康 · 学术 | Reaction of the Day No. 1644

Photocatalytic Reductive Desulfonation of Aryl Tosylates

Kasmier Vicioso, Jonathan Santoro, Zachary Coren, and Rashanique D. Quarels*

Department of Chemistry and Biochemistry, Rowan University, Glassboro, New Jersey 08028, United States

—J. Org. Chem., 2025, 90(47), 16828-16832.

Recommended by Shi Li_MOC

KEYWORDS: Photo Chemistry, Reduction, Desulfonation(反应类型), O-H (成键类型), Aryl Tosylates(原料), Phenols (产物), 10-Bromoanthracen-9(10H)-one (Br-Ant) (其他)

ABSTRACT: 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.

Background and This Work

Substrate Scopes

Proposed Mechanism

Summary and Comments

Rashanique D. Quarels et al. have developed a photoredox-catalyzed deprotection reaction of aryl tosylates resulting in a moderate to high yield of the resulting phenols. The authors acknowledge that halogens, especially aryl chlorides and fluorides, undergo competitive side reactions. The photoreductive tosylate deprotection method demonstrated divergence from other synthetic methods avoiding the use of strong nucleophiles or strong acids for S-O bond cleavage. This approach offers chemoselectivity in the presence of ester and ether bonds. This strategy also tolerates various functional groups (i.e., alkene, ketone, cyano, and nitro groups) and holds promise for application in the late-stage deprotection of aryl tosylate protecting groups on small molecules as well as complex bioactive molecules.