. The result is a marked regioselectivity towards 6-membered ring products, via an excited state proton transfer.