While aldehydes are commonly used as starting materials for benzothiazole synthesis (see Part 3), only one example has been reported where primary alcohols were directly employed . MIL-100(Fe) 11 demonstrated catalytic activity in the oxidative condensation of alcohols with oaminothiophenols to form 2-substituted benzothiazoles 33 under visible-light irradiation, using molecular oxygen (O₂) as the oxidant (Scheme 8). This reaction accommodates a wide substrate range, yielding medium to high product conversions. Mechanistic studies, including controlled experiments and ESR analysis, suggest a superoxide radical (O₂ • ⁻)-mediated pathway. The radicals are generated via the reduction of O₂ by photogenerated Fe²⁺ species within Fe-O clusters of MIL-100(Fe). The reaction rate-determining step involves the photo-oxidation of alcohols to aldehydes. Aromatic alcohols with electron-withdrawing groups (e.g., Cl, NO₂) exhibit lower conversions (46-56%) compared to those with electron-donating groups (e.g., p-OCH₃, p-CH₃), which show higher conversions (92-96%). However, steric hindrance, such as from o-OCH₃, o-CH₃, or p-CH(CH₃)₂ substituents, slightly reduces the conversion (78-85%) relative to unsubstituted benzyl alcohol. Aliphatic alcohols also react, but with significantly lower conversion rates (38-42%). The proposed mechanism (Scheme 8) involves the excitation of MIL-100(Fe) 11 under irradiation, leading to charge separation with electron transfer from O₂⁻ to Fe³⁺ in Fe₃O clusters, generating Fe²⁺. The Fe²⁺ species reduces O₂ to O₂ • ⁻ radicals, with concurrent oxidation back to Fe³⁺. Alcohols are oxidized to aldehydes via benzylic intermediates through O₂ • ⁻-mediated dehydrogenation. The in situ generated aldehyde undergoes condensation with o-aminothiophenol, facilitated by Lewis acidic Fe³⁺ sites in MIL-100(Fe). The resulting benzothiazoline intermediate is further oxidized by O₂ • ⁻ radicals to yield 2phenylbenzothiazole. MIL-100(Fe) 11 thus functions both as a photocatalyst and a solid Lewis acid to enable this tandem reaction. Scheme 8. MIL-100(Fe) 11 catalyzed synthesis of benzothiazoles 33.