Synthesis and Structure of New Anilino Derivatives of Angular Azaphenoxazine Dye by Buchwald-Hartwig Cross Coupling Protocol

Synthesis and Structure of New Anilino Derivatives of Angular Azaphenoxazine Dye by Buchwald-Hartwig Cross Coupling Protocol

¹Ojarikre Enoo, ¹Mgboh Vivian Onyinyechi ²Wokpara Iheanyichukwu, ³Ikenazor Herbert, ⁴Awemu G.A.

¹Department of Industrial Chemistry, Madonna University, Elele, Rivers State, Nigeria

²Department of Biochemistry, Madonna University, Elele Campus, Rivers State, Nigeria

³Department of Medical Laboratory Science, Madonna University, Elele , Rivers State, Nigeria.

⁴Department of Pharmaceutical Chemistry, Madonna University, Elele, Rivers State, Nigeria

Email: ojasmotivation@yahoo.com

ABSTRACT

New anilino derivatives of angular azaphenoxazine were obtained via Buchwald-Hartwig cross-couplingreaction. This was achieved by first synthesizing the intermediate 6-chlorobenzo[a]-11-azaphenoxazin-5-one by anhydrous base catalyzed condensation reaction between 2-amino-3-pyridinol and 2,3-dichloro-1,4-naphthoquinone. The palladium catalyzed Buchwald-Hartwig cross coupling of this electron rich 6-chlorobenzo[a]-11-azaphenoxazin-5-one with aniline and paranitrophenol, employing Pd(OAc)₂, 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)piperazine ligand and Na₂CO₃ in a 1:1 mixture of 1,4-dioxacyclohexane (1,4-dioxane) and N,N-dimethylformamide as solvent at 90^o C, afforded the highly coloured anilino derivatives 6-phenylaminobenzo[a]-11-azaphenoxazin-5-one and  6-(4-hydroxy-phenylamino)-benzo[a]-11-azaphenoxazin-5-one in 50% and 75% yield respectively. Structural assignments were established by spectroscopic (UV,IR, ¹H and ¹³C NMR).

Keywords: Anilino, angular, anhydrous, azaphenoxazine, Buchwald-Hartwig, cross-coupling