200510-95-8Relevant academic research and scientific papers
A new route to ring-fused pyrazines: Imidazo[4,5-b]quinoxalines by a simple oxidation-annulation sequence
Herzoge, Svenja,Buehrdel, Gunther,Beckert, Rainer,Klimas, Susann,Wuerthwein, Ernst-Ulrich,Grimme, Stefan,Goerls, Helmar
experimental part, p. 4049 - 4057 (2010/03/24)
Novel tricyclic 4H-imidazo[4,5-b]quinoxalines were synthesized by a new orfto-annulation process starting from 4Himidazoles and cerammonium nitrate (CAN) as oxidation reagent in the presence of potassium carbonate as base. This reaction is interpreted as
Bis-amidines as useful building blocks for heterofulvenes and -fulvalenes
Mueller,Beckert,Goerls
, p. 601 - 606 (2007/10/03)
An easily feasible synthesis for bis-amidines of type 3 was developed via an aminolysis reaction of imidoyl chlorides 1 with gaseous ammonia. Depending on the nature of the electrophilic cyclization reagent, these amidines show a different reactivity. On treatment with orthoesters, the fused imidazoles 5 were obtained which involved the participation of two different kinds of nitrogen atoms in the cyclization. In contrast to this, carboxylic acid chlorides are able to react selectively at the NH2-groups under formation of the fulvenoid 4H-imidazoles 6. The same regioselectivity was observed for chlorodimethylimmonium chloride thus leading, via the dimerization of cyclic orthoamides, to the 1,4,5,8-tetraazafulvalenes 8.
5-ring-cycloamidines - Deeply coloured heterocycles with unusual properties. I synthesis and spectral features
Atzrodt, Jens,Brandenburg, Joerg,Kaepplinger, Christian,Beckert, Rainer,Guenther, Wolfgang,Goerls, Helmar,Fabian, Juergen
, p. 729 - 734 (2007/10/03)
The cycloacylation reaction of benzamidines with bis-imidoylchlorides 1 derived from oxalic acid was investigated. For example, treatment of benzamidine with 1 gives the new 4H-imidazoles (3a-1) in yields up to 92%. Because of rapid H-transfer processes i
