Non-symmetric phenazines were synthesized via the Buchwald-Hartwig amination of ortho-bromoazobenzenes with anilines under micellar conditions, using the commercially available surfactant Kolliphor EL in water, followed by an acid-promoted 6π-electrocyclization-aromatization process. Two different synthetic pathways to obtain the ortho-bromo azo intermediates were explored, namely the palladium catalysed selective ortho bromination of azobenzenes and the diazo coupling of ortho-bromo diazonium salts with N,N-dimethylaniline, imidazole, phenol, sodium methanesulfinate and ethyl chloroformate.
Yousif, D., Monti, M., Papagni, A., Vaghi, L. (2020). Synthesis of phenazines from ortho-bromo azo compounds via sequential Buchwald-Hartwig amination under micellar conditions and acid promoted cyclization. TETRAHEDRON LETTERS, 61(46) [10.1016/j.tetlet.2020.152511].
Synthesis of phenazines from ortho-bromo azo compounds via sequential Buchwald-Hartwig amination under micellar conditions and acid promoted cyclization
Yousif D.;Monti M.;Papagni A.;Vaghi L.
2020
Abstract
Non-symmetric phenazines were synthesized via the Buchwald-Hartwig amination of ortho-bromoazobenzenes with anilines under micellar conditions, using the commercially available surfactant Kolliphor EL in water, followed by an acid-promoted 6π-electrocyclization-aromatization process. Two different synthetic pathways to obtain the ortho-bromo azo intermediates were explored, namely the palladium catalysed selective ortho bromination of azobenzenes and the diazo coupling of ortho-bromo diazonium salts with N,N-dimethylaniline, imidazole, phenol, sodium methanesulfinate and ethyl chloroformate.
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