title: Palladium catalyzed synthesis and physical properties of indolo[2,3-b]quinoxalines.
abstract: A series of indolo[2,3-b]quinoxaline derivatives were efficiently synthesized from 2,3-dibromoquinoxaline by two pathways. A one-pot approach using Pd-catalyzed two-fold C-N coupling and C-H activation reactions gave indolo[2,3-b]quinoxaline derivatives in good yields, but with limited substrate scope. In addition, a two-step approach to indolo[2,3-b]quinoxalines was developed which is based on Pd-catalyzed Suzuki coupling reactions and subsequent annulation by Pd-catalyzed two-fold C-N coupling with aromatic and aliphatic amines. The electrochemical and photochemical properties of indolo[2,3-b]quinoxaline derivatives were investigated. These studies show that 6-(4-methoxyphenyl)-6H-indolo[2,3-b]quinoxaline showed the highest HOMO energy level and lowest band gap.
authors.affiliation: Institut für Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany. peter.langer@uni-rostock.de thanhtuandang@hotmail.com.
authors.forename: Tran Quang
authors.initials: TQ
authors.lastname: Hung
authors.forename: Do Huy
authors.initials: do H
authors.lastname: Hoang
authors.forename: Ngo Ngoc
authors.initials: NN
authors.lastname: Thang
authors.forename: Tuan Thanh
authors.initials: TT
authors.lastname: Dang
authors.forename: Khurshid
authors.initials: K
authors.lastname: Ayub
authors.forename: Alexander
authors.initials: A
authors.lastname: Villinger
authors.forename: Aleksej
authors.initials: A
authors.lastname: Friedrich
authors.forename: Stefan
authors.initials: S
authors.lastname: Lochbrunner
authors.forename: Gerd-Uwe
authors.initials: GU
authors.lastname: Flechsig
authors.forename: Peter
authors.initials: P
authors.lastname: Langer