Decarboxylative Radical Sulfilimination via Photoredox, Copper, and Brønsted Base Catalysis

Abstract

AbstractSulfilimines, the aza‐variants of sulfoxides, are key structural motifs in natural products, pharmaceuticals, and agrochemicals; and sulfilimine synthesis is therefore important in organic chemistry. However, methods for radical sulfilimination remain elusive, and as a result, the structural diversity of currently available sulfilimines is limited. Herein, we report the first protocol for decarboxylative radical sulfilimination reactions between sulfenamides and N‐hydroxyphthalimide esters of primary, secondary, and tertiary alkyl carboxylic acids, which were achieved via a combination of photoredox, copper, and Brønsted base catalysis. This novel protocol provided a wide variety of sulfilimines, in addition to serving as an efficient route for the synthesis of S‐alkyl/S‐aryl homocysteine sulfilimines and S‐(4‐methylphenyl) homocysteine sulfoximine. Moreover, it could be used for late‐stage introduction of a sulfilimine group into structurally complex molecules, thereby avoiding the need to preserve labile organosulfur moieties through multistep synthetic sequences. A mechanism involving photocatalytic substrate transformation and copper‐mediated C(sp3)−S bond formation is proposed.