Deactivation of Cationic Cu^I and Au^I Catalysts for A³ Coupling by CH₂Cl₂: Mechanistic Implications of the Formation of Neutral Cu^I and Au^I Chlorides

Care should be exercised when using CH 2 Cl 2 as a solvent for reactions in which amines are a reagent, since undesirable deactivation of cationic copper(I) and gold(I) catalysts to form the corresponding inactive neutral chloride complexes [LMCl] (M=Cu or Au) can occur as a result of the generation of hydrogen chloride in the medium. Cu I and Au I deactivation has been proved for the Mannich three‐component coupling reaction. A series of Cu I and Au I complexes with potential mechanistic implications were isolated and characterized by X‐ray crystallography.