Polymer-supported eosin Y as a reusable photocatalyst for visible light mediated organic transformations

Abstract

Rapid synthesis of highly stable polymer-supported eosin Y for visible light-driven photoxidation of thioethers to sulfoxides and phenylboronic acids to phenols.

Synthesis of Enantiopure Sulfoxides by Concurrent Photocatalytic Oxidation and Biocatalytic Reduction

“…Having a fast and selective biocatalyst for the enantioselective reduction in hand, the unselective oxidation of 1 b was investigated in greater detail (Scheme 1, blue box). Light‐dependent sulfide oxidation has been reported using a perylene diimide photocatalyst [33] as well as metal catalysts like [Ru(bpy) 3 ] 2+ , [34] eosin Y, [35] tetraacetyl riboflavin, [36] porphyrins [37] and thioxanthone derivatives, [38] all almost exclusively applied in organic solvents. Initial experiments were performed, using the commercially available and rather inexpensive 2‐chloro‐thioxanthen‐9‐one P1 as photocatalyst ( P ) in different solvents (MeOH, EtOH, ACN, H 2 O, see Supporting Information, Table S3).…”

Scalable and Recyclable Heterogeneous Organo‐photocatalysts on Cotton Threads for Organic and Polymer Synthesis

“…In this study, oxidation of thioanisole to methylsulfinylbenzene (Scheme B) was selected as a model organic reaction to investigate the photocatalytic ability of immobilized EY for the generation of singlet oxygen and subsequent oxidation. As reported by Selvaraj and co‐workers, the optimized reaction solvent system for oxidation of thioether to sulfoxide with polymer supported EY as the photocatalyst was using a mixed solvent containing MeCN and water at a volume ratio of 4 to 1. Therefore, we employed the similar conditions as the starting point to perform the oxidation of thioanisole with EY@cotton thread, using MeCN/H 2 O (4/1) as solution in the open air.…”

“…Hence, immobilization of EY on an appropriate support to form a recyclable photocatalyst is anticipated to address this crucial issue. Various solid supports, such as silica particles, graphene oxide, metal‐organic frameworks, polymer supports, and magnetic nanoparticles have been utilized for EY immobilization. These immobilization systems have demonstrated enormous success in both organic transformations and polymer synthesis.…”

“…In this regard, various catalyst immobilization approaches have been developed according to surface characteristics of different supporting materials. For instance, electrostatic absorption has been utilized to immobilize EY onto either functionalized magnetic nanoparticles or polymer supports as reported by Wang and Selvaraj, respectively. Hydrogen bonding and π‐π stacking between EY and graphene oxide has been used to prepare EY functionalized graphene as photocatalysts for water reduction …”

Eosin Y: Homogeneous Photocatalytic In-Flow Reactions and Solid-Supported Catalysts for In-Batch Synthetic Transformations

“…The EY3 and EY4 anionic forms of Eosin Y can be tethered by ionic interactions to a positively charged ion-exchange resin. In this sense, very recently, Selvaraj and co-workers reported the realization of a polystyrene-supported Eosin Y (PS-eosin Y, 15) through an anion-exchange reaction (Scheme 10a) as a reusable photocatalyst for visible light-mediated organic transformations such as the oxidation of thioethers to sulfoxides and phenylboronic acids to phenols under open atmospheric air [32].…”