The Ullmann Synthesis of Biaryls

The uses of the Ullmann Biaryl Synthesis - the condensation of two molecules of aryl halide in the presence of copper to form a carbon-carbon bond with elimination of copper halide - for the preparation of symmetrical and unsymmetrical biaryls, biphenylenes, and to effect ring closures are discussed. The cocondensation Ullmann reaction for the formation of oligophenylenes is also mentioned. 1. Selected Examples of Novel Syntheses 2. Tables of Aryl Halides Used Table 1, Aryl halides used in the synthesis of symmetrical biaryls Table 2, Aryl halides used in the synthesis of unsymmetrical biaryls 3. Synthesis of Biphenylenes 4. Closure of Five-membered and Larger Rings 5. The Cocondensation Ullmann Reaction 6. New Developments in Reaction Techniques 7. Mechanism of the Ullmann Reaction and Related Copper-Promoted Reactions