Synthesis of 6-Anilino Derivatives of benzo[a]phenoxazin-5-one and related Aza Analogues via Palladium-catalyzed Buchwald-Hartwig Amination Reaction

The synthesis of new 6-anilino derivatives of angular phenoxazine dye was thoroughly investigated. This was accomplished by the condensation of 2-aminophenol with 2, 3-dichloro-1, 4-naphthoquinone in an alkaline medium to furnish a good yield of the intermediate, 6-chlorobenzo [a]phenoxazine-5-one (6). BuchwardHartwig cross-coupling of the intermediate with various amines, viz 2-amino-4-methylpyridine, 2-aminopyrazine, 2-amino-5-nitropyridine, 2-aminopyridazine, 2-amino-3-hydroxypyridine, aniline, 4-nitroaniline, 4-aminophenol and 2-aminophenol via water-mediated catalyst activation protocol in DMF/toluene solvents mixture at a temperature of 110 oC yielded the amino derivatives 6 (a-i) respectively. Structures were established by spectral analyses and micro-analytical data.