In 2020, Singh and He independently developed photochemical methodologies for synthesizing benzothiazoles directly from substituted anilines and inorganic isothiocyanates (Scheme 38). The first method utilizes a photoredox-catalyzed addition/cyclization cascade between thiocyanate radicals and anilines, employing Ru(bpy)₃Cl₂ 1 as the photocatalyst under visible-light irradiation . This protocol is highly versatile, accommodating a wide range of substituents, including CH₃, i-Pr, t-Bu, OCH₃, PhO, F, Cl, Br, CF₃, CN, SCN, CO₂Et, MeO₂S, and PhCO, and affords 2aminobenzothiazoles 109 in moderate to excellent yields. Upon visible-light excitation, Ru 2+ is promoted to its excited state Ru 2+ *, which undergoes SET with SCN⁻ to generate the thiocyanate radical A and Ru + . Atmospheric oxygen oxidizes Ru + back to Ru 2+ , completing the photoredox cycle while forming the superoxide radical anion (O₂⁻ • ). The thiocyanate radical reacts with aniline to form radical intermediate B, which is oxidized to cationic intermediate C. Deprotonation of C produces intermediate D, followed by an intramolecular cyclization where the nucleophilic amino group attacks the thiocyanate moiety, yielding the final product 109. The second method involves a visiblelight-initiated, malic acid-promoted cascade coupling/cyclization of anilines and KSCN with ambient air as the oxidant . Singlet oxygen (¹O₂), generated from molecular oxygen (O₂) under visible-light irradiation, reacts with thiocyanic acid (produced in situ from KSCN and malic acid). This interaction generates the thiocyanate radical A and hydroperoxyl radical. Li and co-workers developed a visible-light-promoted acceptorless dehydrogenation of 2,3dihydrobenzothiazoles 112 using a combined photoredox and cobalt catalysis system to afford benzothiazoles 113 (Scheme 40) . Under blue LED irradiation, Ru(bpy)₃²⁺ transitions to its excited state Ru(bpy)₃²⁺*, which is oxidatively quenched by Co III to produce Ru(bpy)₃³⁺ and Co II via SET. A subsequent SET from 112 to Ru(bpy)₃³⁺ generates intermediate A, regenerating Ru(bpy)₃²⁺. The intermediate A undergoes deprotonation and electron loss to yield the final product 113. Simultaneously, the Co II formed is reduced to Co I , which reacts with protons to form Co III -H. This intermediate either undergoes protonation to produce H₂ or homolytic cleavage between two Co III -H species to evolve H₂. This method, operating under mild reaction conditions at ambient temperature, provides a sustainable approach to synthesizing benzothiazoles and related azaheterocycles, with potential applications in reversible dehydrogenation-hydrogenation systems for H₂ storage.