Next, the substrate scope was investigated (Figure ). For 1a-TFA, it is noteworthy that the reaction proceeded smoothly even at a larger scale up to 1.15 mmol. In the case of 1b-TFA, the para-insertion product 2b was obtained in a 50% yield. The reaction was also applicable to trisubstituted pyrroles, yielding the corresponding pyridines (2ca, 2cb). Notably, the introduction of Boc and Ac groups enabled insertion at sterically more demanding positions to produce 2cb. 2,3,4,5-Tetraphenylpyrrole (1d) exhibited high yields, particularly when the TFA was used as PG, resulting in the desired pyridine with a 96% yield (2da, 2db). Conversely, reactions involving di-substituted pyrroles were unsuccessful, possibly due to side reactions such as homo-coupling via radical cation being favored (unsuccessful substrate scope is summarized in Supporting Information, Section 4.6). Regarding the scope of diazo ester, tert-butyl α-diazoacetate was also suitable for this reaction, and its reaction with 1a-TFA yielded 2e. Redox-active diazo esters were also compatible with this reaction, and the corresponding para-inserted product (2f) was successfully obtained, which could be useful for subsequent reactions such as photocatalytic borylation. The reaction with other N-containing five-membered aromatic compounds, such as indole-and imidazole-derivatives, afforded the corresponding quinoline-and pyrimidine-derivatives, respectively (2g-i).