Cooperative photoredox catalysis

Abstract

Visible-light photoredox catalysis has been experiencing a renaissance in response to topical interest in renewable energy and green chemistry. The latest progress in this area indicates that cooperation between photoredox catalysis and other domains of catalysis could provide effective results. Thus, we advance the concept of cooperative photoredox catalysis for organic transformations. It is important to note that this concept can bridge the gap between visible-light photoredox catalysis and other types of redox catalysis such as transition-metal catalysis, biocatalysis or electrocatalysis. In doing so, one can take advantage of the best of both worlds in establishing organic synthesis with visible-light-induced redox reaction as a crucial step.

Visible light-induced transition metal-catalyzed transformations: beyond conventional photosensitizers

“…Using other light sources, such as CFLs or UVA lamps, led to lower efficiency. Interestingly, addition of external photosensitizers 2 to the reaction mixtures and use of UV-induced dimeric gold species 3e resulted in diminished yields. Investigation of the scope of this transformation indicated that substrates bearing both electron releasing- ( 90b ) and withdrawing substituents ( 90c ), as well as sensitive functionalities ( 90d-e and 90g ), were well tolerated.…”

“…All of which have been previously reported under dual gold/photoredox catalysis. 2 Interestingly, oxyarylation of alkene 94 was performed under photoirradiation with Au-catalyst and resulted in moderate yield of 95 (Scheme 24c). In sharp contrast, Glorius previously reported that under visible light-induced Au-catalysis, oxyarylation of 94 required a PC in order to promote the reaction ( 96a ), without which only 4% of the oxyarylation product ( 96b ) was obtained.…”

“…This area can be systemized into three main categories: (A) Visible light photocatalysis, which involves photosensitization by a photocatalyst (PC) that enables the transformation to occur either via redox-, atom transfer-, or energy transfer process (Figure 1). 1 (B) Cooperative/dual photocatalysis, 2 which synergistically combines the first strategy with a transition metal catalysis (TM-cat.). In this case, the PC employed is the sole photo-absorbing species that engages either a redox- or energy transfer process with the traditional TM catalyst in order to facilitate the transformation.…”

“…Lately, this important fast growing area has been extensively reviewed. 2 Typically, for the first two categories, the PCs employed are photoactive organic molecules, or Ir-, Ru-, or Cu-TM complexes bearing conventional bipyridyl and/or phenanthroline ligands. 1 Recently, a new area which deviates from the above-mentioned paradigm has emerged (C).…”

Tandem Reactions Combining Biocatalysts and Chemical Catalysts for Asymmetric Synthesis

“…Organic transformations are afforded by combining photoredox with transition-metal complexes, or electrocatalysis [69]. Recently, photoredox has entered the realm of biocatalysis to form a more synergistic framework for catalysis of challenging reactions under mild conditions.…”