Rapid Access Hetero-Amino Derivatives of Angular Phenoxazine Dye
1Ojarikre Enoo & 2Uchechukwu C. Okoro
1Department of Industrial Chemistry, Madonna University, Elele Campus, Rivers State, Nigeria
2Department of Pure Industrial Chemistry, University of Nigeria, Nsukka, Nigeria
Email: ojasmotivation@yahoo.com
ABSTRACT
The synthesis of nine hetero-amino derivatives of the angular phenoxazine, 6-chlorobenzo[a]phenoxazin-5-one is reported. New hetero-amino derivatives of 6-chlorobenzo[a]phenoxazin-5-one dye were obtained via palladium catalyzed Buchwald-Hartwig cross coupling reactions. This was achieved by first synthesizing the intermediate, 6-chlorobenzo[a]phenoxazin-5-one by anhydrous base-catalyzed condensation reaction between 2-aminophenol and 2,3-dichloro-1,4-naphthoquinone. Palladium acetate catalyzed Buchwald-Hartwig cross coupling of the intermediate with various readily available amines via water mediated catalyst preactivation procedure in a mixture of 1:1 mixture of toluene and N,N-dimethylformamide as solvent and 1,4-bis(2-hydroxy -3,5-di-tert-butylbenzyl)piperazine ligand at a temperature of 110oC yielded the previously unknown highly coloured amino derivatives in good yields. Structural assignments were established by spectroscopic techniques (UV, IR, 1H and 13C NMR).
Keywords: Hetero-amino, angular phenoxazine, preactivation, water-mediated, Buchwald-Hartwig, cross coupling.
