Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents

Abstract

Visible light-activated reactions continue to expand and diversify. The example shown here is a Birch reduction achieved by organophotoredox reagents.

Organometallic catalysis under visible light activation: benefits and preliminary rationales

“…However, two years later the same group revised their previous mechanism after detailed experimental spectroscopic and mechanistic investigations into the excited states of these Ni complexes [58] (Scheme 25). Through further experimental studies, the authors found that the previously computationally assigned 3 MLCT 1 state 137*, although generated upon excitation, decays to another long-lived state. This state was determined to be a tetrahedral 3…”

“…Through further experimental studies, the authors found that the previously computationally assigned 3 MLCT 1 state 137*, although generated upon excitation, decays to another long-lived state. This state was determined to be a tetrahedral 3…”

“…This methodology could be successfully applied to the coupling of various aryl phosphine oxides with aryl halides in moderate to good yields. 3 MLCT excited states (137*). Consequently, they proposed that these excited states could in fact engage in photoinduced electron transfer with another Ni(II) aryl halide complex 137.…”

“…The merger of organometallic catalysis and photoredox catalysis, also called metallaphotocatalysis, is an ever-expanding field of great interest to the chemical research and industrial communities [1]. Photocatalysis with Ru(II) and Ir(III) complexes has stimulated and promoted significant advances due to their strong absorption properties in the visible region, remarkable redox properties upon photoexcitation and long-lived excited states [2,3]. The merger of photoredox catalysis with transition metal-catalysis overcomes the limitations of both strategies, and offers unprecedented opportunities for functional group tolerance and selectivity [1,4].…”

Photocatalytic Alkylation of α-(Trifluoromethyl)Styrenes with Potassium Xanthogenates

“…Radical reactions constitute a rapidly developing branch of synthetic organic chemistry [1]. The advent of photocatalysis has offered novel opportunities in radical chemistry, primarily associated with methods for the generation of radical intermediates [2][3][4]. Recently, we described an approach for the direct generation of free radicals from aliphatic thiols via their in situ conversion into zinc thiolates with subsequent abstraction of the sulfur by triphenylphosphine [5] (Scheme 1) The key idea of this method is that a combination of a thiolate and a phosphorus (III) reagent upon photoredox oxidation leads to a free radical and the strong phosphorus-sulfur double bond.…”