Serendipitous synthesis of unsymmetrical porphyrazine: Incomplete transesterification during macrocyclization

Abstract

The macrocyclization reaction of dimercaptomaleonitrile derivative containing biphenylmethylsulfanyl substituents with methoxycarbonyl groups resulted in an unexpected synthesis of unsymmetrical porphyrazine in which one of the methoxycarbonyl groups was not transesterificated. The UV–Vis, MS MALDI, and various NMR techniques were utilized to characterize the obtained product. Two-dimensional techniques, including 1H–1H COSY, 1H–13C HSQC, and 1H–13C HMBC, allowed to assign the 1H and 13C chemical shifts to the corresponding hydrogen and carbon atoms in the porphyrazine structure.