Visible-Light-Triggered C–C and C–N Bond Formation by C–S Bond Cleavage of Benzylic Thioethers

Abstract

The cleavage of sulfidic C-S bonds under visible-light irradiation was harnessed to generate carbocations under neutral conditions and synthesize valuable di- and triarylalkanes as well as benzyl amines. To this end, photoredox catalysis and direct photoinduced C-S bond cleavage are used as complementary approaches and participate in the versatility of the general strategy. Extensive mechanistic studies have demonstrated the diversity of the reaction mechanism at work in these different reactions.

Visible Light Enables Aerobic Iodine Catalyzed Glycosylation

“…Cr(ddpd) 2 BF 4 has been described in the same context, as have been Rose Bengal and Ru(bpy) 3 2+ . The latter compound was recently reported in a thioether activation through singlet oxygen …”

“…It should be noted that the ability of photogenerated singlet oxygen to oxidize organic sulfides has also been reported . A recent example of such a reaction is the C–S bond cleavage of thioethers by Ru(bpy) 3 2+ ‐generated 1 O 2 . Based on these reports, an alternative mechanism for the formation of glycosyl cation 18 , which proceeds through radical intermediates, can be conceived.…”

Photochemical Functionalization of Heterocycles with EBX Reagents: C−H Alkynylation versus Deconstructive Ring Cleavage**

“…Ar ange of benzyl sulfidesw eres ynthesized and tested in the reactionc onditions, as the benzylic position was expected to be easier to oxidize as recently reported by Masson and co-workers. [22] In this case, the amount of sulfide could be reduced to 5equiv with no loss in reactivity,w hile using CH 2 Cl 2 as the solvent. [20] Unfortunately,f urtherr eduction of the amount of the thioether led to diminished yields.…”

Visible‐Light‐Induced Cleavage of C−S Bonds in Thioacetals and Thioketals with Iodine as a Photocatalyst

“…In their report, molecular iodine both acted as a photocatalyst for singlet oxygen generation and as a π‐Lewis acid. Recently, Masson and coworkers showed that benzylic thioethers can be oxidized to the radical cations through a combination of Ru(bpy) 3 (PF 6 ) 2 and molecular oxygen . Notably, this report revealed that singlet oxygen cleaves C−S bonds through oxidation.…”