Base-Triggered Oxidative Addition to Gold

The coordination of secondary phosphine oxides (SPO) was shown to efficiently promote the activation of C(sp(2))-I bonds by gold, as long as a base is added (NEt3, K2CO3). These transformations stand as a new type of chelation-assisted oxidative addition to gold. The role of the base and the influence of the electronic properties of the P-ligand were analyzed computationally. Accordingly, the oxidative addition was found to be dominated by Au ->(Ar-I) backdonation. In this case, gold behaves similarly to palladium, suggesting that the inverse electron flow reported previously (with prevailing (Ar-I)-> Au donation, resulting in faster reactions of electron-enriched substrates) is a specific feature of electron-deficient cationic gold(I) complexes. The reaction gives straightforward access to (P=O,C)-cyclometallated Au(III) complexes. The possibility to chemically derivatize the SPO moiety at Au(III) was substantiated by protonation and silylation reactions.

Automated summary

The coordination of secondary phosphine oxides (SPO) efficiently activates C(sp(2))-I bonds by gold with the addition of a base. This represents a new chelation-assisted oxidative addition reaction. Computational analysis reveals that Au ->(Ar-I) backdonation dominates the oxidative addition, similar to palladium behavior. The reaction produces (P=O,C)-cyclometallated Au(III) complexes, and the SPO moiety at Au(III) can be derivatized through protonation and silylation reactions.