title: Highly efficient and regiospecific photocyclization of 2,2'-diacyl bixanthenylidenes.
abstract: In contrast to the reversible photochemistry of the 2,2'-substituted bixanthenylidenes (1a-f), the photocyclization of 2,2'-diacyl bixanthenylidenes (1g-j) reveals an irreversible process where the initial cyclic intermediate C(E) can undergo a rapid [1,11] hydrogen shift to form stable isomer C'(E) in a degassed solution, which cannot revert to the starting compound, so giving a highly efficient and regiospecific photocyclization.
authors.affiliation: Department of Chemistry, Joint Laboratory of Green Synthetic Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Mao
authors.forename: Qing-Qing
authors.initials: QQ
authors.lastname: Wu
authors.forename: Ming-Guang
authors.initials: MG
authors.lastname: Ren
authors.forename: Qin-Hua
authors.initials: QH
authors.lastname: Song