Tailoring photocatalysts to modulate oxidative potential of anilides enhances para-selective electrochemical hydroxylation

Abstract

Phenolic compounds have long captivated the interest of organic synthesis, particularly in their quest for selective hydroxylation of arenes using H₂O as a hydroxyl source. However, the inherent high reactivity and low redox potential of phenols often lead to undesirable overoxidation byproducts. To address this challenge, herein, we develop an electrophotochemical approach, finetuning substrate oxidative potential and enabling para-selective hydroxylation of anilides. This method showcases versatility, accommodating a wide array of substrates, while revealing high regional selectivity and compatibility with diverse functional groups. Moreover, the protocol allows facile late-stage functionalization of biologically active molecules. Mechanistic investigations demonstrate the activation of anilides by the excited state photocatalyst, effectively decreasing their oxidative potential and enhancing regional selectivity during hydroxylation. By using this protocol, important drug molecules such as Paracetamol, Fenretinide, Practolol, and AM404 could be synthesized, demonstrating the applicability of this approach in drug synthesis and late-stage functionalization.

Phenolic compounds have long captivated the interest of organic synthesis, particularly in their quest for selective hydroxylation of arenes using H₂O as a hydroxyl source but the inherent high reactivity and low redox potential of phenols often lead to undesirable overoxidation byproducts. Here the authors develop an electrophotochemical approach, finetuning substrate oxidative potential and enabling para-selective hydroxylation of anilides.