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Dual photoredox catalysis has revolutionized the field of cross‐coupling reactions, enabling the discovery of numerous highly efficient reactions. This breakthrough is attributed to the exceptional combination of nickel catalysis with photoredox catalysis. Nickel exhibits both oxidative addition and reductive elimination processes, and a wide range of oxidation states (ranging from I to IV) accessible within a single catalytic cycle. Furthermore, nickel complexes are capable of catalyzing various processes through radical mechanisms. The latest feature has proven to be incredibly potent in facilitating the formation of new C−C and C−X bonds (X=H, O, S, N). The powerful combination of photoredox and nickel catalysis reveals an expansive domain of unexplored possibilities. It offers unparalleled opportunities for improving reactions and exploring innovative pathways. Under photoredox conditions, it is possible to form nucleophilic reactive organometallic intermediates, useful in reaction with electrophiles. We have devoted a research program towards the rediscovery and use of organometallic reagents, introduced by Corey, Hegedus, and Semmelack many years ago. The results unveiled the extraordinary capabilities of photoredox catalysis, enabling the creation and efficient utilization of potent nucleophilic organometallic reagents under mild conditions, free from the need for strong bases or stoichiometric metal reductants. [ABSTRACT FROM AUTHOR]

Dual photoredox catalysis is modifying the approach to sustainable metal catalysis based on metals in low oxidation state, as the use of stoichiometric metal as reductants are avoided. In this study, we showcase the potential use of vanadium in a dual photoredox process, allowing us to effectively control the formation of V(II) and its corresponding chemical reactions. A diastereoselective pinacol coupling with aromatic aldehydes is described. The process shows broad scope, and interestingly, unprotected salicylic aldehydes are compatible with the reaction protocol. Additionally, among all the ligands investigated we found that inexpensive bipyridines control the diastereoselection of the reaction favoring the d,l chiral compound (dr>20:1 for most of the aldehydes investigated). To promote the reaction and avoid an unproductive and not stereoselective radical coupling of the generated ketyl radical, the use of [DMQA]+, a stable organic dye, was found crucial. Furthermore, this dye possesses the remarkable capability of efficiently capturing light in the red segment of the visible spectrum, effectively raising efficiency of the protocol. The utilization of red light carries notable advantages in terms of penetration and safety, making it particularly significant. Moreover, careful photophysical investigations were able to give indications about the mechanism of the reaction. [ABSTRACT FROM AUTHOR]

A new meso‐naphthalenyl BODIPY was designed for the efficient generation of long‐lived triplet excited state under irradiation with green light. The new, heavy atom‐free organic chromophore was employed in a benchmark example of dual palladium and photoredox catalysis, highlighting the applications of BODIPY dyes as photoredox catalysts. [ABSTRACT FROM AUTHOR]

Aldehydes, photoredox, titanium catalysis, vinylogous aldol reaction, -Vinyl- -Hydroxy Esters Front Cover: A Dual Photoredox- and Cp2TiCl2-Catalyzed Approach for the Direct Access to -Vinyl- -hydroxy Esters (Eur. J. Org. Keywords: aldehydes; photoredox; titanium catalysis; vinylogous aldol reaction; -Vinyl- -Hydroxy Esters EN aldehydes photoredox titanium catalysis vinylogous aldol reaction -Vinyl- -Hydroxy Esters 1 1 1 10/12/23 20231009 NES 231009 B The Front Cover b celebrates the combination of photoredox catalysis with titanium catalysis and all the exciting and stimulating transformations that can be achieved without the use of metal reductants. [Extracted from the article]