General method for the high yield preparation of 2-(4-X-phenylene)amine-1,4-naphthoquinones (X = ferrocenyl, OMe, Me, I, Cl, and NO2) from 2-methoxy-1,4-naphthoquinone and investigation of H+ and Mg2+ catalysts with DFT calculations

A rapid and simple method for the high yield preparation of 2-(4-X-phenylene)amine-1,4-naphthoquinones from 2 -methoxy-1,4-naphthoquinone, in boiling MeOH, using MgCl2 and p-toluenesulfonic acid as catalysts is described. This methodology has been applied successfully to the synthesis of electron donor (4-OMe, 4-Me, 4-ferrocenyl) and electron withdrawing (4-1,4-Cl, 4- and 3-NO2) aniline derivatives. The effect of both H+ and Mg2+ as catalysts was investigated using DFT calculations carried out at the B3LYP/6-31G(d) level. The electronic properties of the novel 2-(4-ferrocenylphenylene)amine-1,4-naphthoquinone 3b were investigated and show that the ferrocenyl and the methoxy group have similar electron donor properties in 2-(4-methoxy)amine-1,4-naphthoquinone 3a. (C) 2008 Elsevier B.V. All rights reserved.