Synthesis of Functionalized Aryl Derivatives of 1,11 Diazabenzo[a]phenoxazin5one and 1 Azadibenzo[a,j]phenoxazin5one via PdCatalyzed MizorokiHeck Reaction

Jude I. Ayogu; Uwazulonye H. Okei; Uchechukwu C. Okoro

Volume : V, Issue : VII, July - 2016

Synthesis of Functionalized Aryl Derivatives of 1,11 Diazabenzo[a]phenoxazin5one and 1 Azadibenzo[a,j]phenoxazin5one via PdCatalyzed MizorokiHeck Reaction

Jude I. Ayogu, Uwazulonye H. Okei, Uchechukwu C. Okoro

Abstract :

?e synthesis of functionalized angular phenoxazines and related benzo[a,j] analogues was thoroughly explored. ?is was achieved by initial preparation of the two intermediates used for the Heck coupling from two key precursors. ?e first precursor was obtained by multistage conversion of 8–hydroxyquinoline to 7–chloroquinoline–5,8–quinone. ?e second was obtained by diazotization of aniline and coupling with 2–napththol followed by reduction of the resulting product to yield 1–amino–2– naphthol hydrochloride. ?e two intermediates, 1,11–diazabenzo[a]phenoxazin–5–one and 1–azadibenzo[a,j]phenoxazin–5–one were afforded by reacting 7–chloroquinoline–5,8–quinone with 2–amino–3–hydroxypyridine and 1–amino–2–naphtol hydrochloride respectively in anhydrous basic medium. ?ereafter, each intermediate was coupled with 4–iodophenol, 2–iodobenzoic acid and 4–iodonitrobenzene, refluxing for 4 h at 60 oC using Pd(dppb)Cl2, 1,4–bis(2–hydroxy–3,5–di–tert–butylbenzyl)piperazine, K2CO3 and methanol as the catalyst, ligand, base and solvent correspondingly to yield the derivatives (20a–c) and (21a–c) respectively. Structures of the synthesized compounds were established by spectroscopic methods (UV–VIS, FTIR, 1H–NMR, 13C–NMR mass spectroscopy).