Photoinduced Copper-Catalyzed para-Selective C–H S-Arylation of Benzylic Oxime Carbonates with Sulfenamides

Abstract

The direct C–H functionalization of arenes is a highly atom-economic strategy for molecular assembly; however, controlling regioselectivity, especially at the para-position, remains a long-standing hurdle. Herein, we present a dual copper/photoredox catalytic system that enables the para-selective C–H functionalization of benzylic oxime carbonates with sulfenamides. Unlike classical transition metal-catalyzed arene C–H bond activation strategies, our method employs a radical-mediated dearomatization process to achieve selective activation of the para C–H bond in arene. Utilizing a cooperative system of tetrakis(acetonitrile)copper(I) hexafluorophosphate and thioxanthen-9-one under visible light, a para-carbon radical is generated via photoinduced decarboxylation/dearomatization of the oxime carbonate; subsequently, under copper catalysis, this radical reacts with a sulfenamide to enable C–S/N=S bond reorganization, accompanied by subsequent rearomatization, ultimately leading to the construction of desired sulfilimine. This method is characterized by mild reaction conditions, broad substrate generality, and excellent functional group tolerance, offering a versatile tool for the selective preparation of functionalized sulfilimines. Moreover, the late-stage functionalization of complex bioactive scaffolds and versatile product derivatizations further demonstrate the synthetic utility of this approach.

Keywords

Photocatalysis / Copper catalysis / Dearomatization / Rearomatization / Arene C–H S-arylation / Benzyl alcohols / Sulfilimines / Selectivity

References

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