18443-20-4Relevant articles and documents
Synthesis of Quinone Derivatives of Benzannelated Heterocycles with Bridgehead Nitrogen
Begunov,Sokolov,Filimonov
, p. 1383 - 1391 (2020/10/02)
Abstract: A facile synthesis of para-quinones derived from fused benzimidazoles with a bridgehead nitrogen atom was developed. The heterocyclic quinone core formed as a result of reductive cyclization of ortho-nitroarenes containing alicyclic and aromatic azaheterocycles. Functionalization of 1,2,3,4-tetrahydro- and pyrido[1,2-a]benzimidazoles via SEAr, condensation, and reduction reactions allowed synthesis of amino derivatives which were oxidized with KNO3 in H2SO4 to obtain novel heterocyclic quinones.
Formic acid as a sustainable and complementary reductant: An approach to fused benzimidazoles by molecular iodine-catalyzed reductive redox cyclization of: O -nitro- t -anilines
Nguyen,Ermolenko,Al-Mourabit
supporting information, p. 2966 - 2970 (2016/06/09)
Molecular iodine was found to be an excellent catalyst for reductive redox cyclization of o-nitro-t-anilines 1 into fused tricyclic or 1,2-disubtituted benzimidazoles 2. A range of functional groups such as halides (F, Cl, Br), methoxy, ester, trifluoromethyl, cyano, pyridine and even nitro groups were tolerated using formic acid as a clean, safe, user-friendly and complementary reductant. When iodine was used in a stoichiometric amount (50 mol%), the methodology allowed the direct synthesis of benzimidazole hydroiodides 2·HI in high yields by simple precipitation from the reaction mixture.
Methine dyes
-
, (2008/06/13)
The invention relates to a new class of pyrrolobenzimidazole, benzimidazoloisoquinoline and dipyrodinobenzodiimidazole in cyanine sensitizing dyes derived therefrom and their use in silver halide emulsions, and to methods for preparation of such new dyes.