Access to a Phthalazine Derivative Through an Angular cis-Quinacridone.

Intramolecular electrophilic cyclization of a bisanthranilate afforded an angular cis-quinacridone compound, which condensed with hydrazine to give a phthalazine derivative. A [2+2+2] cyclization reaction occurred at the C-N double bond position of phthalazine when reacted with dimethyl acetylenedicarboxylate. The structures of these novel compounds were confirmed by crystallographic analysis. The phthalazine derivative decomposes back to quinacridone at ambient condition in the dark and as a solid with a half lifetime of about 22 months.