Photoorganocatalysis. What for?

Abstract

In the reactions reviewed, an organic molecule under irradiation catalyzes a chemical reaction. The activation is based either on hydrogen or on electron transfer. Commonly used photoorganocatalysts are aromatic ketones, quinones, heterocycles, dyes; intermediates formed are radicals, radical ions and ions from precursors such as alkanes, alkenes, amines, ethers etc. Oxidation (mainly oxygenation) and reduction processes are obtained along with the α-functionalization of amines and ketones, conjugate additions, cycloadditions etc. The key characteristic of the method is the smooth generation of highly reactive intermediates under mild conditions.

Photocatalytic fluoroalkylation reactions of organic compounds

“…This can be done either via atom transfer or via a redox process. 9 The excited state potential energy surface reached by these excited POC overcomes the high energy barriers of thermal reactions, catalytic or not, which can only be accessed employing extremely aggressive reagents or harsh reaction conditions.…”

“…94,95 Excellent review articles do exist on photoorganocatalysis. 9 Once the optimized reaction conditions for trifluoromethylation are met, 106 the scope and limitations of the reaction can be explored in Scheme 41. Electron-rich arenes afford the corresponding products in good yields.…”

“…This methodology has been playing a relevant role in carbon-carbon bond formation reactions. 9 In this way photoredox catalysis can accomplish radical transformations which are not accessible employing conventional azo or peroxide initiators.…”

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

“…In this sequence 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. [10][11][12][13][14][15] In their revolutionary work in this area, MacMillan, [16] Yoon [17] and Stephenson [18][19] have used Ruthenium and Iridium complexes as the photoredox catalyst, which has inspired the development of several powerful methods for various chemical transformations useful in organic synthesis.…”

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.…”