title: A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles.
abstract: A short and robust approach for the synthesis of 2-(hetero)aryl substituted thieno[2,3-b]indoles from easily available 1-alkylisatins and acetylated (hetero)arenes has been advanced. The two-step procedure includes the "aldol-crotonic" type of condensation of the starting materials, followed by treatment of the intermediate 3-(2-oxo-2-(hetero)arylethylidene)indolin-2-ones with Lawesson's reagent. The latter process involves two sequential reactions, namely reduction of the C=C ethylidene double bond of the intermediate indolin-2-ones followed by the Paal-Knorr cyclization, thus affording tricyclic thieno[2,3-b]indoles.
authors.affiliation: Postovsky Institute of Organic Synthesis, Ural Division of the Russian Academy of Sciences, Ekaterinburg, 620990, Russia ; Ural Federal University named after the First President of Russia, B. N. Yeltsin, Ekaterinburg, 620002, Russia.
authors.forename: Roman A
authors.initials: RA
authors.lastname: Irgashev
authors.affiliation: Postovsky Institute of Organic Synthesis, Ural Division of the Russian Academy of Sciences, Ekaterinburg, 620990, Russia ; Ural Federal University named after the First President of Russia, B. N. Yeltsin, Ekaterinburg, 620002, Russia.
authors.forename: Arseny A
authors.initials: AA
authors.lastname: Karmatsky
authors.affiliation: Postovsky Institute of Organic Synthesis, Ural Division of the Russian Academy of Sciences, Ekaterinburg, 620990, Russia ; Ural Federal University named after the First President of Russia, B. N. Yeltsin, Ekaterinburg, 620002, Russia.
authors.forename: Gennady L
authors.initials: GL
authors.lastname: Rusinov
authors.affiliation: Postovsky Institute of Organic Synthesis, Ural Division of the Russian Academy of Sciences, Ekaterinburg, 620990, Russia ; Ural Federal University named after the First President of Russia, B. N. Yeltsin, Ekaterinburg, 620002, Russia.
authors.forename: Valery N
authors.initials: VN
authors.lastname: Charushin
keywords: Lawesson’s reagent; Paal–Knorr reaction; aldol-crotonic condensation; isatin; methyl ketones; thieno[2,3-b]indole