Electronic effects of ring substituents on triplet benzylic biradicals

Article abstract of DOI:10.1021/ol0528383

UV irradiation of α-(o-alkylphenyl)acetophenones with a methoxy or cyano substituent para to the o-alkyl group of the α-aryl ring has revealed that a methoxy group slightly increases the stereoselectivity but not the quantum yield of indanol formation, whereas a cyano group greatly lowers both diastereoselectivity and quantum efficiency, confirming the likelihood that hydrogen-bonding of the hydroxy group to the α-phenyl ring plays an important role in the cyclization of the photogenerated triplet 1,5-biradical intermediates.