Metal‐Free Desulfonylation Reaction Through Visible‐Light Photoredox Catalysis

Abstract

The desulfonylation of β‐arylketosulfones has been achieved in good to excellent yields by using 3‐W blue LEDs light, 1 mol‐% organic dye eosin Y bis(tetrabutylammonium salt) as photocatalyst, and diisopropylethylamine as reducing agent. Mechanistic studies demonstrate that oxidative quenching of the excited eosin Y by β‐arylketosulfones plays a crucial role in the present photoredox catalytic cycle.

Eosin Y Catalyzed Visible-Light-Promoted Aerobic Oxidative Cyclization of 2-Aminobenzothiazole

“…Recently, a superior alternative to transition metal photoredox catalysts, especially metal-free organic dyes such as eosin Y, fluorescein, Rose Bengal, Nile Red, Perylene and Rhodamine B have been used as economically and ecologically superior surrogates for Ru(II) and Ir(II) complexes in visible-light promoted organic transformations involving SET [20][21][22][23] (single electron transfer). These organic dyes have got much more attention with the last few years also due to easy handling, eco-friendly and have great potential for applications in visible-light-mediated organic synthesis [24][25][26][27] which fulfils the basic principle of green chemistry.…”

Sulfur‐Center‐Involved Photocatalyzed Reactions

“…developed a photoredox desulfonylation of β‐arylketosulfones [Eq. (90)] . Laser flash photolysis experiments helped to reveal the oxidative quenching process between excited TBA–Eosin Y and β‐arylketosulfones 242 with an electron transfer rate constant ( k ET ) of 1.1×10 5 s −1 .…”

Visible Light Promoted Allylic C–H Oxidation

“…[12,13] The visible light photoredox catalysis has recently received much attention in organic synthesis owing to readily availability, sustainability, non-toxicity and ease of handling of visible light. [14][15][16][17][18][19] Recently, a superior alternative to transition metal photoredox catalysts, especially metal-free organic dyes such as eosin Y, fluorescein, rose bengal, nile red, perylene and rhodamine B have been used as economically and ecologically superior surrogates for Ru(II) and Ir(II) complexes in visible-light promoted organic transformations involving SET [20][21][22][23] (single electron transfer). These organic dyes have got much more attention with the last few years also due to easy handling, eco-friendly and have great potential for applications in visible-light-mediated organic synthesis [24][25][26][27] which fulfils the basic principle of green chemistry.…”