Benzimidazole Derivative Synthesis via Visible Light Photo-Redox: An Eco-Friendly Path to Bioactive Heterocyclic
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Abstract
Using visible-light-induced photo-redox catalysis, a sustainable and environmentally friendly method for the synthesis of benzimidazole-based heterocyclic compounds has been established. Under green LED irradiation (λ = 535 nm, 18 W) in tetrahydrofuran (THF) at room temperature, the procedure uses Eosin Y as an effective, metal-free photosensitizer. Eosin Y (1 mol%) and THF performed best, according to optimization experiments, yielding the target product 2-(furan-2-yl)-1H benzimidazole in an isolated yield of 82% after 70 minutes. The process involves photoexcitation of Eosin Y, generation of radicals, and subsequent formation of a benzimidazole derivative via a single-electron transfer (SET) pathway. IR, ¹H NMR, ¹³C NMR, and ESI-MS investigations verified the product structure. This green LED-mediated technology has several advantages over traditional thermal approaches, including great atom economy, energy efficiency, metal-free operation, and quicker reaction times.
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