<i>p</i>-Nitrophenyl[36]trithianonaphyrin(1.0.0.1.0.0.1.0.0) with a Weak Antiaromatic Character

Abstract

Since the discovery of expanded porphyrins,1,2 more investigations have been conducted from many viewpoints. In the early stages of studies on expanded porphyrins, most investigations involved the preparation of synthetic expanded porphyrins, or improvements in their syntheses.3 A recent study on expanded porphyrins, however, was conducted from the viewpoints of aromaticity, chemical modification, and conformation.4 In the intervening years, the investigation of expanded porphyrin chemistry has included the construction of a new p system.5 In 1992, Ibers and co-workers6 inserted a thiophene moiety into a bipyrrole unit to construct a new 26p-aromatic macrocyclic compound via McMurry coupling. The incorporation of a thiophene moiety into the bipyrrole unit was expected to produce a large macrocyclic compound, 2,5-bis(4propyl-2-pyrrolyl)thiophene, because of the distances between these outer a-pyrroles. As herein described, we investigated new antiaromatic macrocyclic ligands to react a 2,5-bis(4propyl-2-pyrrolyl)thiophene unit with p-nitrobenzaldehyde. The compound 2,5-bis(4-propyl-2-pyrrolyl)thiophene (1) was synthesized by a method reported by Ibers and co-workers. Compound 1 was reacted with p-nitrobenzaldehyde using p-Nitrophenyl[36]trithianonaphyrin(1.0.0.1.0.0.1.0.0) with a Weak Antiaromatic Character