Synthesis of Symmetrical 1,4-Diarylphthalazines

Abstract It is well known that 1, 4-diarylphthalazines are prepared by condensation of the appropriate ortho-diaroylbenzenes with hydrazine hydrate.1 As ortho-diaroylbenzenes can be obtained by oxidation of ortho-dibenzylbenzenes, a rapid method is proposed to obtain the ortho-dibenzylbenzenes (Ia) and (Ib) by reaction of the highly reactive2 veratrol with para-chloro- or ortho-chlorobenzyl alcohol in sulfuric acid. The products obtained gave by oxidation the ortho-diaroylbenzenes (IIa) and (IIb), which were transformed into the 1,4-diarylphthalazines (IVa) and (IVb) by treatment with hydrazine hydrate.