Studies on novel polycyclic heterocycles: synthesis of new naphthaquinoxaline and naphthazaquinoxaline derivatives from naturally occurring quinones

Abstract

A facile synthesis of novel polycyclic heterocycles namely naphthaquinoxaline and naphthazaquinoxaline derivatives is carried out by the reaction of lapachol and β-lapachone, naturally occurring naphthoquinones with o-phenylene diamine and 2,3-diaminopyridine. Regioselectivity in the reaction of β-lapachone with 2,3-diaminopyridine is confirmed by single crystal X-ray diffraction of a representative compound 6,7-dihydro-8,8-dimethyl-8H-pyrano[3',2':4]-naphtha[2,1-e]pyrido[2,3-b]pyrazine; C₂₀H₁₇N₃O, crystallizes as orthorhombic in the space group Pbca with cell parameters a =9.793(3)Å, b=17.514(6)Å, c=18.334(6)Å, V=3144.5(17) ų, Z=8,1.332 mg/m³, R₁=0.3076, WR₂=0.3595.