Singh and co-workers introduced a one-pot method for the facile synthesis of 2aminobenzothiazoles 100 directly from arylisothiocyanates 101 and secondary amines (Scheme 35). The reaction proceeds through initial heating of a solution of arylisothiocyanate and secondary amine in DMF at 65°C for 2-5 hours, generating the corresponding N-arylthioureas in situ. Subsequent photocatalysis using eosin Y under green LED irradiation, along with N,N-diisopropylethylamine as a and an air affords the products 100 in good yields (78-97%) at room temperature. This protocol is highly functional-group-tolerant, accommodating both electrondonating and electron-withdrawing substituents. However, arylisothiocyanates bearing electrondonating groups on the aromatic ring exhibit faster reaction rates and slightly improved yields compared to their electron-withdrawing counterparts. The proposed mechanism involves photoredox catalysis, where eosin Y is photoexcited to its singlet state (¹EY*), followed by intersystem crossing (ISC) to its more stable triplet state (³EY*). A reductive SET from the intermediate A to ³EY* generates the thioacyl radical B, which undergoes 5-endo-trig intramolecular cyclization to form intermediate C. Subsequent interaction with the superoxide radical anion leads to the final product. ). This anion is reoxidized to its ground state by molecular oxygen, concurrently producing O₂⁻ • . Deprotonation of A by O₂⁻ • results in the formation of thiyl radical B, which undergoes regioselective intramolecular radical addition to produce carbon radical C. A subsequent SET with HO₂ • yields intermediate D, which reacts with the superoxide anion to furnish the final cyclized product 102. DFT calculations provide additional support for the proposed mechanism. Furthermore, He and co-workers demonstrated that the same transformation can be achieved under DMSO/oxygen conditions using long-wavelength UVA light (385-390 nm), eliminating the need for a photocatalyst.