We speculated that the NR-triggered cyclization could be extended towards the formation of 6-membered ring systems, leading us to investigate the formation of cinnoline to further demonstrate the synthetic potential of our strategy. Thus, we used 2-(2nitrobenzyl)ethanamine (7) to explore the NfsA-triggered cinnoline formation. However, the 3,4-dihydrocinnoline (9) formed from the intramolecular condensation of 2-(2nitrosobenzyl)ethanamine (8) must first undergo tautomerization to 1,4-dihydrocinnoline (10) and oxidation to the final product cinnoline (11). The last step in particular was not fully completed after 24 hours, resulting in a mixture of 45 % 10 and 40 % 11, while only traces of 9 and 14 % 7 remained (Figure ). In the reaction with BaNTR1, 89 % of substrate 7 remained, while 6 % 10 and 4 % 11 were formed. Overall, NfsA and BaNTR1 showed the same reactivity towards all substrates tested, with NfsA always being more active.