Gold(I) Complex with a Photoactive Ligand Behaves as a Two-in-One Dual Metallaphotoredox Cross-Coupling Catalyst

Abstract

We herein describe the use of a gold complex with a naphthalene-di-imide-functionalized N-heterocyclic carbene (NDI-NHC) ligand, which was used as a photocatalyst for a variety of reactions. Due to the presence of the naphthalene moiety in the ligand, the complex can be used for the photogeneration of singlet oxygen, behaving as a photocatalyst in the endoperoxidation and peroxidation of cyclic and acyclic alkenes, and also in the selective oxidation of a simulant of sulfur mustard to its related nontoxic sulfoxide. The same complex was used as catalyst for two model oxidative C−C coupling reactions, namely, the coupling of aryldiazonium salts with alkynylsilanes and with mesitylene. These two catalytic reactions are a good indication that the (NDI-NHC)-Au(I) complex can behave as an effective dual metallophotoredox catalyst but with the particular feature that both the photosensitizer and the metal catalyst are contained in the same compound, thus constituting a very rare type of a "two-in-one" metallophotoredox catalyst. The participation of the Au(I)/Au(III) couple in the catalytic process was demonstrated by the isolation of a Au(III) complex, which was obtained via a self-photoactivated photoredox reaction.

Photooxidative Reaction of β-Oxoamides with Amines for the Synthesis of Pyrrolin-4-ones under External Photocatalyst-Free Conditions

“…Herein, we report a trifluoroacetic acid (TFA)-catalyzed dimerization of enamines under visible-light conditions using air as the terminal oxidant. As a two-in-one strategic catalyst, TFA promoted the 1 O 2 generation and inhibited the [2 + 2] adduct fragmentation (Scheme C).…”