Electroreductive Desulfurative Transformations with Thioethers as Alkyl Radical Precursors**

Abstract

Thioethers are highly prevalent functional groups in organic compounds of natural and synthetic origin but remain remarkably underexplored as starting materials in desulfurative transformations. As such, new synthetic methods are highly desirable to unlock the potential of the compound class. In this vein, electrochemistry is an ideal tool to enable new reactivity and selectivity under mild conditions. Herein, we demonstrate the efficient use of aryl alkyl thioethers as alkyl radical precursors in electroreductive transformations, along with mechanistic details. The transformations proceed with complete selectivity for C(sp3)−S bond cleavage, orthogonal to that of established transition metal‐catalyzed two‐electron routes. We showcase a hydrodesulfurization protocol with broad functional group tolerance, the first example of desulfurative C(sp3)−C(sp3) bond formation in Giese‐type cross‐coupling and the first protocol for electrocarboxylation of synthetic relevance with thioethers as starting materials. Finally, the compound class is shown to outcompete their well‐established sulfone analogues as alkyl radical precursors, demonstrating their synthetic potential for future desulfurative transformations in a one‐electron manifold.

Vaska's complex–PMHS combination enabled mild and chemoselective reduction of sulfoxides to sulfides with low catalyst loading

“…Sulfides 1 h and their derivatives such as sulfonium salts have found widespread applications in organic synthesis, e.g. in the Corey–Chaykovsky reaction, 9 as chiral ligands, 5 a as alkyl radical precursors for C–S functionalization, 10 for α-functionalization of cyclic sulfides, 11 in trifluoromethylation reactions, 12 as electron donor–acceptor (EDA) complexes (charge transfer complexes) for photocatalyst-free photochemical reactions, 13 etc . Moreover, the sulfide motif is found in many bioactive natural products 7 a and plays important roles in pharmaceutical, 7 material, informatics, and energy fields (Fig.…”

Electrochemical desulfurative formation of C–N bonds through selective activation of inert C(sp3)–S bonds

“…9 a Most recently, Lundberg's group has also contributed to the field by reporting electroreductive desulfurative transformations utilizing thioethers as alkyl radical precursors. 11 These transformations include hydrodesulfurization, carboxylation, and Giese-type cross-coupling. However, it is worth noting that the achievement of high conversion of the starting feedstock and high yields in these processes requires the use of various sacrificial anode materials (Scheme 1b, right).…”