In our previous study on the synthesis of dibenzoaza [7]helicenes, acyclic precursors like 67 were effectively utilized. In this study, the extended analogs 6n and 8n were synthesized using Pd-catalyzed Suzuki-Miyaura cross-coupling reactions, followed by oxidation with [bis(trifluoroacetoxy)iodo]benzene (PIFA) to afford a series of benzannulated aza[n]helicenes (hereafter referred to as [n]AH) (n = 9, 11, 13, 15, 17, 19). In the case of aza[n]helicenes with n = 9, 13, 17, aryl bromides 3m were synthesized by Pd-catalyzed cross-coupling reactions of excess amounts of 1-bromo-2-iodobenzene or aryl dibromide 1m with α-borylated indole 2 (Scheme 1). Next, aryl boronic acid pinacol esters 4m-Bpin were synthesized via cross-coupling reactions of 3m with α-borylated pyrrole and subsequent Ir-catalyzed borylation. Dipyrrole dibromide 5 was coupled with a small excess of 4m-Bpin in the presence of 5.0 mol% XPhos Pd G2 and excess potassium carbonate in THF/H2O to afford the acyclic precursors 6n. Finally, oxidative fusion reactions of the acyclic precursors with PIFA at low temperatures afforded the corresponding [n]AHs. For [n]AHs with n = 11, 15, 19, aryl bromides 3m were used as coupling partners. Tripyrrole diboronic acid pinacol ester 7 was coupled with a small excess of the synthesized aryl bromides 3m in the presence of 5.0 mol% XPhos Pd G2 and an excess of potassium carbonate in THF/H2O at room temperature to afford acyclic precursors 8n, although the yields were moderate probably because of the competing protodeboronation reactions. Similarly, the oxidative fusion of acyclic precursors 8n by PIFA afforded [n]AHs. All six [n]AHs were purified using silica-gel column chromatography and recrystallization from THF/n-hexane in open air. All [n]AHs were characterized by 1 H-and 13 C-NMR, and HR-MS (See the Supporting Information, SI). 1 H-NMR spectra of the obtained [n]AHs were measured in DMSO-d6 at room temperature with one drop of hydrazine monohydrate to prevent the generation of oxidized species. For all [n]AHs, NMR spectra reflecting the C2-symmetric structures were obtained. The terminal benzene protons (indole-H) shifted considerably upfield, indicating that these aromatic protons were located above other aromatic rings. Notably, upfield shifts in the signals in the aromatic region were observed as the helical length increased, probably because of the enhancement of anisotropic shielding by the π-electron of the stacked aromatic rings (Figure -45).