Abstract

Copper(II) salts are widely applied for the halogenation of aromatic and heteroaromatic systems, the halides. In coupling reactions, CuCl2 has been used as a catalyst for the benzylation of aromates, the synthesis of alkanes, and the preparation of diacetylenes, cyclohexenones and symmetric biaryls. It has further proved suitable for stereoselective cyclization to lactones, carbon-nitrogen coupling and lactamization, and for the simple preparation of aroylaminohydrazones, the allylic amination of olefins, the carbonylation of alkylamines, and heterocyclizations to pyrrolidinones, pyridinones, pyrroles and dihydrofurans. The dehydrogenation of carbocycles and heterocycles can be used in the synthesis of gibberelic acid, for the aromatization of oestrogen derivatives and for the conversion of dihydrouracils to uracils. From tetrahydroisoquinolines, dihydro derivatives have been formed, while dihydropyridazines in the presence of Cu(II) salts yield pyridazines. Similarly, the oxidations of cyclohexane, adamantane and methylcatechol to benzoquinone, and amines to nitriles have been performed. The conversion of aldehydes to nitriles and benzyl radical cyclizations to butyrolactones have been achieved. Protection and deprotection, and various other Cu(II) halide-mediated reactions are also discussed.

Keywords: Copper(II) salts, Olefins, Halogenation Reactions, Carbon-Carbon Coupling, Lactonization, CARBOCYCLES, OXIDATIONS