Organic molecular sieves adorned with s-tetrazine: an efficient platform for gram-scale organic photoredox catalysis

Abstract

The chemical industry in the emerging era requires efficient and stable porous catalysis technology. In this context, porous photocatalysis has emerged as a recycled and energy-efficient synthetic strategy in accordance with the fundamental principles of clean chemistry. Organic molecular sieve (OMS) catalysts, known for their easily adjustable structures and exceptional properties, can serve as potential platforms aiming at the production of fine chemicals. The report showcases a concise synthesis of a TZ-OMS photocatalyst with s-tetrazine via an FeCl₃ catalyzed Friedel–Crafts reaction, combined with a salt-modulated strategy to enhance its surface area (694–900 m² g⁻¹). TZ-OMS significantly facilitated the concise synthesis of benzimidazoles at the gram-scale (up to 99% yield) in both batch and flow reactions using EtOH under air and light conditions. Notably, the continuous flow photocatalysis here fulfills the requirements of green chemistry through its simplified design, high efficiency and reusability. Moreover, TZ-OMS demonstrated exceptional recyclability with 13/24 iterative runs for 5 mmol/0.2 mmol scale and remarkable stability. The findings provide insights into the practical approach for efficient and large-scale production of fine chemicals using OMS photocatalysts.