A Study of Gold(I/III) Redox Events by Means of Photredox Catalysis

Chapter 1. Photoredox Catalysis Unlocks Single-Electron Elementary Steps inTransition Metal Catalyzed Cross-CouplingA brief survey of photoredox/transition metal dual catalysis is provided. The central message of this chapter is that the photoredox catalysis enables transition metal catalysts to access open-shell intermediates that could rapidly undergo desired elementary steps such as oxidative addition, transmetallation, and reductive elimination.Chapter 2. Visible light-mediated gold-catalysed carbon(sp2)-carbon(sp) cross-couplingA dual photoredox and gold-catalysed cross-coupling reaction of alkynyltrimethylsilanes and aryldiazonium tetrafluoroborates is described. The reaction proceeds through visible-light mediated oxidative addition of aryldiazoniums, transmetalation of alkynyltrimethylsilanes and aryl-alkynyl reductive elimination. Exclusive selectivity for silyl-substituted alkynes is observed, with no reactivity observed for terminal alkynes.Chapter 3. The Mechanism of Photoredox-Catalyzed C−C and C−N Bond Formation byArylation of IPrAu(I)−CF3 and IPrAu(I)−SuccinimideHerein we report on the photoredox-catalyzed gold-mediated C(sp2)−CF3 and C(sp2)−N coupling reactions. By adopting gold as a platform for probing metallaphotoredox catalysis, we demonstrate that cationic gold(III) complexes are the key intermediates of the C−C and C−N coupling reactions. The high-valent gold(III) intermediates are accessed by virtue of photoredox catalysis through a radical chain process. In addition, the bond-forming step of the coupling reactions is the reductive elimination from cationic gold(III) intermediates, which is supported by isolation and crystallographic characterization of key Au(III) intermediates