A Facile and Regioselective Synthesis of Trans-Heterofunctionalized Porphyrazine Derivatives

New methodology was developed for the selective synthesis of regiochemically defined porphyrazines of the form M[pz(A 2;B 2 )] (shown in Chart 1) where A and B represent peripheral functionalization attached to the β-positions of the pyrroles. Specifically, phthalonitriles or derivatives thereof with sterically bulky groups in positions 3 and 6, in particular 4,7-bis(isopropyloxy)-1,3-diiminoisoindoline ( 3 ) act as a “trans director” when macrocyclized with heteroatom-appended maleonitriles under Linstead conditions, the result being preferential formation of the trans -M[pz(A 2;B 2 )] pigment where A = SR, NMe 2, OR, as well as R (shown in Chart 2). Linstead crossover macrocyclization of 3 with 4, 11, 15, and 18 gave pigments 10, 14, 17, and 19, respectively. These pigments were characterized by 1 H NMR, 13 C NMR, UV−visible spectroscopy, mass spectrometry, microanalysis, and 17 was characterized by single-crystal X-ray analysis.