Photocatalytic Reductive Desulfonation of Aryl Tosylates

This communication describes the reductive deprotection of aryl tosylates to their corresponding phenols in up to 93% yield using visible-light photocatalysis. In this new methodology, the photoexcited enolate generated from the deprotonation of 10-bromoanthracen-9-one and subsequent excitation is capable of selectively cleaving the S-O bond on the aryl tosylate substrate, releasing the phenolate anion. Moreover, this deprotection method does not perturb common functional groups. Thus, this transformation affords an orthogonal deprotection strategy and has potential for use in the late-stage deprotection of aryl tosylates in organic synthesis and medicinal chemistry. The design, scope, and limitations are discussed.