Understanding of the aromatic properties and magnetically inducedc urrent densities of highlyc onjugated chromophores is importantw hen designing molecules with strongly delocalized electronic structure.L inear extension of the triphyrin(2.1.1) skeleton with an annelated benzo [b]heterocyclef ragment modifies the aromatic character by extending the electron delocalization pathway. Two-electron reduction leads to an antiaromatic triphyrin(2.1.1) ring and an aromatic benzo[b]heterocycles ubunit. Current-density calculations provide detailedi nformation about the observed pathways and their strengths.Extending the p-electron system in conjugated molecules is an important area of research, because the conjugation pathway exhibits notable influence on the opticala nd magnetic properties. [1] Linear extensions of the acene p cloud by annelation of molecular rings lead to different aromatic behavior of five-and six-membered rings. [3,4] As idef usion of af ive-membered ring to acene cores results in major differences in the electron delocalization with the bridging heteroatom separating the aromatic and antiaromaticmoieties. [5] Triphyrins(2.1.1) (Scheme 1) are triangularly shaped, contracted porphyrinoids whose structural constraints significantly affect their electronic properties. [2] The C2 bridge (1,S cheme1) makes it possible to merge an acene to the triphyrin macrocycle potentially resulting in molecular structures with novel optical andm agnetic properties as well as an unusual aromatic character. [2d,e] We have synthesized novel molecular structures with benzo[b]furan and benzo[b]thiophene annelated to triphyrin(2.1.1) (2,S cheme 1). The annelated arene ring may influence the global aromatic properties by incorporating the external ben-zoic (C6) ring into the delocalization pathway.T he synthesized macrocycles can also functiona sb oron(III)l igands forminga ntiaromatic complexes as shown in this work.Triphyrins 2a and 2b wereo btained by acid-catalyzed condensation of reagents 3a and 3b,r espectively.T hey were efficiently synthesized via Suzuki-Miyaura coupling from easily obtainable or commercially availables tarting materials (2,3-dibromobenzo[b]heterocyclea nd pyrrole-boronic acid), [6] followed by at hermolytic deprotection. [2d,e] 2a and 2b were isolated with ay ield of 10 %a nd 12 %, respectively.T he small coordination core of the macrocycle leads to av ery efficient entrapment of ap rotonm aking it possible to isolate the cationic form. As the counterion of the condensationp roduct was unknown,w ereplaced it with ac hloride anion by using ap reviously reported approach. [2d,e] Characterization and further studies were performed on the chloride derivatives. The X-ray analysis performed for 2b has confirmed the postulated pattern ( Figure S44).2a (2b)h as aU V/Vis spectrum that is typical for aromatic porphyrinoids with aS oret-like band at 415 nm (430 nm) and a set of Qb ands that reach 600 nm (620 nm). The bands are redshiftedb y4 0-50nmc ompared to triphyrins(2.1.1) such as 1b [2b] and 1c, [2f]...