Rose Bengal Immobilized on Cellulose Paper for Sustainable Visible‐Light Photocatalysis

Abstract

This work reports the heterogenization of Rose Bengal dye on simple cellulose paper sheets (Cell-RB) through copper-catalyzed azide-alkyne click ligation. The photocatalytic properties of Cell-RB under green LED irradiation were evaluated in a series of dehydrogenative transformations for the functionaliza-tion of N-aryltetrahydroisoquinolines and quinoxalin-2(1H)ones. The excellent photocatalytic activities observed, associated to the ease of recovery with simple tweezers, highlight the strong assets of Cell-RB with respect to traditional homogeneous organic photocatalysts.

Immobilized Rose Bengal as Photocatalyst for Metal‐Free Thiocyanation of Azaheterocycles under Continuous Flow Conditions

“…One possibility to solve this issue consists in anchoring the photocatalyst onto an inert support; [28] in this way, the catalytic species could be easily removed upon a completed reaction, facilitating the work-up and, possibly, the reuse in further transformations. [29,30] Few examples of Eosin Y [31 -34] and Rose Bengal [34][35][36][37][38][39][40][41][42] supported materials have been already reported in literature, and their use in photochemical applications confirm that the treatment and purification of the target compound have been greatly facilitated. In this context, we wish to report here our findings on the use of Rose Bengal supported onto Merrifield resin in the direct photochemical metal-free C-3 thiocyanation of indoles under continuous flow conditions, originally reported by Li and coworkers.…”