Aryl alkyl ethers are ubiquitous in natural feedstocks such as lignin, which represents the largest potential source of high-value aromatics in nature. Additionally, benzyl/alkyl-based protection strategies are commonly employed in total synthesis involving sensitive alcohol and or phenol motifs. As such, the development of ambient technologies towards ether C-O bond activation represents a continued field of interest for synthetic chemists. Photoredox catalysis has been extensively studied as a powerful tool to induce C_X bond cleavage (X = N, O, etc.) towards the generation of carbon centered radicals for further functional group interconversion. However, reports of photoredox-based ether C_O bond activations are rare due to the high bond dissociation energy (83_86 kcal/mol) and high reduction potentials found in the C_O bond. Thus far, these challenges have largely been circumvented by employing α-functionalized ethers and introducing motifs designed to increase the overall redox potential within the window of commercially available photocatalysts. A noteworthy addition to current light-mediated ether C_O bond activations would be a technology capable of tolerating traditional ethers without the need for expensive photocatalysts. Herein, we present an operationally simple reductive C_O Cleavage of aryl alkyl ethers using base and light.

Photocatalyst-free, light mediated reductive C_O cleavage of aryl alkyl ethers

ACS Spring 2022

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